Browse Topic: Chassis

Items (14,982)

Prognostic Thermal Modeling and Control of a Carbon–Ceramic Brake Disc for Electric Sports Cars under Racetrack Conditions

14-15-03-0020

10/1/2026

Carbon–ceramic brake discs in high-performance electric sports cars are vulnerable to heat fade under racetrack conditions, where repeated high-speed braking can raise disc temperature above the material’s safe limit of 1200°C. Three-dimensional finite-volume analysis is accurate but inefficient for long transient track events. To improve efficiency, a one-dimensional lumped capacitance method (LCM) is proposed to predict brake disc temperature evolution. A speed-dependent cooling coefficient links disc thermal response to vehicle operating conditions. The model is validated against wheel-end temperature measurements of sports cars on the Zhuzhou International Circuit and Nürburgring Nordschleife Circuit. It is then used to assess three thermal control measures: an external air director, increased disc thermal mass, and higher regenerative braking contribution. The model reproduces the measured trend with acceptable error and predicts that the baseline disc temperature can peak at 1445°C in a four-lap Zhuzhou scenario and 1540°C in a Nürburgring scenario. The air director provides substantial cooling but is insufficient on its own. A system-level safe temperature of 1050°C is achieved only when the disc size is increased to 410 mm × 40 mm and regenerative braking deceleration is raised to at least 0.1 g in combination with the air director scheme. The proposed LCM provides a practical and computationally efficient tool for early-stage brake thermal design of sports cars.

Fan, Yang, Huang, Longsheng, Shao, Xingyang, Huang, Taishuo, Liao, Yinsheng

Disc Wheel and Hub or Drum Interface Dimensions - Truck and Bus

J694_202609 (Current)

9/28/2026

This SAE Recommended Practice contains dimensions and their tolerances concerning disc wheel to hub or drum interface areas for truck and bus applications. Disc wheels designed only for single wheel applications (not dual wheels) for light trucks and special or less common applications are not covered in this document.

Truck and Bus Wheel Committee

Stuck-Assist: A Large Multimodal Model-Based Stuck Recovery Assist for Driving on Off-Road Deformable Terrains

2026-01-7513

9/22/2026

Recent advancements in off-road autonomy have shown significant progress in perception, planning, and control frameworks, including end-to-end learning approaches. Comprehensive results have been demonstrated in both simulation and real-world experiments; however, there are significant challenges in critical cases that need further evaluation. One such challenge is the immobilization of autonomous ground vehicles (AGVs) in unstructured off-road environments, which can significantly impact agriculture, space exploration, military operations, and search and rescue missions. Addressing this problem requires recovery strategies that are context-sensitive, adaptable to terrain and vehicle conditions, and effective in integrating multimodal inputs. To this end, this paper investigates the use of a large multimodal model (LMM) providing higher-level planning assistance with human-in-the-loop evaluations for vehicle recovery after immobilization in unstructured off-road terrain. The experimental simulation platform developed was based on the Algoryx (AGX) Dynamics engine for high-fidelity terramechanics interaction and vehicle physics combined with Unreal Engine 5. This platform was further integrated with a driving simulator equipped with steering wheel and pedal interfaces for human-in-the-loop experiments. We evaluated ten representative unstuck scenarios across two deformable terrains (loose sand and compact sand) under two modes: an unskilled baseline, where participants attempted recovery unaided, and a co-intelligence mode, where participants used LMM advisory instructions. The results show that LMM assistance improved stuck recovery rates by 70% compared to unaided and unskilled human driving.

Bhosale, Mayuresh, Whitson, Jordan A., Vahidi, Ardalan, Jia, Yunyi

Terrain-Aware Probabilistic Prediction of Suspension Component Forces in Unmanned Ground Vehicles

2026-01-7509

9/22/2026

Unmanned ground vehicles (UGVs) operating in unstructured environments must account not only for terrain traversability but also for terrain-induced loads that affect component durability. Existing path planning approaches primarily consider obstacle avoidance and mobility, while neglecting cumulative structural degradation due to repeated loading. High-fidelity physics-based simulations can capture these effects but are computationally prohibitive for real-time applications. This study investigates machine learning-based surrogate models for predicting vehicle component reaction forces from terrain height sequences generated using a controlled parametric terrain formulation. Both feed-forward and recurrent neural network architectures are evaluated, and ensemble-based probabilistic techniques are incorporated to quantify predictive uncertainty. Results show that the ensemble long short-term memory (Ens-LSTM) model achieves the lowest prediction error (mean absolute error of 0.621 kN) while maintaining narrow 95% prediction intervals (3.22–4.28 kN). A simpler ensemble feed-forward network (Ens-NN) achieves comparable accuracy (0.626 kN) with reduced model complexity. These results demonstrate that data-driven surrogate models can provide accurate and uncertainty-aware force predictions, enabling the integration of structural reliability considerations into fatigue-aware path planning for UGVs.

Chua, Yang Kang, Mundiwala, Mohammad, Wang, Xudong, Castanier, Matthew, Hu, Zhen, Hu, Chao

Research on Electro-Hydraulic Composite Braking Control Strategy for Four-Axle Electric-Drive Special Vehicles

02-20-01-0005

9/22/2026

Four-axle electric-drive special vehicles are often deployed to execute complex tasks under extreme operating conditions. Their harsh working environments, stringent dynamic-response requirements, and high energy demand for mobility impose higher requirements on both the energy-regeneration efficiency and braking safety of the braking system. To address these issues, this article proposes an electro-hydraulic composite braking control strategy for four-axle electric-drive special vehicles. First, a braking axle-load transfer model for the four-axle electric-drive special vehicle is established, enabling axle-to-axle braking force distribution based on axle loads. Second, considering the motor torque characteristics and battery charging characteristics and by establishing an anti-lock braking prediction model, an electro-hydraulic composite braking torque allocation strategy with safety-range constraints on motor braking torque is designed. Then, to enhance vehicle safety during emergency braking, an adaptive super-twisting sliding-mode variable-structure anti-lock braking system (ABS) controller is proposed, and based on this ABS controller, an emergency braking control strategy is developed in which the motor braking torque is pre-reduced to within a safe range, with motor-dominant and hydraulic auxiliary modulation. Finally, simulation and real-vehicle tests demonstrate that the proposed electro-hydraulic composite braking control strategy improves the motor braking energy recovery rate under service braking conditions, reduces the braking distance, and enhances braking safety under emergency braking conditions.

Jin, Liqiang, Peng, Jinxin, Ke, Yuan, Peng, Silun, Li, Jianhua, Xiao, Feng

Experimental Comparison Between Real and Simulated Battery Pack Efficiency in Light Quadricycles Using a Custom Inertia Dynamometer

2026-24-0008

9/21/2026

This study compares the energy efficiency of a real battery pack and a simulated battery pack using a hardware-in-the-loop battery emulator, through experimental testing on a dedicated inertia dynamometer for light quadricycles. The investigated LiFePo4 battery pack has a nominal voltage of 48 V and a nominal capacity of 100 Ah. Initial characterization identified a reduced State of Health based on capacity (SOHC), with a measured usable capacity of 48 Ah (from the nominal 100 Ah) and a corresponding reduction in charge acceptance capability. The emulator was configured to replicate the degraded battery characteristics, including the open-circuit voltage (OCV)-SOC relationship, internal resistance, and current limitations, enabling a direct comparison between simulated and experimental dynamic behavior. The experimental setup was designed to overcome the limitations of conventional chassis dynamometers for low-mass, independent four-wheel-drive quadricycles operating without mechanical friction braking systems. Multiple driving cycles were reproduced using a PLC-based closed-loop control system, with data acquisition performed via CAN communication. The comparative analysis highlights significant differences during regenerative braking events. While the emulator accurately reproduces baseline electrical behavior under mild operating conditions, the aged battery exhibits strong limitations during both high-power acceleration and severe deceleration phases. In particular, increased internal resistance and transient electrochemical polarization lead to premature saturation of charge acceptance, resulting in rejection of high-frequency current transients. Consequently, the experimentally observed energy recovery is significantly lower than the theoretical values predicted by the emulator. In addition, due to the absence of mechanical braking, the reduced regenerative capability directly leads to speed tracking deviations, as the required braking torque cannot be fully achieved. These results identify battery degradation as a key physical constraint affecting both energy efficiency and dynamic braking performance, highlighting the importance of improved electro-thermal and aging-aware model calibration for realistic system-level simulations.

Sementa, Paolo, Vaglieco, Bianca Maria, Altieri, Nunzio

Characterisation of Brake Wear PM2.5 and PN10 Emissions Across Pad/Disc Technologies, Light-Duty Vehicle Types, and Braking Behaviours Under Real World Conditions

2026-24-0022

9/21/2026

Targeted brake emissions investigations undertaken within the Department for Transport’s Non-Exhaust Emissions programme are described in this paper. The non-exhaust emissions study aimed to improve understanding of particulate mass and particle number emissions from friction braking, and to quantify the influence of component selection, vehicle technology, operating conditions, and emissions control measures. A brake enclosure and sampling methodology, developed in an earlier project phase, was refined to improve airflow control, reduce leakage, and minimise artefacts. The updated system incorporated MPEC (hot and cold), APC10, DMS500, and eFilter instruments, enabling simultaneous measurement of volatile and non-volatile PN10, plus PM2.5. Nine brake pad formulations and two disc types were evaluated using a common C-segment platform during chassis dynamometer and on-road drive cycles, and under specific controlled braking events. Speed, deceleration and temperature effects on PM2.5 and PN10 emissions were investigated. The common platform testing included ICE, PHEV, and EV variants to capture test mass and regenerative braking influences, together with assessments of aged components. Results showed clear, repeatable differences between pad formulations, with low dust/ceramic pads yielding the lowest PM2.5 and PN10 emissions. Disc type effects were minimal, while component ageing/conditioning reduced emissions and improved repeatability. Brake temperature and energy input dominated emissions behaviour: dynamic braking produced the highest emissions, these increasing with road speed and disc temperature. Regenerative braking reduced EV and PHEV PM2.5 versus ICE, but PN10 remained comparable due to the dominance of non-volatile PN emissions during friction braking events. Increased vehicle mass led to proportionally higher emissions.

Andersson, Jon

Structural Robustness and Regime-Dependent Uncertainty in a Reduced-Order Physics Model for Vehicle Fuel Consumption Using Monte Carlo Analysis

2026-24-0015

9/21/2026

Accurate prediction of vehicle fuel consumption typically relies either on simplified empirical correlations or on high-fidelity simulations that are computationally expensive. However, the structural robustness of reduced-order physics-based models under parametric uncertainty has not been systematically quantified. In particular, the interaction between model simplifications and uncertainty in vehicle and fuel properties across different operating regimes remains insufficiently investigated. This study presents a reduced-order physics-based framework derived from fundamental force and energy balances to estimate fuel consumption in L/100 km. The model includes aerodynamic drag, rolling resistance, inertial effects, drivetrain efficiency, and fuel lower heating value. Unlike purely empirical formulations, the proposed structure preserves physical interpretability while remaining computationally efficient. Monte Carlo simulations are employed to propagate simultaneous uncertainties in vehicle mass, drag coefficient, rolling resistance, engine efficiency, and fuel energy content. Thousands of randomized realizations are executed to quantify output variability, compute confidence intervals, and evaluate robustness indices. In addition, regime-dependent dominance transitions are analyzed by comparing urban and highway operating conditions. Results show that parameter influence is strongly dependent on speed regime: mass and rolling resistance dominate in low-speed conditions, while aerodynamic parameters become dominant at high speeds. Fuel energy content and efficiency exhibit nearly linear inverse relationships with consumption. The reduced-order structure demonstrates stable variance behavior under realistic uncertainty ranges, supporting its suitability for parametric studies and alternative fuel assessment. The proposed framework contributes a systematic evaluation of structural robustness in simplified physics-based fuel consumption models and provides a scalable methodology for uncertainty-aware automotive performance analysis.

Gutierrez, Marcos, Taco, Diana

Simulation-Based Development and Evaluation of Heat-Quantity-Based Thermal Operating Strategies for Automotive Applications

2026-24-0012

9/21/2026

Thermal management of hybrid electric vehicle (HEV) powertrains requires the simultaneous conditioning of multiple components operating at fundamentally different temperature levels. For thermal management systems, which directly couple the thermal circuits of the internal combustion engine (ICE), electric motor and inverter (EMINV), and traction battery (BAT) for example via controllable three-way valves and a ring-circuit, the decision of when and which components to couple has a direct impact on overall powertrain efficiency. Existing thermal operating strategies rely on empirically defined temperature thresholds and fixed component priority rankings, without quantifying the actual efficiency benefit associated with each coupling decision. This paper presents the development and simulation-based evaluation of a heat-quantity-based thermal operating strategy for a prototype HEV at TU Darmstadt. The strategy introduces three new computational modules — a Q-Indicator quantifying the thermal surplus or deficit of each component, an η-Indicator evaluating real-time component efficiencies as a function of temperature and operating point, and a Δη module computing the combined efficiency gain of each potential coupling pair prior to actuation. Coupling is executed only when the combined efficiency delta is positive, replacing empirical prioritization with a quantitative, efficiency-driven decision mechanism. The strategy is evaluated against an uncoupled baseline (REF-0) and a temperature-threshold-based predecessor strategy (REF-1) across a representative commuter cycle at ambient temperatures of −10 °C, 0 °C, and +30 °C using a co-simulation environment comprising a 1D ring-circuit fluid model in AVL Cruise M and a backward-facing 0D drivetrain model in MATLAB/Simulink. The results demonstrate measurable improvements in battery preconditioning and system efficiency at cold and moderate ambient temperatures. The heat-quantity-based strategy achieves comparable or superior thermal outcomes to the threshold-based approach while activating ring-circuit coupling more selectively. At warm ambient conditions, the strategy correctly withholds intervention based on a negative efficiency delta evaluation, confirming robust scenario-adaptive behavior. The findings highlight the potential of efficiency-driven coupling logic as a generalized and physically grounded basis for thermal operating strategy development in electrified powertrains.

Stenger, Erik, Fiore, Luis, Weimer, Niko, Beidl, Christian

Global–Regional Energy Balance Climate Modeling Framework for Country-Level Temperature Projections Based on CO₂ Radiative Forcing

2026-24-0021

9/21/2026

This study presents a computational framework for estimating country-level temperature projections based on global radiative forcing from CO₂ emissions. The methodology integrates a carbon-cycle accumulation module, a logarithmic radiative forcing formulation, and a dynamic one-box energy balance model (EBM) to simulate global mean temperature evolution. Atmospheric CO₂ concentration is computed from cumulative global emissions using an airborne fraction parameter. Radiative forcing is then determined using the established logarithmic relationship between concentration and forcing. The global temperature response is calculated dynamically by solving the transient energy balance equation, incorporating effective heat capacity and climate sensitivity parameters. To regionalize projections without relying on high-resolution General Circulation Models (GCMs), an empirical regional amplification factor is introduced. This coefficient is derived from historical regression between observed regional and global temperature anomalies. The resulting formulation enables country-level temperature estimation as a scaled response to global mean warming while preserving physical consistency with radiative forcing theory. The framework is computationally efficient and suitable for implementation in lightweight numerical platforms, enabling rapid scenario testing of emission pathways. Although the model does not resolve atmospheric circulation, precipitation changes, or nonlinear feedback variability at regional scales, it provides a transparent and physically grounded approach for comparative warming assessments across countries. The proposed methodology establishes a structured link between global climate energetics and regional temperature response, supporting engineering-oriented climate risk analysis and emission policy sensitivity evaluation.

Gutierrez, Marcos, Taco, Diana, Sampietro-Saquicela, Jose, Bermudez-Herrera, Leandro, Valencia-Ortiz, Nakira, Ulloa de Souza, Raul

Long-Stroke Air-Brake Actuator Marking

J1817_202609 (Current)

9/21/2026

This SAE Recommended Practice describes a marking system to distinguish long-stroke from standard stroke for service, parking, and combination air-brake actuators and components. Said actuators are used for applying cam-type foundation brakes by slack adjuster means.

Truck and Bus Brake Actuator Committee

Understanding Tyre Wear Particle Emissions: Volatile Dominance, Variability, Coarse Particles and Measurement System Development for Chassis Dynamometer Use

2026-24-0018

9/21/2026

This paper presents a set of targeted tyre emissions studies carried out within the UK Department for Transport’s (DfT) Brake and Tyre Emissions programme. The work was aimed at improving the measurement of airborne particles generated by tyres, and at examining the factors that influence particle number and particle mass emission. It also explored physical tread wear. To achieve this, a revised sampling duct system was developed with high extraction flow and partial wrap-around of the tyre, and a coarse hard-wearing surface was applied to the chassis dyno roller. The sampling system supplied Total PN4, PN10 (volatile and non-volatile), PM2.5, and particle size instrumentation. Several tyre types were selected to represent a broad range of sizes, constructions, manufacturers, compounds, and mileages. Tests were performed on a dedicated chassis dynamometer testing facility using PG42, WLTC, and RDE based cycles, together with additional cycles designed to investigate the influence of temperature, speed, and braking. Tread depth and tyre mass were recorded before and after the test programme to determine wear rates, and macro particle sampling was undertaken to assess particle size distribution beyond the airborne PM2.5 range. Airborne particle measurements showed that tyre PN is dominated by volatile ultrafine particles below 10 nm, with the non-volatile PN10 fraction representing only a small proportion of the total. PM2.5 mass from tyres was generally low and often near the detection limit, with most of the physical wear mass present as large particles (>50 μm) rather than as respirable material. Wear rates varied across tyres but showed no consistent relationship with airborne PM2.5 or PN10. Tyre temperature had the clearest influence on airborne PN emissions: elevated temperatures and high speed/braking conditions produced higher volatile and non-volatile PN. Overall, the study provides improved understanding of tyre-related airborne particle formation, the limitations of PM2.5 and PN10 as regulatory indicators, and the role of tyre temperature and operating conditions in determining emissions. The findings support the development of future tyre wear measurement methods and associated regulatory frameworks.

Andersson, Jon, Campbell, Michael, de Vries, Simon, Kramer, Louisa, Marshall, Ian, Southgate, Jason, Waite, Gary

Parking Brake Drawbar Pull Test Procedure - Truck and Bus

J1729_202609 (Current)

9/16/2026

This SAE Recommended Practice provides a test method and instructions for measuring performance of parking brakes on air- or hydraulic-braked vehicles equipped with in-wheel or drive-line parking brakes. This procedure applies to truck-tractors, trailers, trucks, and buses.

Truck and Bus Brake Systems Committee

Road Vehicles - Wheels for Commercial Vehicles and Multipurpose Passenger Vehicles - Fixing Nuts - Test Methods

J1965_202609 (Current)

9/16/2026

This SAE Recommended Practice applies to fasteners/fixing nuts as specified in SAE J694 and SAE J1835 used for disc wheels and demountable rim attachment respectively. Only the test methods necessary to ensure proper wheel or rim assembly are specified. Fasteners for less common and special applications are not included.

Truck and Bus Wheel Committee

The Biomechanics of Brake Pedal Feel

2026-01-0796

9/14/2026

Brake pedal feel is arguably the most important driver-facing characteristic of a vehicle’s brake system, as it represents the main interaction between the brake system and the driver and is experienced by the driver in every trip taken. It has traditionally been characterized by three fundamental curves - deceleration versus force at the pedal pad, deceleration versus travel at the pedal pad, and travel at the pedal pad versus force (which is derivable from the other two curves). These characterizations, while useful, stop short of describing what the driver actually experiences - felt through the forces in and contraction of his or her leg muscles. When brake pedal feel is traced away from the brake pedal pad and into the driver’s leg, a complex new system emerges, containing the brake system and the biomechanics of the driver. This expanded system is now subjected to - but can also help explain - influences such as seating position, foot position, brake pedal geometry, and the driver’s own biometrics (such as leg and foot dimensions). The present research covers the creation of a simplified biomechanical model of the driver and the brake system, and the use of this model to illustrate the influence of these new elements of the system and human-machine interactions on the driver’s perception of brake pedal feel. Observations are corroborated, to the extent possible while respecting propriety, to human driver feedback from clinics and from the field.

Antanaitis, David, Antanaitis, Rebecca, Morris, Brock

Further Investigation of Brake Squeal: Effect of (Inboard/Outboard) Pads Property Differential

2026-01-0799

9/14/2026

It was reported earlier that the wear differential between the inboard pad and the outboard pad leads to brake squeal generation. The (inboard/outboard) pads wear differential can occur due to hardware issues such as brake pad drag and/or two different wear rates of the (I/O) pads, which is caused by two different material properties of the pads although the pad formula may be the same. It is found that (I/O) pads compressibility differential/hardness differential/friction differential are all interrelated and that they contribute to brake squeal generation in addition to the inboard pad tangential/radial taper wear. A method has been found to separate the inboard pad friction and the outboard pad friction and to estimate each friction coefficient.

Liu, Richard, Wu, Shane, Wu, Godot, Zou, Tianlang

Safe State Definition and Verification for Distributed Multi-Controller EMB Architectures

2026-01-0800

9/14/2026

The Electro-Mechanical Brake (EMB) system is an essential technology for safe braking in modern vehicles. However, the adoption of multi-controller architectures has introduced new challenges to conventional Safe State strategies. Traditionally, the Safe State defined in functional safety means "function shutdown," and in accordance with ISO 26262-1:2018 (Part 1: Vocabulary), aims for an "operational mode without risks exceeding reasonable levels." However, in the multi-controller architecture of EMB systems, the Fail-Operational Safe State concept is applied, where the system continues to provide limited functions even in the event of faults. It is essential to verify whether such operational modes actually satisfy the safety requirements of ISO 26262-3 and ISO 26262-4. This paper redefines the Safe State according to failure modes in EMB systems, analyzes system state transitions, and presents a coherence analysis methodology for validating the availability of resources required to provide limited functions in the Fail-Operational Safe State. Through this approach, potential design defects in multi-controller-based EMB systems can be detected early, validated across 1,149,952 fault scenarios with zero total-failure outcomes, and traceability of functional safety requirements can be established.

Kim, Kang San

Influence of Ferritic Nitrocarburizing with Smart-ONC® on the Modal and Damping Behavior of Gray Cast Iron Brake Rotors

2026-01-0798

9/14/2026

Ferritic nitrocarburizing (FNC) with in-process post-oxidation has been developed as a production-capable surface engineering solution for gray cast iron (GCI) brake rotors to meet the Euro 7 non-exhaust particulate emission limits. While prior investigations have demonstrated significant PM₁₀ reduction, improved corrosion resistance, and stable braking performance, the influence of FNC on noise, vibration, and harshness (NVH) performance requires systematic evaluation. This study quantified the relative contributions of the alloy composition, rotor geometry, and FNC treatment to the modal frequency and damping behavior. Seven ventilated disc types from multiple foundries were characterized to assess the composition-driven variability. In addition, 120 production discs (ventilated and solid) were measured before and after FNC processing to isolate the treatment effects. Modal properties were obtained using impulse-hammer testing under free–free boundary conditions in accordance with VDA 301, and damping was evaluated using the half-power bandwidth method (Q-factor). The results show that the natural frequency is governed primarily by geometric parameters, scaling with the friction-ring thickness and disc diameter. In contrast, the damping behavior is dominated by the alloy composition and graphite morphology. Variations in silicon, chromium, and carbon equivalent produced a 3–4× difference in the Q-factor across foundries. FNC treatment had a negligible effect on the natural frequency (<1%) but produced a measurable increase in the Q-factor, typically 7–10% for solid discs and 22–32% for ventilated discs. The findings establish a clear hierarchy of influence: composition controls the damping, geometry controls the frequency, and the FNC introduces a secondary shift. Within production-relevant composition windows, FNC + Smart-ONC® does not represent a limiting factor for the NVH performance of Euro 7–compliant brake systems.

Awe, Samuel Ayowole, Holly, Mike, Winter, Karl-Michael

Electro-Hydraulic Brake-by-Wire and Off-the-Shelf ABS Integration: Control Design and Hardware in the Loop Validation

2026-01-0795

9/14/2026

This work presents the design of a control logic for an electro-hydraulic brake-by-wire in series with an off-the-shelf ABS unit for motorsport applications. Validation is performed through hardware-in-the-loop testing with a complete hydraulic layout, including the brake-by-wire actuator, the ABS module, and brake calipers. State of the art electro hydraulic brake-by-wire systems are increasingly adopted in top level motorsport and are now transitioning to high performance road vehicles, in combination with ABS and ESC. However, due to motorsport regulations, racing brake-by-wire systems do not incorporate ABS functionality. To combine the performance of motorsport grade actuators with the ease of use required for non professional drivers, a series configuration between brake-by-wire and ABS represents a natural solution. This architecture is also relevant for future road vehicle applications, offering additional redundancy for autonomous driving ready systems. A dedicated hardware-in-the-loop test rig has been developed to perform experimental testing of the complete brake system. Wheel dynamics are simulated in real-time using a single-axle vehicle model, and wheel speed signals are reproduced via a sensor emulator. Preliminary tests show that the original pressure-based brake-by-wire control strategy exhibits poor performance during ABS activation, as ABS operation significantly alters system behavior. To address this issue, an improved control strategy is proposed, introducing a dedicated control mode activated during ABS operation, with a smooth transition back to nominal control once ABS activity ceases. Experimental results demonstrate that the proposed strategy maintains closed-loop stability, avoids excessive pressure oscillations and piston end stop conditions, and, most important, does not interfere with ABS operation. Overall braking performance is fully preserved.

Milivinti, Massimiliano, Gimondi, Alex, Gobbi, Massimiliano, Cantoni, Carlo

Advanced Brake Force Distribution and Pad Wear Life Integration in Supervisory Electronic Brake Control System for Combination Vehicles

2026-01-0797

9/14/2026

Commercial vehicle fleets frequently operate with tractors that connect to different trailers and dollies, resulting in combinations with varying brake pad wear across wheel ends. Traditional brake-force distribution strategies do not consider these pad-life differences, which can lead to uneven brake utilization, irregular maintenance intervals, and increased total cost of ownership (TCO) in mixed-trailer operations [7, 9]. While modern electronically controlled braking systems (EBS) already incorporate pad wear based braking for the tractor itself [5], these capabilities do not extend across the entire vehicle combination because trailer-side communication is typically limited to standardized CAN protocols such as ISO 11992 and J1939 [1, 2, 3]. As braking systems become more software defined and rely heavily on distributed electronic communication, ensuring the authenticity and integrity of trailer originated brake information becomes essential for both functional safety and cybersecurity [6]. In the proposed architecture, trailers and dollies communicate brake related data to the tractor over the ISO 11992 Tractor-Trailer CAN (TT-CAN) network [1, 2], allowing the tractor Brake Control ECU to securely validate the source of the information and register each towed unit for health aware braking. Once authenticated pad life data is available, the tractor constructs a combination level brake health map covering every wheel end in the configuration. During normal braking, a supervisory allocator computes wheel end specific brake pressure targets that bias braking toward wheel ends with greater remaining pad life while ensuring full compliance with stopping distance regulations and stability requirements [4, 7]. By integrating authenticated pad wear information with tractor hosted supervisory control, the system improves braking consistency across mixed combinations, harmonizes pad utilization, enhances maintenance predictability, and reduces TCO while meeting the safety and cybersecurity expectations of modern commercial vehicle fleets.

Ganesha, Vinodkumar

A Study on TSC (Technical Safety Concept) Design and Verification in EMB (Brake by Wire) Systems

2026-01-0801

9/14/2026

The Electro-Mechanical Brake (EMB) system is a dry-type Brake-by-Wire technology that eliminates hydraulic components and directly controls friction braking using electrical actuators at each wheel. The EMB architecture consists of a Main Center Control Unit, a redundant Backup Center Control Unit, and four Wheel Control Units communicating via CAN FD. Due to its direct involvement in vehicle braking, compliance with ISO 26262 functional safety requirements is critical. As system complexity increases, potential risks such as hardware failures and communication faults must be systematically addressed. The proposed TSC was developed according to ISO 26262, covering the concept phase (Part 3), system-level development (Part 4), and software implementation (Part 6). Safety goals and Functional Safety Requirements derived from HARA are used to guide system architecture design and TSC development. Key design principles include modularity, redundancy, fault detection, and fail-safe operation. Verification is conducted at both system and vehicle levels using ECU-in-the-Loop Simulation (EILS), Hardware-in-the-Loop Simulation (HILS), and real-vehicle tests. Fault scenarios, including Main Center Control Unit failures and CAN communication losses, are injected using a custom LabVIEW-based fault injection tool. The study evaluates Fault Tolerant Time Interval (FTTI) settings, error handling mechanisms, and control handover strategies under fault conditions. The results show that redundancy and localized communication enable stable operation and smooth control transfer within the FTTI window without noticeable impact on braking performance or driver awareness. This study demonstrates the robustness of the proposed EMB architecture. Future work will focus on prognostics and maintenance strategies to support safe deployment in autonomous and electric vehicles. [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Kim, Dokun

Aerodynamic Disc Brake Drag: An Elusive Source of Variability

2026-01-0802

9/14/2026

The ever-present drive to increase vehicle range and efficiency has resulted in disc brake caliper requirements at or near zero residual drag. It is increasingly critical to understand and design around potential edge cases that can drastically increase off-brake drag. One frequently observed, but often misunderstood, phenomenon is drag induced by aerodynamic forces surrounding the brake pad. Complex airflow characteristics surrounding the pad in the brake corner environment can lead to Venturi Effect induced air pressure differentials on each side of the pad, leading to transient, yet pronounced, increases in brake drag. This paper will follow a case study during which brake pad pressure differentials were discovered and objectively measured, review the Venturi Effect as it relates to brake corners, and explore modelling approaches for identifying and correcting designs that are prone to this phenomenon.

Robere, Matthew, Tresmondi, Thales

Study on the Friction Characteristics of Disc Brakes with Ceramic Surfaces for High Performance Vehicle

2026-01-0827

9/14/2026

In this study, various methods were reviewed to simultaneously satisfy the high-temperature braking performance required for high-performance vehicles and the brake dust criteria by environmental regulations. Among them, the characteristics of two types of Brake disc with ceramic composite surfaces were evaluated to prevent disc wear even under the condition of using metallic friction materials with excellent fade performance. As a result of the evaluation, carbon ceramic disc without metal-to-metal contact during braking showed superior characteristics compared to hard metal cladding disc.

Kim, Yoon Cheol, Yeongwoo, Cho, Kim, Youngmin

Modeling Brake Torque Hysteresis for Chassis Controls Hardware in the Loop Simulation

2026-01-0824

9/14/2026

It is hardly a new trend for on road, vehicle intensive tuning and testing of chassis control features such as Anti-Lock Brakes, Traction Control, and Electronic Stability Control to move away from vehicle testing and towards non-vehicle test platforms such as Hardware-In the Loop (HIL) simulations and even further into pure math-based simulations. However, a significant acceleration of these activities has been occurring recently in the automotive industry, reducing or eliminating calibration time on vehicles and amplifying the demand for highly representative, non-vehicle test platforms to validate and even calibrate chassis controls features. In current state of the art HIL simulation, the input (brake pressure) to output (brake torque) of each wheel brake in a vehicle’s brake system is modeled relatively simplistically, including at most pressure and brake temperature sensitivities, usually in lookup table form. Each brake corner contains over 20 different friction interfaces, which in turn can cause hysteretic behavior (a difference in the output for a given input, depending on whether the brake is applying or releasing against the hysteretic friction). This hysteresis is neglected in most state of the art HIL simulations. Past studies by General Motors have shown that the importance of brake corner hysteresis in vehicle level, customer facing performance of chassis controls features can range from inconsequential to significant. With the crescendo-ing demand for high quality non-vehicle based methods for assessing chassis controls function, the effect of hysteresis is no longer academic. The present study starts with HIL based simulations, establishing the effect of brake corner hysteresis on one of the most visible chassis controls behaviors. An inertia dynamometer-based test was developed to exercises the subject brake corners through apply and release cycles, thus enabling any hysteretic behavior to be observed and characterized. Machine Learning models were trained with these data to represent brake corner hysteretic behavior and then deployed into an HIL simulation rig. The impact of these models – representing brake corner hysteretic behavior – was characterized for straight line stopping distance on low, medium, and high coefficient road surfaces.

Antanaitis, David, Ridenour, Nick, Miller, Bryan, Karnjate, Timothy

Development and Production of Weight-Reduced Steel Hat Brake Discs: A Contribution to Automotive Lightweighting

2026-01-0821

9/14/2026

The automotive industry's transition towards electrification, particularly in the passenger car (PC) and light commercial vehicle (LCV) segments, has intensified the focus on vehicle lightweighting to maximize battery range and efficiency. Conventional brake systems in electric vehicles (EVs) are subject to minimal mechanical wear due to regenerative braking, making corrosion the primary cause of component failure and replacement. This paper details the development and production of an innovative lightweight brake, which addresses these challenges. The "Cast-In" brake disc combines a traditional gray cast iron friction ring with a pre-finished, deep-drawn steel hat through a specialized composite casting process. This design achieves a significant reduction in unsprung mass—1.6 kg per disc in a 390mm x 36mm example—directly contributing to improved vehicle dynamics and energy efficiency. Key manufacturing challenges, including ensuring a robust material bond, preventing casting defects, and sealing the steel hat during casting, have been overcome through advanced process controls, simulation, and a patented sealing system. Furthermore, a novel, enhanced corrosion protection system has been developed and validated to meet the required service life of over 10 years, addressing the specific demands of e-mobility. With production scheduled to begin in April 2026, this technology is a milestone for modern braking solutions in the era of electrification.

von Reth, Thomas

Finite Element-Based Wear Analysis of Brake Pads

2026-01-0817

9/14/2026

Brake pad wear progressively changes the pad–disc contact interface and can influence braking performance, wear uniformity, and component durability. This study presents a finite element-based procedure for predicting brake pad wear under braking conditions using generalized Archard’s wear law as the base framework. The method combines contact-pressure and slip-distance calculations with iterative geometry updating in Abaqus using the UMESHMOTION and USDFLD subroutines so that accumulated wear and evolving contact conditions can be continuously reflected during the analysis. To improve robustness in repeated-cycle wear simulation, a wear-direction algorithm, an extrapolation factor, and a contact stiffness scale factor are incorporated to reduce element distortion, enhance numerical stability, and control computational cost. Because temperature-dependent friction behavior, contact conditions, and material-property variations are strongly coupled in actual braking, their combined influence is represented through an effective wear coefficient calibrated from physical data using regression analysis, instead of independently modeling them. The proposed procedure was applied to burnish and subsequent evaluation modes, and the predicted wear results were compared with test measurements. Among the regression models considered, the log-linear model provided the best overall agreement with the experimental wear data. The results show that the proposed framework can reproduce both mean wear and location-dependent wear trends with good agreement over the evaluated operating range. The proposed procedure offers a practical numerical workflow for predicting brake pad wear under temperature-dependent operating conditions while maintaining acceptable numerical stability and computational cost.

Song, Seong Il, Joo, Sang Don, Kim, Min Sock, Kerszberg, Nicolas, Lee, Heewook

Precision Simulation and Test of Drag Torque for Carbon Ceramic Disc Brakes with In-Wheel Electric Motor

2026-01-0813

9/14/2026

Aiming at the industry pain points of low simulation accuracy and lack of authoritative closed-loop experimental verification for the drag torque of special brake calipers for in-wheel electric motors, this study takes the hub motor-integrated carbon-ceramic inboard caliper as the research object. The inboard caliper layout has been realized on Protean’s in-wheel motor products [12], while the matching integration of the C/C-SiC brake disc with such an inboard structure for a compact hub-motor layout is original and covered by Chinese invention patent CN120207087A[15]. The inboard caliper is defined as a special brake structure installed on the inner side of the brake disc/hub motor cavity (distinguished from the traditional outboard caliper mounted on the outer side of the brake disc), which is specially adapted to the compact assembly space of in-wheel motors and realizes structural integration of braking and driving systems. This study proposes a high-precision finite element simulation method coupling the nonlinearity of piston seal material with bilateral parallel return springs. The simulation boundary conditions are calibrated by matching the bench test working conditions. To verify the simulation results, the drag torque bench test is carried out in accordance with the industry standard [13], realizing a complete closed loop of simulation modeling and experimental verification. Although a certain numerical deviation exists, the high consistency in core trends and key evolutionary nodes, together with a low error (≈5.6%) within the initial 0.9–1 rotation regime, demonstrates that the model reasonably reproduces the generation and attenuation mechanisms of drag torque during the early rotation stage.

Meng, Dejian, Liu, Yuqi, hu, Pengfei, Li, Birui, Shao, Jiyong

Comparison of the Surfaces and Coefficients of Friction of Truck Brake Pads Tested on a Flywheel Test Bench and a Scaled Tester – A Case Study

2026-01-0826

9/14/2026

Mechanical brakes have been used and studied in many areas of mechanical engineering and automotive technology for decades. However, the processes in the contact zone have not yet been described with sufficient accuracy. One reason for this is the inability to observe the contact zone during contact. Studies show that replacing a friction partner with a visually transparent material affects the processes in the contact area. Researchers are therefore forced to examine the surfaces of the contact partners after the actual contact has taken place. Various measuring systems, such as microscopes or laser sensors for surface structure measurement, are used to measure the surfaces of the brake pads. Due to shorter measuring times, mainly only smaller samples from measurements using pin-on-disc tribometers are examined for this purpose. However, various studies show that the friction and wear values of pin-on-disc tribometers cannot be transferred to real brake systems. For this reason, surface measurements are performed on full-size truck brake pads in this publication. For this purpose, the SN6 truck brake from Knorr and the corresponding brake pads were subjected to defined load scenarios. The load scenarios comprise four different surface pressures of 0.8, 1.7, 2.5, and 3.3 MPa, as well as three different starting speeds of 10, 20, and 40 km/h. The rotational masses used in the flywheel test bench correspond to an equivalent translational mass of approximately 9 t. For each combination, 450 braking test cycles were performed. Following each measurement cycle, the surfaces of the brake pads are photographed and measured using a laser triangulation sensor. In addition, the contact surface between the brake pads and brake disc is examined using pressure measurement film. In addition to a qualitative and quantitative evaluation of the surfaces of the truck brake pad from the truck brake, a comparison is made with a partial lining sample of the same truck brake pad, which has been tested on a partial lining test bench under comparable test scenarios.

Rosenthal, Tobias Richard, Wiest, Daniel Christian, Meyer, Henning Jürgen

Correlation of Tribological Characteristics with Brake Emission Factors in Automotive Disc Brakes

2026-01-0829

9/14/2026

Following the recent introduction of the Euro 7 regulations, research on non-exhaust emissions, including brake wear particles, has increased. However, full-scale dynamometer tests are affected by complex variables such as vehicle class and brake system specifications, which makes it difficult to analyze the unique characteristics of friction materials independently. Previous studies have predominantly focused on comparing emission levels by friction material composition or on disc surface treatments, and quantitative correlations, resolved by friction material type, between the physical wear mass of friction materials and the Brake Emission Factor (BEF), remain scarce. In this study, the brake emissions from various friction materials were precisely measured using a scale dynamometer reflecting the UN-GTR No. 24 standards. By applying the WLTP cycle, a quantitative correlation was derived between the friction characteristics and the BEF for each braking section. The results show that BEF varies with friction material type depending on the friction- and wear-related factor, while disc wear and total wear were confirmed, regardless of friction material type, to be common key indicators that exhibit a statistically high correlation with BEF.

Jang, Pan Gyu, Kim, Duck Hyeon, Jeong, Yoon Oh, Kwon, Sung-Wook, Jung, Kwang Ki, Lee, Jungju

A Multi-Body Dynamic Analysis of Click Noise Generated in Rear Brake Caliper

2026-01-0815

9/14/2026

As customer awareness of brake-related NVH (Noise, Vibration and Harshness) continues to increase across the automotive industry, noise originating from braking systems is increasingly regarded as important indicator of vehicle quality. Among these issues, intermittent click noise from rear brake caliper is commonly noticed during low-speed driving and initial brake application and is frequently associated with customer dissatisfaction. In the automotive industry, this noise has primarily been addressed through empirical design modifications and component-level testing. However, due to its low reproducibility and impulsive response characteristics, making quantitative prediction and root-cause identification during the design phase difficult. While most previous brake NVH research has mainly focused on continuous vibration phenomena such as squeal and groan, fewer studies have examined single-event impact noise related to pad-to-carrier clearances, contact transitions, and frictional nonlinearity from a simulation-based perspective. In this study, rear brake caliper click noise is defined as a dynamic phenomenon inherent to conventional caliper mechanical architecture. A Multi-Body-Dynamic model was developed using RecurDyn to reproduce the observed behavior incorporating pad-to-carrier clearance, friction characteristics, and component compliance. Brake dynamometer testing was conducted to measure acceleration and noise response, and correlation with simulation results was performed. Simulation and tests were carried out using a caliper geometry whose improvement effectiveness had been confirmed in prior applications, demonstrating that the applied approach can qualitatively and reproduce the occurrence tendencies and key characteristics of rear caliper click noise. The simulation-test integrated approach is applicable to early-stage NVH risk assessment and to the validation of countermeasures for click noise in production vehicles. Future work will focus on improving analytical modeling and prediction of click noise through development of a new model incorporating key design parameters.

Choi, Hyeontae, Kim, Sangbum, Park, Ilho, Kim, Taeuk, Kwon, Yongsik, Yang, Soonhong, Ma, Jaehyeon, Kim, Jinwook

Design Considerations for Optimizing the Wheel Bearing Outer Ring Bolt-Mounting Pattern for Reduced Drag

2026-01-0830

9/14/2026

Electric vehicles (EVs) impose more demanding operating conditions on wheel bearing systems due to increased vehicle mass, higher drive torque, and the need to maximize energy efficiency and driving range. These factors elevate the loads transmitted through the bearing to knuckle joint and often require higher clamp loads to ensure joint integrity. However, higher clamp loads amplify distortion of the wheel bearing outer ring, increasing rotational drag and reducing bearing durability. Controlling outer ring distortion is therefore critical for EV wheel bearing design, as well as for high performance vehicles that experience severe lateral loads at the hub to knuckle interface. This paper investigates key design considerations for optimizing the wheel bearing outer ring and its mounting interface to minimize distortion under elevated clamp loads. A comprehensive CAE-based Design of Experiments (DOE) is used to evaluate the influence of multiple bolt-mounting patterns including rectangular, square, and trapezoidal configurations and the relative alignment of the bolt pattern between the outer ring and knuckle. The study also compares the performance of M12 and M14 fastener variants across loading conditions representative of EV and high-performance applications. The results identify geometric and interface design parameters that significantly reduce outer ring out of roundness, thereby lowering drag torque and improving long-term bearing life.

Mandhadi, Chaitanya Reddy, Lee, Seungpyo, Bovee, Benjamin, Callaghan, Kevin

Further Investigation of the Variables Affecting Brake Squeal: Dual-Piston and Single-Piston Calipers with NAO Pads

2026-01-0825

9/14/2026

An earlier publication reported that brake squeal occurrence increases with increasing (inboard/outboard) pads wear rate difference in the case of a front dual-piston (twin-piston) caliper for a GVW vehicle of 2,510 kg fitted with Lowmet pads of straight chamfers and diamond chamfers. The current investigation was undertaken to find out if a front dual-piston caliper for a heavier vehicle (GVW 3,200 kg) fitted with NAO pads of straight chamfers, and a lighter single-piston caliper (GVW 2,100 kg) fitted with NAO pads of straight chamfers behave the same or not, using the SAE J2521 and Los Angeles City Traffic simulation procedures. In all cases, brake squeal is found to increase with increasing (inboard/outboard) pads wear rate differences (wear differentials); increasing pad radial taper is associated with increasing (I/O) pads wear differential; pad tangential taper lowers the (I/O) pads wear differential. Increasing friction coefficients do not relate to increasing squeal occurrences. To minimize brake squeal occurrence, caliper should be designed to minimize (I/O) pads wear differential.

Sriwiboon, Meechai, Rhee, Seong Kwan, Sukultanasorn, Jittrathep, Khathinhorm, Nicha, Kunthong, Jitpanu

A Study on the Development of Brake Moan Analysis for CTBA Vehicles Using Simulation

2026-01-0814

9/14/2026

Moan noise is a low-frequency noise occurring in the 170–500 Hz frequency ranges. While it frequently appears in vehicles equipped with a rear Coupled Torsion Beam Axle (CTBA), the exact cause, generation mechanism and clear solutions remain unidentified. For those reasons, we have developed a moan noise analysis method capable of representing the moan noise phenomenon in vehicles with rear CTBA along with an automation tool. From these results, we can use moan analysis models to reduce real moan noise problems. Consequently, this not only enhances customer satisfaction and vehicle quality but also significantly increases the work efficiency of vehicle designers through design modification in the preliminary stages of vehicle development

Kim, Sungho, Kim, Jeongkyu, Hwang, Jaekeun, Kang, Donghoon

Predicting Wear of NAO Brake Pad Using Scaled-Down FMVSS 135 Testing and Machine Learning

2026-01-0808

9/14/2026

Brake pad wear is a major and growing source of non-exhaust particulate emissions, projected to reach 1.3 million tons annually by 2030 and contributing up to roughly 55% by mass of non-exhaust traffic-related PM10 in urban environments, underscoring the need for improved durability and material optimization. This study investigates a three-stage eXtreme Gradient Boosting (XGBoost) ensemble paired with a residual Fully Connected Neural Network (FCNN) corrector to predict brake pad wear rate and support formulation optimization. Experiments used a simplified FMVSS 135 protocol on a Universal Mechanical Tester (UMT) simulating realistic braking across eight friction regimes. Wear rate was the sole machine-learning prediction target, while coefficient of friction (CoF) was retained as an input feature rather than a target. Despite a limited but high-quality 280-cycle dataset, regime-aware stratified splitting, sample reweighting, and hyperparameter optimization enabled robust generalization. The three-stage XGBoost ensemble with residual FCNN correction achieved a global held-out test R2 of 0.976 for wear rate prediction. A Taguchi L8 design of experiments defined the brake pad compositions, reducing experimental time and material consumption compared to conventional approaches. The framework demonstrated strong agreement between measurements and predictions for the dominant low-severity regime, while per-regime analysis identified the high-severity minority regimes as the priority for additional data collection, since within-regime R2 remains negative for every regime given current sample sizes. A sequence-aware mean absolute scaled error (MASE) analysis further shows that, despite the high global R2, none of the four pipeline stages currently outperforms a naive one-cycle persistence forecast on absolute error, a distinction reported here for transparency. The scalable architecture enables straightforward integration of additional material and process parameters, supporting iterative brake formulation development in industrial settings and, by reducing empirical testing requirements, sustainable brake material development with reduced replacement frequency and associated emissions.

Katakam, Abhishek, Eslamiat, Hossein, Kancharla, Sai Krishna, Filip, Peter

Thermomechanical Fatigue Life Prediction of Grey Cast Iron Brake Rotors Using Advanced Material Models and Elastic-Plastic Fracture Mechanics

2026-01-0816

9/14/2026

A unified thermomechanical fatigue (TMF) life-prediction methodology is presented for lamellar graphite (grey) cast iron brake rotors operating under the severe transient thermal loads that arise in brake dynamometer durability testing. The workflow links four ingredients within a single rotor-level framework: transient nonlinear finite-element analysis, temperature-dependent inelastic constitutive modeling, a mechanism-based short-crack TMF damage model, and an elastic-plastic (nonlinear) fracture-mechanics crack-growth simulation. Two constitutive descriptions are exercised for the structural analysis — the standard rate-dependent Chaboche viscoplastic model available in Abaqus, and a user material subroutine (UMAT) that couples Chaboche viscoplasticity with continuum damage in order to reproduce the tension–compression asymmetry of cast iron. The resulting stress, strain, and temperature histories drive a multiaxial thermomechanical fatigue Damage (DTMF) computation that estimates crack initiation and early extension, after which a nonlinear fracture-mechanics procedure simulates crack-front advance toward through-thickness failure. Both constitutive models correctly localize the crack-initiation site on the rotor inner diameter, consistent with the dynamometer observations; for the loading histories examined, the standard Chaboche model yields lives in closer agreement with test. The crack-growth simulation reproduces the rapid post-initiation propagation seen experimentally and resolves branch-wise differences in crack-front evolution through the rotor section.

Lee, Heewook, Garcia, Arnoldo, Liu, Yi, Hazime, Radwan, Boughanmi, Heni, Kassir, Abdallah

Data to Decisions: An AI-Driven Test Intelligence Platform for Integrated Analysis of Raw Data, Test Reports, and Specification Compliance in Brake System Validation

2026-01-0807

9/14/2026

Validation of brake systems is increasing in complexity due to electrification, software-defined architecture, integrated control modules, and higher functional safety requirements. Although physical testing remains the primary source of engineering evidence, interpretation of results including DVP&R/PVP&R compliance verification, anomaly detection, documentation, and milestone decision support continues to rely heavily on manual engineering analysis. This results in extended feedback cycles, inconsistent interpretation across teams, and limited traceability between raw data, reports, and governing specifications. To support engineers with more objective validation processes, there is a growing need for structured, data-driven intelligence that transforms dispersed test artifacts into actionable engineering decisions. This paper presents Data to Decisions, an AI-driven Test Intelligence Platform designed for integrated analysis of raw measurement data, test reports, validation plans, and specification requirements in brake system development. The platform has been applied to foundation brake systems (EPB and hydraulic calipers), brake control modules (IBC/EB100), and related actuation subsystems. It ingests heterogeneous inputs including DVP&R documents, customer specifications, test summaries, deviation logs, parameter files, and build configurations and converts them into structured, traceable validation datasets. A specification centered reasoning framework extracts governing limits, acceptance thresholds, instrumentation requirements, and staged validation criteria directly from source documents. Using natural language processing, rule-based logic, and pattern recognition models, the system evaluates both discrete and continuous data sets over an unlimited range of performance characterization metrics such as leakage, drag torque, piston travel, fatigue life, NVH behavior, structural durability, and actuator performance characteristics. Results are assessed against extracted specification limits to automatically identify compliance gaps, borderline conditions, parameter inconsistencies, and build-specific variations. All findings are traceable to original requirements and test evidence. The platform further enables closed-loop validation by linking physical test outcomes with virtual analysis results, supporting correlation studies and identifying opportunities for test optimization or targeted retesting. Automated generation of engineering and management level summaries reduces documentation effort while improving consistency and auditability. Pilot deployments demonstrate reduced manual data review effort, improved traceability of specification compliance decisions, enhanced anomaly detection, and faster decision making during and after DV and PV milestones. By combining rule-based validation logic with AI and Generative AI for document interpretation, pattern recognition, and automated summarization, the platform supports engineers in efficiently navigating large volumes of test data and specifications. This paper presents the system architecture, compliance evaluation methodology, and deployment results, illustrating how AI-enabled test intelligence can serve as a practical decision-support layer in modern brake system validation workflows.

Divakaruni, Saikiran, Willey, Joseph, Srivastava, Namrata, Sankar, Arya, Namala, Divya, Gowtham, Rahul Sangani

Physics-Informed Machine Learning Digital Twin of Electro-Mechanical Brakes for Clamp-Force and Friction Estimation

2026-01-0806

9/14/2026

Recently, there has been a drastic shift in the industry towards wire architectures like steer-by-wire and brake-by-wire. For safe and accurate force control, diagnostics, and consistent performance over the operating envelope, accurate plant modeling of the Electro-Mechanical Brake (EMB) is important. Classical approaches involved linearized dynamic EMB models and the use of the characteristic stiffness curve for calibration at the operating points. These methods often perform poorly over regions where hysteresis, compliance, and friction are strongly nonlinear. Prior research on state or force estimation for EMB has focused on pad contact detection, thermal adaptation, and hysteresis-aware clamp force estimation. However, there are still accuracy gaps in practical applications during transients and under shifting friction regimes. In this work, a digital twin based on Physics-Informed Machine Learning is introduced, following the governing dynamics of the actuator-caliper assembly of EMB while learning (i) a physically significant parameter—system damping (Bsys) and (ii) a non-linear friction term constrained as a function of the actuator motion states and operating conditions. Non-linear friction is captured through gray-box friction formulation and learning unmodeled residual dynamics such as hysteresis and backlash. An EMB test stand is used to collect steps, ramps, holds/engagements, APRBS, and swept-sine excitations, with signals including time-aligned force command, motor torque/current, actuator position/velocity, and pad force measurement from a force sensor for model training. Results demonstrate a decrease in pad-force prediction error, along with non-linear and residual friction estimation. The resulting digital twin can enable sensor-less force estimation, friction compensation design, predictive analytics, and health monitoring through tracking parameter drift and friction signatures.

Rai, Prakhar, Gadhvi, Tirth

Architecting Safety-Critical Systems for AI-Enabled Software-Defined Vehicles: A Compute, Timing, and Isolation Framework with a Brake System Case Study

2026-01-0811

9/14/2026

Software-defined vehicle (SDV) platforms are reshaping safety-critical system design by consolidating braking and other motion-control functions on centralized heterogeneous edge compute that also executes physical-AI workloads. This consolidation breaks traditional assumptions of fixed ECUs and simple timing envelopes, complicating assurance of determinism, isolation, and fail-operational behaviour for ASIL-D brake functions. Building on a decentralized brake-by- wire (BbW) architecture with dual controllers, redundant low-voltage power grids, and smart electromechanical brake corner actuators, this paper proposes a systems-level framework for architecting safety-critical functions in AI-enabled SDVs along three dimensions: compute, timing, and isolation. The framework classifies conventional and AI-based functions and maps them to heterogeneous compute classes; defines architectural patterns that combine safety islands, power-domain redundancy, and hardware partitioning to support freedom from interference; and formalizes timing domains and contracts that bound latency, jitter, and failover dynamics across sensors, centralized controllers, and decentralized actuators. The contribution is not a new AI algorithm, but a safety-oriented architectural framework that constrains how AI-enabled functions may be integrated into fail-operational by-wire systems. A BbW case study with edge-resident AI observers and anomaly detectors shows how the framework complements System Analysis Tool (SAT)– based failure modelling and clarifies trade-offs among safety isolation, latency, and AI performance while preserving braking safety guarantees under continuous software evolution.

Srinivasaraghavan, Soumyasudharsan

Real-Time Estimation of Brake Temperature using Physics-Informed Machine Learning Model

2026-01-0810

9/14/2026

The current work presents a novel approach to estimating brake surface temperature in real-time to aid in brake wear prognostics. Brake prognostics involve estimating brake pad wear in real-time, which enables its predictive maintenance. Brakes are a safety-critical system for vehicles; therefore, they require accurate and robust pad wear estimation to ensure vehicle safety. However, it involves several challenges. The estimation of pad wear is fundamentally a two-stage process: the first stage involves the accurate prediction of brake pad surface temperature, while the second stage utilizes this thermal history to calculate cumulative material wear. A significant challenge in estimating brake pad wear without an expensive sensor is that it is sensitive to the surface temperature prediction; any error in the thermal model propagates and compounds in the wear prediction stage. To identify surface temperature, traditional physical sensors are often cost-prohibitive or prone to failure in the harsh thermal and mechanical environments of the wheel end, necessitating a robust virtual sensing solution that can capture complex, non-linear heat transfer dynamics. The current work addresses the above challenge of identifying temperature dynamics using a Physics-informed Machine Learning approach. We employ Symbolic Regression (SR), a data-driven method that discovers the underlying mathematical expression of the system dynamics by searching for the optimal functional relationship between variables. SR provides an interpretable model that can be generalized across automotive platforms, offering a transparent, computationally efficient, and analytically tractable alternative to traditional ‘black box’ models. To generate the temperature dataset, a test vehicles were equipped with thermal sensors and underwent various braking scenarios. The SR-based virtual sensing model demonstrated strong and consistent predictive fidelity across all braking conditions tested. Under mild braking scenarios, the model achieved a Mean Absolute Percentage Error (MAPE) of approximately 6.0% in predicting brake surface temperature. This performance remained highly robust under mixed and harsh, high-speed braking, the most thermally demanding scenario, yielding MAPEs of only 11.6% and 11.9%, respectively.. Across all regimes, this level of temperature estimation fidelity directly limits error propagation into the downstream brake pad wear prediction stage, enabling reliable, sensor-less, cloud-based brake health monitoring at scale.

Gannavarapu, Shivadath, Pal, Anuj, Fan, Mengdi

Application of Electrochemical Noise Analysis for Rapid Assessment of Corrosion Resistance in Anodized AlSi Alloys

2026-01-0803

9/14/2026

This study presents a rapid and fully quantitative method for evaluating the corrosion resistance of anodized Aluminum-Silicon (AlSi) alloys through Electrochemical Noise Measurement (ENM). Laboratory specimens and brake components of EN AC-45300 (AlSi5CuMg) are anodized and characterized using both ENM and Neutral Salt Spray (NSS) testing to establish a correlation between the two methodologies. The results reveal a clear and consistent relationship between the logarithm of the noise resistance (Log(Rn)) and the NSS exposure time, demonstrating that ENM captures the key electrochemical features governing corrosion initiation. By providing an objective and data-driven assessment based on measurements acquired within approximately 40 hours, ENM offers a significantly faster and more quantitative approach for predicting NSS performance, thereby reducing validation times of anodized AlSi components.

Abello, Mary Angel, Mezzomo, Lorenzo, Mataloni, Valentina, Bonfanti, Andrea, Bertasi, Federico

Predicting Temporal Friction Torque of Drum Brake Systems: A Mixed-Effects Random Forest Approach

2026-01-0809

9/14/2026

Drum brake systems are becoming increasingly important in electric vehicles (EV) and purpose-built vehicles due to cost competitiveness and EURO-7 particulate emission regulations. Despite this trend, drum brake friction behavior remains incompletely characterized due to its dependence on multiple coupled variables: temperature history, braking conditions, and component interactions. To address this gap, this study presents a method for developing a time-series friction torque prediction model using the Mixed-effects Random Forest (MERF) machine learning framework. Time-series data collected from sensors during drum brake dynamometer tests were analyzed to identify the key variables that govern the friction torque. Significant inputs were selected through Exploratory Data Analysis (EDA), considering test-to-test variability and potential mixed effects, and were then used to train and tune the MERF model. Model performance was evaluated by comparing predicted friction torque with measured torque, and prediction error was quantified by using Mean Absolute Error (MAE) to check whether predicted model is reliable. The proposed prediction model demonstrates a high level of agreement with experimental measurements, confirming that the MERF approach can effectively capture the non-linear and transient characteristics of drum brake friction torque from time-series sensor signals. These results indicate that friction torque estimation is feasible using only sensor signals already available from conventional test instrumentation, without additional dedicated sensors. This capability is expected to support broader applications, including brake performance prediction for vehicles equipped with drum brakes and enhanced simulation of drum brake thermal performance across operating conditions.

Yoon, Jungro, Cho, Sunghyun, Kim, Wonjoon

A Virtual Methodology to Define Air Tightness Criterion for Brake Calipers Based on Experimental Data

2026-01-0818

9/14/2026

Air tightness in brake calipers is a critical requirement for ensuring braking system reliability and safety. However, defining a clear and practical analytical criterion for air leakage prediction remains challenging due to the complex contact behavior at the seal–piston interface. This study presents a virtual methodology to define an air tightness criterion for brake calipers based on experimental evaluation and structural analysis. The seal squeeze ratio was selected as the primary design variable to evaluate its effect on sealing performance. Test samples with different seal squeeze ratios were manufactured, and air tightness was tested under controlled pneumatic pressure to determine when leakage occurred. In parallel, a finite element (FE) structural analysis was conducted to simulate the seal installation process and quantify the resultant contact pressure distribution between the seal and the piston surface. To support reliable structural analysis, preliminary experiments were performed to determine the hyperelastic properties of the seal elastomer. Furthermore, the seal squeezing force was experimentally verified. The experimental results showed that low seal squeeze ratio caused leakage, demonstrating that seal compression strongly affects sealing performance. Based on these observations, an analytical criterion was established using the contact pressure between seal and piston, with a minimum contact pressure defined to prevent air leakage. Although a direct quantitative correlation between air leakage and contact pressure was not determined, the proposed criterion provides a practical and physically meaningful basis for evaluating air tightness. This methodology allows designer to predict sealing performance during the product design, reducing a necessity for extensive testing and enabling more efficient and reliable brake caliper development.

Cho, Inyong, Kim, Beomseok

Predicting Brake Squeal Occurrence Using Machine Learning with Temporal Feature Analysis of Braking-Torque Test Data

2026-01-0812

9/14/2026

The automotive industry's paradigm shift toward autonomous driving and electrification has introduced new competitors threatening market dominance through differentiated value propositions. In this highly competitive landscape, delivering irreplaceable customer value requires providing sustainable and authentic luxury experiences. Quiet driving represents a tangible value that customers genuinely appreciate. Brake squeal—high-frequency noise arising from friction-induced vibration during braking—negatively impacts customer satisfaction and must be suppressed. Despite significant advances in brake squeal prediction modeling, the irregular nature of squeal generation mechanisms has prevented the development of a generalized predictive model applicable to product development processes. Development and verification remain largely experimental. This limitation constrains early-phase design validation, as brake squeal is highly sensitive to chassis and braking system design. When squeal issues emerge during post-design evaluation, fundamental improvements to pad materials become difficult. Consequently, damping characteristic tuning is employed for mitigation, incurring substantial development costs. This study addresses this challenge through systematic feature engineering of time-series braking data—brake torque, disc rotational speed, disc temperature, and brake pressure—collected during squeal evaluation tests. Based on the hypothesis that environmental conditions and brake system characteristics influence mechanical behavior, time-series features exhibiting strong predictive association with squeal occurrence were derived, and a machine learning model was developed to predict squeal occurrence probability using these features as input variables. The model's predictive performance was validated by comparing squeal probability predictions derived from independent torque performance evaluation data against actual squeal evaluation results. This validation confirms that the model successfully predicts squeal occurrence probability from dynamometer torque performance data alone. Consequently, this approach enables the prediction of squeal occurrence probability in early development phases before formal noise assessment is conducted, streamlining the development process and significantly reducing verification costs while contributing to quieter driving experiences.

Cho, Sunghyun, Yoon, Jungro, Kim, Yoon Cheol, Kim, Jeongkyu, Kim, Sungho, Baek, SongYi, Kim, Won Joon, Choi, Kyung Rok

Evaluation Method for Driving Safety on Highway Successive Curves

2026-99-1568

9/11/2026

To evaluate the driving safety performance of continuous curves, this study developed a safety assessment model using a human-computer interaction simulation platform. First, three indicators are selected, including the driver’s heart rate variability, the rate of change in steering wheel angle, and trajectory lateral deviation, which together form a driving safety evaluation indicator system. Secondly, through significance testing and range analysis. Through analysis, four key curve-related elements are identified as having a notable influence on the overall evaluation indicators. A global optimization algorithm using multivariate nonlinear regression is then applied to establish the driving safety model. Finally, taking a dual four-lane highway in Sichuan province as an example, the safety of the successive curve in the project is evaluated. Empirical results show that when the intermediate straight line section H ≤ 4.23, driving is hazardous; 4.23 < H ≤ 4.46, driving is relatively hazardous; 4.46 < H ≤ 4.78, driving is relatively safe; H > 4.78, driving is safe. For oval-shaped curve segments, when H ≤ 4.53, driving is hazardous; 4.53 < H ≤ 5.32, driving is relatively hazardous; 5.32 < H ≤ 5.86, driving is relatively safe; H > 5.86, driving is safe. Through this method, the driving safety of successive curves can be effectively evaluated, particularly with a focus on driver comfort and safety. This provides valuable references for assessing driving risks associated with different combinations of curve elements.

Huang, Yongheng, Zhang, Ruizheng, Sun, Chao, Zeng, Xinjie, Zheng, Liwen

2025 International Conference on Intelligent Equipment, Vehicle Engineering and Automation Control

2026-99-1100

9/11/2026

TOC

Tobolski, Sue

Research on Torque Allocation Control of Multi-Articulated Vehicle

2026-99-1123

9/11/2026

The multi-articulated vehicle uses distributed drive mode. Due to its large degree of freedom of movement and the large number of driving shafts, different torque distribution methods affect the operational stability of the vehicle, how to coordinate and distribute the torque of each driving motor has become an urgent problem to be solved. To improve drive stability of the multi-articulated vehicles, propose a layered torque allocation control strategy. The upper-layer sliding mode controller determines the required additional yaw moments of each car body based on the linear reference model, the controller is characterized by swift response and a strong ability to resist interference. The lower-level allocation module comprehensively considers the torque output limitations of the electric hub motors, the prevailing road adhesion state, and the corrective yaw moment constraints given by the upper layer, and constructs an optimization objective function centered on the uniformity and stability of tire load. The optimal distribution of driving forces for each wheel is completed by solving this function dynamically. To validate the strategy's effectiveness, a vehicle dynamics model is built in the multi-body dynamics software ADAMS/View. Using a joint simulation framework integrating ADAMS/View and MATLAB®/Simulink, the effect of the layered control strategy is evaluated in comparative simulation with uncontrolled situation under U-turn and single lane change conditions. The simulation outcomes demonstrate that, compared to uncontrolled situation, the yaw rate deviation of each car body under the torque layered control are significantly reduced, and the adhesion utilization rate of tire is also effectively controlled, thereby the driving stability is improved.

An, Guanbo, Zhang, Liwei

Study on Brake Efficiency Airworthiness Requirements and Verification of Transport Category Aircraft

2026-99-1404

9/11/2026

Braking efficiency is one of the key indicators for evaluating the performance of braking systems on transport category aircraft. The value of braking efficiency is directly related to the safety of aircraft deceleration processes, especially during landing, and it is also critical for civil aircraft operators to improve operational efficiency on routes. This paper presents the airworthiness regulation requirements related to braking efficiency, requirements for aircraft wheels and tires, requirements for runway pavement types, major sources of contaminants, and specific requirements for simulating wet runway conditions using different contaminants. This paper analyzes effective methods for calculating braking efficiency, including the pressure method, torque method, and slip ratio method, and introduces the approaches for acquiring data of relevant parameters. Combining experience from braking efficiency verification work, the paper demonstrates the specific test procedures for the actual measurement of braking efficiency. Based on measured data such as braking pressure, wheel speed, and aircraft speed during braking, as well as the wheel dimensions and rotational inertia of wheels and brakes, the specific braking efficiency values under different calculation methods are derived. The paper compares the differences in braking efficiency values obtained by various calculation methods for similar braking processes, analyzes the causes of these differences, and demonstrates that the accuracy of braking efficiency calculated by different methods is acceptable. Additionally, the same calculation method is applied to compute the braking efficiency of multiple braking deceleration processes, which demonstrates that the method has good repeatability and can be stably used for braking efficiency calculation. This verification method provides a reference for the certification work to ensure that the braking efficiency of transport category aircraft complies with airworthiness and performance requirements.

Feng, Yibo

Experimental Study on Handling Stability of an 8×4 Heavy-Duty Truck

2026-99-1122

9/11/2026

To analyze the handling stability of an 8×4 heavy-duty truck, a multi- body dynamics model of the heavy truck was established in ADAMS. Simulation tests for minimum turning radius, double lane change, steering wheel step input, and steady-state returnability were conducted on this model. Analysis of the simulation and experimental results revealed that, except for the significant discrepancy between the rigid-flex coupling model simulation results and the actual values in the returnability experiment, other experimental results were relatively close to the simulation data, indicating that the established vehicle model has high accuracy. It can provide a basis for the subsequent optimization design of this vehicle type.

He, Wenjian, Dong, Fulong

Design and Research of Large-Tire Replacement Robots

2026-99-1127

9/11/2026

In view of the large volume and weight of the tires of mining dump trucks and the difficulty in replacing them, a large tire replacement robot is proposed based on the tire parameters and the tire replacement process. The overall research scheme for the robot was developed using the functional analysis method, and the functional element solution and combination were completed. Based on the best solution obtained, a three-dimensional model of the tire changing robot was established using the SolidWorks software, followed by control system design and workflow analysis. To investigate the robot's operational kinematics, a simulation was conducted in the SolidWorks Motion module. The motion curve of the flipping platform during its operational state was obtained. A finite element simulation of the robot's front support beam was performed using ANSYS Workbench to obtain its stress and deformation contours under both no-load and heavy-load conditions. The structural parameters of the front support beam were optimized, focusing on its mechanical characteristics under heavy-load conditions, and the response surfaces of different parameters were obtained. The optimization yielded a 9.599 kg reduction in the mass of the front support beam. The maximum stress of the grasping mechanism under static simulation analysis is 50.617 MPa, with the maximum deformation of 0.4221 mm occurring at the end of the mechanical hand. Ground contact simulation for the robot's walking tires was conducted with Abaqus. Employing the Mooney-Rivlin hyperelastic model, this study investigated the mechanical response of the tire to static and dynamic loading, leading to the identification of the optimal operational load. The simulation results show that there is no interference among the various mechanisms of the large tire changing robot during operation. It can quickly complete the tire installation and removal tasks with precise control, and its strength and rigidity meet the requirements. This verifies the rationality and feasibility of the robot. The research on the large tire changing robot can provide a new approach for the maintenance of large transport vehicles such as mining dump trucks.

Tian, Liyong, Zhang, Haijian

Research on a Brake Energy Recovery Strategy Based on Improved ANFIS

2026-99-1134

9/11/2026

This paper addresses the issue of regenerative braking energy recovery in new energy vehicles and designs and optimizes a braking force distribution strategy. The strategy uses an ANFIS controller to dynamically optimize the proportion of front-axle regenerative braking force. The introduction of a pruning algorithm reduces computational complexity, thereby enabling a significant increase in mileage while maintaining stable driving performance. Co- simulations integrating Simulink and AVL Cruise, alongside Hardware-in-the-Loop (HiL) tests, the proof is that this strategy can still maintain excellent stability under different braking intensities. Moreover, it exhibits significantly higher energy recovery efficiency compared to benchmark strategies, while its effectiveness and real- time performance are successfully validated.

Lin, Hui, Zhao, Xuezhan, Tian, Jiahao

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