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Development of a laboratory brake for a flywheel mass test rig for variable pad sizes and shapes with a force distribution unit for ideal contact pressure and a topography measurement system for in-situ recording of surface changes and wear

2025-01-0331To be published on 09/15/2025

Pin-on-disc tribometers are used to determine the frictional behaviour and boundary layer dynamics of material pairings. Material pairings are examined under defined conditions in order to make statements about the friction behaviour and wear. Pairings for real brake systems with larger pad sizes can be tested on flywheel mass test benches in order to provide proof of suitability. This is mainly due to a lack of knowledge about the scaling behaviour of friction linings. The Department of Machinery System Design at TU Berlin has combined the classic approach of a pin-on-disc tribometer with a flywheel mass test rig (up to 12.78 kgm²) and thus set up a laboratory brake on which material pairings with different pad shapes and sizes (up to 48 cm²) can be examined. The flywheel mass test stand consists of an adjustable DC-motor that drives a shaft on which variable flywheel masses and brake disks can be installed. The variability allows for different kinetic energies at different friction

Heuser, Robert Michael, Rosenthal, Tobias Richard, Wiest, Daniel Christian, Meyer, Henning Jürgen

Durable aluminum alloys for brake disc and rotor applications

2025-01-0358To be published on 09/15/2025

Lightweight materials are essential in reducing the overall weight and improving the efficiency and performance of ICE and electric vehicles. The use of aluminum alloys is critical in transitioning to a more energy sustainable and environmentally friendly future. The accessible combinations of high modulus to density and strength to weight ratios, as well as their excellent thermal conductivity, make them an ideal solution for weight reduction in vehicles, thereby improving fuel efficiency and reduce emissions generated during braking events. Aluminum alloys with high strength and lifetime thermal stability have been industrialized for usage in brake rotor applications. Amongst the most used aluminum alloys with high thermal stability are 2618 and 4032 used both in aerospace and automotive industries. However, when it comes to prolonging the life of a product at temperatures that exceed 200°C, these alloys will degrade their properties quickly within the first 300 hours. Therefore, a

Duchaussoy, Amandine, Lorenzino, Pablo, Franklin, Jack, Tzedaki, Maria

Challenges in Quantifying Tire Wear Particle Emissions on an Outer Drum Test Bed

2025-01-0352To be published on 09/15/2025

Tire wear is a major source of microplastics and airborne particles (<10 µm), posing environmental and health risks. Accurate quantification is essential for regulatory control. This study develops a method to measure tire wear and tire wear particles on an outer drum test bed while achieving realistic wear rates. A key challenge is the necessity of de-gumming methods, such as talcum powder, to prevent tire adhesion to the drum. However, this complicates emission measurements. The test bed at TU Graz features an enclosure with flow-optimized baseplates and AirKnifes to minimize background emissions. The sampling system, compliant with GTR-24 (brake wear), includes two AVL Particle Counters, two PM-Samplers, and an ELPI+ for size distribution analysis. Results show that background emission reduction is critical for accurate measurement. The de-gumming method increased tire wear rates by a factor of 10 but introduced additional particle sources. Size distribution analysis revealed clear

Schubert, Ludwig, Arias Torres, María Alejandra, Bigl, Stephan, Steiner, Gerald, Huber, Michael, Lex, Cornelia

Brake System Homologation: A Holistic, Simulation-based Approach

2025-01-0351To be published on 09/15/2025

To comply with EU7 in a first step brake systems of newly homologated passenger cars and light commercial vehicles up to 3.5 tons must fulfil the upcoming certification limits, according to the EU7 implementation timeline. Based on a wide range of brake emission measurements since 2022, it can be seen that almost no brake system is fulfilling these currently foreseen limits. Brakes have been optimized for decades now for mainly performance and comfort improvements, but now legal emission requirements are acting as a game changer and huge efforts will be necessary to fulfil new and tradtitional purposes, which are causing new modelling and testing approaches to understand the complete vehicle picture with all its attributes. A possible contribution to solving this challenge is the use of the vehicle-specific individual friction brake share coefficient ("iFBSC"), which is currently mostly evaluated by performing a WLTP-Brake cycle on a roller testbed and analysing the relative amount of

Grojer, Bernd

Dynamic analysis of automotive wheel bearings

2025-01-0366To be published on 09/15/2025

Bearings are mechanical components that support loads and transmit rotational motion. With the increasing demand for high-value-added products, such as semiconductors, aerospace components, and robotics, the need for more precise and diverse applications has grown. Consequently, accurate bearing performance prediction and evaluation technologies have become essential. Bearing performance prediction is generally classified into static and dynamic approaches. Traditionally, research has primarily focused on static and quasi-static predictions based on bearing theory. However, these methods have a significant limitation in that they fail to accurately consider the actual behavior of bearings. As a result, the necessity for prediction methods based on numerical analysis, which can account for the time-dependent behavior of bearings, has been increasingly recognized. In this study, dynamic analysis of bearings was conducted to evaluate their behavior over time. First, dynamic analysis of

Lee, Seungpyo

Modeling and Experimental Study on the Sealing Performance of Automobile Brake Fluid Reservoir

2025-01-0354To be published on 09/15/2025

The brake fluid reservoir is an indispensable part of the hydraulic brake system. Due to the development of the electronic hydraulic brake system (EHB), the requirements for the sealing performance of the reservoir are also improved accordingly, and the traditional reservoir can no longer meet the current performance requirements. Based on a traditional brake fluid reservoir, this paper breaks through the traditional method of verifying the design through bench test, increases the evaluation standard of dynamic sealing performance test, supplements the problem of missing sealing simulation model, and adopts the method of combining modeling and simulation with bench testing to study the current sealing performance requirements. Through the establishment of high-precision static sealing performance simulation model and dynamic sealing performance simulation model under different working conditions, the simulation data of the current evaluation metrics are obtained. In order to further

Wang, Shiqi

Design Considerations for Wheel Bearing Outer Ring for Electric Vehicles

2025-01-0367To be published on 09/15/2025

Electric vehicles demand better drag performance from wheel bearings in order to achieve longer range. Electric vehicles are heavier than their corresponding ICE vehicles. They also have higher torque output. Due to this there would be higher loads at bearing to knuckle joint. The higher loads may require higher clamp loads to keep the joint secure. The higher clamp load may increase wheel bearing outer ring distortion or out of roundness. The outer ring distortion would increase the drag permanently and reduce the bearing life. So, it is critical to minimize outer ring distortion even after the assembly with higher clamp load and throughout the life. In this paper it is planned to cover the design considerations for wheel bearing outer ring and knuckle interface to keep distortion minimum. A DOE will be used to understand the effects of M12 vs. M14 mounting bolts, knuckle stiffness, OR mounting area, knuckle bolt PCD, bearing outer ring flange thickness. A 2nd DOE will investigate the

Mandhadi, Chaitanya Reddy, Callaghan, Kevin, Sutherlin, Robert, Lee, Seungpyo, LEE, YEONSIK, Bovee, Benjamin

Improving the Comparability of Brake Wear Solid Particle and Total Particle Number Emission Measurement

2025-01-0362To be published on 09/15/2025

Authors (not in final order): Sampsa Martikainen, Madlen Pramstrahler, Christoph Weidinger, Christian Wanek-Rüdiger, Michael Huber, Andreas Rainer      The United Nations Global Technical Regulation (GTR) defines the framework for brake wear emission measurements. The definitions and limits for the emission measurement system, such as sampling configuration and allowed background concentration, are a part of it. The particle number (PN) measurement is divided into Solid Particle Number (SPN) and Total Particle Number (TPN), referring to the emitted particles that exclude, or include, volatile particle matter, respectively. In this study we present conclusions drawn from a large set (>700) of PN emission factors, regarding the comparability of SPN and TPN, uniformity of particle concentration in the sample transport tunnel, and the effect of background concentration on the final emission result. Additionally, we evaluate the suitability of a flow splitter in the brake wear PN

Martikainen, Sampsa, Pramstrahler, Madlen, Weidinger, Christoph, Rainer, Andreas, Engler, Dieter, Huber, Michael

Accuracy Requirements for the Road Friction Coefficient Estimation of a friction-adaptive Automatic Emergency Braking System as a Software Solution for Integrated Chassis Control

2025-01-0349To be published on 09/15/2025

The number of traffic accidents in longitudinal traffic has been significantly reduced by the series introduction of Automatic Emergency Braking (AEB) systems. Nevertheless, more than a third of these accidents still cannot be prevented because, according to the German Federal Statistical Office (Destatis), they are caused by wet or snow-covered roads. For this reason, current research work is focusing on adapting the functionality of AEB systems to the road condition by an estimated value of the road friction coefficient. This paper uses simulation to determine the accuracy with which the road friction coefficient must be known for a friction-adaptive AEB system to prevent rear-end collisions in statistically relevant Euro NCAP test scenarios, even on wet and snow-covered roads. The friction-adaptive AEB system, which is being developed at IAV GmbH as a customizable software solution for Integrated Chassis Control (ICC), uses the estimated value of the road friction coefficient to

Ahrenhold, Tim, Wielitzka, Mark, Binnewies, Tomas, Henze, Roman

A Study on the Development of Optimal Brakes for Electric Vehicles Using Simulation

2025-01-0345To be published on 09/15/2025

As the internal combustion engine vehicle change into the electric vehicle, we can use regenerative brake. It can improve not only the energy consumption, but also reduce the hydraulic brake usage. The less hydraulic brake usage mitigates the heat load on the brake disc. From this reason, the lightweight brake can be used in the electric vehicle. However, when the lightweight brake is applied, the brake NVH can be increased. The optimization design of the lightweight brake should be done to prevent the brake NVH. In this paper, the optimal brake disc thickness and brake interfaces are determined by using of disc heat capacity analysis. The lightweight brake should be optimized by using of the brake squeal analysis. We can verify the results from both analysis and tests. Finally, we can have the lightweight brake, which is competitive in terms of cost, weight and robust to the brake NVH

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

The Challenges of Measuring Residual Brake Drag using Different Test Apparatuses and Methods to Mitigate Inaccuracies.

2025-01-0343To be published on 09/15/2025

As automotive manufactures have tried to set themselves apart by reducing emissions, and increasing vehicle range/fuel economy by eliminating any energy loss from inefficiencies on the vehicle, the brake corners have been an area of interest to reduce off-brake torque to zero in all conditions. Caliper designers can revise some attributes like piston seal grooves, and pad retraction features to reduce drag, but even if a caliper is designed perfectly in all aspects, trying to measure it in a reliable and repeatable manner proves to be difficult. There are many ways to measure brake drag all with ranging complexity. Some of the simplest measurements are the most repeatable, but it excludes the majority of the vehicle inputs. The most vehicle representative testing requires the most complex equipment and comes with the most challenges. This paper will focus mainly on the different ways residual brake drag can be measured, the pros and cons to each of them, the problems trying to measure

Retting, Joshua

Effective way to eliminate and reduce Brake Judder issue during combined cornering & braking event in SUV.

2025-01-0363To be published on 09/15/2025

Sports Utility Vehicles (SUV) are designed largely for off - roading capability, superior ride & comparable handling characteristics analogous to sedans. Wheel Ends Systems Design engineer are exploring new avenues to improve the vehicle cornering and stability at high speeds. During vehicle cornering driver applies the required brake force to reduce the vehicle speed for maintaining vehicle direction and stability. Due to the combined cornering and braking, high frequencies vibrations will be dampened by suspension bushings and dampers. However, low frequency vibrations from the braking systems - brake judder will be present while driving the vehicle. These vibrations will be transferred through the chassis transfer path from brake disc, brake pad, knuckle and this creates discomfort to driver at the vehicle floor, brake pedal & steering wheel. Bearing offset, Bearing Orientation and bearing camber stiffness are the vital parameters among the wheel ends parts and significantly aids in

Thomas, Joseph Pravin, Deivasigamani Purushothaman, Balakrishnan, Singh, Ram Krishnan

A Novel Framework for Elastic Constants and Damping Ratio Optimization of Friction Material in Brake Squeal Simulations

2025-01-0350To be published on 09/15/2025

Friction material properties critically impact brake squeal simulation outcomes due to their nonlinear and transversely isotropic behaviours, which vary with load type and direction. To improve the reliability of brake squeal predictions, this study introduces the Transversely-isotropic Elastic Constants Optimization (TECO) method, a novel multi-dimensional constrained optimization framework for refining the elastic constants and damping ratio of friction materials. By integrating experimental testing, finite element analysis (FEA), and an advanced optimization technique - Gradient Response Surface Algorithm (GRA), the TECO method minimizes discrepancies between simulated and experimental data, ensuring accurate characterization of elastic properties. The TECO method offers significant advantages, including flexibility and robustness, making it an effective alternative to ultrasonic measurements and traditional optimization techniques, especially for anisotropic friction lining

Philip, Rony, Muralidharan, Sudharsan, Mohanam, Gopalakrishnan

Real-Time HIL Testing and Validation for Multi-ECU Smart Brake Systems: Design, Implementation, and System Optimization

2025-01-0344To be published on 09/15/2025

This paper presents applied methodologies and results from real-time Hardware-in-the-Loop (HIL) testing of smart braking systems, based on experience gained during European Tier-1 supplier development programs. It outlines how HIL accelerated control software validation, enhanced fault coverage, and improved development cycles for emerging technologies like brake-by-wire and regenerative braking systems. As braking systems evolve to meet the demands of electrification and autonomy, their complexity has grown significantly requiring robust, scalable, and safety-focused validation techniques. Modern smart braking architectures often employ decentralized control, with individual ECUs managing each brake corner. To ensure safe and reliable operation of such systems, a real-time HIL test bench was developed to simulate a wide range of driving conditions and validate critical functionalities including Anti-lock Braking System (ABS), Vehicle Dynamics Control (VDC), and regenerative braking

Sathiyamoorthy, Pradeepraja

Development of a design system for wheel bearings including prediction functions for the finite element method using Lasso regression and Bayesian optimization

2025-01-0365To be published on 09/15/2025

Wheel bearings play a critical role in providing smooth rotation when vehicles move in straight line and turning motions. Automotive electrification continues to accelerate, emphasizing specific market demands such as lightweighting, lower torque, and quietness. In addition to the above requirements, reduced development timing for automotive programs is required. Recently, the number of bearing manufacturers that utilize Model-Based Development (MBD) have been increasing in order to reduce development time. NTN has developed an integrated calculation automated system which is called Axle Bearing Integrated Calculation System (ABICS) that automates each step of the design processes for third generation hub bearings. After ABICS was released, man-hours per development project were reduced by 80 percent compared to previously used design flows in which each step of the design processes had been performed by a human. In order to further reduce development timing, even more focus has been

Kitada, Tatsuya, Barrett, Rob, Matsubuchi, Hiroki, Suma, Hiroto

Analysis of Front Axle Wheel End Temperature Measurements in Heavy-Duty Trucks

2025-01-0364To be published on 09/15/2025

The Front Axle wheel end assembly is a critical component of Vehicle functionality, comprising a wheel hub positioned to rotate smoothly on an Axle spindle. This rotational movement is enabled by bearings positioned between the hub and the spindle, allowing for frictionless rotation. The Front Axle wheel ends' temperature typically depends on several factors such as type of Vehicle, Load & driving conditions and health of the components involved. In general, the wheel ends can become warm during normal operation owing to friction generated by the rotation of the wheels and the interaction of various mechanical components such as Bearings and Brakes. However, if the temperature of the wheel ends becomes excessively hot, it could indicate potential issues such as Overheating brakes, Wheel bearing problems, improperly inflated tyres, and faulty components. As temperature rise, materials tend to expand. This expansion can affect the dimensions of critical components in the Front Axle wheel

P, Mahendran, Jayaraman, Karthik, R, Sabari, B, Ellavarasan, Bhanja, Subrat Kumar

Effects of Moisture Behavior on Corrosion Stiction in Friction Materials

2025-01-0333To be published on 09/15/2025

This study investigates the correlation between moisture behavior and corrosion stiction mechanisms in NAO friction materials. While previous studies on corrosion stiction have primarily focused on electrochemical approaches, this study aims to elucidate the mechanism by examining moisture behavior within the friction material. Although recent research has explored changes in pad properties in humid environments, most studies have primarily focused on variations in pad stiffness and friction coefficient. To date, no studies have investigated the behavior of moisture within pads using Fick’s Second Law and its impact on corrosion stiction. In this study, Fick’s Second Law was applied to model moisture behavior in friction materials. The diffusion coefficient and maximum moisture content were quantified, revealing that moisture behavior in the friction material can be divided into two distinct stages: one following Fick’s Second Law and the other not. For NAO friction materials

Choi, Nakcheon, Ju, Joungsu, Youn, Deokki

Water Interaction and its Effect on the Tribological Behavior of NAO friction materials.

2025-01-0336To be published on 09/15/2025

Moisture is known to be a relevant factor during a friction material life, affecting tribological behaviors such as friction coefficient and torque variations. In this study we investigated the interaction between friction materials and water; employing various techniques such as contact angle measurements, soaking, and exposure to controlled environmental condition changes. For this study, specifically selected materials were studied to highlight differences and understand mechanisms. Material modifications, in particular, organic content and hydrophobic agents, were examined. Characterization results showed that brake pads hydrophobicity can be influenced by water interaction conditions; even low-wettability surfaces, such as those treated with hydrophobic modifiers, can still absorb water depending on internal factors (e.g., porosity) and external conditions (e.g., contact time, humidity). Additionally, we investigated the capacity of a friction material to adsorb water and desorb

Iodice, Valentina, Durando, Pietro, Balestra, Simone, Pellerej, Diego

Achieving Euro 7 Compliance: Cost-Effective Brake Wear Particle Emissions and Performance with FNC-Smart ONC® GCI Rotors

2025-01-0332To be published on 09/15/2025

Over the past few years, NITREX has developed an advanced ferritic nitrocarburizing process combined with a specialized post-oxidation treatment known as FNC + Smart ONC®. This innovative approach allows the use of grey cast iron brake rotors in their original form, significantly reducing PM 10 emissions to levels below the Euro 7 limits for most vehicles equipped with at least some recuperative braking capabilities, all without compromising performance. We have rigorously tested these rotors according to several industry standards, including SAE J2707B (Block Wear Test including Highway), GRPE-81-12 Emission Test (Full WLTP Brake Cycle 6 Times), and SAE J2522 (AK-Master Performance). These tests were designed to compare the behavior of treated rotors against standard untreated rotors, as well as to evaluate performance with different lining materials. Additionally, our process addresses the issue of corrosion, which is particularly relevant for brake rotors that experience less use in

Winter, Karl-Michael, Holly, Mike

Impact of Return Spring Positioning on Brake Drag Forces and Gaps

2025-01-0330To be published on 09/15/2025

This study investigates the impact of return spring positioning on brake drag forces and brake gaps in an S-Cam brake assembly. A detailed analysis reveals that the offset placement of the shoe return spring leads to a shoe tilting phenomenon, resulting in uneven brake gaps. This misalignment reduces the clearance on the dust cover side, increasing drag forces and adversely affecting brake performance, fuel efficiency, and liner wear. To address this issue, an optimized design is proposed, that effectively eliminates tilting, restores uniform brake gaps, and significantly reduces drag forces. Validation through dynamometer testing confirms the effectiveness of the revised spring placement in minimizing brake drag and improving system efficiency. By optimizing return spring positioning, the study highlights improvements in braking efficiency, extended brake liner life, and enhanced durability of the braking system. The findings underscore the importance of precise spring placement in S

Rajput, Ganesh, ambekar, Prasad, PREMLAL, P, Mittal, Jayant

Influence of Titanate Composition and Particle Size on Friction Stability and Wear in Brake Pads

2025-01-0337To be published on 09/15/2025

Stable friction and low wear are essential for reliable brake performance. This study investigates the effects of platelet titanate particle size and chemical composition on the tribological behavior of brake pads. We examined platelet titanates with varying particle sizes and compositions—potassium titanate and potassium magnesium titanate—to understand their impact on friction stability, wear resistance, and transfer film formation. Characterization techniques included X-ray diffraction (XRD) for phase identification, thermogravimetric analysis (TGA) for thermal stability, pin-on-disc friction testing, and scanning electron microscopy (SEM) for wear surface analysis. The results show that platelet titanate particle size and composition significantly influence transfer film characteristics. Brake pads with potassium magnesium titanate and optimized particle size formed a more uniform and robust transfer film, improving friction stability and reducing wear rates. These findings

Jara, Diego Chavez, Conforti, Michael

Further Investigation of Variables Affecting Brake Squeal: Porosity Effect on Lowmet Pad Properties

2025-01-0335To be published on 09/15/2025

As Lowmet pad porosity increases, pad hardness decreases; pad ISO compressibility increases; the nominal friction coefficient increases (SAE J2522); and the disc wear/pad wear decreases. Brake squeal occurrence is affected by the total wear of disc and pads; the wear differential between the inboard pad and outboard pad; pad tangential taper; and pad hardness/material damping. Also, pad chamfer shape has a strong influence on brake squeal occurrence.

Rhee, Seong Kwan, Rathee, Aman, Singh, Shiv Raj, Sharma, Devendra

Effect of Casting Microstructure on the Mechanical Performance of Recycled EN AC-43200 Al-Si Alloy

2025-01-0357To be published on 09/15/2025

Nowadays, the automotive industry is moving toward the reduction of CO2 emissions implementing different strategies. Beyond the direct reduction of emissions from the vehicles, an important role is played by the production of parts made with recycled materials. This is particularly relevant for automotive components (e.g., brake calipers and steering knuckles) produced using cast Aluminium-Silicon (Al-Si) alloys, whose primary production from bauxite is highly energy-intensive. However, recycled cast Al-Si alloys could have different mechanical performances with respect to their primary counterparts, due to the presence of impurity elements from the recycling process. For this reason, it becomes fundamental to study the effect of different casting parameters (e.g., molten alloy temperature, sprue design and mould temperature) on the solidification microstructure of recycled, cast Al-Si alloys and, as a consequence, on the mechanical performances of the material. In this context, this

Pavesi, Arianna, Barella, Silvia, D'Errico, Fabrizio, Bonfanti, Andrea, Bertasi, Federico

Applying Specialized System Analysis for Brake by Wire in Software Defined Vehicles: The Development of a System Analysis Tool (SAT)

2025-01-0355To be published on 09/15/2025

In the rapidly advancing field of automotive engineering, the emergence of Software-Defined Vehicles (SDVs) has introduced complex design and functionality challenges, particularly with respect to braking systems. A main concept of SDV electrical architecture is centralizing vehicle controls and decoupling this control software from sensing and actuation mechanisms. This paradigm shift, specifically when applied to Brake by Wire (BbW) systems, leads to the decentralization of brake actuation, and requires precise coordination among numerous electronic components for effective braking command execution. The absence of mechanical backup in BbW systems necessitates additional fail-safe redundancies, further complicating the system. A comprehensive model that elucidates these component interdependencies is essential for enhancing engineers' optimization of system design. This paper introduces a custom-built System Analysis Tool (SAT), complemented by a specialized methodology, tailored

Heil, Edward, Zuzga, Sean, Babul, Caitlin

Dynamic Model of Brake Vacuum Booster Using Hybrid Methodology

2025-01-0356To be published on 09/15/2025

This study primarily focuses on dynamic modelling of the brake vacuum booster used in a typical four wheeled passenger vehicles, under brake apply condition. Vacuum Booster is a key component of brake actuation system whose primary function is to multiply the force received from brake pedal. A hybrid methodology consisting of FEA and dynamic 1D simulation of the vacuum booster has been constructed in this study by accommodating its compliance. The brake vacuum booster consists of two chambers namely vacuum and apply chamber, the force multiplication in vacuum booster occurs because of pressure difference between these two chambers. The Hybrid methodology not only captures its flow dynamics, fluid structural interaction but also accommodates the structural interaction that happens between the ratio disc (rigid body) and the reaction disc (hyper elastic body) with the help of finite element analysis. The result from finite element analysis is then fed into the equation of motion of

Iyengar, Sharan Yoganand, Chinnakandan, Mani Saravanan, Gopalan, Seshadri

Enhancing Brake Pedal Feel in Hydraulic Brake high tonnage Vehicles Using Hydro-Actuated Vacuum Assist Booster

2025-01-0359To be published on 09/15/2025

Brake pedal feel is very important factor for driver brake application confidence. In Indian low and medium truck application, driver is loading vehicle with max overload condition and, pedal feel deteriorated with increased in vehicle GVW. However, brake system aggregate size increment with respective weight increment is not feasible due to modulator architecture of vehicle. To overcome this concern, we have developed innovative solution “Remote hydro-actuated vacuum assist booster”. In this proposal, Actuator unit is a hydraulic tandem master cylinder assembled inside driver cabin. The hydro-actuated vacuum assist booster is consisting of slave cylinder and vacuum assist booster with hydraulic tandem master cylinder (HAVB) located on chassis. Driver’s foot input force is transferred from the brake pedal to the hydro-actuated vacuum assist booster (HAVB) via an actuator unit. The hydro actuated vacuum assist boosters have amplified driver input force and generate hydraulic pressure

Sonar, Milind, Shaikh, Matin Hanif

Brake Drag Optimization: A Perspective on Virtual and Physical Tools for Developing Near-Zero Drag Sliding Calipers

2025-01-0360To be published on 09/15/2025

The ever-increasing prevalence of electric vehicles in the global market continues to push automakers towards more stringent brake drag requirements. As OEMs seek to differentiate themselves with greater vehicle range to offset consumer anxiety as a barrier for entry to EVs, brake caliper suppliers see requirements for zero or near-zero drag at the component level becoming commonplace. Despite this pressure, many practical concerns exist with torque measurement capabilities in the sub 1.0 N-m range. Additionally, the authors have observed an industry tendency to employ suboptimal engineering methodology for assessing drag concerns, with trial and error attempts continuing to perplex engineers more than it provides solutions. This paper will seek to reintroduce to the reader the basic physics of brake drag from a fundamental free body diagram level, review statistical approaches for characterizing the individual forces acting within the caliper, and propose a simple – yet effective

Robere, Matthew, Retting, Joshua

Bolstering Driver Braking Confidence – Considerations for “Deceleration Adder” Technologies

2025-01-0353To be published on 09/15/2025

Over the life of a typical vehicle, a average can be expected to apply the brakes on the order of 1.6 million times – almost 9 times per mile and over 290 times per day, and an “exuberant” driver can be expected to do this over 2.2 million times. Without question, the driver becomes accustomed to how the vehicle responds to braking control (and all of the normal variation around it), and even develops expectations for how it will respond the next time the brakes are employed. In the rare event of a failure or malfunction in the brake system, that results in an appreciably different vehicle response to the brake brake input, this can be surprising and even alarming to the driver, sometimes to the extent of causing hesitatation in braking. Fortunately, with the rise of mechatronic braking actuators in the 1980’s and 1990’s, features such as “Driver Brake Assist” (which provides additional pressure beyond what the primary brake actuator can at the time) and “Panic Brake Assist” (which

Antanaitis, David

Enhancing robustness of electro-hydraulic Brake-by-Wire actuators via linear Active Disturbance Rejection Control

2025-01-0341To be published on 09/15/2025

In recent years, motorsport has increasingly focused on environmental concerns, leading to the rise of hybrid and fully electric competitions. In this scenario, electric motors and batteries take a crucial role in reducing the environmental impact by recovering energy during braking. However, due to inherent limitations, motors and battery cannot fully capture all braking power, necessitating the use of standard friction brakes. To achieve an efficient balance between electric motors and friction brakes, the brake pressure can no longer be directly controlled by the driver. Instead, it must be computed by the Vehicle Control Unit (VCU) and sent to a smart actuator, i.e. the Brake-By-Wire (BBW), which ensures that the required pressure is applied. The standard approach to achieve precise pressure control is to design a nested Proportional-Integral-Derivative (PID) control architecture, which requires an accurate nominal model of the system dynamics to meet the desired tracking

Gimondi, Alex, Dubbini, Alberto, Riva, Giorgio, Cantoni, Carlo

Preliminary Multi-Physics Modelling and Characterization of a Magneto-Rheological Brake

2025-01-0347To be published on 09/15/2025

Magneto-Rheological (MR) Fluid is a smart material used in several applications for its ability to switch from fluid behaviour to solid-like conditions if a magnetic field is present. The dependency of viscosity on magnetic field makes this fluid suitable for braking system of electric vehicles, thanks to its high controllability and response time in the whole operative range. The main parameters that influence the behaviour of the fluid, and so the braking action of the system, are magnetic field and rotational velocity. In general, the extremely variable properties make complicated to simulate the system and its behaviour in different operating conditions. Therefore, after some simulations a physical prototype is necessary to experimental verify the response of the braking system at different driving conditions. The aim of this paper is the development of a virtual model of Magneto-Rheological Brakes whose validity is extended to different driving conditions. This goal can be

De Luca, Elena, Imberti, Giovanni, de Carvalho Pinheiro, Henrique, Carello, Massimiliana

A Study on the Prediction Method of Durability Characteristics of Brake Judder using Simulation

2025-01-0346To be published on 09/15/2025

In order to predict the durability characteristics of the brake judder, it is determined by analyzing the brake DTV (Disc Thickness Variation) and BTV(Brake Torque Variation) through the durability evaluation of the brake system or the vehicle. However, this method requires the real products and takes a long time to derive the result. When judder problems occur due to durability, there are many difficulties in deriving improvement plans through test methods. Therefore, in this study, CAE was used to derive the initial wear amount of the disc, and a method of predicting DTV after durability was developed using the results.

HWANG, JAEKEUN, KIM, SUNGHO, Kim, Jeongkyu, Kang, Donghoon

Caliper Rattle Noise Simulation based on Explicit Solver and BEM

2025-01-0348To be published on 09/15/2025

Brake caliper rattle noise is difficult to simulate. Many CAE engineers have been introducing rattle vibration not noise.Previous rattle noise simulation presented relative displacement results calculated by normal mode analysis, or vibration dB level not noise dB level. However rattle noise is combination of continuous impact noise. Impact noise should consider reflection, diffraction and refraction caused by transient nonlinear contact and local vibration especially during very short contact event. To simulate the impact noise, vibration and acoustic characteristics should be analyzed based on simple structure because there are many mechanisms to explain the impact noise.In this paper, rattle noise is simulated by LS Dyna which has explicit solver and BEM solver. The correlation between the test and CAE was conducted with simple beam rattle, and caliper system level which is corresponding to car maker test specification. Finally caliper system level rattle noise simulation can be

park, joosang

Active Online Estimation of the Electromechanical Brake Coulomb Friction

2025-01-0342To be published on 09/15/2025

Electro-mechanical braking (EMB) system has emerged as a potential candidate that serves the brake-by-wire technology. Several mechanisms [1] are used to transmit the clamp force, where each has efficiency losses due to static friction and viscous damping. Compensating these losses is essential for accurate responses whether for meeting the performance goal for EMB and improving the stopping distance. Mathematical and empirical models [1,2,3] are used to estimate these losses so that clamp force is accurately estimated and controlled. However, none of these models are capable of addressing the part-to-part variation or predicting the impact of other noise factors on these losses such as operating temperature and degradation. The purpose of this work is to online estimate the EMB coulomb friction by introducing an external torque command over a period of time while observing the system’s response. This approach continuously measures the coulomb friction while the system is in normal

Aljoaba, Sharif, Rajavenkitasubramony, Ramakrishnan, Dobbs, Jeremy

Actuator-to-vehicle joint estimation of clamping force for sensorless control of the electro-mechanical brake system

2025-01-0338To be published on 09/15/2025

The electro-mechanical brake (EMB) is a promising brake actuating system for electrified vehicle. To enhance the system function safety while saving space from redundancy sensors, this paper studied sensorless climbing force control for the EMB where a new climbing force estimator is proposed by fusing the information from vehicle dynamics and EMB states. The work was done with three contributions: 1) The priori clamping force characteristics were implemented to build the estimator with two parallel models, one of which was derived from the actuator rigid-body dynamics while the other was derived from vehicle longitudinal dynamics model; 2) a weighted-sum function is developed to fuse the estimation results from the two parallel models; 3) a proportional-integral observer utilizing wheel speed residual signals was developed to correct the initial estimates iteratively. Comparative study was conducted on a co-simulation platform and the results showed that the proposed method can reduce

Xing, Yipu, Zhou, Quan, Li, Congcong, Han, Wei, Zhuo, Guirong, Xiong, Lu

Methodology for Replicating and Quantifying Clicking-Noise Phenomenon in Gen 3 Wheel Hub Bearings and CVJ Using NVH Analysis and Data Processing

2025-01-0368To be published on 09/15/2025

This paper presents a comprehensive methodology for replicating and quantifying the clicking-noise phenomenon occurring between Generation 3-wheel hub bearings and Constant Velocity Joints (CVJ), particularly in electric vehicles (EVs) where quiet operation makes this noise more noticeable. The study focuses on characterizing the system through contact pressure and distribution measurements, alternating torque tests, and advanced NVH (Noise, Vibration, and Harshness) data processing. The methodology includes detailed descriptions of the physical phenomena, driving conditions generating the noise, and the specific test setup used to simulate real-world conditions. The NVH analysis employs high-pass filtering techniques to isolate clicking-noise events from background noise, ensuring accurate identification and quantification. Promising solutions, such as SKF's laser texturing technology, are evaluated for their effectiveness in reducing the clicking noise without the need for additional

Nardicchia, Riccardo, Mauro, Ivan

A Novel Simulation Method for Vehicle Brake Wear Emissions

2025-01-0361To be published on 09/15/2025

The effective reduction of particulate emissions from modern vehicles has shifted the focus to tire, brake, road wear and re-suspended particulate emissions. To meet future EU air quality standards and even stricter WHO targets for PM2.5, a reduction in non-exhaust particulate (NEP) emissions seems to be essential. For this reason, the EURO 7 emissions regulation contains limits for PM and PN emissions from brakes and tire abrasion. Graz University of Technology develops test methods, simulation tools and evaluates technologies for the reduction of brake wear particles and is involved in and leads several international research projects on this topic. The results are applied in emission models such as HBEFA (Handbook on Emission Factors). In this paper, we present our brake emission simulation approach, which calculates the power at the wheels and mechanical brakes, as well as corresponding rotational speeds for vehicles using longitudinal dynamics equations integrated in the

Landl, Lukas, Ketan, Enis, Hausberger, Stefan, Dippold, Martin

Further Investigation of Disc Pad Compression during ISO Compressibility and Dynamic Modulus Measurements

2025-01-0334To be published on 09/15/2025

In an earlier publication, it was reported that the pad compressibility measured under 160 bars on Lowmet formulas keeps decreasing with increasing number of repeated measurements due to unrecoverable residual deformation of the friction material combined with increasing moisture adsorption, which increases the hardness of the friction material. This current investigation was undertaken to find out if this same phenomenon occurs for NAOs under a low pressure of 100 bars during the compressibility measurement and under 45 bars during the dynamic modulus measurement. In all cases, it is found that the same phenomenon occurs, meaning that friction materials become permanently compressed without full recovery, making them harder to compress and raising up the modulus. The dynamic modulus of friction material attached to a backplate is found to be underestimated by 3.5% as compared with the friction material without the backplate, using the iETEK estimation method.

Sriwiboon, Meechai, Rhee, Seong Kwan, Sukultanasorn, Jittrathep

Optical diagnostic analysis of methane combustion performance and emissions while incorporating ammonia and multiple flames in a spark-ignition engine

2025-24-0023To be published on 09/07/2025

The current state of internal combustion engine technology necessitates the use of cleaner fuels with lower carbon content in order to mitigate CO2 release into the atmosphere. Ammonia and methane show potential as alternatives to traditional hydrocarbon fuels due to their ability to reduce carbon emissions. This study investigated the use of different energy fractions of ammonia in a methane mixture to reduce carbon-based emissions. However, ammonia, being a less reactive fuel with a lower flame speed than methane, may negatively impact engine performance. To address this, the study employed a multiple flame generation approach to accelerate the combustion rate. The experiment was carried out on a single-cylinder four-stroke optical research engine. To initiate multiple flame fronts, a customized metal liner with four equi-spaced spark plugs was utilized. To compare the results with conventional spark-ignition conditions, one spark plug was placed at the center of the cylinder head

Uddeen, Kalim, Tang, Qinglong, Shi, Hao, Turner, James

Design of a pure synchro-reluctant machine with asymmetrical poles for high-speed applications

2025-24-0129To be published on 09/07/2025

In this article, the authors present the various choices made to design a magnet free and directly recyclable pure synchro-reluctant (Pure-SynRel) machine with asymmetrical poles operating at a maximum speed of 21,000 rpm dedicated to automotive. This project was carried out by identifying design levers and optimizing the magnetic circuit in order to remove 3 well know issues of this topology: maximizing the power factor to reduce the inverter rating and cost, minimizing sources of NVH and torque ripples in particular, and finally maximizing the efficiency in use to close the gap with magnet technologies (PMaSynRel). The sizing of stator components such as the choice of winding (concentric or distributed, full or fractional pitch, round or hairpin wire) and rotor components (number of poles pairs, shape and number of barriers, etc.) are explained. The optimizations methods and the mechanical solutions used to reach the max speed are also detailed. A machine with symmetrical poles was

Applagnat-Tartet, Antoine, Milosavljevic, Misa, Delpit, Pierre

Simulation based dynamic thermal emulation unit for thermal preconditioning and emulation of hardware components on the thermal testbed

2025-24-0137To be published on 09/07/2025

Electrification of vehicles plays an important role in the transformation pro¬cess towards sustainable mobility in the individual and transport sector. As a result, new challenges must be met during the development process with regard to the vehicles overall energy management system. A key challenge is the development of thermal management systems to optimize overall vehicle efficiency and to minimize ageing effects of the powertrain com¬ponents while maintaining passenger comfort. Efficiency and ageing effects are highly dependent on the conditioning state of the powertrain components due to their high thermal sensitivity with simultaneously narrow thermal operating limits. Comfort functions like cabin air conditioning have to be fulfilled as well, which has to be considered by the thermal management system. To develop innovative solutions for thermal management systems at an early stage of the development process, thermal emulation can be used to substitute hardware components

Weimer, Niko, Hohenberg, Günter, Beidl, Christian, Fiore, Luis, Stenger, Erik, Seib, Rico

A Novel Nozzle Orifice Design of a Heavy-Duty Diesel Engine to Achieve Higher Thermal Efficiency with Significantly Reduced Heat Loss

2025-24-0037To be published on 09/07/2025

Recently, it has been widely recognized that increasing compression ratio is one of the essential technologies for improving thermal efficiency of heavy-duty diesel engines. However, while a higher compression ratio contributes to improved thermal efficiency, it also causes increased heat loss, which can surpass the efficiency gains. Therefore, more effective heat loss reduction technologies should be developed. Despite various attempts, including thermal barrier coatings which are well known as the measure for surface temperature swing, no existing technology has successfully achieved a significant reduction in heat loss while simultaneously improving thermal efficiency across a wide operating range. In this study, a novel nozzle orifice design to improve thermal efficiency was investigated. The offset orifice nozzle has holes drilled offset of less than 0.5 mm from the radial center of the nozzle. The experimental results demonstrated that the offset orifice nozzle achieved

Mukayama, Tomoyuki, Uchida, Noboru

Optimizing an H2 combustion system and investigating abnormal combustion through advanced visualization techniques

2025-24-0061To be published on 09/07/2025

The rapidly evolving mobility sector is facing the dual challenge of market expansion and the need for significant emissions reduction. Most of the transition tends to go in favor of electrification, yet it’s widely assumed that no single solution is perfect. Thus, hydrogen as an energy-vector presents a compelling alternative. H2 internal combustion engine use a well-known architecture and utilizes existing production facilities making it a viable short-term and cost-effective option. This context prompted us to investigate the hydrogen spark-ignited internal combustion engine, focusing specifically on critical combustion issues. Various studies have identified recurring challenges such as managing abnormal combustion and achieving high specific power. During our in-house developments, we also faced abnormal combustions and sought to determine the root cause of these issues. Initially, using a modular single-cylinder engine, a combustion system has been optimized regarding injection

Londos, Benoit, Serrano, David, Gautrot, Xavier, Colliou, Thierry, Bardi, Michele, Bramoullé, Clément, Cordier, Matthieu, Rouleau, Loic

Investigation of a Lambda Leap Strategy for Hydrogen Internal Combustion Engines to Balance Efficiency, Performance, and Vehicle Packaging

2025-24-0070To be published on 09/07/2025

The paper reports investigations into employing a “lambda leap” strategy for hydrogen internal combustion engines (H2ICEs), wherein inherently low NOx emissions are afforded at light load via operation at lambda 2.5 or leaner, and at higher load by operation at stoichiometry with a three-way catalyst. This approach means it is necessary under transient operation to “leap” between high values of lambda and stoichiometry from one cycle to the next, in order to avoid completely the area where high combustion NOx is generated away from lambda = 1; this is because lean catalysis of NOx will be extremely challenging there. The requirements for the cam profiles and valvetrain hardware to achieve this strategy are discussed, and a 2.0 litre in-line 4-cylinder engine configuration with the necessary valve gear functionality is modelled. The efficiency results on an operating map are then presented. In turn, this data is used to model the hydrogen consumption of two vehicles (one a saloon car

Fong Cisneros, Eric J., Kodaboina, Raghu Vamsi, Vorraro, Giovanni, Turner, James W. G.

Study of a CI Engine for off-road in Diesel-Hydrogen Dual Fuel Configuration

2025-24-0055To be published on 09/07/2025

Hydrogen as fuel in internal combustion engines is a promising solution for reducing greenhouse gas emissions, as its combustion produces only water vapor. One potential application is in dual fuel (DF) engines, where diesel is used to ignite the mixture, and hydrogen serves as the primary fuel. However, there is limited literature on the use of hydrogen in compression ignition (CI) engines for off-road applications running in dual fuel diesel/hydrogen, which motivates this study. The focus is on a 3-cylinder, 1-liter naturally aspirated (NA) engine with a compression ratio of 17.5:1 equipped with direct injection (DI) for diesel. Retrofitting the engine with 3 port fuel injectors, it was possible to feed the engine with hydrogen by the control system elaborated in the laboratory. The study aims to analyze dual fuel diesel/hydrogen combustion characteristics and the emissions across different engine speeds (from 1600 rpm to 3600 rpm) and loads (30%, 50% and 70%). The dual fuel

Gelé, Raphaël, Mancaruso, Ezio, Rossetti, Salvatore, Rousselle, Christine, Brequigny, Pierre

Analysis of Momentum Flux Distribution in Jets Produced by a Hydrogen Direct Injection System

2025-24-0065To be published on 09/07/2025

The adoption of hydrogen as carbon-free fuel for internal combustion engines in both transport and off-road applications could offer a significant contribution towards carbon neutrality. In the technical pathway to the conversion of conventional engines operating with liquid fuels to hydrogen, a key role is played by the injection systems. In particular for direct-injected combustion systems, the achievement of an adequate capability to control the gas jets development and the following mixing with air in the combustion chamber is mandatory in order to govern the heat release rate, so to obtain high efficiency levels while limiting the knock tendency and NOx formation. In order to achieve this complex task, the development of effective diagnostic methodologies for a satisfactory characterization of high-pressure gas jets is required in order to obtain a proper matching with the combustion chamber design and air charge flow structure. In the present paper, the jet produced by a

Postrioti, Lucio, Fontanesi, Stefano, Martino, Manuel, Maka, Cristian, Breda, Sebastiano, Falcinelli, Francesco, Ricci, Andrea

Water Injection Effects on a Heavy-Duty Hydrogen SI Engine

2025-24-0050To be published on 09/07/2025

Hydrogen engines have gained interest recently, as they present a promising alternative for the decarbonization of heavy-duty transport, aligning with carbon neutrality regulations. This study investigates the effects of inlet manifold water injection on a heavy-duty hydrogen fueled spark ignition single cylinder engine, focusing on moderating abnormal hydrogen combustion and its impact on performance, thermal efficiency and exhaust emissions. Water injection has been identified as a potential solution to mitigate the challenges associated with hydrogen combustion, such as pre-ignition and knock, by reducing the reactivity of the mixture (reducing temperature and increasing the dilution). The lower reactivity of the mixture allows running richer lambdas without spontaneous preignition mitigating boosting requirements for full load and transient performance. Experimental results demonstrate that water injection significantly improves engine performance, thermal efficiency and exhaust

Peñin Garcia, Alfonso Jose, Valls Claramunt, Carles, Rivas, Manuel, Birnstingl, Johannes, Wieser, Martin, Martin, Jaime, Novella, Ricardo

Zero-Carbon Port Fuelling for Heavy Propulsion Through a Recuperated Split Cycle Engine

2025-24-0044To be published on 09/07/2025

Upcoming global emissions regulations demand innovation in heavy-duty road and marine transport. This research explores emissions-compliant concepts using both experiments and simulations focused on the Recuperated Split Cycle Engine (RSCE), which separates compression and expansion to enable internal heat recovery and quasi-isothermal compression. A single-cylinder research engine representing the expansion cylinder of an RSCE demonstrated direct injection diesel and port injection hydrogen co-firing. A validated Chemkin-Pro Multi-Zone model first reproduced, then extended this work, evaluating partial diesel substitution with hydrogen or ammonia alongside secondary working fluids (SWF’s liquid N₂, H₂O, NH₃). For the extension, two variants of the split cycle architecture were employed; the RSCE in combination with hydrogen fueling for the heavy-duty road sector, and the novel recuperated reformed split cycle engine (R2SCE), a new architectural and simulation contribution enabling on

Wylie, Elisa, Panesar, Angad

Influence of Gas Pressure Levels on Injection Timing, Combustion Anomalies, and Emissions of a Hydrogen Gas Engine

2025-24-0053To be published on 09/07/2025

A former diesel heavy duty engine was retrofitted to hydrogen operation in attempt to simultaneously facilitate the shift from fossil to renewable fuels and maximize the quantity of reusable engine parts. Changing the fuel in this case does not make a properly working engine, the burning process needs to be in premixed flame. Rather than diffusional flame. Therefor an additional ignition source is necessary. A well-known characteristic of hydrogen is the low need for ignition energy and the wide range of ignitable air/ fuel ratios. Both need to be considered to reach a diesel engine equivalent performance. In spark ignited internal combustion engines, port fuel injection (PFI) and direct injection (DI) are commonly used. Some disadvantages such as weak volumetric efficiency and combustion abnormal phenomena like backfire connected to PFI. To further improve the volumetric efficiency, high boost pressures are needed. To maximize volumetric efficiency injection timing after intake valve

Rößlhuemer, Raphael, Fellner, Felix, Fitz, Patrick, Prager, Maximilian, Jaensch, Malte

New Hybrid Powertrain architectures for European Passenger Car Market

2025-24-0097To be published on 09/07/2025

The present paper describes a comparative analysis of different hybrid architectures and optimization of the total energy efficiency on passenger car applications. The first part of the study is devoted to providing simulation results of different type of hybrid architecture, highlighting their advantages and disadvantages with numerical simulation on different type of use cases, not only on legislated cycles but also on RDE use cases representative of customer behavior. The outputs of the usage of Passenger cars for the EU market highlights interesting results not yet published. The above mentioned analysis opens the window to (1) study new control strategies for optimizing the total energy consumption in different scenarios and (2) investigate options for maximizing the efficiency of the overall powertrain system.

Amati, Nicola, Marello, Omar, Mancarella, Alessandro, Cavallaro, Davide, Ianni, Luca, Cascone, Claudio, Paulides, Johannes JH

Ammonia Combustion with Ignition Improvement Measures in a High-Speed Marine Application

2025-24-0025To be published on 09/07/2025

Ammonia (NH3) has gained significant attention as a zero-carbon fuel which is capable of supporting global decarbonization goals, especially in the maritime transportation and power generation sectors. Its hydrogen density, storage feasibility, established production methods, and transportation infrastructure are key benefits which contribute to its potential both as a hydrogen carrier and as a direct fuel. The study investigates the combustion characteristics and emission profiles of ammonia on a spark ignited 2.13L single cylinder engine with the goal of evaluating ammonia as a single fuel. This displacement is representative of the typical cylinder displacement of small to mid-size engines for marine applications on sportfishing boats and as auxiliary power units. Challenges to consider for ammonia combustion are its high ignition energy requirement and low laminar flame velocity. Several methods were employed to compensate for these properties such as increasing compression ratio

Li, Zhengling, Lückerath, Moritz, Pischinger, Stefan, Boberic, Aleksandar, Franzke, Bjoern, Dhongde, Avnish, Jagodzinski, Bartosch, Burrows, John, Korkmaz, Metin

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