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Experimental Characterization and Optimization of a Staggered Rotor System for Heavy-Lift Urban Air Mobility Drones2026-01-0661To be published on 07/01/2026
The increasing adoption of drones in Urban Air Mobility (UAM) applications has intensified the need for compact, high-thrust, and energy-efficient aerial platforms capable of lifting heavy payloads under variable environmental conditions. Conventional coaxial rotor systems, while offering high lift density and reduced footprint, suffer from aerodynamic wake interference that decreases overall thrust efficiency. To address this limitation, a staggered rotor configuration was proposed and experimentally investigated to enhance thrust and stability performance. Controlled thrust stand tests were conducted with lateral rotor spacing varied from 0.25 to 1.0 times the propeller radius, while wind conditions were simulated using a Windshaper system to apply time-dependent gust loads under different payload scenarios. Results demonstrated that the coaxial arrangement exhibited an efficiency loss of about 15%, whereas the staggered configuration reduced this loss to approximately 7%, showing
Santhani, Raju, S, Syam Narayanan, B, Tarun Kumar, Rajalakshmi, P
The History of the International Powered Lift Conference Across Five Decades of V/STOL Progress2026-01-0662To be published on 07/01/2026
This year, SAE International hosts the 2026 edition of the International Powered Lift Conference (IPLC), which focuses on the latest developments in vertical and/or short takeoff and landing (V/STOL) aircraft research, concepts and programs. IPLC is a joint technical meeting, held approximately biennially, co-sponsored by the American Institute of Aeronautics & Astronautics (AIAA), the Royal Aeronautical Society (RAeS), SAE International and the Vertical Flight Society (VFS). Because each technical society hosts IPLC only once a decade, staff turnover at the societies creates a lack of knowledge and historical context of the event. This paper provides a formal record of the history and legacy of the IPLC, and its progress in highlighting the technical and programmatic progress of V/STOL over the ages.
Hirschberg, Michael J.
Conceptual Design and Aerodynamic Configuration of the Relithia Nova: A 2000kg Hybrid-Electric STOL Aircraft2026-01-0660To be published on 07/01/2026
This paper presents the conceptual design of the Relithia Nova, a hybrid-electric Short Take-Off and Landing (STOL) aircraft engineered to provide essential connectivity to remote regions with limited aviation infrastructure, such as the South Pacific and Caribbean. Designed with a Maximum Take-Off Mass (MTOM) of 2,000 kg, the aircraft accommodates six occupants, including the pilot, and is optimized for operations on short, unprepared airstrips up to 2,000 ft elevation. The Relithia Nova employs a series-hybrid propulsion architecture featuring two wing-mounted turboshaft engines coupled with electric generators that drive propulsive rotors via a high-capacity lithium-ion energy storage system. This configuration ensures sustained power for high-lift generation while reducing emissions. Aerodynamically, the aircraft utilizes a high-aspect-ratio wing (AR=8.67) based on the NACA 23012 airfoil, chosen for its favorable lift-to-drag characteristics in subsonic flow (Mach 0.23 cruise
Chikwanha, Hendrick Tafadzwa
Revisiting the Ball-Bartoe Jetwing and other USB Powered Lift Aircraft: Lessons Learned2026-01-0663To be published on 07/01/2026
This paper will revisit an area of STOL operations and Powered Lift aircraft design that has been limited in scope, and at best, very specialized when it comes to research, aircraft manufacture, and experimentation. Five aircraft have been flown successfully using the Upper Surface Blowing (USB) powered lift configuration: The Ball-Bartoe Jetwing, the Boeing YC-14, the Antonov An-72, the NASA / Boeing QSRA experimental aircraft, and the National Aerospace Laboratory Aska STOL Research aircraft. A background of the technology will be given, what connects them as far as USB technology, discuss the main lessons learned, and briefly dwell on other configurations that are close relatives of the USB configuration. An extensive review of the existing USB literature will be fundamental for the development of this paper. Although all the unclassified USB projects that have been constructed and tested will be discussed (successful and unsuccessful), the main thrust of the paper will be the Ball
Pinero, Erasmo
Vibration Synthesis and Seat Dynamics Compensation for Single-Axis Seat Vibration in Driving Simulators2026-01-0673To be published on 06/20/2026
Realistic seat vibration reproduction is essential for delivering authentic haptic cues and enhancing driver immersion in driving simulators. Unlike direct playback of road recordings, simulator applications require vibration synthesis that responds interactively to driver inputs and vehicle dynamics. Reproducing these vibrations at the seat is complicated by actuator bandwidth, cross-axis coupling, and the dynamic behavior of the seat structure, which can alter the intended target response. This work presents vibration synthesis and seat dynamics compensation methods implemented on a dual-axis seat vibration reproduction system equipped with horizontal and vertical actuators. Frequency Response Functions (FRFs) were measured to characterize the system dynamics under both single-axis and dual-axis excitations, capturing direct responses as well as cross-axis effects. Run-up, coast-down, and combined excitation tests were then used to evaluate performance under more operational
Muthu Chaiphas, Joshua Daniel, cuenca, Jacques, Bianciardi, Fabio, Colangeli, Claudio, Deckers, Elke, Denayer, Hervé, Janssens, Karl
Spatial Optimisation of Inner Dash Acoustic Performance using Reciprocal Holography2026-01-0712To be published on 06/20/2026
As acoustic requirements for NVH trim components become more demanding – driven by cost, weight, and increasingly, sustainability – there is growing pressure to optimise performance across multiple criteria. In complex components such as the inner dash, performance is often assessed in isolated. However, this fails to reflect real-world conditions, where contributions from ancillary systems, the instrument panel, and variable noise sources such as the power unit, gearbox, and tyres are significant. Traditional Transmission Loss (TL) measurements provide averaged results that can overlook spatial variation and lead to suboptimal design choices. To address this, an approach is presented that uses reciprocal holography to map the spatial TL performance of an inner dash. This method enables a more representative and targeted design process for achieving effective acoustic performance in fully built vehicle environments. Furthermore, the spatial Transmission Loss data can be combined with
Harry, Evan, Eandi, Giacomo
Joint estimation of inputs and states for multi-axis vibration environment testing2026-01-0683To be published on 06/20/2026
Monitoring the states of a structural dynamic system is often challenging, as direct measurements are costly or even infeasible. Estimating “hard-to-measure” quantities from a limited set of output-only data is therefore of great interest and useful for the application of Structural Health Monitoring (SHM) systems. This work proposes a virtual sensing methodology for state estimation in structural dynamics based on a tuned Kalman Filter, combined with a model order reduction technique to ensure low computational cost. The approach aims to overcome the limitations of dense embedded physical sensor networks by reconstructing unmeasured responses from limited measurements. The methodology is validated numerically and experimentally on a notched aluminum beam, representative of an overhanging automotive component, subjected to multi-directional base excitations on a 3D shaker to emulate realistic operating conditions.
Salazar Colunga, Rodrigo, Pandiya, Nimish, Dindorf, Christian, Naets, Frank
Active Learning Supported Metadata Extraction from NVH Simulations2026-01-0720To be published on 06/20/2026
Simulations can only be searched, reused and leveraged as trainings data for machine learning methods if they possess suitable metadata. Manually obtaining this metadata is time-consuming and requires expert knowledge. Consequently, there is often a lack of metadata, and this prohibits the reutilisation of simulation data. Therefore, automated frame works for metadata extraction are essential to quickly, effortlessly and cost-efficiently obtain this information. At present, there are no existing toolboxes for Finite-Element-Simulation data and current Large Language Models are not usable. Nevertheless, machine learning methods are a promising solution for this task. However, classical supervised machine learning methods cannot be used due to the high effort for labelling. Therefore, classical rule-based extraction algorithms are an alternative for fundamental metadata extraction. For more enhanced tasks, where more context is necessary, they are not usable. Active Learning is the
Luegmair, Marinus, Gröttrup PhD, Sören
Methodology Development for EDM Vibro-acoustic Assessment using Simulation Measurement Comparison and RCA2026-01-0691To be published on 06/20/2026
The virtual development of Electric Drive Modules (EDM) for Battery Electric Vehicles (BEVs) requires proven and predictive methodologies. One part of the development investigates the vibro-acoustic assessment for low and high frequencies over the targeted operating range. The efficient usage of such a methodology requires the understanding of the accuracy and the validity of the achievable results as well as the derivation of suitable improvement measures for goals that have not been achieved. The usage of reference data from experimental investigations and a detailed root-cause analysis (RCA), to directly link a specific response and behavior to the excitations, modal content and transfer functions, is an essential and non-trivial part of the methodology development. This paper describes the development of such a methodology using the example of a new EDM virtual model for Noise, Vibration and Harshness (NVH) analysis, the simulation approach, validation, and evaluation procedure. It
Klarin, Borislav, Pevec, Denis, Resch, Thomas, Esposito, Sara, D'Alessandro, Vincenzo, Spanu, Giorgio
NVH Design and Refinement of Dedicated Hybrid Engine on Range Extender Electric Vehicle2026-01-0688To be published on 06/20/2026
Traditional NVH (Noise, Vibration, Harshness) refinement is reactive, addressing issues post-prototype. In contrast, this work establishes NVH as the primary driver in early engine development for range extender electric vehicles (REEVs). Customer demands for imperceptible engine operation [1] - intensified by absent masking noise in electrified powertrains [2] - necessitate a proactive methodology: Usage-Driven Operating Profile: Analysis of >500,000 km fleet driving data identified statistically dominant operating conditions. This enables precise NVH focus areas and proactive avoidance-zone definition in the engine operational map. Vehicle-Driven Target Setting: Subsystem-level NVH targets (e.g., <58 dB(A) idle noise → engine-level) were rigorously derived from vehicle imperceptibility requirements and the dominant usage profile. Preventive Design Optimization: Architectural choices (stiffness-enhanced bedplate block), component tuning (crankshaft/flywheel dynamics), and subsystem
wang, hao, zhang, guiqiang
Feasibility of Hybrid Dynamic Substructuring for Structural Modifications in Automotive Suspension Subsystems2026-01-0697To be published on 06/20/2026
Recent advancements in system-level NVH (Noise, Vibration, and Harshness) development methodologies have improved target cascading and enabled more efficient system-level optimization. Dynamic substructuring facilitates the virtual integration and modification of multiple subsystems and the prediction of changes in overall transfer functions. In practical automotive applications, advanced frequency-based substructuring has been applied to virtually modify system parameters—such as mass and stiffness—at multiple points in a target system, allowing prediction of the resulting effects and optimization of parameter changes without physical intervention. This study extends the methodology by introducing an enhanced substructuring approach capable of addressing not only basic parameter modifications but also large-scale structural changes. The proposed process involves identifying the characteristics of a base system assembly and a target subsystem, decoupling the subsystem from the assembly
Cho, Munhwan, Boelens, Jelle, Reichart, Ron, de Klerk, Dennis, Ahn, Jiho
Development and Standardization of a Compensation Method for Measurement Equipment Effects to Improve Blocked Force Accuracy in Physical Tires2026-01-0698To be published on 06/20/2026
Although the tire system is not developed in-house but supplied by tire manufacturers, it is a critical component that significantly affects overall vehicle performance, including NVH. To ensure the supplied tires meet vehicle performance targets, our company provides detailed development guidelines, defining block force—closely related to road noise—as a key NVH performance index. As virtual tire development is introduced, manufacturers will submit block force data from virtual models with initial tire designs, enabling early prediction of tire and vehicle-level performance. However, this approach is still under evaluation, with unresolved challenges such as the absence of clear block force target-setting methods and limited accuracy in current virtual evaluations. To address this, we propose using block force measurements from mass-produced or prototype tires as a basis for data-driven target setting and as a reference to enhance virtual model accuracy. Since block force data is
ahn, youngeun, Kang, Min Kyoo, Kim, Yong Dae, Reichart, Ron, Kim, Yonghun, Han, Inhyuk, JI, Unjin, Lee, JeongHwan
A Modular Method for Certified Virtual Validation of NVH Performance in Automotive Platforms2026-01-0684To be published on 06/20/2026
This work presents a modular engineering methodology (DigPhBalance - Digital Physical Balance) for the virtual validation of Noise, Vibration, and Harshness (NVH) performance in automotive development. The approach addresses the inefficiency of repeated physical testing across vehicle variants by introducing a structured two-phase process—Launcher and Reskin—centered on quantitative performance indicators with formal acceptance thresholds. In the Launcher phase, a digital replica of the base vehicle is built and iteratively correlated with physical test data. Validation is governed by objective indicators of confidence, conformity, and correlation, each evaluated against predefined thresholds. Once validated, the model becomes a certified reference, enabling its reuse across derivative configurations in the Reskin phase. Physical testing is only required if indicators fall below threshold, with a final gate test on pre-series vehicles ensuring industrial robustness. DigPhBalance
Celiberti, Lucia, Camia, Andrea
Mid-High frequency structure-borne transmission in full vehicles trimmed body models using a reverberant finite element approach2026-01-0706To be published on 06/20/2026
The simulation of structure-borne energy flow within a full vehicle trimmed body at mid and high frequencies has always been a challenge due to the large computational cost associated with standard deterministic simulations. This is a particularly pressing problem given that the electrification of the vehicles is extending the presence of structure-borne sources to higher frequencies. While the improvement of computational hardware has allowed OEMs to shift the limit of standard Finite Element (FE) approaches to higher frequencies, no methods have been proposed in the literature that tackle the full frequency range for industrial-sized problems. In this paper, a simulation methodology that uses wave-based processing of the original low-frequency finite element input deck to compute the coupling loss factors is proposed to model structure-borne noise in complex systems at mid and high frequencies. The methodology is validated against numerical and experimental data.
Errico, Fabrizio, Legault PhD, Julien, Mordillat, Philippe, Zerrad, Mehdi
Validation of an adaptive order Finite Element model for transmission loss simulation of trimmed automotive structures2026-01-0707To be published on 06/20/2026
Vehicle electrification and increasing demands for driving comfort present significant challenges for designing effective noise control treatments in modern vehicles. Lightweight, low-emission designs often compromise acoustic efficiency. One way of compensating this is through the use of multi-layer ‘trim’ material configurations to mitigate noise across a wider frequency range. Traditional 3D finite element models, while accurate and even needed to capture the full dynamic behaviour, become computationally prohibitive for complex automotive structures like firewalls, which feature intricate shapes, high curvature, and material compression. This computational burden limits design exploration and timely noise performance predictions. This paper introduces the use of an innovative adaptive higher-order finite element method to address these challenges. The method utilizes a fixed finite element discretization of trim components and surrounding acoustic fluid, incorporating an automated
Van Genechten, Bert, Vansant, Koen, Purohit, Bimal, Effinger, Veronika
Vibroacoustic Analysis and Optimisation of an Electric Refrigerant Scroll Compressor2026-01-0722To be published on 06/20/2026
In electrified vehicles, auxiliary units can be a dominant source of noise, one of which is the refrigerant scroll compressor. Compared to vehicles with combustion engines, e-vehicles re-quire larger refrigerant compressors, as in addition to the interior, the battery and the electric motors must be cooled. Various types of excitation in the compressor cause vibrations on the compressor surface and the emission of airborne noise. Fluid dynamic forces resulting from the cyclic compression principle act on flow-conducting components, while alternating forces caused by the imbalance of the eccentrically running compressor scroll or by torque fluctua-tions on the drive shaft are transmitted to the housing via the bearings. In order to identify the sound generation mechanisms in the compressor, the vibrations of the compressor surface were measured using a laser scanning vibrometer and the sound radiation was characterised using a sound intensity probe. This paper illustrates the
Saur, Lukas, Beer, Gabriel, Fritzsche, Marco, Becker, Stefan
Simulation and Analysis of Flow and Acoustic Induced Structural Vibration2026-01-0696To be published on 06/20/2026
For analysing flow and acoustic induced structural vibration, a run time fully coupled framework combining a hybrid CFD-CAA approach with a modal response simulation was validated and presented at the ISVNH 2022 (SAE Technical Paper 2022-01-0938). In this contribution we show the application of this method on a production vehicle, simulating the flow and acoustic induced vibration of the bonnet. The simulation setup of this study resolves the geometry of the vehicle including the complex details of the bonnet structure, the frunk and the engine compartment. The FEM model for the modal analysis of the bonnet takes into account the complex boundary conditions at the bearings and provides the eigenmodes relevant for the low frequency range. Simulations are conducted in an undisturbed wind tunnel setup and the resulting vibrations are compared to acceleration measurements under wind tunnel and road conditions. Due to the employed hydrodynamic acoustic split approach, the relevance of the
Schwertfirm, Florian, Ocker, Joerg, Hartmann, Michael
Application of Tone-to-Noise Ratio for Early Diagnosis and Control of Electric Drive Whine2026-01-0686To be published on 06/20/2026
High-frequency whine from electric drive systems has become a critical issue restricting the improvement of vehicle sound quality. Traditional evaluation methods struggle to accurately identify masked whine risks in the early research and development (R&D) phase, due to incomplete hardware of prototype vehicles and high interior background noise. This often leads to problems being delayed until the mass production stage, resulting in high rectification costs. To address this issue, this paper proposes and validates an early risk assessment method based on the Tone-to-Noise Ratio (TNR). First, the generation mechanism of Electric Drive (E-Drive) whine is systematically analyzed, identifying the electromagnetic noise of the electric motor and the gear whine of the reducer as the two dominant noise sources. To address this bottleneck, the TNR psychoacoustic metric is introduced to quantify the perceptual salience of tonal noise relative to background noise, which effectively mitigates the
YUN, ZHAO, Hui, Hui, gao, Pan, Xiao, Zhongdi, zan, chen, Teng, Charlie
AI-Based Package Tray Design Method for Controlling Acoustic Modes in a Sedan2026-01-0716To be published on 06/20/2026
• In this study, we propose a methodology for predicting the acoustic modes and natural frequencies of a sedan using artificial intelligence and demonstrate the feasibility of controlling its acoustic characteristics by modifying the hole distribution of the package tray. In typical sedan structures, the cabin cavity and trunk cavity are acoustically coupled through holes in the package tray. The distribution of these holes significantly affects the natural acoustic modes and frequencies of the vehicle. However, once the exterior shape of the vehicle is finalized during the design phase, options for structural modifications to mitigate noise issues caused by these modes become extremely limited. To address this challenge efficiently, we develop a deep learning-based neural network model trained on data derived from a simplified acoustic analysis model of a sedan that includes a package tray. Finite element analysis is performed to generate acoustic modes and natural frequencies, which
Lee, Jin Woo, Cho, Jaeho, Nam, Younsic, Han, Yongha
A Self-Learning Framework for NVH CAE Analysis2026-01-0718To be published on 06/20/2026
The vibro-acoustic performance of a vehicle is a critical factor in customer perception of quality and comfort. Optimizing for Noise, Vibration, and Harshness (NVH), particularly road noise, presents a persistent challenge in the automotive development cycle. While modern FEM analysis is essential, the increasing complexity and sheer volume of CAE simulation data often overwhelm manual interpretation, potentially leading to prolonged development times or sacrifices in resulting comfort quality. To address these challenges, this paper introduces the application of CDH/ACE (Autonomous Computational Experiments), a framework that combines conventional CAE simulation workflows with machine learning in an iterative cyclic process. This creates a self-learning and self-correcting system that autonomously defines, performs, and learns from computational experiments. By building predictive models from simulation data, the framework intelligently guides the design exploration to achieve
Visser, Rene
Effect of Backing PU Foam Material Properties on Acoustic Insulation Pad Insertion Loss2026-01-0678To be published on 06/20/2026
The effect of backing PU foam material on the insertion loss of insulation pads was investigated. First, the material properties affecting the resonant frequency—which determines the insertion loss—were theoretically identified, and practical methods for calculating both the resonant frequency and the insertion loss of the insulation pad were developed. These methods were then applied to evaluate how changes in material properties influence the resonant frequency and insertion loss of the insulation pad. It was found that Young's modulus, Poisson's ratio, and thermal characteristic length are the primary material properties that affect these outcomes. The optimal levels of these properties, which are beneficial for interior noise reduction, are derived and presented in this study.
Chae, Ki-Sang, Lee, Moonseok, Kim, Hyunwoo
Best-in-Class NVH Optimisation for Electric Powertrains, Holistic Front-Loading Approaches2026-01-0689To be published on 06/20/2026
Achieving best-in-class Noise, Vibration, and Harshness (NVH) in electric powertrains demands a paradigm shift in development methodology. This paper presents a holistic, front-loaded approach to NVH optimisation, leveraging simulation models, machine learning, and target cascading to deliver superior results. By attacking NVH at the source, and integrating data-driven techniques early in the design cycle, significant reductions in development time and reliance on traditional testbed loops are realised. Machine learning algorithms are utilised to accelerate root cause analysis and refine simulation accuracy, while target cascading ensures alignment of system-level performance objectives down to subsystem contributions. Combined, these strategies enable rapid and robust NVH optimisation, setting the benchmark for next-generation electric powertrain development. several application and real life exmaple are shown.
Mehrgou, Mehdi, Garcia de Madinabeitia, Inigo, Graf, Bernhard, Gojo, Josef
Investigation of Spline-Induced Excitation Forces in Electric Drive Units via Flexible Multibody Dynamic Simulation2026-01-0692To be published on 06/20/2026
This study investigates the NVH characteristics of the spline coupling that connects the motor and reducer shafts in an electric drive unit, using flexible multibody dynamic simulations. Focusing on the source stage of the NVH analysis process, the excitation force magnitude and spline trajectory are examined under various spline design conditions. The study compares spline fit types (side fit vs. major fit), clearance vs. interference conditions, and variations in tooth number and module size. All spline configurations are designed to meet AGMA safety factor requirements. Side fit splines exhibit lower first-order excitation forces compared to major fit splines, but significantly higher excitation forces at higher orders. This leads to increased spline trajectory amplitude and amplified whirling of the input shaft. Since the input gear is directly coupled to the input shaft, this whirling behavior induces eccentricity in the gear itself. In particular, clearance fit conditions result
KIM, Dong-Jun, HWANG, Seung Gyu, KIM, Donghee, Kim, Seon Hyeong, LEE, SangHan, Grant, George, Halse, Christopher
NoiseSphere: An AI-Based Approach for Dynamic and Large-Scale Noise Mapping2026-01-0719To be published on 06/20/2026
Noise pollution is a major environmental and health challenge, yet its strong spatial and temporal variability makes comprehensive mapping highly complex. Current approaches under the European Noise Directive (END) provide only partial coverage and often lack temporal dynamics. The NoiseSphere project, fundet by the Austrian Research Promotion Agency FFG, develops an AI-based methodology for dynamic, large-scale noise prediction and mapping. A machine learning model is trained on heterogeneous data sources, including semantically enriched Sentinel-2 satellite imagery, OpenStreetMap road data, floating car data (traffic density and speed), and existing noise maps. The model is refined through integration of noise emission data and validated using targeted in-situ measurements. Two case studies, one located in an urban environment (Graz) and the other one in a rural region near Linz demonstrate the model’s applicability across contrasting settings. By combining remote sensing, traffic
Girstmair, Josef
PSYCHOACOUSTIC ANNOYANCE MODELS ASSESSMENT FOR AUTOMOTIVE FAN-SYSTEMS2026-01-0672To be published on 06/20/2026
Because of automotive electrification, fan systems previously hidden by internal combustion engines could become key contributors to the overall noise behavior. Metrics like overall Sound Pressure Level or Loudness are first order metrics enabling ranking. Yet, second order factors, that are relevant to assess annoyance, are not correctly described using a single criterion. This paper studies the applicability of various Psychoacoustic Annoyance (PA) models in an attempt to address subjective perception of sound quality. Based on pairwise comparison through a jury test with a set of 8 noises at a similar global level, the combined impact of several psychoacoustics metrics was previously determined. This computation includes a signal modulation metric, a frequency content balance and a tonal criterion. To assess this approach, the correlation for fan-system noise annoyance ranking based on its jury test is compared with several PA criteria, starting from initial Zwicker and Fastl model
Scouarnec, Denis, Bennouna, Saad
High-frequency mount characterization: a comparison of methodologies2026-01-0693To be published on 06/20/2026
The rapid electrification of the automotive industry introduces new challenges in noise, vibration, and harshness (NVH). In particular, in a virtual prototyping phase of the e-vehicles development, the rubber mounts are often one of the key elements to be considered when analysing the structure borne noise contributions. Having an accurate experimental characterization of the mount dynamic stiffness curves is therefore very relevant. However, conventional mount characterization methods are often pushed to their limits, partly due to the use of stiffer bushings, and partly because the frequency range of interest is extended toward higher frequencies. When using inverse substructuring, the dynamic stiffness curves can be obtained from frequency response function measurements. The required test setup consists of excitations and responses, located on each side of the mount via dedicated fixtures. The measured frequency response functions are reduced into 6 degrees of freedom representation
Bianciardi, Fabio, Forrier, Bart, Minervini, Domenico, Barbieri, Marco, Janssens, Karl
An Experimental Setup for Vibroacoustic and Fluid-Borne Noise Characterization of Electric Refrigerant Compressors using R1234yf or R7442026-01-0724To be published on 06/20/2026
The increasing electrification of vehicles leads to a broader range of tasks for heating, ventila-tion and air conditioning systems and a shift in its priority assessment. Air conditioning systems in electric cars are no longer primarily responsible for cooling the passenger compartment, but also have to temperature-control the battery, especially during rapid charging, which repre-sents a high-load operating point. Additionally, the elimination of the combustion engine as a major noise source brings the NVH behaviour of the refrigerant compressor a higher priority in product selection. In order to investigate the vibration and acoustic behaviour, as well as fluid dynamic forces resulting from the cyclic compression principle of an electric refrigerant compressor, a test rig was previously developed, allowing compressors to be operated and measured isolated in an anechoic chamber under various defined operating points. This test rig has been expanded in two ways within the scope of
Beer, Gabriel, Saur, Lukas, Schwarz, Manuel, Zemsch, Stefan, Becker, Stefan
Spatial Noise Acquisition at the Driver's Position in an Electric Vehicle with Increased Accuracy2026-01-0723To be published on 06/20/2026
In vehicles with electrified powertrains, high-frequency tonal noise components have become increasingly prominent and can be perceived as particularly annoying by the driver. While recent advancements in international standardization—such as ECMA-74 and ECMA-418—have led to powerful new algorithms for tonal noise visualization and analysis, like our Tonality-Heatmaps, the measurement side still lacks sensor setups that adequately reflect the spatial sensitivity of noise, especially for tonal components. This challenge is amplified in enclosed vehicle cabins, where room modes create local minima and maxima that become increasingly dense at higher frequencies. As a result, even small head movements can lead to noticeable differences in perceived tonal noise. Current measurement approaches do not sufficiently account for this spatial variability. This contribution addresses the absence of tailored solutions for the driver’s position by introducing an improved microphone arrangement that
Schecker, Daniel, Rittenschober, Thomas
A New Approach to Identify Rigid Body Rotations When Measuring the Body Distortion of a Full Vehicle2026-01-0682To be published on 06/20/2026
The Opening Distortion Fingerprint (ODF) is a method to evaluate the overall body stiffness of a vehicle using the Multi Stethoscope (MSS). Using the MSS, the time history of distortion in diagonals located at all body openings and cross sections of a vehicle are captured. Evaluation of the ODF is applicable in both test and Multibody Dynamics (MBD) simulation. It has been found that the Evaluation-line (E-line) method, which is used for the distortion calculation, gives valid results in the absence of large rotations originating from rigid body modes that occur at low frequencies. The E-line method measures the relative displacement between two points in a local coordinate system. One straightforward way of identifying the frequency at which the large rotations start to make the E-line results invalid, is to compare the distortion in the local z-component (pointing in the direction of the diagonal) of the E-line method with the total distance (i.e. the total deformation of the
Olger, Emma, Lindkvist, Lisa, Piiroinen, Petri, Karypidis, John, Pena, Milton, Bäcklund, Jesper, Appelgren, Peter, Marberg, Henrik, Ugale, Pravin, Weber, Jens
Improving reliability of an automotive power electronic unit using Locally Resonant Metamaterials2026-01-0701To be published on 06/20/2026
The shift from internal combustion to electric vehicles necessitates addressing new challenges posed by novel components, materials, manufacturing processes and different operating regimes. This includes assessing new types of excitations and damages from a reliability perspective. This paper investigates a solution to enhance the reliability of the Printed Circuit Board (PCB) within a Power Electronic Unit (PEU). PCBs are critical electronic and mechanical supports for functional components (e.g. diodes, transistors, resistors) in numerous applications. Controlling critical vibration levels is crucial to prevent electronic component breakage and subsequent PEU functionality loss. Existing solutions often focus on improving sensor-PCB bonding, surface treatments, or stiffening components’ support structures. The proposed approach, instead, exploits Locally Resonant Metamaterials (LRMs) to reduce the vibrational load experienced by the PCB. LRMs are created by adding resonating elements
Tincani, Sara, Claeys, Claus, Deckers, Elke, Pandiya, Nimish, Dindorf, Christian
Frequency Based Substructuring as Key Enabler for New NVH Root Cause Analysis Types in FE Simulations2026-01-0710To be published on 06/20/2026
Noise, vibration, and harshness (NVH) performance is critical in the automotive development process, yet identifying the true root causes of unwanted dynamic behavior remains a challenge in full vehicle or system‑level finite element (FEM) models. This work demonstrates how frequency based substructuring (FBS) provides an efficient framework for understanding NVH and facilitates new root cause analysis types and processes. To begin, we prove the high numerical accuracy of the FBS algorithm deployed in the BETA CAE software by comparing its results with those obtained without substructuring. Then we illustrate how FBS supports new root cause analysis types, starting with a new variant of transfer path analysis (TPA). While standard TPA assesses the paths between only two system components, the new expanding TPA is a multi-step process that identifies the most critical path across all components in a fully automated way. Furthermore, if the FBS workflow starts with a modal representation
Herbst, Markus
Dynamic characterisation and modelling of Electric Cables under representative load conditions2026-01-0676To be published on 06/20/2026
Electric high voltage (HV) cables are commonly used in automotive applications and very prominently in electrified vehicles. These cables are potential flanking transmission paths for structure-borne sound in a broad frequency range and must therefore be included in the NVH design process. Electrical high voltage cables exhibit non-linear mechanical characteristics, when exposed to significant bending the internal geometry of the cable will change and a curvature dependent bending stiffness will result. The electrical cables envisaged in the current publication feature a helically wound stranded aluminium wire core. This conductive core is covered by, in sequence, a silicone rubber insulation, a braided aluminium wire shield with aluminium foil to minimize electromagnetic interference and a silicone rubber outer sheath. An extensive measurement campaign was carried out to dynamically characterize cable specimen of different lengths and cross sections in terms of multi-degree of freedom
Nijman, Eugene, Buchegger, Blasius, Böhler, Elmar, Zeller, Bernhard, Rejlek, Jan, Faksa, Lukáš, Lukavsky, David
Analytical Magnetic Circuit Modeling and Parameter Estimation of a PMSM for Spatial Harmonics and Radial Forces Characterization2026-01-0677To be published on 06/20/2026
Electromagnetic excitations originating from air-gap flux distortions and radial forces are a dominant source of noise and vibration in Permanent Magnet Synchronous Motor (PMSM) operating at low-to-medium speeds. While finite-element analysis provides detailed insights into these effects, it is computationally intensive and often requires precise geometrical data. Conversely, conventional dq0-based models fail to represent slotting effects and nonsinusoidal fluxes, limiting their accuracy in harmonic prediction. This paper proposes an analytical model of a three-phase PMSM based on a Magnetic Equivalent Circuit (MEC) to accurately identify spatial harmonics and compute current-induced radial forces. An offline parameter estimation procedure is employed to characterize the magnetic circuit, making the model adaptable to various motor topologies and pole configurations without relying on detailed geometry. The proposed approach enables the derivation of the machine’s electrical and
Luciano, Ludovica, Doria-Cerezo, Arnau, Salamone, Nicolò
Regularized Inverse Methods for Tire Noise Source Identification and Pass-by Noise Estimation in Electric Vehicles2026-01-0709To be published on 06/20/2026
Tire exterior noise has become increasingly critical in vehicle acoustics due to two key developments: updated pass-by noise regulations, which amplify the relative contribution of tire noise, and the rise of Battery Electric Vehicles (BEVs), which lack traditional powertrain noise. Design trends in BEVs—such as increased vehicle mass from battery packs and the widespread use of large-diameter, wide, low-profile tires—further intensify tire noise due to stiffer constructions and altered contact dynamics. A common method for predicting tire noise is the source-transfer-receiver model, where the tire is represented by a set of monopoles with volume velocity Q derived from near-field measurements. Acoustic propagation is modeled via p/Q transfer functions. Despite its simplifications, this approach is practical for vehicle development, enabling clear separation between source and transfer mechanisms and facilitating targeted noise control strategies. In previous work, we proposed a
Morin, Benjamin, Di Marco, Federico, Horak, Jan, Lafont, Thibault, Kim, Minkyu, Kang, Min Kyoo, Yoo, Ji Woo
Standardized Equivalent Tire Load measurements delivered by suppliers to an OEM enabling consistent and comparable simulation input.2026-01-0699To be published on 06/20/2026
Part- or component-level tests are commonly performed by Tiers and OEMs to investigate the NVH behavior and loading mechanisms. However, because test bench dynamics differ from those of the actual vehicle environment, correlating measured sound, acceleration, and forces between bench and vehicle often proves challenging. Blocked forces offer a way to address this issue, as they provide test bench– and vehicle–independent load representations, effectively enabling different Tiers to deliver consistent load data, which OEMs can then to better tune excitation and noise transmission on their vehicles. This paper focuses on 2 test bench compensation techniques, involving pure test and a simulation models of the tire, to obtain accurate blocked-forces. The compensation techniques are validated on four testbenches of different companies.
Reichart, Ron, de Klerk PhD, Dennis
Holistic sound package design for optimal NVH and carbon footprint of a BEV2026-01-0708To be published on 06/20/2026
Vehicle sound packages are usually designed to provide a given level of vehicle NVH comfort, under weight and cost constraints. Optimal comfort results can be obtained by considering the interaction of all the parts as a full physical system. So far, extensive research has already been performed and published on optimizing vehicle sound packages to achieve effective noise reduction at lowest cost and weight. Nowadays, due to the urgency of the transition to carbon neutrality, sound packages must also address the reduction of the full vehicle life cycle carbon emissions. Sound package components should use materials that have a low emission impact during production and that are suitable for recycling at the end of the vehicle’s life. This entails reconsidering the material solutions chosen for the sound package as a whole, rather than for each individual component. This article describes the design process of a sound package involving NVH, sustainability, and weight/cost requirements
Courtois, Theophane, Cardillo, Marco, Criscione, Mattia, Gerges, Youssef, Massocco, Andrea
Study on Interior Noise Contribution and Improvement Measures for the Door System of a Premium Vehicle2026-01-0675To be published on 06/20/2026
It has been observed that in recently developed advanced vehicles, the door system contributes significantly to interior noise levels. In this study, the noise transmission paths through the door system were investigated and effective improvement measures were explored. In order to determine the noise transmission paths through the door system and to establish effective countermeasures, door buck tests were conducted. In addition, under the same conditions, simulations were carried out using a Finite Element-based acoustic analysis tool to evaluate the effectiveness of modifications that could not be tested experimentally. While attaching sound-absorbing pads to the rear surfaces of door trims is a commonly used method for improving noise transmission, the most effective approach was found to be the addition of sound-absorbing materials between the door outer panel and the module panel, as well as reducing the vibration of the door outer panel itself.
Chae, Ki-Sang, Jang, Jinung, Jeong, Hojung, Do, Hyuncheol, Han, Jinwoo, Yi, Jaebok, Bak, Seong-Jae, Jeong, ChanHee
Early-Stage BIW Design Evaluation Using Higher-Order Beam–Shell Hybrid Models2026-01-0674To be published on 06/20/2026
Achieving favorable NVH and durability performance in the vehicle requires sufficient static and dynamic stiffness of the Body-in-White (BIW). Virtual development of BIW performance targets in the early stages is essential to minimizing costly modifications in later phases. In the automotive industry, full-scale finite element models are widely used for this purpose, offering high fidelity and enabling virtual performance evaluation. However, their complexity and the significant computational resources they demand limit their practicality for early-stage sensitivity and optimization studies. Beam-based models offer a faster alternative, but conventional formulations based on Euler or Timoshenko theory often fail to capture the complex deformation behaviors of thin-walled structures typical of BIW designs. This limitation generally leads to poor correlation with detailed models unless artificial joint flexibility is introduced. To address these challenges, we propose a hybrid modeling
Kim, Jin Hong, Gang-Won, Jang
NEW CORRELATION APPROACH FOR BODY DISTORTION OF A COMPLETE VEHICLE USING MBD AND TEST RESULTS2026-01-0680To be published on 06/20/2026
By using a fully trimmed vehicle body as flexible body (MNF model) in a complete vehicle Multibody Dynamics (MBD) analysis, the simulation setup gets considerably closer to the test conditions compared to only using a linear FEM approach. Since the MBD analysis includes the nonlinear behavior of the wheel suspension, the gravity and the rigid body modes of the vehicle, it brings the correlation between simulation and test to a new and more comprehensive level. As correlation criteria, the results of the so-called Multi Stethoscope (MSS) are used. The MSS captures the time history of distortion in all body openings and cross sections and enables a detailed stiffness evaluation of the body using the so-called Opening Distortion Fingerprint (ODF). The ODF gives the quasi-static response while the Operational Deflection Shape (ODS), which is another result of the MSS measurements, reflects the dynamic response. Apart from the different individual steps of this new correlation approach, the
Lindkvist, Lisa, Olger, Emma, Piiroinen, Petri, Karypidis, John, Pena, Milton, Bäcklund, Jesper, Appelgren, Peter, Marberg, Henrik, Ugale, Pravin, Weber, Jens
Optimizing recycled and recyclable PET felt lightweight formulations for best acoustic insulation as poroelastic springs with minimum weight2026-01-0702To be published on 06/20/2026
For sustainability reasons, the automotive market is requesting 100% mono-material noise treatments, particularly for the end-of-life recycling without any part separation operation. But also, the OEMs require super light, highly performance insulating noise treatments for electric vehicles in order to extend vehicle autonomy. PP meltblown fiber felts present good mono-material characteristics with very good absorption, but generally not so good insulation properties behind an airtight barrier due to lack of stiffness. Moreover, these PP meltblown fiber felts are relatively expensive and not thermoformable, thus obliging to use them as 2D die-cut parts behind existing hard or soft trims classically. The optimization approach proposes to return to 100% thermoformable recycled and recyclable PET formulations blending unusual coarse mechanical specific fibers, in order to optimize the viscothermal exchanges, while maintaining good mechanical properties, with microfibers for best
Duval, ARNAUD, lei, lei, WILKINSON, Alexandre, DELINSELLE, Eric
Development of a Convolutional Autoencoder-Based Unsupervised Classification and Visualization Model for Extracting Feature Frequency in C-EPS Fault Diagnosis2026-01-0717To be published on 06/20/2026
In the automotive industry, deep learning models such as convolutional neural networks, autoencoders, and transformers have been actively studied to improve defect detection rates in End-of-Line (EOL) processes. However, applying these approaches to the field of Noise, Vibration, and Harshness (NVH) faces several practical challenges. ① Difficulty in securing sufficient training data and risk of overfitting due to longer evaluation times compared to other data types. ② Label imbalance caused by the relatively small amount of defective data. ③ Reduced labeling accuracy due to human error. ④ Decreased model robustness under domain shifts such as jig variations, evaluation environments, signal-to-noise ratio (SNR), and the occurrence of new abnormal noises. ⑤ Constraints in application due to compatibility issues with existing evaluation equipment. To address these issues, this study proposes an unsupervised learning-based method for classifying operating noise data of Column-type
Park, Jun-Seo, Jo, Hyeon-Choel, Cho, In-Je, Seo, Jae-Yong, Yoo, Seong-Sik
The Influence of Interior Noise on Just-Noticeable Speed Differences in Conventional and Electric Vehicles2026-01-0671To be published on 06/20/2026
Electric vehicles (EVs) and internal-combustion-engine vehicles (ICEVs) differ fundamentally in their in-cabin acoustics, notably the attenuation or absence of engine-order content. Prior work reports associations between reduced engine sound, speed underestimation, and poorer speed maintenance; however, research on how EVs’ new sound affects speed perception and control is scarce, and most newer studies focus on comfort and subjective pleasantness rather than speed perception per se. Addressing this gap, the present study uses a two-interval, two-alternative forced-choice (2AFC) paradigm to directly measure just-noticeable differences (JNDs) in speed under ICEV, EV, and silent conditions. Thirty participants performed a 2AFC task in which, on each trial, they viewed two first-person highway clips (reference vs. comparison) and indicated which appeared faster. Results from ANOVA and post-hoc tests indicate that at the 40 km/h reference speed participants showed no clear differences
LI, Zhenxian, Parizet, Etienne, Colangeli, Claudio
Robustness Analysis for A Computationally efficient Virtual Sensing Framework in time-domain for Exterior Vibroacoustics problems2026-01-0721To be published on 06/20/2026
Reconstruction of acoustic radiation from vibrating structures is central in vibroacoustic, as full-field sound information is essential for identifying radiation mechanisms and improving structural-acoustic performance. Conventional microphone-based measurements are limited by spatial sampling constraints and high experimental cost, while purely numerical approaches such as Finite Element Method (FEM) simulations, particularly in the frequency domain, offer flexibility but are strongly affected by parameter uncertainties, discretization errors, and imperfect boundary conditions. To overcome these drawbacks, this work develops a hybrid time-domain framework that couples vibration measurements with FEM-based acoustic models. The FEM model is reduced using Krylov subspace projection, yielding a compact state-space representation that captures the dominant vibroacoustic modes while remaining computationally efficient for sequential data assimilation. The acoustic radiation domain is
Dong, Luyao, Cai, Yinshan, Denayer, Hervé, Deckers, Elke
Electric drive unit housing ribbing for low noise radiation2026-01-0687To be published on 06/20/2026
Although propulsion noise often constitutes a minority of the overall noise in electric vehicles, it remains an important quality indicator due to its high-frequency tonal character, which is undesirable even at low levels. There are many factors that influence the interior car levels of propulsion noise, i.e. gear whine and electric motor whine. The primary ones to consider are the electric drive units (EDU) internal forces, but also secondary properties such as EDU housing design and encapsulation, vehicle sound pack and mount isolation play important roles. This work focuses on EDU housing design and more particularly on the housing ribbing that enables attachment point stiffness and housing strength, but which can also cause problems in terms of noise radiation. Numerical parameter studies on geometrical properties such as length dimensions, thickness and curvature were performed on single ribs of different types. For each design iteration, the key performance indicators radiated
Lennström, David, Malm, Oskar, wurzinger, Jakob, Cederlund, Johan
Experimental Validation of Frame-Dependent Gyroscopic Frequency Splitting in a Freely Rotating Tire Using Wireless MEMS Accelerometers and Scanning Laser Doppler Vibrometer2026-01-0700To be published on 06/20/2026
Gyroscopic effects split circumferential traveling-wave resonances of rotating structures into forward and backward branches. This work first analyzes the splitting in the co-rotating (Lagrangian) frame to provide physical intuition for the evolution of the two branches with spin speed. A transformation to the inertial (Eulerian) frame is then derived, showing that the observed frequencies are shifted by a kinematic Doppler-like term that acts with opposite sign on the forward and backward waves, leading to different Campbell-diagram slopes depending on the observation frame. The resulting framework is validated experimentally on a freely rotating, unloaded tire using two complementary sensing modalities: wireless on-tire accelerometers (co-rotating view) and a scanning laser Doppler vibrometer (inertial view). A frequency-domain SVD-based identification (FDD/ODS-SVD) is used to extract poles and deformation patterns over a range of spin speeds, enabling Campbell diagrams in both
del Fresno Zarza, Javier, Naets, Frank
A contribution to the probabilistic road noise simulation using a Non-Parametric Variability Modeling2026-01-0711To be published on 06/20/2026
An application of a Non-Parametric Variability Modeling (NPVM), as introduced by Pr. Soize, of a full vehicle road noise simulation, is an opportunity to highlight some applicative issues of such a stochastic approach. First, the convergence of the stochastic computations is considered by introducing the probabilistic modal density of the considered model as an indicator of the system intrinsic dynamic behavior. Since the probabilistic model induces a spread of modal frequencies, the upper range shows a lack of modes, deviating from the actual system modal density. The study of this deviation leads to the modal truncation criterion required to achieve a relevant probabilistic modal density in a targeted frequency range. The required margin in order to achieve a proper convergence of the probabilistic problems appears larger than expected. Then, using appropriate parameters, road noise simulation is investigated in the framework of the stochastic modeling. After the capability of the
Gagliardini, Laurent, Glandier, Christian, Bauer, Eric, Straka, Andreas, Fiedler, Uwe
Transmission Loss of Vehicle Components Using Virtual SEA: Validation and Modeling Challenges2026-01-0705To be published on 06/20/2026
In the automotive industry, controlling noise transmission through vehicle components is essential for passenger comfort and regulatory compliance. Traditionally, Transmission Loss (TL) is estimated using simplified CAD-based metrics, which lack accuracy at high frequencies and for complex assemblies. This study presents an industrial application applying the Virtual SEA (Statistical Energy Analysis) method to evaluate TL for firewall. Modeling complex vehicle components introduces challenges, such as representing fluid-structure and trim interactions, with spatially varying trim thicknesses. The study discusses strategies for subsystem adaptation and analytical trim modeling, highlighting the importance of managing untrimmed zones and spatial averaging effects. The proposed workflow integrates laboratory measurements of trim materials, advanced subsystem definition, diffuse sound field excitation and radiation in free conditions. Virtual SEA results are systematically validated
Orselli, Joseph, Jacquemin, Gaetan
NVH Aspects of DC Charging2026-01-0703To be published on 06/20/2026
The deployment of high-power DC charging infrastructure for electric vehicles introduces new challenges in managing noise, particularly in public environments where acoustic comfort and regulatory compliance are essential. Noise emissions from both charging stations and vehicles during charging are a concern for operators of charging parks regarding customer experience and sound immission regulations. AVL employed a structured three-step approach to develop a non-expert tool for assessing the noise radiation of charging stations and vehicles during the charging phase. In a first step, AVL characterized the noise emissions with sound power measurements. Secondly, the measurement results were transferred to the virtual domain. To achieve this, the vehicles and charging station were characterized in the simulation with multiple monopole sources supported by transfer function measurements. This simulation model was validated against the sound power measurement results. After successful
Gojo, Josef, Polanz, Markus, Graf, Bernhard, Langjahr, Paco, Mehrgou, Mehdi
Influence of Common Mode Voltage Reduction Algorithms on High-Frequency Sideband Vibrations in PMSMs2026-01-0695To be published on 06/20/2026
Space Vector Pulse Width Modulation (SVPWM) induces Common Mode Voltage (CMV) in three-phase Voltage Source Inverters (VSIs). This CMV generates high-frequency sharp edges that can lead to significant leakage currents, which, in drive applications, may accelerate motor bearing degradation and cause winding insulation failure. To mitigate these issues, alternative modulation strategies such as Active-Zero State PWM (AZSPWM) and Near-State PWM (NSPWM) have been proposed in the literature. These techniques aim to reduce CMV and thereby decrease the degradation of electrical drives. This paper analyzes the Noise, Vibration, and Harshness (NVH) performance of AZSPWM and NSPWM compared with conventional SVPWM. The two CMV reduction schemes are tested on interior permanent magnet synchronous motors (IPMSMs) to evaluate their effectiveness in lowering CMV, as well as their impact on high-frequency sideband vibration harmonics. The results show that, although CMV is effectively reduced
Khamis, Mahmoud Aly, del Corral, Victor, Doria-Cerezo, Arnau, Tatar, Andrei Alexandru
Bridging Simulation And Reality: Incorporating Seal Contact Detachment Into Stick–Slip Prediction2026-01-0714To be published on 06/20/2026
Preventing stick–slip in virtual vehicle development combines virtual displacement data with experimental sliding tests. If the calculated relative displacement at a contact exceeds the distance of two stick–slip impulses, that contact could be a potential noise source. Such risks can be mitigated only by design changes or alternative sealing concepts. Stick–slip tests provide the experimental reference, showing how often a frictional pairing produces impulses over a defined sliding distance. The basis for this assessment is Multibody Dynamics (MBD) simulations, which compute component deformations during virtual drives and derive relative displacements at contact interfaces (e.g. in the sealing gap between body and closure), representing the theoretical sliding distance that enables stick–slip effects. Yet, this combined approach has overlooked a critical factor: the deformability of automotive seals. Due to their elastomeric properties and geometry, seals can elastically follow
Strangfeld, Martin, Fritz, Susanne, Weber, Jens, Rosell, Anneli
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