Dániel Feszty

14053852300

Publications - 23

The Impact of Pitch Error on the Dynamics and Transmission Error of Gear Drives

Dániel Feszty Krisztián Horváth

Publication Name: Applied Sciences Switzerland

Publication Date: 2025-07-01

Volume: 15

Issue: 14

Page Range: Unknown

Description:

Gear whine noise is governed not only by intentional microgeometry modifications but also by unavoidable pitch (indexing) deviation. This study presents a workflow that couples a tooth-resolved surface scan with a calibrated pitch-deviation table, both imported into a multibody dynamics (MBD) model built in MSC Adams View. Three operating scenarios were evaluated—ideal geometry, measured microgeometry without pitch error, and measured microgeometry with pitch error—at a nominal speed of 1000 r min−1. Time domain analysis shows that integrating the pitch table increases the mean transmission error (TE) by almost an order of magnitude and introduces a distinct 16.66 Hz shaft order tone. When the measured tooth topologies are added, peak-to-peak TE nearly doubles, revealing a non-linear interaction between spacing deviation and local flank shape. Frequency domain results reproduce the expected mesh-frequency side bands, validating the mapping of the pitch table into the solver. The combined method therefore provides a more faithful digital twin for predicting tonal noise and demonstrates why indexing tolerances must be considered alongside profile relief during gear design optimization.

Open Access: Yes

DOI: 10.3390/app15147851

Systems engineering in automotive product development: A guide to initiate organisational transformation

Dániel Feszty Tibor Dory Tamás Kolossváry

Publication Name: Journal of Open Innovation Technology Market and Complexity

Publication Date: 2023-12-01

Volume: 9

Issue: 4

Page Range: Unknown

Description:

Systems Engineering (SE) is an engineering method that has rarely been applied in Automotive Product Development, despite its noticeable positive effects in other engineering fields. With increasing interests, firms and scholars have started to discover its impact in the segment, however internal hurdles appear when it comes to implementation practices at organisations across the industry. This paper presents a comprehensive guideline, results and good practices on the SE implementation, developed in Formula SAE (FSAE), which is a relevant model environment of automotive industry. The impact of applying SE show project results improvement in cost, time and quality aspects, although, the maturity of SE should be assessed at the system of systems level. Outcomes gained from FSAE have been validated by in-depth interviews with SE experts, engineers and managers affiliated at technical development departments of 4 different automotive OEMs. These practitioners provide evaluated practices as employee involvement, applying learning by doing, and playing with architectures relevant and feasible in industrial setting, however emphasized expected impeding factors as sluggishness and general resistance to organisational changes.

Open Access: Yes

DOI: 10.1016/j.joitmc.2023.100160

Comparison of Clustering-Based Virtual SEA Subsystem Generation Models

Dániel Feszty David Sipos

Publication Name: Journal of Theoretical and Computational Acoustics

Publication Date: 2023-09-01

Volume: 31

Issue: 3

Page Range: Unknown

Description:

Building a valid Statistical Energy Analysis (SEA) model is far from straightforward in real life applications because it has to comply with certain requirements. Since intuition-based SEA subsystems do not always entirely meet these, more advanced methods such as clustering techniques have been proposed for model building. This paper focuses on the comparison of different clustering techniques from SEA model validity point of view in the case of a simplified car body model. Besides the compliance with the SEA theory, each obtained model is compared to a reference finite element simulation to assess its accuracy.

Open Access: Yes

DOI: 10.1142/S2591728523500081

Approximation of the stiffness of laminate stacks of electric motors subjected to cyclic loads

Dániel Feszty Balázs Pere Viktor Szabó

Publication Name: Materialpruefung Materials Testing

Publication Date: 2023-08-01

Volume: 65

Issue: 8

Page Range: 1202-1208

Description:

Electric motors in automotive applications are subjected to high thermal and structural loads, while having strict requirements regarding dimensions, mass, and costs. The design of such motors requires sophisticated simulation models. The laminate stack in the rotor of such a motor is made of steel sheets and behaves transversally isotropic: the radial stiffness is equivalent to steel, and in the axial direction, it has a highly progressive nonlinear stiffness characteristic. The loading and unloading stiffness curves change from cycle to cycle when subjected to repetitive loads. In this paper, the usage of a single approximating curve to describe the longitudinal stiffness of the laminate stack is proposed. This approximation can be used in FEM models to reproduce the structural nonlinear behavior of such a laminate stack using a simpler approach than implementing the full loading and unloading curves in a material model, at a price of negligible loss of precision.

Open Access: Yes

DOI: 10.1515/mt-2022-0382

UNDERSTANDING AND ACCEPTANCE OF SYSTEMS ENGINEERING IN AUTOMOTIVE PRODUCT DEVELOPMENT

Dániel Feszty Tibor Dory Bálint Filep Tamás Kolossváry

Publication Name: Decision Making Applications in Management and Engineering

Publication Date: 2023-04-01

Volume: 6

Issue: 1

Page Range: 70-91

Description:

Systems Engineering (SE) is a new engineering method for many firms in Automotive Product Development that expectedly advances their development processes to meet their stakeholder needs more effectively. Literature suggest that understanding and acceptance are key factors in the implementation, however comprehensive modes for their increase are barely discussed. In this paper, we propose a Participatory Action Research based on multiple research elements to find an effective technique for gaining understanding and acceptance on SE in a validated model environment of automotive industry called Formula SAE. We present practical outcomes at each steps of the implementation process and analyze the effect of improvements in the context of strategy, structure processes.

Open Access: Yes

DOI: 10.31181/dmame04012023k

Validation of finite element connection modeling by comparison of experimental and virtual power injection methods

Dániel Feszty Marcell Treszkai David Sipos

Publication Name: Journal of Vibroengineering

Publication Date: 2023-01-01

Volume: 25

Issue: 1

Page Range: 209-225

Description:

There are several ways to obtain the matrix of damping loss factors and coupling loss factors for Statistical Energy Analysis. The most recent approach is Virtual SEA, where the Power Injection Method is performed virtually on a finite element model. In order to validate this approach, the most common connection types are investigated in this paper through an L-junction of two coupled steel plates. Virtual SEA and experimental Power Injection Method results are compared in a bent, line welded, superglued and spotwelded variants. The respective finite element connection representation is also validated during the comparison. It was found that with the correct simulation setup, Virtual SEA provides good agreement with the experimental results. In case of the spotwelded variants, further investigations were necessary regarding the parameters of the connection. The influence of these parameters was evaluated and the greatest source of deviations in the results is found.

Open Access: Yes

DOI: 10.21595/jve.2022.22754

The effect of the preload determination process on dynamic mechanical properties

Dániel Feszty Balázs Vehovszky Attila Schweighardt

Publication Name: Journal of Physics Conference Series

Publication Date: 2023-01-01

Volume: 2677

Issue: 1

Page Range: Unknown

Description:

NVH simulation and experimental methods are getting more and more important because of the increased customer needs for reliability and comfort. In order to obtain appropriate NVH simulation results accurate material properties have to be provided as input parameters. In case of the dynamic mechanical property determination of acoustic viscoelastic foams the results may vary greatly depending on the measurement settings and the quality of the measurement. This study evaluates the effect of the preload determination process on dynamic mechanical properties and the repeatability of the dynamic compression tests. Finally, conclusions are drawn and suggestions are made for the settings.

Open Access: Yes

DOI: 10.1088/1742-6596/2677/1/012007

Optimization of damping pad distribution on body-in-white car structure

Dániel Feszty Marcell Treszkai David Sipos

Publication Name: Journal of Vibroengineering

Publication Date: 2022-01-01

Volume: 24

Issue: 2

Page Range: 386-393

Description:

Structure-born noise is one of the most important contributors to the interior noise in a vehicle cabin. This can be effectively reduced by placing damping pads with special material properties along the chassis and on the large, radiating panels. This paper proposes a new methodology for the optimization of placing these pads as a part of a full vehicle acoustic simulation in Actran Virtual SEA. With this new strategy, it was possible to reduce the among of damping pads on a real car structure by 33 % while keeping the same acoustic performance. This was validated by investigating the mean velocity of the floor panel in two load cases and compared to the original damping pad layout to the optimized one.

Open Access: Yes

DOI: 10.21595/jve.2021.22158

Possible Applications of Quantum Computing, Especially in Vehicle Technology: A Review Article

Dániel Feszty István Lakatos Ferenc Ignácz

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2022-01-01

Volume: 50

Issue: 3

Page Range: 245-251

Description:

Given the current trend in the development of quantum computing, it can be expected that it will revolutionize many areas of science, including vehicle technology. In this review, we present the current research results of quantum computing technology and its possible application potential in the field of vehicle technology and structural simulation. In addition, we provide an overview of the current challenges, difficulties, and future of quantum computing.

Open Access: Yes

DOI: 10.3311/PPTR.16547

Damping determination by the half power bandwidth method for a rectangular flat plate with bitumen damping layer application

Dániel Feszty Balázs Vehovszky Marcell Treszkai

Publication Name: Journal of Vibroengineering

Publication Date: 2021-08-01

Volume: 23

Issue: 5

Page Range: 1267-1277

Description:

Damping Loss Factor (DLF) is an important input parameter in Statistical Energy Analysis (SEA) simulations, therefore its accurate determination via measurement is crucial from simulation accuracy point of view. This paper presents a methodology for the accurate measurement of DLF via the Half Power Bandwidth Method (HPBM) for three test cases: A) a rectangular steel plate, b) the same plate with viscoelastic bitumen sheets imposed on the middle of plate and c) the same plate with the viscoelastic bitumen sheets placed randomly. The aim of the different bitumen layer applications was to develop a methodology for representing them in Statistical Energy Analysis, since this simulation technique takes into account only the coverage of the damping layers but not their distribution over a panel. Measurement of the DLF in random locations on the plate gave the appropriate parameters for the simulation. Measurement results were then applied in SEA simulations, which showed good agreement with the experimental results in all test cases, with the maximum difference of only 2 dB.

Open Access: Yes

DOI: 10.21595/jve.2021.21938

Welding distortion generated uncertainties in the vibrational behavior of a ladder-like structure

Dániel Feszty Marcell Treszkai David Sipos

Publication Name: Proceedings of Inter Noise 2021 2021 International Congress and Exposition of Noise Control Engineering

Publication Date: 2021-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Recent developments in acoustic simulation methods allowed engineers to assess the vibroacoustic behavior of various type of structures within a virtual environment, thus allowing the replacement of prototype-based development with simulations. However, there are some factors, that cannot be considered in simulations in advance. In the present study, the effect of the distortions generated due to welding on a ladder-like structure equipped with flat plates was investigated. The measured acceleration frequency response functions were compared to finite element simulation results. The measured responses differed significantly from the simulation, even in the low frequency ranges, where the global modes were not expected to be altered or vanished. Investigation of the simulated results revealed that the additional modes were related to the vibration of the plates, which were assumed to be flat, instead of considering the warping caused by the welding process. After measuring the approximate deformation of the plates, an updated simulation model was made, introducing an approximate curvature in them. The results obtained with the updated simulation model performed much better in the low frequency range as well as in the third octave-averaged frequency bands up 1200 Hz. The sensitivity of the warping was also systematically evaluated.

Open Access: Yes

DOI: 10.3397/IN-2021-2844

Effect of junction type on the vibroacoustic response of a system of plates

Dániel Feszty Marcell Treszkai

Publication Name: Proceedings of Inter Noise 2021 2021 International Congress and Exposition of Noise Control Engineering

Publication Date: 2021-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Modelling of junctions is one of the most challenging tasks in vibroacoustics, especially for Statistical Energy Analysis (SEA), where the results heavily depend on the damping (DLF) and coupling loss factors (CLF). Also, it is an interesting question to determine that to what extent does the DLF or CLF contribute to the overall vibroacoustic characteristics of a structure? The aim of this paper is to investigate via measurements and SEA simulations the effect of the ratio of DLF and CLF on the response of a system for various junctions, such as riveting, bolting, line and point welding, between two steel plates. Loss matrices are determined experimentally by the Power Injection Method in the 200-1600 Hz frequency range. The simulation was performed in the ESI VA One software by using its analytical CLF formulations and compared to experimental data. For the reference case, a bended plate structure was considered, representing an ideal junction between two subsystems. This was equipped with damping foils to ensure the same weight and then compared to the results from other joints. Results showed that increasing the CLF could be more effective than focusing on increasing the DLF.

Open Access: Yes

DOI: 10.3397/IN-2021-2565

NVH characterization of a ladder-like welded structure using finite element analysis and experimental method

Dániel Feszty Balázs Vehovszky Attila Schweighardt

Publication Name: Advances in Acoustics Noise and Vibration 2021 Proceedings of the 27th International Congress on Sound and Vibration Icsv 2021

Publication Date: 2021-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

In vehicle industry, considering a chassis, the evaluation of the experimental modal analysis is usually done up to 80 Hz, since the modal density is increasing with frequency. In addition, the deviation between the measurement and simulation is getting more significant at higher frequencies. The purpose of this study is to extend the usable test range and to improve the accuracy of the results both in case of measurement and FE (Finite Element) simulation. Present paper introduces the vibrational characterization of a ladder-like welded structure. This test case represents a simplified model of a vehicle's frame consisting of rod-like elements with high stiffness, connected to each other in welded junctions. Although such simulational and experimental modal analysis procedures are widely used in practice, results can significantly change according to the used method and the fine-tuning of parameters. For this reason, a further goal is to find the best measurement and simulation technique for the given structure. During the FE analysis different modelling solutions and element types were compared. In order to discover the effect of the manufacturing inaccuracies, the same measurements were performed on two distinct, but theoretically identical samples. The influence of the experimental setup (e.g. excitation and fixing method) and settings were investigated as well. Finally, FE simulation and experimental results are compared using Frequency Response Functions.

Open Access: Yes

DOI: DOI not available

Simulations of poroelastic materials in a complex acoustic system using frequency-dependent parameters in the mid-frequency range

Dániel Feszty Janos Kun

Publication Name: Proceedings of Inter Noise 2021 2021 International Congress and Exposition of Noise Control Engineering

Publication Date: 2021-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Efficiency requirements prompt manufacturers to develop ever lighter acoustic packages in vehicles. Poroelastic materials are essential to achieve the desired interior noise level targets and thus the simulation of their effects is of utmost importance in NVH analyses. However, it is challenging to achieve good validation between finite element method (FEM) based simulation results and measurements in the mid-frequency range (400-1000 Hz). One possible reason could be the lack of using frequency-dependent Biot-paremeters describing the poroelastic materials (PEM) characteristics of trims. The present research aims to employ frequency-dependent Biot-parameters for the PEM materials to investigate the acoustic response of a scaled car-like steel structure composed of flat plates and U-section stiffeners enclosing an air cavity. Porous acoustic material is applied to the walls of the cavity. The focus of the study is to understand the effect of applying frequency-dependent Young's modulus and damping values for the PEM parameters in the 100-1000 Hz range. Simulation results obtained from ESI VPS FEM solver are compared with measurements, with particular focus on the interior sound pressure levels. The simulation methodology, including discretization techniques, structural damping and fluid damping applications are described in detail.

Open Access: Yes

DOI: 10.3397/IN-2021-2869

Power Injection Method-based Evaluation of the Effect of Binding Technique on the Coupling Loss Factors and Damping Loss Factors in Statistical Energy Analysis Simulations

Dániel Feszty Marcell Treszkai Alexander Peiffer

Publication Name: Manufacturing Technology

Publication Date: 2021-01-01

Volume: 21

Issue: 4

Page Range: 544-558

Description:

Measurement results on the Damping Loss Factor (DLF) and Coupling Loss Factor (CLF) between two steel plates is presented for 19 different junction types. The junctions involve joining technologies, such as line welding, point welding, bolting, riveting, gluing or their combinations, and with varying spacing between the junction points and the angle between the plates. From the measurement results, the DLF and CLF values were calculated by the Power Injection Method for the purposes of being applied in Statistical Energy Analysis simulations. Four excitations were applied at each subsystem by impact hammer, while the response was recorded at sixteen response points at each subsystem. The measured CLF values were compared to each other from various aspects. Data were compared to the results obtained from SEA simulations by using the built-in analytical formulas. In general, good comparison was observed, although the results appeared to be somewhat dependent on the frequency band. Finally, it was examined whether replacing the DLF values with data obtained for an uncoupled flat plate, as well replacing the CLF values with data from analytical formulas leads to acceptable accuracy of the simulation results.

Open Access: Yes

DOI: 10.21062/mft.2021.065

Extended Solution of a Trimmed Vehicle Finite Element Model in the Mid-Frequency Range

Dániel Feszty Jonathan Jacqmot Antoine Guellec Markus Brandstetter David Sipos

Publication Name: SAE Technical Papers

Publication Date: 2020-09-30

Volume: Unknown

Issue: 2020

Page Range: Unknown

Description:

The acoustic trim components play an essential role in Noise, Vibration and Harshness (NVH) behavior by reducing both the structure borne and airborne noise transmission while participating to the absorption inside the car and the damping of the structure. Over the past years, the interest for numerical solutions to predict the noise including trim effects in mid-frequency range has grown, leading to the development of dedicated CAE tools. Finite Element (FE) models are an established method to analyze NVH problems. FE analysis is a robust and versatile approach that can be used for a large number of applications, like noise prediction inside and outside the vehicle due to different sources or pass-by noise simulation. Typically, results feature high quality correlations. However, future challenges, such as electric motorized vehicles, with changes of the motor noise spectrum, will require an extension of the existing approaches. In this paper, the vibro-acoustic frequency response of an existing MSC Nastran FE model is extended using the Actran Statistical Energy Analysis (SEA) approach, Virtual SEA. In Virtual SEA, the necessary information required to build the SEA system is extracted from the FE models. The fluid-structure Coupling Loss Factors (CLF) are computed through the Statistical modal Energy distribution Analysis (SmEdA) method. This method is a suitable candidate to account for acoustic trim effects based on analytical approach. The case studied consists of a trimmed body car model transfer function calculation. The result of the case study is an extensive correlation study containing measured and simulated transfer functions in low and mid-frequency range. Simulation results are derived from two approaches, FE method and Virtual SEA method.

Open Access: Yes

DOI: 10.4271/2020-01-1549

Design of acoustic cavity test apparatus for validation of mid-frequency response of a plate-cavity system

Dániel Feszty Tamas Turcsik Janos Kun

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020

Publication Date: 2020-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The mid-frequency range acoustic response between 400-1000 Hz has gained particular interest in the automotive industry recently. Simulation of this region is challenging due to the non-negligible statistical effects, especially when acoustic trim is applied. In order to be able to investigate the effect of these materials in the presence of an air cavity, this paper describes the design methodology behind the design and manufacturing of two test apparatuses that include an air cavity. The apparatuses were designed to serve as a validation tool for Finite Element Method (FEM) and Statistical Energy Analysis (SEA) simulations, which meant that an optimal size had to be found based on the number of fluid modes in the cavity. Two types of plate-cavity apparatuses have been designed: one with “rigid walls” and one with “soft walls”. In the “rigid wall” cavity, the walls are made out of concrete since these boundary conditions can be perfectly represented in simulations. In the “soft wall” cavity, the walls are made of steel plates and this allows validation of coupling loss simulations between multiple structural subsystems as well as an air cavity. Details of the joining methods, geometries, material selections are elaborated to fully describe the theoretical and practical implications of the designs.

Open Access: Yes

DOI: DOI not available

Methods for improving the mid-frequency acoustic simulation of a lightly damped plate

Dániel Feszty Marcell Treszkai Tamas Turcsik Janos Kun

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020

Publication Date: 2020-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The constantly evolving customer demands in the automotive industry necessitates vehicle manufacturers to perform ever more accurate acoustic simulations. Acoustic simulations especially in the mid-frequency range (400 Hz - 1000 Hz) pose particular challenges: statistical methods lack the necessary modal density for accuracy, while Finite Element Methods (FEM) have difficulty accounting for statistical effects. In order to resolve the conflict that FEM solvers face, an academic case is investigated. A flat plate of 650x 750 mm in free-free condition is examined as a low-complexity platform to investigate the sensitivity of FEM simulation results to parameters, such as the value of structural damping, the frequency dependency of structural damping as well as the variations in the plate thickness due to manufacturing tolerances. FEM simulations were performed using ESI VPS and compared to measurements. Results show that slight variations in plate thickness and Young`s modulus can have significant impact on the frequency response. Results have shown that a 0.5% variation in the thickness already has a pronounced effect on frequency response peak locations, especially between 600 and 1000 Hz. Beside this, the paper provides novel results on evaluating the effects of frequency dependency of structural damping on the results.

Open Access: Yes

DOI: DOI not available

Modal analysis of the tubular space frame of a formula student race car

Dániel Feszty Balázs Vehovszky Attila Schweighardt

Publication Name: Manufacturing Technology

Publication Date: 2020-08-06

Volume: 20

Issue: 1

Page Range: 84-91

Description:

This document presents the characterization of the dynamic mechanical properties of a racecar's frame. First, it introduces the applicability of modal analysis, then the modal analysis of a lightweight vehicle chassis will be detailed, which is the focal point of this paper. This analysis was performed to determine some of the modal parameters, in order to reduce the noise of the vehicle, the probability of a component failure and to improve the comfort. The simulation part of the applied analysis was based on dynamic FEM (Finite Element Method). The measurement part of it was based on measuring the FRFs (Frequency Response Functions), with the help of accelerometers fixed at the nodes of the frame. The excitation signals were provided by a shaker connected to the chassis. In order to provide good quality results, the processing and evaluation of the simulated and measured data has to be done properly, which is discussed in detail. However, one dominant factor of a modal analysis is to find the optimal measurement setup. For this reason, the details of the measurement setup will be included. Hence one of the goals was to improve the coherence curves of the FRFs. Thanks to the presented techniques, the coherence curves managed to be improved and the results of the simulation and the measurement were found to be in good agreement.

Open Access: Yes

DOI: 10.21062/mft.2020.013

Evaluation of acoustic frequency methods for the prediction of propeller noise

Dániel Feszty Mark T. Kotwicz Herniczek Jong Park Sid Ali Meslioui Fred Nitzsche

Publication Name: AIAA Journal

Publication Date: 2019-01-01

Volume: 57

Issue: 6

Page Range: 2465-2478

Description:

The accuracy of several computationally inexpensive acoustic frequency methods is evaluated across a range of propeller geometries and operational conditions. The acoustic models considered predict both near-field and far-field harmonic noise. The implemented models approximate or ignore chordwise noncompactness such that they do not require chordwise aerodynamic data, and therefore do not need to be coupled to a panel or grid-based aerodynamic solver. Each implemented method is compared to 14 test cases originating from nine separate published acoustic experiments. The experimental data considered encapsulate a range of propeller geometries, blade numbers, microphone locations, tip speeds, and forward Mach speeds. The implemented acoustic models demonstrate reasonable agreement with the experimental data, particularly for the prediction of the maximum tonal noise for which Hanson’s model showed the greatest overall accuracy with an average error of 5.9 dB. Using different prediction models based on the freestream velocity reduces the error to 4.7 dB. The presented results suggest that the implemented acoustic methods remain a valuable resource for propeller noise prediction, especially for design and optimization studies, in which a low runtime is important.

Open Access: Yes

DOI: 10.2514/1.J056658

Potential errors of acoustical testing induced by stinger excitation

Dániel Feszty Balázs Vehovszky Attila Rábel Dániel Goór Zoltán Gazdagh

Publication Name: 25th International Congress on Sound and Vibration 2018 Icsv 2018 Hiroshima Calling

Publication Date: 2018-01-01

Volume: 1

Issue: Unknown

Page Range: 304-311

Description:

Using a shaker-stinger-structure setup for excitation is a common method nowadays for acoustical testing, however, the geometrical and material properties of the stinger and its fastening method can induce unwanted artefacts to measured characteristics. These uncertainties were artificially reproduced and their effects on the driving point mobility (DP) and frequency response function (FRF) were examined. Stinger buckling phenomena was found to have significant effect both on DP and on FRF. More parameters were investigated experimentally and analytically, which have influence on the buckling phenomena, such as the stiffness of stinger end mounting, axial or radial pretension or slightly bent stinger shapes. The effect of these artificial errors were directly quantified. Furthermore, practical failures - as loosening of threaded mounting adapters - were reproduced and evaluated too. As a consequence, direct practical suggestions for stinger applications were formed, considering the excitation force and frequency range of interest.

Open Access: Yes

DOI: DOI not available

A Method for Measuring Normal and Shear Stiffness of Laminate Stacks of Electric Motors

Dániel Feszty Balázs Pere Dániel Harrach Viktor Szabó

Publication Name: Periodica Polytechnica Mechanical Engineering

Publication Date: 2023-01-01

Volume: 67

Issue: 2

Page Range: 110-117

Description:

Structural simulations of electric motors require precise material models. Laminate stacks that are made of several identical steel sheets are particularly challenging to simulate using FEA. The structural stiffness of laminate stacks usually follows transversal isotropic behavior. Measuring a complete laminate stack used in passenger cars is challenging due to its size and the high testing load needed to reach real loads experienced while in operation. A new method capable of performing such measurements is presented in this article, with the help of equipment normally used for testing structures used in civil engineering. Two sets of exemplary results are presented utilizing this measurement procedure, that were performed on a real automotive rotor laminate stack: axial compression stiffness from a cyclic test, and shear stiffness at various axial preload levels. In the axial compression load case, the loading and unloading curves form a hysteresis, that changes in every test cycle. Shear stiffness shows high dependance on the axial compression preload. After loading and unloading the stack with shear loads, significant plastic deformations remain.

Open Access: Yes

DOI: 10.3311/PPme.20505

Surface Waviness of EV Gears and NVH Effects—A Comprehensive Review

Dániel Feszty Krisztián Horváth

Publication Name: World Electric Vehicle Journal

Publication Date: 2025-09-01

Volume: 16

Issue: 9

Page Range: Unknown

Description:

Electric vehicle (EV) drivetrains operate at high rotational speeds, which makes the noise, vibration, and harshness (NVH) performance of gear transmissions a critical design factor. Without the masking effect of an internal combustion engine, gear whine can become a prominent source of passenger discomfort. This paper provides the first comprehensive review focused specifically on gear tooth surface waviness, a subtle manufacturing-induced deviation that can excite tonal noise. Periodic, micron-scale undulations caused by finishing processes such as grinding may generate non-meshing frequency “ghost orders,” leading to tonal complaints even in high-quality gears. The article compares finishing technologies including honing and superfinishing, showing their influence on waviness and acoustic behavior. It also summarizes modern waviness detection techniques, from single-flank rolling tests to optical scanning systems, and highlights data-driven predictive approaches using machine learning. Industrial case studies illustrate the practical challenges of managing waviness, while recent proposals such as controlled surface texturing are also discussed. The review identifies gaps in current research: (i) the lack of standardized waviness metrics for consistent comparison across studies; (ii) the limited validation of digital twin approaches against measured data; and (iii) the insufficient integration of machine learning with physics-based models. Addressing these gaps will be essential for linking surface finish specifications with NVH performance, reducing development costs, and improving passenger comfort in EV transmissions.

Open Access: Yes

DOI: 10.3390/wevj16090540