Balázs Vehovszky

26434072100

Publications - 24

Dynamic and quasi static stiffness characterization of a lamination stack of an electric motor

Balázs Vehovszky Zoltán Gazdagh Viktor Szabó

Publication Name: Heliyon

Publication Date: 2024-11-15

Volume: 10

Issue: 21

Page Range: Unknown

Description:

The development of electric motors for automotive applications requires precise material models to simulate structural strength and NVH (Noise, Vibration, and Harshness) properties. Modeling the behavior of lamination stacks, composed of stacked steel plates, presents significant challenges. This study conducted dynamic and quasi-static experiments at various preload levels on an unmodified automotive lamination stack. Significant discrepancies were identified between stiffness values obtained from static and dynamic measurements. Consequently, using dynamically obtained stiffness values in static models, and vice versa, leads to inaccuracies and should be avoided. These results enhance the precision and efficiency of simulations used in the design and optimization of electric motors.

Open Access: Yes

DOI: 10.1016/j.heliyon.2024.e39693

Concept of a Novel Energy Management System for Microgrids and Energy Communities

Balázs Vehovszky Zoltán Weltsch Bernadett Rádli-Burján Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 919-924

Description:

The green transition of the global energy system presents considerable economic and technological challenges. One of them is the local and temporal difference between available energy sources and energy demand. To overcome this problem, two conceptual solutions can be considered: one is the use of an energy carrier that is suitable for medium- and long-term storage and safe transportation of energy. Carbon-based fuels (or novel alternatives, like hydrogen) or electric energy are the solutions currently used; however, we are facing their environmental or technical limitations. The other one is the synchronisation and intelligent control of sources and consumers, which could significantly decrease the storage and transportation needs. The current article discusses such a solution through a conceptual example. For the conceptual design of an advanced energy management system, the main related system elements shall be defined, and characteristic properties must be assigned to them. Input parameters for the energy management strategy must be given and prioritised. All this information enables the system to calculate and define instantaneous operational optimum. Also, an intelligent control system should take time-dependent processes and parameters into account, which can be deterministic or stochastic. As a result of this study, an energy management system concept that is based on realistic components and use cases is proposed, and its applicability to a local energy community is evaluated.

Open Access: Yes

DOI: 10.3303/CET24114154

Concepts and Examples of Carbon-Free, Self-Sufficient Local Energy Systems

Balázs Vehovszky Zoltán Weltsch Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 931-936

Description:

The necessity of the “green revolution” in the field of energetics is not a question anymore; however, switching the current fossil fuel-based energy ecosystem to a fully renewable-based one poses enormous challenges. The historical structure of the present, centralised energy production infrastructure, as well as the fundamentally different characteristics of the three main fields of usage (electricity generation, heating and transportation), are among the most substantial hindering factors. The future energy system has to be much more flexible in several respects, with a fundamental contribution of smaller, independent energy communities. The current study focuses on the realisation aspects of such a small-scale energy community (or micro/nano-grid), considering the suitable technological solutions as well as the cost concerns. A high number of pilot projects and case studies around the world prove that the technical feasibility of a local grid/energy community is no longer a question. The real challenge is to find the appropriate incentives and strategy to catalyse the required transition at the legislation, system operator and end-user level as well. The outcomes of the present work contribute to this goal by pointing out the application potentials of a modular, scalable microgrid system based on a currently running microgrid-realization project at the ZalaZONE proving ground.

Open Access: Yes

DOI: 10.3303/CET24114156

Combination of Sustainable Agriculture and Renewable Energy Systems

Balázs Vehovszky Zoltán Weltsch Bernadett Rádli-Burján Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 913-918

Description:

It is now not a question anymore that the fossil fuel-based energy system of human civilization has to be converted into a sustainable energy cycle during the 21st century. In most cases, the introduction of related, novel energetical technologies and solutions leads to disadvantageous interferences with other fields of life. Perhaps the most critical example is the competition between the energy sector and the food industry for valuable agricultural land. Although the two utilization purposes are generally considered mutually exclusive, there are agro-energetical solutions where the two goals are not just indifferent, but they expressly increase each other's efficiency. Such solutions are the agro-photovoltaic systems, where photovoltaic panels are installed in a way that is advantageous for the crops below them. Some plants, such as berries, prefer shady to semi-shady environments, which can be optimally provided under partially covered PV fields. With the active control of the PV panels, ideal shading conditions and even mechanical protection can be ensured in case of extreme weather events. With the appropriate selection of the crop plants and the PV installation, cultivation processes are not hindered, can be highly automated, and the energy needs can be fully covered by the local PV system. From the above description, it is clear that the realization of efficient agro-photovoltaic systems is not just possible but really prosperous. This study offers a more detailed overview of currently realized solutions around the world, as well as a thorough planning process of an agro-photovoltaic project at the ZalaZONE test center, optimized for the Hungarian climatic and agricultural conditions and possibilities.

Open Access: Yes

DOI: 10.3303/CET24114153

Control of transfer function distortion during RPM-sweep testing of e-drive systems

Balázs Vehovszky Zoltán Gazdagh D. Acs B. Fukker

Publication Name: Proceedings of ISMA 2024 International Conference on Noise and Vibration Engineering and Usd 2024 International Conference on Uncertainty in Structural Dynamics

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 3779-3787

Description:

This study is focusing on the distortion phenomenon of the vibrational resonance peak when testing an e-drive assembly via RPM-sweep excitation. As the ramp rate increases, the measured response function deviates more and more from the stationary response. This distortion leads to a reduced peak amplitude, a shift in resonant frequency, changes in response shape and consequently, results in an increased half-power bandwidth, eventuating an increased apparent modal damping. These changes in the response are dependent on the sweeping direction and other physical parameters as well, like oil pressure and -temperature. The phenomenon was investigated earlier for linear systems, but not for operational testing of rotary machines, where the characteristics of the spectrum distortion are governed by different principles and are influenced by many other physical factors. A novel way for handling amplitude distortion of e-drives during transient testing is elaborated, which can be used to optimize RPM-sweep rate and other measurement parameters.

Open Access: Yes

DOI: DOI not available

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

Methodology and Realization of Indoor Pass-by Noise measurement for passenger cars

Balázs Vehovszky Zsolt Gaszner

Publication Name: Journal of Physics Conference Series

Publication Date: 2023-01-01

Volume: 2677

Issue: 1

Page Range: Unknown

Description:

Nowadays the protection of human life is extremely important, and for this purpose the vehicles must go through a homologation process before the introduction to market. If we look at the acoustical requirements, one of the most important test procedures is the Pass-by Noise (PBN) measurement, which defines the noise emission limit value, when the observer stands beside the vehicle passing him by. There are two versions: Exterior (or Outdoor) and Indoor (or In-room) Pass-by Noise (IPBN) measurement. Former is presently the only accepted method for homologation; however, environmental and weather conditions could strongly influence its feasibility. For this reason, IPBN got into focus, with better suitability for development purposes and the prospect, that it will be accepted later for the homologation process too. This paper focuses on the IPBN method: gives an overview on the setup and presents the details of a realized test-measurement campaign. Beside the 2 most important points: the measuring room and the position of the sensors, the measurement devices, vehicle location and connection to measurement system, the measuring program and the whole process are presented together with some preliminary results related to different characteristics of the vehicle.

Open Access: Yes

DOI: 10.1088/1742-6596/2677/1/012004

Comparative analysis of stiffness measurement methods for lamination stacks in electric machines

Balázs Vehovszky Zoltán Gazdagh Viktor Szabó

Publication Name: Journal of Physics Conference Series

Publication Date: 2023-01-01

Volume: 2677

Issue: 1

Page Range: Unknown

Description:

With the increasingly strict global regulations on vehicle emissions, the demand for electromobility has risen due to its potential to reduce local emissions. However, designing an electric motor for use in passenger cars poses significant challenges. The e-motor should operate reliably in various climates with good mechanical and electrical characteristics, be lightweight, withstand repetitive thermal and structural loads, be cost-effective, and - last but not least - exhibit good noise and vibration properties. To meet these requirements, virtual testing through simulations has become the most efficient and economical approach, enabling the identification of weaknesses and unwanted behaviors before physical prototyping. This paper focuses on the testing of lamination stacks, a critical component of electric motors. Two methods of stiffness measurement for such parts are compared: static stiffness determination and dynamic analysis. The former involve compressing the specimen and measuring the force-displacement response, while dynamic method uses the restoring force surface method to obtain the stiffness and damping characteristics. The study highlights the importance of considering nonlinearity in stiffness measurements. The stiffness of lamination stacks varies depending on the pretension state, and a significant hysteresis exists between the loading and unloading curves. The paper discusses the experimental procedures for each method. The findings emphasize the necessity of accurate stiffness characterization for different applications, such as structural strength, modal analysis, dynamic analysis, and noise-vibration-harshness (NVH) studies. The research contributes to the development of electric machines by providing insights into effective stiffness measurement techniques for lamination stacks.

Open Access: Yes

DOI: 10.1088/1742-6596/2677/1/012002

A Comprehensive Review of the Simulation Methods for Analysis at the Pore-scale

Balázs Vehovszky H. Szűcs Brian Sanders

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2023-01-01

Volume: 51

Issue: 2

Page Range: 105-116

Description:

Fluid flow through porous material is relevant in different fields of engineering, such as in engine and vehicle development, and can be supported through CFD simulation. Numerical simulations at the pore-scale can be used to replace or reduce expensive laboratory measurements. These methods offer a valuable opportunity to connect the pore-scale properties of the porous material with displacement processes on the continuum-scale. Furthermore, they allow researchers to specify crucial flow properties, e.g., capillary pressure, which are crucial for REV-scale research. Three main methods, direct numerical, pore network modeling, and hybrid approaches, are widely used in order to analyze the pore-scale mechanics of fluid flow behavior through porous materials with CFD simulations. The present comprehensive review demonstrates and highlights the significant advantages, disadvantages, and critical challenges in the pore-scale fluid flow simulations. The main challenges include the characterization of material properties, and up-scaling process from pore to continuum or field-scale.

Open Access: Yes

DOI: 10.3311/PPtr.18452

A General Framework for the Experimental Characterization of Nonlinearities and its Application to a Laminated Assembly of an Electrical Motor

Balázs Vehovszky Simone Manzato Simona Anna Ottaiano Zoltán Gazdagh

Publication Name: SAE Technical Papers

Publication Date: 2022-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The vehicle industry being in the middle of transformation, the development of electric drives has come into engineers' focus. The parameter evaluation of dynamic systems can be cumbersome when having nonlinearity in the structure, for example nonlinear stiffness characteristics. In such case, the standard linear approach, including EMA (Experimental Modal Analysis), modal superposition, FRF measurement (Frequency Response Function) and modal synthesis can not be applied. However, one of the main challenges in addressing nonlinearities is the lack of general tools to approach them. In this paper, a general framework to study nonlinearities in a structural dynamic context is presented. The method relies on standard random and sine sweep testing approaches to detect and localize nonlinearities, and on dedicated processing techniques to analyze the data and extract information on the nature of the analyzed nonlinearity. This approach is then used to study the behavior of an assembly of a lamella package of PMSM (Permanent Magnetic Synchronous Machines), where permanent magnets are embedded in the laminations. The magnets are surrounded by resin that holds them in place in their grooves. Characterizing the dynamic properties of such a structure is a relevant task in engineering development, for verifying numerical predictions. In this case, the relative motion of lamellas as well as the heavy influence of the polymer resin's properties may result in nonlinear behavior.

Open Access: Yes

DOI: 10.4271/2022-01-0944

Influence of frequency resolution in case of frequency response function measurement in structural dynamics

Balázs Vehovszky Zoltán Gazdagh

Publication Name: Acta Technica Jaurinensis

Publication Date: 2021-11-24

Volume: 14

Issue: 4

Page Range: 508-520

Description:

Frequency resolution is an essential parameter in acoustical testing, even if we are using numerical or experimental method, for example when determining frequency response function (FRF) of a dynamic mechanical system, or executing modal analysis based on the FRFs. Finer resolution leads to more accurate results, at the expense of longer calculation/measurement process and larger data size. This parameter is generally set based on rules of thumb, prior practice or with big margin for safety. This results in waste time and data storage if the required frequency resolution is overestimated, or even significant errors in the results, if it is underestimated. Present paper offers a direct, method for the conscious determination of optimal frequency resolution. It is based fully on theoretical considerations, and investigates amplitude and phase distortion at resonances as target parameters. Beside defining the steps of the process, it is tested on a real structure, and the results are presented as well, proving the applicability and the appropriateness of the method. With this method, development engineers get a practical tool for adjusting the parameters of dynamic measurements and simulations.

Open Access: Yes

DOI: 10.14513/actatechjaur.00618

Possibilities of porous-structure representation – an overview

Balázs Vehovszky H. Szűcs

Publication Name: Acta Technica Jaurinensis

Publication Date: 2021-11-24

Volume: 14

Issue: 4

Page Range: 553-576

Description:

Porous media can be found in all areas of scientific life, such as medicine, civil engineering, material science, fluid dynamics. Computing has achieved high efficiency and computational capacity – so far. However, three-dimensional Computational Fluid Dynamics (CFD) simulations of microstructure remain significant challenges. Pore-scale simulations can help understand the physical processes and determine macroscopic parameters such as the high-frequency limit of dynamic tortuosity, viscous, and thermal characteristic lengths. Independent of whether the computational problem is two or three-dimensional, the geometry as input parameter must be prepared. For this reason, geometry representation methods play a crucial role in the analysis at the pore-scale, especially in numerical simulations. In this article, an insight into microstructures’ visualization capabilities is provided essentially for CFD simulations.

Open Access: Yes

DOI: 10.14513/actatechjaur.00591

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

Investigation of frequency dependent mechanical properties of porous materials using dynamic mechanical analyzer and frequency-temperature superposition theory

Balázs Vehovszky Attila Schweighardt

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:

In acoustic design of engineering applications - such as in the acoustic analysis of passenger vehicles - poroelastic materials are of great importance. One of the most influencing properties in determining their noise-reduction potential is the storage modulus. The purpose of this study is to examine the frequency dependence of storage modulus of selected porous acoustic materials at least up to 1000 Hz. This is executed by using the combined use of dynamic mechanical analyzer and frequency-temperature superposition theory. All other methods for measuring the storage modulus fall short in determining frequency-dependence above 100 Hz: quasi-static mechanical analyzer is mostly used for determining an averaged constant value deduced from low-frequency measurements, while the usage of an electromagnetic shaker capable for high-frequency excitation may include effects of fluid motion inside the pores, thus significantly modifying the results. Frequency-temperature superposition enables to determine the storage modulus values in a wide frequency range, based on low-frequency measurements, where fluid-structure interaction is negligible. It was found that the modulus varied significantly up to and beyond 1000 Hz, and thus, acoustical characterization of these materials can be significantly improved using the proposed method. The work concludes with recommendations to improve the accuracy of the results.

Open Access: Yes

DOI: 10.3397/IN-2021-2859

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

Development of 1D and 3D acoustic simulation methods for transmission loss based on transfer matrix measurement results

Balázs Vehovszky Balázs Kuti Zoltán Gazdagh Attila Schweighardt Miklós Szendrő

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:

During the acoustical characterization of a component of a building, machine or vehicle, the normal incidence sound transmission loss is a major factor. Transmission loss simulation is also crucial in designing intake or exhaust elements, such as reflective mufflers. However, there is not enough information in the open literature about the applicable frequency ranges of experimental and 1- and 3D simulation methods. Therefore, the main purpose of this paper is to evaluate the frequency limits of computational and experimental transmission loss analyses of various reflective mufflers. For the validation two in-house impedance tube test benches were designed and multiple measurement setups were investigated. The combination of the four-pole matrix and the two-load methods was used during the experimental part of the study. In order to obtain appropriate transfer function results, distinct setups were evaluated, such as a low-frequency sound source with bigger tube diameter and a high-frequency sound source with smaller tube diameter. The low-frequency setup is suitable for the investigation of the system in the range of 30-500 Hz. The high-frequency setup is capable of measuring from 300 Hz to 2000 Hz, which is the upper frequency limit of the range of interest. Consequently, the in-house system is suitable for measuring the transmission loss in the 30-2000 Hz frequency range. 1D simulations were performed using Ricardo Wave software and 3D simulations were carried out in the STAR-CCM+ software. The upper cutoff frequency of 1D simulation method was determined to be 1500 Hz according to the correlation with the measurements. The frequency range of simulation could be extended up to 2000 Hz by employing 3D simulation for transmission loss calculations. This paper gives insights into the transmission loss measurements with the in-house system and the correlation analysis with different simulation methods.

Open Access: Yes

DOI: DOI not available

Determination of center of gravity and moment of inertia using dynamic testing method

Balázs Vehovszky Zoltán Gazdagh Martin Kaszab

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:

The knowledge of a vehicle's center of gravity (COG) and moment of inertia (MOI) are important from vehicle dynamic and comfort points of view. These parameters can be determined from the CAD model of the vehicle, however, manufacturing inaccuracies and additional elements can modify the values, and experimental validation can be necessary. The determination of COG (and even MOI) can be carried out using classical physical methods, but a more convenient and sophisticated method is offered based on dynamic testing data. The method is known and accessible even in commercial testing software, but a clear recommendation for the optimal input data and the expected accuracy is still not available. The purpose of this study is to define the influencing factors of the measurement and quantify their effect. The introduced method is based on the evaluation of the frequency response functions in the mass-line region. Input data were obtained by using impulse hammer excitation and accelerometers for measuring the response of the structure. The measurements and the evaluations were performed in Siemens LMS Test.Lab software using Rigid Body Calculator module. The results of the dynamic measurement are compared to CAD data and to the COG value got from simple static measurement.

Open Access: Yes

DOI: DOI not available

Development of tire-road noise measuring system

Balázs Vehovszky István Horváth Zsolt Gaszner

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 vehicles there are 3 main noise sources: powertrain noise (e.g. engine, gear engagement or exhaust noise), aerodynamic noise (or wind noise), and the noise from the tire-road contact. The first two are traditionally in the primary focus of vehicle manufacturers, however, due to both the already made powerful developments and the spreading of electric vehicles, the rolling noise is gaining more and more attention during the vehicle development process. There are two major influencing factors of this noise source: tire (geometrical and material) characteristics and road (surface) characteristics. The separation of their contribution is not straightforward, investigated rarely, and the requirements of homologation standards do not expect it neither. However, if one would like to meet the new vehicle pass-by noise regulations, it is more and more inevitable to have a sophisticated break-down of rolling noise. A straightforward solution is the usage of a one-wheel testbench developed directly for acoustical measurements. Such design process is presented in this paper, where the most important requirements are: enabling the users to compare tires from acoustical aspect under totally objective conditions, modelling the typical conditions of vehicles and ensuring data for rolling noise simulations. One further functionality of the testbench is to reproduce the real rolling noise by mounting realistic road surface sections onto the superficies.

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

Vibration damping measurement on car windshields

Balázs Vehovszky Karl Slenczka Tamás Jakubík István Horváth Martin Schuster

Publication Name: Periodica Polytechnica Mechanical Engineering

Publication Date: 2019-01-01

Volume: 63

Issue: 1

Page Range: 1-6

Description:

Knowledge of the damping properties of a windshield is a fundamental element of the acoustical characterization of a car. The measuring method of damping for a windshield is presented in the paper. The damping loss factor – as a basic measure of mechanical damping – was determined experimentally by two means: the reverberation time from impact hammer testing as well as the modal behavior from 3D laser scanning vibrometer measurements. The results proved that the modal shapes have a fundamental effect on the measured damping values.

Open Access: Yes

DOI: 10.3311/PPme.11559

Thermal examination of a simplified exhaust tube-heatshield model

Balázs Vehovszky Tamás Jakubík Marcell Treszkai

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2019-01-01

Volume: 47

Issue: 3

Page Range: 190-195

Description:

Exhaust system and its surrounding is a thermally highly critical part of a vehicle: during forced operation, hottest elements can reach 600 °C. The thermal conditions turn to even more critical if the forced flow leaves off – e.g. when the car stops at a highway parking place. In such a case not only the cooling effect of cross-flow disappears, but the natural convection starts to bring heat toward nearby elements – resulting potential overheating of concerned parts. A measurement setup for modelling such case was built, and different parameters were examined, which have influence on the heating of aluminium heatshield above the exhaust tube. Measurements were complemented by CFD simulations and flow visualization technique aiming the better understanding of evolving thermal and flow conditions.

Open Access: Yes

DOI: 10.3311/PPtr.12109

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

Unlocking the insights of dynamics through experimentation of an electric drive

Balázs Vehovszky Zoltán Gazdagh B. Fukker

Publication Name: Proceedings of ISMA 2024 International Conference on Noise and Vibration Engineering and Usd 2024 International Conference on Uncertainty in Structural Dynamics

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 2022-2030

Description:

This experimental example shows a study of the e-drive lamellae package, where the layered, punched sheets are axially compressed and the permanent magnets are embedded in the laminations. When studying such systems, using Restoring Force Surface (RFS) method allows users to create a snapshot of the behavior of the dynamic system. Due to the potential impact on the end user's perception of vehicle quality, the consideration of the changes in resin stiffness over time, the evolution of the time-dependent dynamic response in systems like Laminated Rotor Cores (LRC) remains an aspect in development. Technology development of nonlinear characterization of Laminated Rotor Cores (LRC) under different conditions allows engineers to understand how the dynamics evolve in time. Aging and hardening of polymer resin coating change the dynamics of the system. This change may be accelerated through thermal and centrifugal stress cycles or micro crack propagation of the resin coating. This investigation guides through the approach of nonlinear detection, and characterization and gives suggestions on how to linearize such systems.

Open Access: Yes

DOI: DOI not available

Dynamic response distortion due to changing excitation frequency

Balázs Vehovszky Zoltán Gazdagh

Publication Name: Ain Shams Engineering Journal

Publication Date: 2025-12-01

Volume: 16

Issue: 12

Page Range: Unknown

Description:

This study addresses the distortion in system response caused by continuously changing excitation frequency. The distortion leads to reduced resonance peak amplitude and shifts the resonance frequency as well. The novelty of this work lies in providing an analytically established, model-based methodology that not only describes but also predicts and enables one to control this distortion, in contrast to existing studies that mainly describe the phenomenon characteristically [1,2]. The proposed approach incorporates the influencing parameters, such as the sweep direction and rate of linearly changing excitation frequency, and applies a first-order ODE (ordinary differential equation) formulation to approximate the distortion. This enables a sensitivity analysis across frequency and damping ranges, which has not been previously reported in the literature. The methodology is validated with experimental data from an E-drive system, demonstrating how optimal sweep rates and other test conditions can be derived from model fitting. While nonlinear effects may occur in E-drives, the present study focuses on their linear regime to isolate distortion effects. The findings provide both fundamental insights into resonance distortion and practical guidelines for improving the accuracy and reliability of swept-excitation-based NVH (noise, vibration, harshness) measurements in engineering applications.

Open Access: Yes

DOI: 10.1016/j.asej.2025.103795