Zoltán Gazdagh

57205129999

Publications - 12

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

Experimental modal analysis based TPA method of wiper system linkage vibration amplification

Zoltán Gazdagh L. L. Szabo M. Bubreg B. Fukker T. F. Varga

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: 3557-3571

Description:

Acoustic transfer functions from mounting points of front wiper systems on vehicle body to driver ear positions can describe vehicle noise transfer properties. Component based TPA methods can be applied to characterize the wiper system as a noise source from the vehicle point of view. The same methods can be utilized to characterize the wiper drive as a noise source from the wiper linkage point of view. The paper presents a method to characterize the transfer properties of the linkage independent from the drive excitation. The linkage amplification method presented here provides force-force transfer functions from drive connection locations to the linkage and mounting point locations of the linkage to the vehicle body. The presented procedure focuses on TPA method within a vehicle component. Synthetized FRFs calculated at drive connection locations and at mounting points of the linkage at measured points of the modal model from experimental modal analysis are used for calculating the linkage amplification functions.

Open Access: Yes

DOI: DOI not available

Rattling detection of electric components

Zoltán Gazdagh J. A. Erdelyi A. Bartus 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: 2799-2813

Description:

The study emphasizes the importance of detecting and addressing the issue of nonlinear phenomena in electronic components, due to their potential implications for structural integrity, damage or malfunction to sensitive electronic elements, and a reduction in overall vehicle reliability. This investigation based on time-domain experimental data facilitates rattling detection that aims to distinguish rattling from other type of nonlinearities. The sample is screwed on a fixture, which is mounted on an electrodynamic shaker that serves as the excitation source. The excitation signal is a closed loop sinusoidal sweep, measured in both directions and at different amplitudes. The paper will focus on several methods for identifying nonlinear phenomena, such as the Poincare map or Hilbert transformation. Phase plots are produced, that serve as a valuable tool for studying anomalies, which can be correlated to the extremes of Lyapunov exponents. The above methods are evaluated on their ability to separate rattling form other phenomena to identify genuine instances of rattling.

Open Access: Yes

DOI: DOI not available

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

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 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

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

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