Marcell Treszkai

57210128374

Publications - 8

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

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

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

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

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

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