Christian Geweth, M.Sc.

Research Associate

Modelling of damping and frequency response function

The acoustic characteristics of vehicles are increasingly perceived as an important quality criterion. For an efficient, resource-saving and economic development, it is desirable to assess the dynamic behavior as early as possible in the development process. In particular, the experimental determination of attenuation values and the balance of simulation models is usually possible only with great effort. It can produce a variety of process parameters, such as storage, excitation and the measurement techniques used affect experimental results. Numerically, the dynamic behavior can already be changed by a structure selection of the attenuation model. The aim of this project is to improve the reproduction precision of attenuation values and transfer functions of complex models. In the first phase, the influence of different model approaches to attenuation of different excitation signals and the windowing used in the calculation of response functions in the frequency domain (FRF: frequency response function) to simple one- and two-degree of freedom systems (DOF: degrees of freedom) was investigated. Next, various methods for determining attenuation of experimental modal analysis on the resulting transfer functions are taken a closer look into.

In the second phase, beams are analyzed as a continuum oscillator. In addition to the abovementioned points, the influence of storage in simulation and experiment is considered in more detail. It is further performed a sensitivity analysis with respect to the cross-linking in the simulation and the influence of the calculated transfer functions. The different attenuation models are compared in Abaqus and optionally further implemented.

In phase three, the sample designated as Urdeckel is sent to several research centers in order to obtain a comparison of different methods of measurement and an insight into the distribution of attenuation measurement. Based on this measurement data, the simulation model is calibrated in Abaqus and the influence of the different parameters investigated further which primarily addresses the uncertainties of different excitation and calculation methods as well as the bearings. One approach is to get through the simulation of storage and smaller deviations in comparison with experimental results.

In the last part of the project, the findings out of a practical component (cylinder block, etc.) are applied and further investigated. Throughout the considered project, a large number of possible influencing factors are analyzed. The investigations on simple models and samples, the effects of the individual effects can efficiently evaluate and identify the reliable relevant factors.

Research Topics:

  • Experimental modal analysis
  • Measuring damping
  • Uncertainty quantification
  • Modeling in ANSYS APDL & Abaqus CAE

Publications

2019

  • Geweth, C. A.; Bosche, S.; Sepahvand, K.; Feng, K.; Marburg, S.: Einfluss verschiedener Lagerung bei der experimentellen Bestimmung von Dämpfungswerten. Fortschritte der Akustik - DAGA : 45. Jahrestagung für Akustik, 18.-21. März , DEGA e.V., 2019Rostock more… BibTeX Full text (mediaTUM)

2018

  • Geweth, C. A.; Moscoso Cires, R.; Martínez Garcia, A.; Marburg, S.: Identifizierung und Analyse potenzieller Fehlerquellen bei der Dämpfungsbestimmung. Fortschritte der Akustik - DAGA 2018 - 44. JAHRESTAGUNG FÜR AKUSTIK,19.-22. MäRZ 2018, DEGA e.V., 2018München more… BibTeX
  • F., Saati; A., Geweth C.; S., Marburg: Vergleich von Inversionsmodellen zur Charakterisierung von porösen Materialien mit starrem Rahmen. Fortschritte der Akustik - DAGA 2018 - 44. JAHRESTAGUNG FÜR AKUSTIK,19.-22. MäRZ 2018, DEGA e.V., 2018 more… BibTeX
  • Geweth, C. A.; Moscoso Cires, R. ; García, A. Martínez; Jagodzinski, D.; Marburg, S.: INFLUENCE OF DIFFERENT MEASUREMENT SETTINGS AND METHODS ON DAMPING. Proceedings of the 6th conference of Noise and vibration emerging methods, 2018Ibiza more… BibTeX
  • Sepahvand, K.; Geweth, C. A.; Saati, F.; Klaerner, M.; Kroll, L.; Marburg, S.: Spectral Representation of Uncertainty in Experimental Vibration Modal Data. Advances in Acoustics and Vibration 2018, 2018, 1-5 more… BibTeX Full text ( DOI ) Full text (mediaTUM)

2017

  • Geweth, C. A.; Langer, P.; Sepahvand, K.; Marburg, S.: Investigation of various damping measurement techniques. The Journal of the Acoustical Society of America 141 (5), 2017, 3576-3576 more… BibTeX Full text ( DOI )
  • Geweth, C. A.; Saati Khosroshahi, F.; Sepahvand, K.; Kerkeling, C.; Marburg, S.: Damage Detection by Experimental Modal Analysis in Fiber-Reinforced Composites. In: Lecture Notes in Civil Engineering. Springer International Publishing, 2017 more… BibTeX Full text ( DOI )
  • Geweth, Ch. A.; Khosroshahi, F. Saati; Sepahvand, K.; Kerkeling, Ch.; Marburg, S.: Damage Detection of Fibre-Reinforced Composite Structures Using Experimental Modal Analysis. Procedia Engineering 199, 2017, 1900 - 1905 more… BibTeX Full text ( DOI )
  • Sepahvand, K.; Khosroshahi, F. Saati; Geweth, C. A.; Marburg, S.: Stochastic structural dynamic analysis with random damping parameters. Proceedings of the 46th International Congress and Exposition on Noise Control Engineering, 2017Hong Kong more… BibTeX Full text (mediaTUM)

2016

  • Geweth, C. A.; Khosroshahi, F. Saati; Sepahvand, K.; Kerkeling, C.; Marburg, S.: Non-destructive testing due to analysis of natural frequencies of multilayer fibre-reinforced composites. Proceedings of the 45th International Congress and Exposition on Noise Control Engineering, 201645th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, INTER-NOISE 2016; Hamburg; Germany; more… BibTeX
  • Geweth, C. A.; Saati Khosroshahi, F.; Sepahvand, K.; Kerkeling, C.; Marburg, S.: Fehlererkennung mittels Eigenfrequenzanalyse bei mehrschichtigen Faserverbundwerkstoffen. Fortschritte der Akustik - DAGA 2016 : 42. Jahrestagung für Akustik, 14. bis 17. März 2016 in Aachen, DEGA e.V, 2016 more… BibTeX
  • Khosroshahi, F. Saati; Geweth, C. A.; Sepahvand, K.; Marburg, S.: Modal Analysis of Membrane String Instruments: Finite Element Modeling and Experimental Investigation. Proceedings of the 45th International Congress and Exposition on Noise Control Engineering, 201645th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, INTER-NOISE 2016; Hamburg; Germany; more… BibTeX
  • Saati Khosroshahi, F.; Geweth, C. A.; Sepahvand, K.; Marburg, S.: Modal Analysis of the Persian Tar: Finite Element Modeling and Experimental Investigation. Fortschritte der Akustik - DAGA 2016 : 42. Jahrestagung für Akustik, 14. bis 17. März 2016 in Aachen, DEGA e.V, 2016 more… BibTeX
  • Wuehrl, M.; Klaerner, M.and Kroll, L.; Riemer, M.; Müller,R.; Landgrebe, D.; Geweth, C. A.; Marburg, S.: PRODUCTION, CHARACTERISATION AND PROCESSING OF METAL PLASTIC COMPOSITES WITH MODIFIED CORE MATERIALS. Tagungsband der Euro Hybrid Materials and Structures 2016, 2016 more… BibTeX

2015

  • Geweth, C.; Sepahvand, K.; Marburg, S.: Abgestrahlte Schallleistung von Strukturen mit unsicheren Parametern. Fortschritte der Akustik, DEGA e.V, 2015 more… BibTeX
  • Geweth, C.; Sepahvand, K.; Marburg, S.: Stochastic radiated sound power of structures with uncertain parameters. Proceedings of NOVEM 2015, 2015 more… BibTeX