CAE-Companion-2018-2019

Engineering WISSEN CAE

Example – Operational strength of a brake protection plate Using the example of a brake protection plate, operational strength analyses [5] were carried out in the time domain and in the frequency domain and were compared. The center of the wheel (Fig. 3 at left) was taken as the excitation point for the measured acceleration load. The corresponding exci- tation PSD of the acceleration is shown in Fig. 3 at the right.

Figure 3: FE model with acceleration at center node (left). Power spectral density of acceleration load (right). The results of the operational strength analyses in the time domain and in the frequency domain are shown in Fig. 4. One can see that the locality of the highly damaged areas demon- strates very good correlation. The absolute damage values of the analysis in the frequency domain are about 80% higher on average than the damage values of the analysis in the time domain. This difference primarily results from the fact that the load time series only shows a single realization of the stochastic process. The damage result of the spectral analysis, however, delivers the expected value over all realizations of the process (described by the PSD). In addition to the good correlation of the damage results, the main advantage of the analysis in the spectral domain is the fact that the computa- tion times are often shorter.

Figure 4: Fatigue result of time domain approach (top). Fatigue result of spectral approach (bottom). Literature [1] T. Dirlik. Application of Computers in Fatigue Analysis. PhD thesis, The University of Warwick, 1985. [2] W. Zhao andM. J. Baker. On the probability density function of rainflow stress range for stationary gaussian processes. Int. J. Fatigue, 14(2):121{ 135, March 1992. [3] D. Benasciutti and R. Tovo. Spectral methods for lifetime prediction under wide-band stationary random processes. Int. J. Fatigue, 27(8):867{877, 2005. [4] G. Petrucci and B. Zuccarello. On the estimation of the fatigue cycle distribution from spectral density data. Proceedings of the institution of mechanical engineers part C - J. Eng. Sci., 213(8):819{831, 1999. [5] http://www.femfat.com/Papers.4940.0.html W. Hinterberger, O. Ertl, C. Gaier and H. Fleischer. Spektrale Schädi- gungsanalyse für multiaxial stochastisch belastete Komponenten.

CAEWissen by courtesy of Engineering Center Steyr, Austria, Author: Dr. Walter Hinterberger. For more information see www.femfat.com

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