Inhaltszusammenfassung

Within the wide field of structural health monitoring (SHM) vibration based techniques play a highly essential role. Either modal analysis or ultrasonics including the field of guided waves are techniques being very much considered. Key parameters in that regard are eigenfrequencies being representative for specific structural phenomena. Once those phenomena change such as generated by damage, new eigenfrequencies emerge which can be observed as nonlinear effects. The ability to get those non...Within the wide field of structural health monitoring (SHM) vibration based techniques play a highly essential role. Either modal analysis or ultrasonics including the field of guided waves are techniques being very much considered. Key parameters in that regard are eigenfrequencies being representative for specific structural phenomena. Once those phenomena change such as generated by damage, new eigenfrequencies emerge which can be observed as nonlinear effects. The ability to get those nonlinear effects monitored allows the respective damages to be detected. An example of increasing interest in that regard is micro-damage evolution such as it can be observed in composite materials. This paper reports on tests performed under very high cycle fatigue (VHCF) on CFRP composite samples where damage has been growing gradually at different stages from the micro up to the macro scale. FFT spectra have been measured based on laser Doppler vibrometry (LDV) and damage size has been analysed using computer tomography. To understand the reasons for the different eigenfrequencies observed the dynamic behaviour of the composite samples has also been simulated by FE analysis. Reasons for those nonlinearities measured are explained from the results of those simulations. These simulation capabilities have further built the basis to configure SHM related sensor systems being specifically trimmed to reliably determine damages to be observed in terms of damage tolerance. Further details on how this is done are explained.» weiterlesen» einklappen

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DDC Sachgruppe:
Ingenieurwissenschaften