PSI - Issue 19

Zhu Li et al. / Procedia Structural Integrity 19 (2019) 528–537 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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stationary PSD loadings. A novel computational modeling approach developed by the present authors is employed to estimate fatigue damage of structural components subject to complex non-stationary random loadings.

Fig. 7. PSD responses between the model and FEA for (a) 40 Hz bracket; (b) 60 Hz bracket; and (c) 112 Hz bracket. Since the computational model showed good correlation with FEA and experiments, the model can be extended to capabilities of simulating multiple degree of freedom systems. Furthermore, complex structures can be represented multi-degree-of freedom systems and their dynamic characteristics can be easily determined by FEA. Therefore, the proposed modeling approach can be integrated with commercial FE packages or fully implemented with finite element codes 4. Conclusions A computational modelling approach was developed to estimate fatigue damage of simplified structural components under complex random-on-random loadings. The modeling approach is based on the underlying concept that the time varying response PSD is decomposed into a finite number of discrete PSD functions. Each PSD function is further divided into narrow frequency bands so that each of narrowbands can be related to Rayleigh distribution of stress cycles. Then, fatigue damage for each of the Rayleigh distributions associated with individual narrowband segments is calculated by Palmgren –Miner’s rule., the cumulative FDI can be obtained by summing up damages of each of all discrete PSD positions. Three structural bracket designs with different natural frequencies were used for numerical FEA model to validate the computational model. The predcited results from the computational model showed a good correlation with the FEA simulation. The computed PSD responses yielded that the swept narrowbands in the input PSD is of considerable significance in the fatigue damage of the excited