The effect of damping on dynamic stress intensity factors in functionally graded materials

Abstract

Functionally Graded Materials (FGMs) are regarded as one of the most promising candidates for future advanced composites in many engineering applications. They can be classified as advanced materials characterized by variation in properties as the dimension varies. Since fracture is a key failure mode of FGMs, successful application of these materials depends on the understanding of their fracture mechanics. In addition, the stresses and displacements caused by dynamic loading can greatly differ from those associated with the corresponding static loading. This research focuses on obtaining Dynamic Stress Intensity Factors (DSIFs) in FGMs using displacement extrapolation method, considering the effect of damping. ABAQUS finite element package is applied to calculate displacement fields in FGMs. Accordingly, a User Material subroutine (UMAT) is written for implementing the continuous variation of material properties, and Rayleigh damping in the numerical analyses. In this research, the variations in properties of FGMs are considered exponentially; and the obtained results are compared with those presented in the technical literature. Then, the effects of different damping ratios on the DSIFs are investigated. According to the obtained results, damping has a significant effect on the DSIFs in FGMs. Therefore, ignoring this issue causes considerable errors in the results.