Issue 39

M. Shariati et alii, Frattura ed Integrità Strutturale, 39 (2017) 166-180; DOI: 10.3221/IGF-ESIS.39.17 178 at static loading condition. The von Mises stress and Longitudinal displacement contours for an axisymmetric cross section of a hollow cylinder with a circumferential crack of length 0.05 m at time t s 26¬ P is illustrated in Fig. 13. [ [ 7LPH V . , 3D P a =0.09 a =0.07 a =0.05 a =0.03 a =0.01 Figure 12 : Plots of SIF vs. time for circumferential crack with various depths embedded in a FG cylinder under impulsive tension. von Mises stress (Pa) Longitudinal displacement (m) Figure 13 : Stress and displacement contours for the axisymmetric cross section of a cylinder with a circumferential crack of length a = 0.05 m under impulsive tension at time t s 26¬ P . To investigate the effect of the material gradient parameter P on the SIF of circumferential crack in dynamic loading condition, some functionally graded hollow cylinders composed of epoxy/glass with different values of parameter P under impulsive tensile load are analyzed. The impulsive tension 1 V MPa at time t 1¬Ƭs is applied to the upper surface of cylinders and the stress intensity factors are obtained at specified time steps ( t s 1¬ P ' ). SIF curves in term of time are plotted in Fig. 14. It is concluded from Fig. 14 that increasing the material gradient parameter P decreases the maximum SIF value so long as P 1 while for P 1 ! the maximum SIF value increases with increasing P . In addition, the speed of stress wave decreases with increasing P .