Key Engineering Materials Vols. 417-418

Abstract: The purpose of this paper is to discuss the nonlocal effect on dynamic crack propagation velocity. Some experimental phenomena in dynamic fracture and simulative results using molecular & atom dynamics were analyzed and discussed in this paper. The authors found that there were still some disagreements on the dynamic crack propagation velocity. Based on these researches, we introduced nonlocal field theories into the estimation of dynamic crack propagation velocity. The dynamic crack propagation velocity is affected not only by the crack instability, but by characteristic length of material. A nonlocal characteristic length parameter M is defined through a double pile-up dislocation model. According to the Mott’s research method for crack velocity in dynamic fracture and the nonlocal field theories, an approximate theoretical dynamic propagation velocity is obtained. And we conclude that the velocity is related to the combined activity of the nonlocal characteristic length parameter M, the velocity of longitudinal wave, constant k, crack length and Poisson’s ratio.

Abstract: An element-free Galerkin method is developed using radial basis interpolation functions to evaluate static and dynamic mixed-mode stress intensity factors. For dynamic problems, the Laplace transform technique is used to transform the time domain problem to frequency domain. The so-called enriched radial basis functions are introduced to accurately capture the singularity of stress at crack tip. The accuracy and convergence of mesh free Galerkin method with enriched radial basis functions for the two-dimensional static and dynamic fracture mechanics are demonstrated through several benchmark examples. Comparisons have been made with benchmarks and solutions obtained by the boundary element method.