1994 Volume 43 Issue 493 Pages 1309-1314
In the present study, impact fracture patterns of triangular plates subjected to an impulsive load are investigated by means of experiments and numerical simulations. The specimens of triangular plate are made of plaster and have several height/base ratios (apex angles). The center of the free base edge of a triangular plate with uniform thickness is subjected to an impulsive load in the in-plane direction, while the sloping side edges are free from stress. The impulsive load is given by an input bar colliding with a striker shot out from a compression air gun. The feature of fracture pattens occurred in the triangular plates are discussed in relation to the effect of the apex angle and the duration of an incident stress into the plates. Numerical analyses for a few fracture patterns are carried out based on a dynamic finite element method using the Newmark-β method. Mechanism of the impact fracture initiation and development in triangure plates is made clear by comparing the experimental results with the numerical simulations. It is found that the origin of fracture coincides well with the region of dynamic tensile stress concentration due to stress wave reflection and reinforcement from the base edge and both sloping sides of the plate. The formation of the region of dynamic tensile stress concentration is strongly governed by the dimensions and apex angle of triangular plates and the duration of an incident stress.
