Circumferential Propagation and Interference Effect of Stress Wave in a Finite Length Strip with Circular Holes

Abstract

A method of reducing the concentration of dynamic stress that utilizes the circumferential propagation and interference effect of a stress wave was investigated. An impact compression load was applied to a strip specimen made of polymethylmethacrylate with circular holes. These holes consist of a central hole and two additional holes on the strip whose respective diameters, d 0 and d 1 , and the distance between the holes, pitch p, were varied. Dynamic elastic stresses on the minimum cross section of the holes were calculated using DYNA3D software to obtain the stress concentration factor K. The value of K at the central hole decreased as the diameter of the additional holes was increased because of the interference of the reflected wave and the circumferential propagation of the stress wave around the edges, which are considered to have reduced the amplitude of the stress at the edge of the central hole. Therefore, this reduction method involving the addition of holes is useful for the impact safety design of mechanical structures. Experiments gave similar results to those obtained by calculations.