Mechanical response of metallic, fiber-reinforced beams to transverse impacts

Abstract

Composite metal beams consisting of steel piano wires embedded in a lead-tin alloy matrix were mounted as cantilevers, and their tips were hit by travelling “hammers”. The durations of the impacts were many times the time of transit of a plastic shear wave along the length of the cantilever. It was found that in contrast to the behavior of cantilevers of isotropic metals, the plastic deformation observed was in the form of shear in the clamped section of the cantilever. To study this phenomenon further, long composite beams were mounted so that their central portions were lightly held in a clamp, and two cantilever sections protruded from each end of the clamp. The tip of one of the cantilever sections was hit by a travelling hammer. The plastic deformation observed after the impact was confined to the shearing of the section held between the clamps; the two cantilever sections simply rotated about their fixed ends. The experiments were analyzed by a simplified elastic-plastic technique, and it is shown that there is good agreement between the experimental observations and the theoretical predictions.