LXXI. The propagation of stress pulses in viscoelastic solids

Abstract

The propagation of short mechanical pulses along rods of three polymers, polythene, polystyrene and polymethylmethacrylate, has been investigated experimentally. The pulses were produced by the detonation of small quantities of explosive at one end of a rod and a condenser microphone was employed to record the displacement of the opposite end. It is shown that if the response of the material to sinusoidal stresses over a wide frequency range is known, the pulse shapes can be predicted accurately by means of a numerical Fourier synthesis. Further, that where the damping loss is not too large and is constant over a wide frequency range, as it is for many polymers, a general solution of the problem can be obtained which gives the pulse shape for all such polymers and for all distances of travel. Some experiments on pulses through blocks of plastic are also described.