HEAD-ON COLLISION OF NORMAL SHOCK-WAVES WITH A RUBBER-SUPPORTED WALL

The head-on collision between a normal shock wave, propagating into a quiescent gas, and a rubber-supported plate was investigated theoretically and experimentally. In the theoretical part, a physical model was developed for describing the collision process. Three different modes in which the rubber could be loaded, due to its collision with the incident shock wave, were studied. They are: uni-axial stress loading, bi-axial stress loading and uni-axial strain loading. In the first two modes the rubber can expand while carrying the shock-wave induced compressive load, and therefore can be treated as an incompressible medium. This is not the case in a uniaxial strain loading where the rubber cannot expand while carrying the shock-wave-induced load. The model developed was based on both the conservation equations and on an appropriate strain-stress relation which describes the rubber behaviour under loading. The model was solved numerically for each of the above-mentioned loading modes. Experiments were conducted in a shock tube; the rubber response to its collision with normal shock wave was studied for the case of bi-axial stress loading. Pressures, in the gas, and stresses, in the rubber, were recorded by using piezoelectric pressure transducers; the shock-wave reflection, in the gas, and the rubber displacement and compression processes were recorded on successive shadowgraphs. Good agreement was found between the experimental and numerical results for the case of bi-axial stress loading. This agreement validates the model developed for the collision process and the reliability of the numerical scheme used for its solution.