An analysis of waveform generation and transmission in longitudinal impact

Abstract

The theory of longitudinal impact and the theory of one-dimensional wave propagation have played important roles in recent advances in the fields of rock drilling and rock mechanics. Of special interest to investigators in these fields have been the analysis of the waveform generated in longitudinal impact and the transmission of the energy of a one-dimensional strain wave form one medium to another. The present research deals in part with the generation of a strain wave as caused by a uniform cylindrical piston impacting on a rod with a rounded end. The theory of Sears, which deals with such an impact, is reviewed and extensions of his theory are presented which permit the prediction of the smooth waveform that is generated in an actual impact. Theoretical and experimental results are compared with respect to the accuracy of prediction. The mechanics of the fracture of rocklike materials is also considered in this paper. The effect of load rate on the force-displacement characteristic of selected rocks is investigated and the results of experimental data are discussed from the standpoint of the significance of rate-of-loading effects at lading rates normally observed in the percussive drilling process. ...