A study of some impacts between metal bodies by a piezo-electric method

Abstract

Continuous measurements of the force throughout impacts between metal cylinders and between a hard sphere and metal flats are described. The force has been measured piezo-electrically. Within their appropriate ranges the theories of elastic impacts due to St Venant and Hertz have been confirmed. For impacts so hard that the elastic regime preceding plastic deformation may be neglected, it is shown that the experimental results agree closely with force-time curves calculated, assuming that deformation is opposed by a constant pressure. This dynamic flow pressure is greater than the similarly defined pressure experienced in static tests and the new information given by the piezo-electric method shows that this difference cannot be accounted for satisfactorily in terms of forces of a viscous type.