Study on impact phenomenon between a sphere and a layered structure

Abstract

As part of a general investigation of impact-printing phenomenon, a series of impact experiments were performed in which the print action was simulated by a freely falling sphere impacting with a horizontal stack composed of ribbon, paper and carbon paper, backed by a steel platen. The principal quantity measured was the coefficient of restitution of the system, which is related to the energy lost during the collision process. In certain cases, a piezoelectric transducer was used to support the stack so that information about contact time and impact force could be obtained.

The behavior of the coefficient of restitution as a function of stack thickness was determined, not only for the case of ribbon, paper and carbon paper, but for various thicknesses of other materials also supported by a hard-steel platen. The latter experiments were performed in order to obtain a better understanding of the nature of the collision process. In general, similar behavior was found for all materials and energies tested.

The empirical results were compared with theoretical models for energy-loss mechanisms and it was concluded that the major energy-loss mechanisms were associated with plastic and viscoelastic phenomenon, rather than with traveling waves.