Viscoelastic impact between a cylindrical striker and a long cylindrical bar

Abstract

Axial impact between a cylindrical striker of finite length and a long cylindrical bar, both of linearly viscoelastic materials, is considered. General results are derived for the impact force, the particle velocity and the strain in the bar in terms of closed-contour integrals. Such results are derived also for the transfer of momentum and energy from the striker to the bar. Numerical results for a striker and a bar made of the same material but with different cross-sectional areas are compared. In viscoelastic impact, unlike elastic impact, the duration of contact may be finite and larger than two transit times for a wave front through the striker due to the formation of a tail of finite length after the main pulse. Furthermore, multiple contacts and separations of the striker and the bar may occur within a range of striker-to-bar characteristic impedance ratios. In the case of viscoelastic impact studied numerically, the duration of contact is at least as long and the momentum and energy transferred are at most as large as in elastic impact. Strains measured at three locations of a polymethyl methacrylate (PMMA) bar impacted by strikers of the same material as the bar agree well with the theoretical results.