Effect of pre-impact waves in an elastic rod on coefficient of restitution

The effect of pre-impact waves on the coefficient restitution (COR) in longitudinal impact a uniform elastic rod linear or bilinear inelastic spring supported by fix rigid wall is studied. models may represent quasi-static response of, e.g., small cylinder bit-rock interaction percussive drilling. accelerated to its momentum either force relatively short duration which generates significant (pre-impact wave case) long does not generate such (reference case). Analytical and numerical results based 1D equation are presented dimensionless form. It shown that work performed accelerating much larger case than reference case, COR generally depends stiffness, elasticity parameter, initial rod-spring separation, transit time. In be significantly smaller case. also unity. A mechanism leading super rebounds with up 1.4261 described.