Multi-body wave analysis of axially elastic rod systems

Abstract Axially elastic rods are basic machine elements in hydraulic hammers, pilers, and percussive drills. The problem to analyse the motion history of such mechanisms is a very complex one, because the rods are simultaneously in large-amplitude axial motion superimposed with a small-amplitude elastic wave motion. The wave motion experiences division to reflected and transmitted components at each rod-rod interface depending on the current boundary stiffness. The wave motion in each rod can be computed by finite elements or, alternatively, in space of semidefinite eigenfunctions. The feasibility of these methods in solving wave propagation problems in multi-rod systems with non-linearly behaving rod-rod interfaces has been investigated and evaluated. The object of the experimental case study is a classical Hopkinson split bar apparatus used in experimental analysis of material response to shock pulses. Another example representing a pile hammering system evaluates the computational performance of the proposed approaches in long-termsimulation of a complete work process.