The research program involves an experimental and analytical investigation of the quasi-static and impact energy dissipation characteristics of structural systems containing metallic tubes as energy dissipating elements. The specific objectives of the research include the following five tasks. In Task 1, the energy dissipation characteristics of clusters of unstiffened and stiffened tubular assemblies will be optimized with respect to their intertubular boundary conditions, their radius to wall thickness ratios, and their strain-hardening and strain-rate properties. Task 2 is concerned with establishing the importance of the initial elastic response of tubes subjected to impact loading resulting in an elastic-viscoplastic response. In Task 3, non- uniform tubular collapse modes will be studied. Task 4 will investigate the behavior of composite (foam-filled) metallic tubes under large deformation conditions. Finally, Task 5 will generalize the one-dimensional structural shock-wave theory developed in previous NSF funded research to two dimensions and employ it to model the impact experiments of Task 1. This research will fill a void in this area of impact mechanics and provide results directly applicable to the development of more efficient and effective metallic energy dissipating systems. Such systems have a life saving potential when employed in safety applications where kinetic energy must be dissipated in a controlled manner such that decelerations remain within allowable limits.
