Impact Load Mitigation With Bi-Stable von-Mises Trusses

This paper examines the potential of a bi-stable von-Mises truss (VMT) connected to viscous damping elements in absorbing impact loads, and reducing loads and accelerations transmitted to the base. A compact sandwich-panel-like element is designed, fabricated and tested in an impact testing machine which comprises of a top plate, a bottom plate, and VMTs in-between that stroke the dashpot as they snap through. The loads transmitted to the bottom plate showed reductions of over 70% for lower drop heights, while reductions approaching 50% were seen for larger drop heights. The introduction of pre-loaded springs in parallel to the VMTs resulted in the prototype not snapping through, except at the largest drop heights tested. The reductions in the transmitted loads were modest for small drop heights but improved as the drop heights increased and snap through occurred. Accelerations transmitted to the bottom plate also showed reductions of 83–88% relative to the upper plate accelerations. A Simscape model of the system showed good overall agreement with tests for loads transmitted to the bottom plate when using the measured loads on the top plate as an input.