Yoshiaki Yasui

Dynamic axial crushing of multi-layer honeycomb panels and impact tensile behavior of the component members

The dynamic impact crushing behavior of multi-layer honeycomb sandwich panels and the impact tensile loading behavior of their material members are examined in this experimental investigation. Honeycomb panels are used in a variety of buffer appliances for absorbing impact energy, and this application requires an understanding of how the construction of such panels affects energy absorption. The multi-layer panels tested in this study consisted of both the uniform type and the pyramid type. Results are presented on the quasi-static and dynamic crushing of honeycombs and more complex prismatic absorbers made up of several layers of honeycombs. The crushing energy absorbing performance of a single or multi-layer built-up panels under the quasi-static velocity to 500 mm/min and the impact velocity to 5 m/s was studied using several kinds of aluminum alloy (A5052, A6451-T6 and T4 materials) honeycomb. To ascertain the impact characteristics of the honeycomb members, high speed tensile tests were also carried out at velocities up to 15 m/s. The dynamic stress states of T6 and A5 materials were found to depend on strain rate. The behavior of these materials was influenced sensitively in response to dynamic impact velocity and mechanical material properties. Crushing for multi-layer honeycomb sandwich panels was observed to occur after the appearance of a stress peak in each layer; the stress peak and subsequent collapse progressed through the layers over time. Pyramid-type panels built from two or three basic panels were observed to be the most effective design from the standpoint of energy absorption ability.

Dynamic Behavior of Partially Liquid-Filled Thin Cylindrical Shells.

This report describes the dynamic behavior of partially liquid-filled thin cylindrical shells which are subjected to vertical excitation. In case too much liquid is contained, the structure is often damaged. The exciting acceleration, the surface deformation and the generated sound, as dynamic behavior of the shell made of a Lummiror polyester sheet, are treated experimentally. The acceleration and the deformation vary with discontinuity as if the transition phenomena occurred. The transition is caused in the lower frequency region at the longer cylinder effective length, that is, with the increased liquid potential head. The frequency response of the shell wall is observed as several spectra which change due to transition. The acoustic spectra of sound generated from the shell depend on the wall response. There are correlations between both characteristics. Therefore, the response condition of the shell wall can be predicted by the acoustic spectrum.