Comparative Study of Several Energy Dissipating Devices

Abstract

Large plastic lateral collapse problem of two geometrically identical hollow cylinders under compressive load is of particular interest in this work, since, the energy absorbed can be characterized by a smooth loaded deflection relation, and these tubes are also easier to build than most other devices. Cylinders of various geometrical parameters (i.e., inside/outside diameter ratios: R = di/do ranging from 0 to 0.473) are used having the same cross-sectional area and length. Superplastic material used in this study has a considerably sensitivity to the quasi-static strain rate in the range of (10-5 to 10-3/s). Hence, this material could be employed as a representative material to simulate the classical engineering material behavior under high strain rate. Comparative study of different structural situations is conducted using four energy dissipating devices designed and investigated by the author in previous works. They are: (1) two geometrically identical cylinders made of superplastic tin-lead alloy can freely expand along their sides and lengths; (2) two cylinders are the same as in (1) but not allowed to expand along their sides and lengths; (3) one cylinder is made from superplastic and the other made from steel and free to deform along its sides and length; (4) the same as in (3) but the cylinder is not allowed to expand along its sides and length. Based on the obtained experimental results, the features of each device in dissipating the energy during the large plastic collapse are investigated. It is concluded that the energy absorbed for a given system decreases with the increase of the R ratio. It is recognized that the highest absorbed energy is obtained in the constrained situation with deformable non-deformable compared to the other situations. Moreover, through the finite element simulations, the flow mechanism in each device is studied and compared to the experimental results.