Effect of Boundary Conditions on the Energy Absorption of Composite Tubes

Abstract

Composite tubes with different cross-sectional shapes, including quarter circle, half circle and three-quarter circle, are axially crushed to study the boundary effects on the energy absorption of cylindrical shells and develop a semi-empirical analysis method for the crashworthy design of composite structures. It is observed experimentally that all specimens crush from the chamfered end and exhibit stable progressive crushing with similar macroscopic failure modes. Experimental results indicate that the load-displacement curves of all specimens are similar to those of full-circle tubes. And the quarter-circle tubes show the lowest energy absorption capability, while the half-circle tubes and three-quarter-circle tubes show almost the same energy absorption capability. It is found that quarter-circle thermoset tubes without and with one free edge provide 19% and 13% higher energy absorption capability than the quarter-circle thermoset tubes with two free edges; while quarter-circle thermoplastic tubes without and with one free edge provide 6% and 2% higher energy absorption capability than the quarter-circle thermoplastic tubes with two free edges, respectively. It is also found that the semi-empirical analysis method based on crush data and boundary effects of the quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.