Effect of cross-sectional geometry on the energy absorption capability of unidirectional carbon fiber reinforced composite tubes

Abstract

Owing to the high strength and stiffness to weight ratios, composite materials are being adopted as a new energy absorption member. As a structural part, square tubes have geometrical advantage because the flat region can be assembled easily with other components in car body during the manufacturing process. In this study, unidirectional carbon fiber reinforced composite tubes with circular and square cross section were fabricated through pultrusion process and tested by quasi-static axial compression. The energy absorption capability of the circular tube was found to be superior to that of the square tube in terms of specific energy absorption. The energy absorbing mechanisms of square tubes were investigated on the basis of precise longitudinal cross-sectional observation through the crush zone tested in step-wise compression. It was found that the fracture mechanisms at the flat wall and the corner were different during crushing. The corner regions seem to support the crush load more effectively. A novel experimental method was designed to determine the energy absorption at the corners and the flat walls respectively. Finally, the difference in specific crushing stress between the corner and the flat wall region is discussed in terms of the influence of geometry. © Freund Publishing House Ltd.