Analysis of torsional failure and bearing capacity of composite thin-walled tubes filled with plastic foam

Torsional buckling and failure of carbon fiber/epoxy resin composite thin-walled tubes (CTWTs) were tested and analyzed, and the effects of torsional buckling on the material failure and failure loads were simulated by finite element method. In order to enhance the torsional bearing capacity of CTWTs, the buckling/failure of the tubes filled with polymer foam were further simulated by ABAQUS. Numerous simulation results show that the buckling of the tube is strongly inhibited by foam core under torque. Because of the usage of crushable foam material, the influence of the elastic modulus and yield strength of the foam materials on the torsional failure modes and loads are studied. With the elastic modulus and the yield strength increasing, the buckling/failure load of CTWTs gradually increases and reaches the ultimate permitted strength of materials. Reasonable selection of the core material can help to obtain higher bearing capacity, and make full use of the high strength properties of composite materials.

I. Introduction

Composite thin-walled tube (CTWT) as a typical structure with high strength and light weight has been widely used in engineering. Compared with the traditional metals, composite material has excellent fatigue resistance properties, which can substantially improve the fatigue life of the component such as the driving shaft. Buckling and failure of CTWTs are the key points for the design analysis in the case of the torque load. According to the theory of thin shells, scholars have obtained the analytic expressions of composite cylindrical shell buckling load under torque in previous [1]–[3]. The buckling loads and modes of composite cylindrical shells under torque were calculated by the geometric nonlinear finite element method [4]. Because of buckling of CTWTs, the torsion bearing capacity of circular tube is reduced, it is great importance to improve torsional buckling load of circular tubes filled with light materials.