Torsion damage mechanisms analysis of two-dimensional braided composite tubes with digital image correction and X-ray micro-computed tomography

This paper investigates the torsion progressive damage and failure mechanism of two-dimensional (2D) braided carbon/epoxy composite tubes. Four kind of samples with four braiding angles, 30 degrees, 45 degrees, 55 degrees, and 60 degrees, are experimentally tested on the static torsion machine. Three-dimensional digital image correlation (3D-DIC) is utilized to monitor the progressive torsional strain and the crack propagation. Also, Microcomputer tomography (Micro-CT) is employed to describe the volume of damages and the torsional damage morphologies inside the specimens. Results indicate that the braiding angle has a significant effect on the torsional mechanical behaviors. Furthermore, the damage modes of 30 degrees and 60 degrees specimens are mainly influenced by the accumulation of the matrix damage, whereas those of 45 degrees and 50 degrees ones are largely dominated by the fiber tows breakage.