Failure mechanism of woven natural silk/epoxy rectangular composite tubes under axial quasi-static crushing test using trigger mechanism

This study investigates the energy absorption response of rectangular woven natural silk/epoxy composite tubes when subjected to an axial quasi-static crushing test using a trigger mechanism. The resulting deformation morphology of each failure region was captured using high resolution photography. The rectangular composite tubes were prepared through the hand lay-up technique, in which 24 layers of silk fabric were used, each with a thickness of 3.4 mm and tube lengths of 50, 80, and 120 mm. The parameters measured were peak load, energy absorption, and specific energy absorption as functions of the tube lengths. Specific energy absorption values decreased with increased length of the composite specimen, whereas total energy absorption increased with the increased length of the composite specimen. The deformation morphology showed that the failure mechanism proceeded in two stages, namely, (i) onset of tear and (ii) propagation of tear, which included progressive buckling and delamination. The composite tubes only exhibited progressive but not catastrophic failure.