Damage evolution in braided composite tubes under axial compression studied by combining infrared thermography and X-ray computed tomography

In this work, the effect of axial yarns on damage behavior of two-dimensional triaxially braided composite (2DTBC) tubes subjected to axial compression was investigated. A novel damage detection method combining infrared thermography and CT scanning was presented. In the area without axial yarns, yarn crossovers were separated from each other due to interlacing patterns. Axial compression caused the braiding yarns to shear deformation like scissors. Inter-yarn de-bonding appeared in crossovers and could not connect. Consequently, it caused a progressively folding failure mode. In contrast, local buckling occurred on axial yarns because of their primary loading behavior. Cracks along the axial yarns formed, which would combine with debonding crossovers caused by the sheared braiding yarn. It resulted in significant inter-layer delamination and consequently splaying failure mode. The energy absorption of composites tube with 18 axial yarns increased by 79.9% at the cost of 27.8% fiber usage more than 3 axial yarns.

Automated summary

This study investigated the effect of axial yarns on the damage behavior of 2DTBC tubes subjected to axial compression. A novel damage detection method combining infrared thermography and CT scanning was proposed. The presence of axial yarns resulted in different failure modes, with interlayer delamination and folding failure occurring in the absence of axial yarns, and splaying failure occurring in the presence of axial yarns. The use of more axial yarns increased energy absorption but also fiber usage.