Tensile damage self-monitoring of carbon fiber/epoxy 3D braided composites with electrical resistance method

Abstract

Electrical resistance method (ERM) has great potential in self-monitoring structural health for carbon fiber composites due to carbon fiber conductivity. Here we report the correlation between tensile damages and electrical resistance changes of 3D braided composites subjected to monotonic and cyclic tensile loading. Experimental and finite element methods were utilized to reveal the electrical resistance variation and damage evolution under monotonic tensile loading. We found that the electrical resistance changes under monotonic tensile loading could be segmented into three regions, namely, linear growth region, transition region and exponential growth region, corresponding to different damage modes. Synchronous and reversible electrical resistance changes at a low strain level (12% of fracture strain) cyclic loading proved the stability and repeatability of self-monitoring capability. While, the abrupt electrical resistance changes at a high strain level (75% of fracture strain), indicated catastrophic failure of the composites. Such kind of correspondence between tensile damages and electrical resistance change under tensile loading enables ERM to achieve the in-situ structural health monitoring of 3D braided composites without relying on external sensors.