Damage evolution monitoring and failure level evaluation of composite bolted joints by MXene/CNTs sensors

Abstract

The composite bolted joints are the weak points of overall structure, lacking an effective and accurate monitoring method. In this paper, a novel MXene/CNTs film sensor with high sensitivity and stability was synthesized for the damage evolution monitoring of composite bolted joints. The correlation between the response signals of the sensors and the mechanical behaviors of the composite structures is established. Based on this research, the damage evolution monitoring and failure level evaluation of composite bolted joints were studied. The damage properties of the composite bolted joints can be reflected in real-time by the resistance change rates of the sensors. The experimental results show that the failure level of composite bolted joints can be divided into four levels (I-II-III-IV) according to the resistance change rates of sensors. Especially when the damage extended to the III stage, the $∆R/R_0$ surged from 0.3 to 0.75. The time point of this step signal occurred about 1 min earlier than the time point of max bearing strength, which can effectively warn the occurrence of structural failure.