Self-Repairing Joints Employing Shape-Memory Alloy Actuators

摘要

This article describes self-sensing and self-repairing bolted joints that employ piezoelectric and shape-memory alloy elements. The piezoelectric materials use electrical impedance analysis to assess the conditions of joints. When damage occurs, the shape-memory washers can automatically regain lost torque. The actuator is a cylindrical Nitinol washer that expands axially when heated. The stress generated by the axial strain compresses the joint members and creates a force, generating a preload and restoring lost torque. Due to the complexity of constitutive modeling, a qualitative analysis by the impedance method is used to illustrate the success of this experiment.