Self-healing bolted joint analysis

The loosening mode of failure of bolted joints is a common form of failure in many structures. Real-time condition monitoring and active control of critical joints will improve the reliability and safety of many structures where bolted joints are used. Impedance-based health monitoring using the electromechanical coupling of piezoelectric materials is used to identify damage. Cylindrical shape memory alloy washers (Nitinol), which expand axially when heated, are used to restore preload in a loose joint. Due to the complexity of constitutive modeling, the impedance method is also used to illustrate success. Additional considerations required for the successful implementation of this promising technique are discussed.