Experimental and Numerical Investigation of Mechanical and Failure Characteristics of CFRP Lap Bar by Acoustic Emission and Micro-CT

Carbon Fiber Reinforced Plastic (CFRP) is particularly suitable for replacing metal materials in the safety lap bars of amusement rides due to its excellent mechanical properties and lightweight nature. To ensure the safety and dependability of the CFRP lap bar, the mechanical characteristics of the lap bar were investigated through a combination of experimental and simulation methods, and the damage behavior is analyzed using acoustic emission (AE) and X-ray micro-computed tomography (micro-CT). Simulation results revealed that the maximum principal stress of the tubular element and lap bar arm was 132.27 MPa, located at the profile alteration point beneath the lap bar arm. The damage behavior of the lap bars was investigated through an analysis of the AE signals generated during the five experimental stages. With the increase in load, a large number of signals with frequencies exceeding 300 kHz appeared, indicating irreversible damage such as fiber pull-out and matrix cracking. In addition, the number of AE signals captured by Sensor 3 corresponding to the bent portion of the lap bar arm exceeded 6,000, representing the largest proportion and indicating that the damage in this area is relatively intensive. Furthermore, the internal damage morphology was reconstructed using micro-CT. The observed damage was primarily caused by interlayer damage. The failure of the CFRP lap bar is attributable to the cumulative effect of multiple damage modes, validating the reliability of the damage mode characterized by AE signals. Eventually, the damage evolution mechanism of the CFRP lap bar was clarified, providing a basis for design optimization and service evaluation.