When impact damage occurs in carbon fiber-reinforced plastic (CFRP) structures, it is barely visible but may cause significant degradation in the mechanical properties of the structure. Hence, a structural health monitoring (SHM) system that can be installed in CFRP mobility structures and is sensitive to impact damage is needed. In this study, we attempted to establish an SHM system based on ultrasonic guided waves, which are generated by inputting a broadband chirp signal into a film-like piezoelectric actuator. The relationship between impact damage size and maximum time-of-flight (ToF) delay was investigated for three types of CFRP plates: woven, non-woven, and hybrid laminates. As a result, it was found that the maximum ToF delay increased linearly with an increase in the damage size for all CFRP laminates. Moreover, the amplitude of the A₀ mode was found to be significantly affected by the damage length in the wave propagation direction. Thus, this SHM method using chirp ultrasonic waves can quantitatively evaluate the size and extent of the impact damage in CFRP laminates.

1. Carbon fibre-reinforced plastic (CFRP) is a composite material with the properties of high stiffness [1], high strength [2], lightweight and excellent corrosion resistance [3]. With these advant...

To reduce the weight of the personal mobility structure, woven CFRP composites that are easy to form complex shapes are suitable. However, since the impact damage occurring in the CFRP structure is barely visible, development of a low-cost structural health monitoring (SHM) system that can be installed in mobility is expected. Hence, we construct an SHM system that transmits and receives ultrasonic guided waves over a broad bandwidth by inputting a chirp signal to a film-like piezoelectric element in this research. We are trying to detect an impact damage that has occurred in woven CFRP laminates by measuring the delay in the propagation time of ultrasonic Lamb wave depending on frequency.