Interpretation of Acoustic Emission Signal from Composite Materials and its Application to Design of Automotive Composite Components

An acoustic emission (AE) technique has extremely high utility for the study of microfailure as well as for the quality assurance of the composite materials. In order to make the AE technique more useful, the following four studies have been performed; (1) in situ failure analysis by SEM to obtain a detailed failure process of the composites and its relationship to the emission origin; (2) dynamic strain energy loss measurement to examine the strain energy loss factor of the composites due to microfailure under vibratory load: (3) laser Raman spectroscopy to measure the stress of the individual fibers in the composites and its change due to microfailure: and (4) thermo-acoustic emissions measurement to observe the emission activity of damaged composites under a thermal cycle Based on the proper understanding of the microfailure mechanism of the composites through the above experiments, the AE technique has been successful in the development of the following automotive composite components: GFRP leaf spring, CFRP propeller shaft, composite aluminum piston, SMC structural components, and FRTP injection-molded components.