A Study on a Novel Impact Test for SHM of CFRP Based on Screwdriver Bit Launch and Electret Microphone

Abstract

Carbon fiber reinforced polymer (CFRP) has recently been the subject of studies due to its increasing use in industry. Many of these studies are focused on topics related to the structural health monitoring (SHM) of this material, as its susceptibility to internal cracks and fissures are unnoticeable to visual inspection. Thus, this work presents the study of two reproducible methods of acoustic emission for two different structural conditions of a CFRP sheet in order to verify the effectiveness of each method in identifying damage, using an electret microphone for monitoring. One of the used methods is the Pencil Lead Break (PLB), which is well known in the literature, and the other is the proposed method, which consists of launching a screwdriver bit on the structure surface. To this purpose, tests were conducted for both methods on the sheet surface before and after the addition of a small metallic body to simulate structural damage. The acoustic waves generated from the tests were captured by the electret microphone attached close to the edge of the CFRP sheet. The results showed that both methods were able to identify the damage on the structure, and the proposed method is viable as a higher acoustic power alternative for monitoring the structural integrity of this type of material.