A nondestructive study on porosity content and fiber orientation in CFRP composite laminates using ultrasonic technique method

Abstract

It is found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites. The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head-to-head miniature Rayleigh probes, but the depth can be increased by increasing the separation distance of the transmitting and receiving probes. Also, a method was utilized to determine the porosity content of composites by processing micrograph images of the laminate. The image processing method developed utilizes a free software package to process micrograph images of the test sample. The results from the image processing method are compared with existing data. Beam profile was characterized in unidirectional CFRP(Carbon fiber reinforced plastics) with using pitch-catch Rayleigh probes and the one-sided and two-sided pitch-catch techniques were utilized to produce C-scan images with the aid of the automatic scanner.