Characterization of localized porosity in laminated composites using ultrasonic interferometry

Localized porosity in stratified carbon fiber–reinforced polymer (CFRP) composites can severely affect mechanical performance and structural integrity. Conventional ultrasonic attenuation methods can quantify residual porosity but cannot characterize clusters of voids. This work presents an ultrasonic interferometric approach for the quantitative assessment of localized porosity in laminated composites. CFRP specimens are manufactured in an autoclave under controlled conditions to introduce defined porosity levels. Through-transmission ultrasonic measurements are compared with an analytical multilayer propagation model including a degraded layer described by multiple scattering theory. Solving the inverse problem enabled estimation of both the location and concentration of void clusters. Results show good agreement with X-ray tomographies, confirming the capability of ultrasonic interferometry for accurate detection of localized porosity and its potential for non-destructive evaluation of laminated composites.