Laser-ultrasonic study of local porosity distribution in CFRP stringer panels

Abstract

The paper presents a method for quantifying the porosity of carbon fiber structures based on laser excitation of probing ultrasonic pulses. A method for estimating the porosity of a material from the experimentally measured phase velocity of longitudinal acoustic waves propagating in it is proposed. Using the example of control samples and real structures made of carbon fiber, the possibility of obtaining distributions of local porosity values in the studied section of the structure is demonstrated. It is shown that in the studied structures there are regions with a significant variation in the value of local porosity. The proposed method can be used to control the quality of manufactured composite structures, as well as to study the internal changes in structure during operation.