Determinating the Volume Content of a Polymeric Matrix in CFRP Structures Using a Laser-Ultrasonic Method

An acoustic method for a quantitative assessment of the volume content of a polymeric matrix in CFRPs is proposed and realized experimentally. For this purpose, a laser-ultrasonic method based on the thermo-optical excitation of broadband pulses of longitudinal acoustic waves is used. A formula for calculating the volume content of the polymeric matrix in a CFRP from experimentally measured phase velocities of longitudinal acoustic waves in this material is proposed. Distributions of the volume content of the matrix in a control CFRP specimen and in a CFRP structure made under similar conditions are obtained. It is shown that the laser-ultrasonic method allows one to detect the areas with excess and deficient matrix content in CFRP specimens and areas of CFRP constructions and to quantitatively assess the spread of matrix content. The spread between the maximum and minimum matrix content observed depends on the shape of the investigated area of the structure. This method can be used for the quality control of composite structures before their exploitation.