Research on Plane Stress Measurement Method For CFRP Based on Array LCR Waves

Stress concentration occurs in composite materials during preparation, processing to assembly and service, and it is crucial to conduct stress detection on them. Composite materials have anisotropic properties, resulting in complex ultrasonic stress relationships. In this paper, an array ultrasonic critical refractive longitudinal plane stress measurement method is proposed. Aiming at the interference of noise on the calculation results of acoustic time difference, a multi-resolution wavelet noise reduction algorithm is designed to process the echo signal. In order to verify the feasibility of the method, stress loading experiments were carried out on Carbon fibre reinforced plastics (CFRP) specimens in the range of 0–160 MPa, and the results showed that the stress measurement error was less than ±8.96 MPa and the angular measurement error was less than ±6.87°. The CFRP structural components in the wing box section specimen were tested for assembly stresses, which provides a basis for future internal stress testing experiments on composite structural components of aircraft.