Lightning damage characteristics of C_f/SiC based on ultrasonic and multi-nondestructive testing methods

According to the characteristics of the internal damage of the C_f/SiC composite material after the lightning strike, this article establishes a high-energy ultrasonic excitation, reception, and high-resolution ultrasonic testing model, achieving high-energy and high-resolution ultrasound C-scan detection of C_f/SiC composite material samples after lightning strikes, and combining digital X-ray and computed tomography methods for damage analysis. When the lightning energy is gradually increased, the lightning stratified damage will occur inside the sample, and the delamination damage area reaches the maximum value of 25182 mm² at the lightning energy of S4. Subsequently, as the energy increases, significant needle-like damage is generated at the needle-stitched area inside the sample, and the area of delamination damage gradually decreases. When the energy continues to increase to the lightning strike energy of S6, as the energy increases, the number of needle-like damage in the sample continues to grow, and penetrating injury appears at the needle suture site. At S8, the maximum number of needle-like lightning damage occurred, with 53 damage points and a total volume of 256.86 mm³, respectively. Through comprehensive analysis, C_f/SiC has excellent resistance to lightning damage, but the needle-stitched carbon fiber in the thickness direction significantly reduces its resistance to lightning penetration.