Study on impact damage characteristic parameters and threshold model for composite material laminates

Laser shock interface bonding force detection technology has significant advantages in assessing the bonding strength of adhesively bonded composite structures. However, current research methods rely on dynamic monitoring of the shock process combined with post-impact microscopic imaging for damage status determination. This approach presents challenges such as a cumbersome process, difficulty in standardizing damage scales, inconsistency between laboratory and field data types and their physical meanings, and limited generalizability of test results. This paper establishes a “mass-spring-damper” response theory model for laser-shocked composite plate structures and introduces a new damage characterization parameter, R. This parameter reflects the residual vibrational energy post-impact and can serve as a threshold indicator for damage determination. By establishing a relationship between laser parameters and the R value, the model facilitates rapid identification of damage stages and quantifies internal damage status with the established threshold model. The model accuracy is validated using laser shock data from two sets of T300 composite laminates. This method addresses the challenges of direct quantification and unified assessment across parameters, providing a reliable basis for parameter selection in engineering applications.