A numerical study on stress wave propagation in quasi-isotropic stacks of Dyneema® compliant composite laminates

This study aims to identify the ballistic mechanisms of quasi-isotropic (QI) panels made from compliant composite laminates, focusing on the propagation of various stress waves. Three hypotheses are proposed that in terms of the propagation of stress waves, incorporating ① longitudinal, ② transverse, and ③ bending waves, QI panels would perform better than the aligned (AL) counterparts, based on simplified theoretical analyses to provide a theoretical basis for the study. 2-, 3-, and 4-ply QI panels are found to absorb approximately 23 % more energy than the aligned (AL) counterparts in the ballistic tests. The finite element (FE) models are developed using hierarchical and global-local approaches, and the results are well agreed with the experimental ones. The results elucidate the influence of QI stacks on the propagation of stress waves. The ballistic mechanisms are ultimately explored and elucidated.