Compression After Multi‐Angle Low‐Velocity Impact Damage Mechanisms of Concave 3D Angle‐Interlock Woven Composite

ABSTRACT In this study, by varying the proportions of four sets of yarns (binder, weft, warp insertion and weft insertion), four concave 3D angle‐interlock woven composites (3DAWCs), named S1(1:1:0:0), S2 (0.5:1:0.5:0), S3 (1:0.5:0:0.5), S4 (0.5:0.5:0.5:0.5), were designed and fabricated. Compression after multi‐angle (90°, 75°, and 60°) impact (CAI) tests on four concave 3DAWCs were conducted. The surface crack propagation and the internal yarn failure patterns were characterized by using 3D profilometer and CT scanning. A concave 3DAWC CAI model at microscale was established for finite element (FE) analysis. The results indicated that the ultimate strength and compressive stiffness of the four 3DAWCs increased as the impact angle decreased. The analysis of surface compression damage shown that the greater the impact angle, the more prone 3DWACs were to crack propagation. The study further revealed that the incorporation of weft insertions into the reinforcement of 3DAWCs were highly effective in enhancing CAI strength. And introducing warp insertions in 3DAWCs could reduce crack propagation. The results of the FE calculation and the CT characterization are highly consistent, which verifies the reliability of the model. The simulation results shown that a reduction in the impact angle leads to an increase in the stress transfer efficiency of the yarn during compression, and the significant deformation of the weft is the main cause of crack propagation.