Abstract: The laminates made by 2D carbon woven plies have better low-speed impact performance than those of unidirectional carbon tape laminates, but the woven ply is weaker than tape ply in in-plane maximal stiffness and strength. The mixed woven composites being laid up by these two kinds of layers alternately can have the advantages of impact performance, stiffness and strength together, and the processibility is good also. In this paper, first, experimental tests are performed on those mixed woven composites with four kinds different proportions of unidirectional plies to determine their stiffness and strength, and then the drop weight impact tests of different energy levels are performed. An ultrasonic C-scan method is used to detect the damage areas. The residual compress strength after impact is also investigated. The best proportion of unidirectional layer in the mixed woven composites considering stiffness, strength and damage tolerance of low-speed impact is studied.

Key words: mixed woven composites, low-speed impact, stiffness, strength