Damage tolerance property tests of 3D braided composites

In order to investigate the damage tolerance properties of 3D braided composites, first, four kinds of 3D braided composites and one kind of laminate composite which were made by the same kind of fiber, matrix and technology were fabricated respectively. Then, low velocity impact tests and compression after impact (CAI) tests of the same composite under different impact energies and different composites under the same impact energy were conducted. Finally, the C-scan damage detection after impact was conducted, and the dent depth, damage area and damage length after impact were also contrasted. The results show that the damage morphology of laminate composites are mainly oval-shaped and the delamination damage is severe, while most of the damage morphologies of 3D braided composites are cross-shaped, and the integrity of 3D braided composites is better. The impact energy inflection points for the laminate composite and 3D braided composites both appear at about 30 J. The compression residual strength of 3D braided composites is higher, and the damage tolerance properties are better than those of laminate composites. The conclusions obtained can provide guidances for the engineering application of 3D braided composites.