Three-dimensional characterization of textile composites

The mechanical and failure behavior of a carbon-fabric/epoxy composite was characterized and appropriate failure criteria in three dimensions were proposed. The material investigated was reinforced with a five-harness satin carbon fiber weave. Test methods were developed/adapted for complete mechanical characterization of textile composites in three dimensions. Through-thickness tensile and compressive properties were obtained by testing short waisted blocks bonded to metal end blocks. The through-thickness shear behavior was determined using a short beam with V-notches under shear. Multiaxial states of stress were investigated by testing in-plane and through-thickness specimens under off-axis tension and compression at various orientations with the in-plane directions. Three types of failure criteria in three dimensions were proposed, limit criteria (maximum stress), fully interactive criteria (Tsai–Hill, Tsai–Wu), and failure mode based and partially interactive criteria (Hashin–Rotem, Sun, NU). The latter, a newly developed interlaminar failure theory, was found to be in excellent agreement with experimental results in the through-thickness direction, especially those involving interlaminar shear and compression.