Temperature effects on the compression behavior and failure of 3-D MWK glass fabric-reinforced epoxy composites

This article reports the temperature effects on the in-plane and out-of-plane compression behavior and failure of 3-D multiaxial warp-knitted glass fabric-reinforced epoxy composites. The damage and fracture morphology are observed from macroscopic and microscopic views, and the failure mechanism is demonstrated. The results show that the temperature has significant effect on in-plane and out-of-plane compression properties, the stress versus strain curves decline, and the properties decrease significantly with increasing the temperature. The temperature of 75°C is a key point, at which change in compression properties occurs, and at 150°C, the materials become plastic. Moreover, fiber architecture and loading modes are also important factors on compression properties of composites. The results also show that the damage and failure patterns vary with temperature, fiber architecture, and loading modes. Under in-plane compression, material A shows local 0° fiber layers delaminating and becomes softening and plasticity with increasing temperature. Material B shows delaminating between 0°, 90°, +45°, and −45° fiber layers along 45° angle and exhibits multiple delaminating at elevated temperatures. Under out-of-plane compression, material A shows multiple local shear fracture with 45° angle and experiences softening, roughness, and expansion at elevated temperatures. Material B exhibits shear brittle failure clearly, and delaminating dominates the main failure with increasing the temperature.