Research of Extreme Service Temperature on the Bending Behavior of Composites for Wind Turbine Blades

This study employed experimental methods to systematically investigate the bending behavior of composite materials at high temperatures. The biaxial warp-knitted fabric (BWKC) and quadaxial warp-knitted fabric (QWKC) were selected as reinforcement and the mixture solution of epoxy resin and curing agent were selected as matrix. The composite specimen was fabricated by vacuum assisted resin film (VARI). Taking into influence of temperature on the bending behavior of composites for wind turbine blades, further investigations have been conducted to analyze the influence of temperature on the mechanical properties of composites. The quasi-bending behavior of BWKC and QWKC in 0°–90°directions at different service temperatures (20℃, 45℃ and 70℃) were analyzed at macro-scale and micro-scale. Results show that the bending strength and modulus were decreased with the increase of temperature. The ultimate normalized strength of BWKC and QWKC composites were decreased by 20.36–23.56%. The behavior such as the stress–strain curves were also obtained. The relationships between bending behavior and temperatures are also obtained by nonlinear fitting with the experimental data, which could be used to predict the bending properties at different temperatures.