Effect of temperature on flexural and interlaminar shear strength properties of carbon-epoxy composites: Experiment and modeling

Carbon fiber composites are known for excellent specific mechanical properties at room temperature. It is important to model the effect of temperature on flexural strength and interlaminar shear strength (ILSS). In this study, T700 carbon fiber composites with two different epoxy resins (Epofine, LY556) were prepared using filament winding and named as TE and TL composites. The dynamic mechanical analysis (DMA) tests revealed T-g of 177 and 192 degrees C for TE and TL composites, respectively. Three-point bending (flexural) and shortbeam shear (ILSS) tests were performed at similar to 20, 0, RT, 90, 105, 150, 170, and 200 degrees C. It was observed that flexural strength and ILSS decreases linearly with increase in temperature. Fracture analysis of flexural samples revealed fiber breakage at similar to 20 degrees C and micro-buckling at elevated temperature are dominant failure mechanisms. Fracture analysis of ILSS samples showed delamination with microcracking at similar to 20 degrees C and plastic deformation of matrix at elevated temperature. A new empirical model was proposed to predict the temperature dependent flexural strength and ILSS. With this model, variation of flexure strength and ILSS with temperature can be estimated from respective values at RT, T-g and storage modulus values from DMA, thus extensive experimentation at high temperatures can be avoided. Highlights Mechanical properties of filament wound composites are tested from similar to 20 to 200 degrees C. Flexural strength and ILSS linearly decreases with increase in temperature. Fiber breakage at similar to 20 degrees C and micro bucking at 200 degrees C are dominant in flexure. Delamination at similar to 20 degrees C and plastic deformation at 200 degrees C are dominant in ILSS. Analytical model for finding temperature dependent flexural strength and ILSS.