Strength and failure characteristics of a glass fiber SMC-R composite under combined tensile and shear stresses

Sheet molding compounds with randomly oriented short fibers (SMC-R) is considered a suitable lightweight alternative for steel and aluminum alloys in many structural automotive components. It is also finding a few applications in the aircraft industry. This study focuses on the quasi-static behavior of a glass fiber SMC-R composite under biaxial loading with a combination of tensile and shear stress components. A butterfly shaped Arcan specimen was used to generate the biaxial loading conditions. It was observed that the failure load is lower under combined tensile and shear loading conditions compared to uniaxial loading conditions. Damage development in SMC-R causes the material to change from a linear behavior to a non-linear behavior at the knee load. The degree of non-linearity increases with increasing shear stress. The failure envelopes based on the nominal principal stresses in the significant section of the Arcan specimen show that von Mises failure criterion used for isotropic materials gives a reasonable agreement with the experimental data.