Design of a New Arcan Fixture for In-plane Pure Shear and Combined Normal/Shear Stress Characterization of Fiber Reinforced Polymer Composites

Abstract : Engineering elastic constants and strength parameters shall be known to the designer in order to predict the structural response of composite materials. These properties shall be determined in various directions as per the designated standards. Testing of composite materials under the combined effect of in-plane shear and normal stress is of great importance. In this work, a new Arcan fixture has been designed, and then manufactured from aluminum alloy AA7075-T73. This test fixture can be used for uniaxial as well as biaxial testing of fiber reinforced polymers (FRPs) laminates in pure shear, and combined normal/shear stress states. Nevertheless, the fixture can be used for other materials where combined in-plane testing is required including metals and polymers. The special butterfly shape Arcan specimen was optimized based on the parametric study in ABAQUS environment by a Python scripting. The objective of the parametric study was to get a uniform shear stress field in the notch section of the specimen which is the cross-sectional area between the two opposite V-notch roots. The domain of the uniform shear stress-strain distribution in the notch section must be greater enough than the size of the strain gauge rosettes where these can be effectively installed for strain acquisition. The experimental set-ups for the realization of pure shear stress, normal stress, and combined normal/shear stress scenarios are schematically elaborated. The pure shear stress-strain response based on the Arcan test was compared with the tensile testing of +/- 45(0) symmetric laminate.