Test MethodComplex yield behavior of polyethylene on oblique angle grooved tensile specimen

In the plane strain grooved tensile (PSGT) methodology of ASTM F2018 standard, a groove in the direction perpendicular to the loading axis allows a biaxial stress state to be generated under a uniaxial loading. The biaxial stress state produced very closely approximates internally pressurized pipes and, hence, is recommended as an alternate test method to actual pipe testing. In this work, the function of the groove in changing the stress state when allowed to vary the groove angle with respect to the loading axis is numerically and experimentally investigated. The results indicated that the yield load of polyethylene resin initially decreased from a plane strain angle of 0°, attained a minimum value at 35°, and then rapidly increased for higher groove angles. It was determined that at 35° a uniaxial stress state prevailed and a maximum value of von-Mises stress existed.