Experimental Investigation of High Density Polyethylene Yield Surface Under Biaxial Loading

A series of biaxial experiments are performed to investigate the yield envelope of high-density polyethylene (HDPE). An Arcan apparatus is achieved in order to load a newly-designed flat specimen “butterfly specimen” to various combinations of tensile/compressive and shear loading. It subjected a central section of the specimen to a uniform state of plane stress. The stresses have local maxima at the central section, thus ensuring that yielding occurs there. The yield stresses are determined from the load-displacement curves and plotted in two-dimensional principal stress. The experimental results are compared with a predicted yield envelope based upon a pressure modified von Mises criterion, which accounts for the difference in tensile and compressive yield stress; additionally the hydrostatic pressure on yielding is also considered. Good agreement is found.