COMPETITION BETWEEN NECKING AND PRE-CUT PROPAGATION IN FRACTURE OF HIGH-DENSITY POLYETHYLENE REVEALED BY TIME COURSES OF STRAINS [Poster #19]
Shengwang HaoGrand Ballroom D
High-density polyethylene pipes are widely used in pressure pipe applications such as water and gas transportation, but both necking and pre-crack effects are still poorly understood. This paper presents experimental observations to highlight strain field evolutions to necking and effects of pre-crack on strain field evolutions in a high density polyethylene material deformed in tension through analyzing spatial distributions of time histories of strains. Necking and its growth along the tension direction dominate the failure behavior of the intact specimen. Necking and crack propagation are both observed in the pre-cut specimen, but the crack propagation eliminates the necking propagation along the tension direction. Energy releases from positions outsides the crack zone lead to the macroscopic load-displacement curve deviates from the trend of the intact specimen. These findings present new recognitions on strain fields evolving to necking and failure induced by the pre-crack that are significant for designing of theoretical models and simulations of polymeric materials and structures.