New energy partitioning approach to the measurement of plane-strain fracture toughness of high-density polyethylene based on the concept of essential work of fracture

This study explores three approaches to determining plane-strain fracture toughness of high-density polyethylene (HDPE), based on the concept of essential work of fracture (EWF). The first approach adopted the traditional method that uses total energy consumed in the testing to determine the plane-strain fracture toughness. The second and the third approaches used energy-partitioning principles to exclude the energy consumption in a later stage of the testing from the calculation of the EWF value. The 2nd approach used a new energy partitioning scheme that excluded the energy consumed at the last stage of plastic deformation; and the 3rd approach was based on an existing energy partitioning scheme proposed by another group, to exclude the energy consumption after the maximum load was reached. The results show that only the 2nd approach generates the EWF value that is independent of the specimen thickness. The paper recommends that the 2nd approach be the most suitable method for determining the plane-strain fracture toughness for ductile polymers like HDPE.