Double-edge-notched tension

DENT double-edge-notched tension specimen... 

Fig. 20. (a) Double-edge notched tension (DENT) specimen and indication where the essential (We) and the nonessential work of fracture (Wp) is dissipated, (b) schematic EWF plot. 

Figure 12.34 Specific total work of firacture Wf versus ligament length / for deeply double-edge-notched tension (DENT) ( ) and single-edge-notched bend (SENS) ( ) 3 mm thick polypropylene random copolymer samples. (Reproduced with permission firom Fasce, Bernal, Frontini, et al., Polym. Eng. Sci., 41, 1 (2001))...

The measurements are carried out on deeply notched specimens, either single-edge-notched tension (SENT) or double-edge-notched tension (DENT) (see Figure 13.22). The total work of fracture Wf consists of two components. First, there is the work expended in the inner zone We, which is called the essential work of fracture. This relates directly to the energy required to fracture the sample and is therefore proportional to the ligament... 

The Essential Work of Fracture (EWF) technique is a valuable tool to determine the fracture behavior of ductile materials such as polyethylenes under plane stress conditions. [1-3]. The method is based on simple tensile tests performed to DDENT (deeply double-edge notched in tension) specimens. The plastic zone generated at the crack tip during the fracture process can be divided in two regions an inner fracture process zone (IFPZ or FPZ), where fracture surfaces are formed, and a surrounding zone called outer process zone (OPT), where the large plastic deformation exhibited by the material is distributed. 

---