Plane Strain Fracture Toughness Testing

The development of practical specimens and procedures for determining plane strain fracture toughness was carried out during the late 1950s and 1960s, largely 

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This stipulation on the allowable extent of plastic deformation at the crack tip cannot be used conveniently in fracture testing. The extent of deformation that would be allowed, however, is equivalent to a specification on the change in load-displacement curve at the maximum load point in relation to the initial slope ie., from elastic to elastic-plastic deformation). This change in slope can be readily measured and is used in plane strain fracture toughness testing. 

Interpretation of Data for Plane Strain Fracture Toughness Testing... 

Figure 4.14. Calibration factors H for use in the analysis of load-displacement records in plane strain fracture toughness tests (after ASTM STP 410) [ ] ...

Fig. 9.10 Effect of critical stress intensity factor on the thickness of the specimen to propagate a crack in aluminum alloy 7075 [22]. Reprinted, with permission, from ASTM STP 463, Review of Developments in Plane Strain Fracture Toughness Testing, copyright ASTM International, West Conshohocken, PA.

Cha Chan, M. K. V., Williams, J. G. Plane strain fracture toughness testing of high density polyethylene. Polym. Eng. Sci. 21 (1981) 1019-1026. 

R. T. Bubsey, J. L. Shannon, Jr. and D. Munz, Development of Plane Strain Fracture Toughness Test for Ceramics Using Chevron Notched Specimens, in Ceramics for High Performance Applica tions HI. Reliability, (Plenum, NY, 1983), pp. 753 771. 

The most common test specimen configurations for performing plane-strain fracture toughness test are the single edge notch bend (SENB or three-point bend) and the compact tension specimens. Hence, for an accurate determination of the plane-strain fracture toughness, a specimen whose thickness exceeds a critical size is required. 

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