ASTM International

Standard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials
 N D5045

Annotation

These test methods are designed to characterize the toughness of plastics in terms of the critical-stress-intensity factor, KIc, and the energy per unit area of crack surface or critical strain energy release rate, GIc, at fracture initiation.

Two testing geometries are covered by these test methods, single-edge-notch bending (SENB) and compact tension (CT).

The scheme used assumes linear elastic behavior of the cracked specimen, so certain restrictions on linearity of the load-displacement diagram are imposed.

A state-of-plane strain at the crack tip is required. Specimen thickness must be sufficient to ensure this stress state.

The crack must be sufficiently sharp to ensure that a minimum value of toughness is obtained.

The significance of these test methods and many conditions of testing are identical to those of Test Method E399, and, therefore, in most cases, appear here with many similarities to the metals standard. However, certain conditions and specifications not covered in Test Method E399, but important for plastics, are included.

This protocol covers the determination of GIc as well, which is of particular importance for plastics.

These test methods give general information concerning the requirements for KIc and GIc testing. As with Test Method E399, two annexes are provided which give the specific requirements for testing of the SENB and CT geometries.

Test data obtained by these test methods are relevant and appropriate for use in engineering design.