Standard Test Method for Determining J-R Curves of Plastic Materials

Importancia y uso:

5.1 A J-R curve produced in accordance with this test method characterizes the crack growth resistances of a wide range of tough polymers and polymer blends (1-5)4 that cannot be obtained in sufficient size and thickness for valid characterization by linear elastic fracture mechanics in Test Methods D5045.

5.2 The J-R curve characterizes, within the limits set forth in this test method, the resistance of a polymeric material to slow stable crack growth after initiation from a preexisting sharp flaw.

5.3 A J-R curve can be used as an index of material toughness for blend or alloy design, material selection, materials processing, and quality assurance (6).

5.4 The J-R curves from bend specimens represent lower bound estimates of J capacity as a function of crack extension, and have been observed to be conservative relative to those obtained from specimen configurations under tensile loading.

5.5 The J-R curves for a given material of constant microstructure tend to exhibit lower slope (flatter) with increasing thickness. Thus, it is recommended that the largest possible specimen with representative microstructure be used.

5.6 The J-R curve can be used to assess the stability of cracks in structures in the presence of ductile tearing, with awareness of the differences that may exist between laboratory test and field conditions.

5.7 A J-R curve may depend on the orientation and propagation of the crack in relation to the anisotropy of the material which may be induced by specimen fabrication methods.

5.8 Because of the possibility of rate dependence of crack growth resistance, J-R curves can be determined at displacement rates other than that specified in this test method (7).

Subcomité:

D20.10

Volúmen:

08.03

Número ICS:

83.040.01 (Raw materials for rubber and plastics in general)

Palabras clave:

crack growth resistance; fracture toughness; J-R curves; plastics; polymers;