ASTM B871-01(2013)

5.1 The significance of the tear test is similar to that of the notch-tensile test, and its primary usefulness is as an indicator of toughness or as a ranking test as described in Test Method E338 and Practice B646.

5.2 Values of the energies required to initiate and propagate cracks in tear specimens are determined by measuring or integrating the appropriate areas under the test curve developed during the test.

5.3 The unit propagation energy (UPE) is the primary result of the tear test. This value provides a measure of the combination of strength and ductility that permits a material to resist crack growth under either elastic or plastic stresses. The UPE value normally will exhibit greater scatter than conventional tensile or yield strength values. In order to establish a reasonable estimate of average properties, it is recommended that replicate specimens be tested for each metal condition being evaluated. The UPE value has significance as a relative index of fracture toughness.

5.4 The ratio of the tear strength to the tensile yield strength is a measure of notch toughness comparable to the notch-yield ratio from notch-tensile tests carried out in accordance with Test Method E338. It is of value in relative ranking of materials with regard to their toughness.5.5 The numerical results of the test are dependent upon the specimen size and geometry, although specimen thicknesses over the range of 0.063 in. (1.6 mm) to 0.100 in. (2.5 mm) have not shown a significant effect on tear strength (TS) and unit propagation energy (UPE).⁶ These values may exhibit a dependency to thickness when the specimen thickness is outside of this stated range and care shall be taken when using this data.

5.6 The tear test can serve the following purposes:

5.7 The reliability of the tear test has been well established by developing reasonably good correlations1.1 This test method covers the static tear test of aluminum alloy products using specimens that are 0.040 in. (1 mm) to 0.250 in. (6.35 mm) thick.

1.2 This test method is applicable to aluminum alloy products having a minimum thickness of 0.040 in. (1 mm).

1.3 This test method provides a measure of both notch toughness and resistance to crack propagation with the primary use as a screening or merit rank test.

1.4 The reliability of the tear test has been established in various research programs by reasonably good correlations between data from the tear tests and fracture toughness tests.1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.