Trouser tear

The two most commonly specified tests are the Die C test and the "trouser tear" (D470) test. Both of these tests measure resistance to tear propagation. Other test shapes include the crescent tear with or without end tabs. This sample shape is often nicked. The "Delft" (IS0816) sample with its internal nick is often used from samples taken from finished products. The exact size of the nick does not appear to be critical to the result. 

The standard calculation is based on the force required for the tear (in Newtons) divided by the thickness of the sample in millimeters. When carrying out the trouser tear, the median force must be taken, as the load varies during the test. 

Trouser-tear G = (2P Vb) - 2wW P, = Eoad at onset of crack growth Rivlin and Thomas, 1953. 

Russian State Standard 14236-81. Polymer Films. Tensile Testing Method. ISO 6383-1 1983. Plastics - Film and Sheeting - Determination of Tear Resistance - Part 1 Trouser Tear Method. 

Good agreement has been reported between tearing energies derived from the test and those from trouser tear measurements [18]. 

ISO 6383-1, Plastics—Film and sheeting- - Determination of tear resistance—Part I Trouser tear method. 1983. 

BS 2782. Method 360B, Determination of tear resistance of plastics film and sheeting by the trouser tear method. 1991. 

Dart Drop Impact Trouser Tear Strength... 

It reduces the problems of forking as experienced with other common test-pieces such as parallel tensile strip, pure shear and trouser tear. 

The so-called trouser tear experiment shown in Figure 12.36 is a particularly... 

Tear resistance was measured at 22°C using a trouser tear specimen described in ASTM D 470-82. The crosshead speed was 500 mm/min. The data reported are averages of results for six specimens. A hand-held Shore Durometer, hardness type "A-2" was used to determine the hardness of the samples, according to ASTM D 2240-75. Specimens were rectangular, 25 mm in length by 13 mm wide. Four plies of sample were used to achieve a thickness of 6.4 mm. Three readings were taken, 6 mm apart on the surface of the four plies. Hardness values measured on the blocks tended to be as much as five units lower. 

The so-called trouser tear experiment shown in Figure 13.41 is a particularly simple case where the equation can be evaluated immediately. After making a uniform cut in a rubber sheet, the sample is subjected to tear under the applied forces P. The stress distribution at the tip of the tear is complex, but provided that the legs are long it is independent of the depth of the tear. 

ASTM D1938, Test Method for Tear-Propagation Resistance (Trouser Tear) of Plastic Film and Thin Sheeting by a Single-Tear Method, 2002. 

There are several types of tear speeimens, with no apparent correlation between types. Some are cut (nicked) to provide a starting point for tearing, while others are not. The most frequently used sample is an unnicked 90 degree angle speeimen listed in ASTM D-624 as Die C and sometimes referred to as Graves Tear. Other speeimens used are a razor-nicked crescent specimen - Die A of ASTM D-624, also referred to as Winkleman Tear -and a trouser tear specimen, so ealled beeause it resembles a pair of men s trousers, of ASTM D-470. 

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