Trouser tear specimen

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. 

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. 

FIGURE 10.2 Mechanical failure tests (a) tensile test on dumbbell specimen (b) tensile test on ring specimen (c) notched crescent and trousers tear specimens (d) Izod impact test machine (Data from HaUinan, A. J., Jr., J. Qual. Tech., 25, 85, 1993) (e) motor-driven brittleness temperature tester. (Data from Book of Standards, ASTM, Baltimore, MD, 1958, 286,356.)... 

Trouser tear 2PX b Pc = load at onset of crack growth w = width of specimen arms a... 

Fig. 4.30 Tear Resistance Ts of carbon black-reinforced elastomers as a function of the CB content the tests were performed with 2 mm thick trouser specimens and a test speed of 100 mm min ...

The most popular method used for quality control uses a pendulum device (Fig. 6.3) to measure the resistance to tear propagation (ASTM D1922). For this test, specified test samples are die cut and include a slit at one end. The tabs formed on either side of the slit are clamped into the device so that when the pendulum is released a so-called trouser leg tear force is applied along the specimen in the direction of the slit. The test device reports the maximum resistive force carried in the film. Commonly, ten specimens in both the machine and transverse direction of the film are tested. 

The other methods include ISO standard method. Tear properties of fabrics — Part 2 Determination of tear force of trouser-shaped test specimens (Single tear method) (ISO 13937-2 2000). 

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