Delft test piece

ISO 34-2 1996 Rubber, vulcanized or thermoplastic - Determination of tear strength -Part 2 Small (Delft) test pieces... 

Tear test pieces are normally stamped from sheet with an appropriate die (see Chapter 4) and then a nick cut if required, although with the Delft test piece both operations are usually done simultaneously. 

Figure 8-21. Cross section of die-cut tear test pieces, (a) Nicked crescent test piece (b) Delft test piece, w = effective width of untom portions.

In ISO 34-2, the result for the Delft test piece is expressed as the force to tear a test piece of standard width and thickness, corrections for variation within tolerance of width and thickness being given ... 

Part 1 Trouser, angle, and crescent test pieces Part 2 Small (delft) test pieces Standard test method for tear strength of conventional vulcanized rubber and thermoplastic elastomers Testing of rubber and elastomers Determination of the tear strength of elastomers Trouser test piece... 

Other standards similar to the above are as follows. ISO 34. 1994 (= BS 903 A3, 1995). Rubber, vulcanized or thermoplastic -Determination of tear strength. Part 1. TroiKser. angle and crescent test pieces. ISO 816, 1983. Rubber, vulcanized Determination of tear strength of small test pieces (Delft test pieces). Here, the force required to tear across the width of a small test piece (2 x 9 x 60 mm) containing a 5 mm wide slit in the center of the specimen is measured. 

With crescent, Delft and angle test pieces only the maximum force reached is recorded, although the change of force along the short tear path could be obtained with a force measuring and recording system having very... 

The quantity directly measured in a tear test is the force on the test piece during testing. Particularly with the trouser method, this force will fluctuate along the tear path. ISO 34 takes the maximum force reached in the case of crescent, angle and Delft methods but for the trouser method a median force is determined in accordance with procedures given in ISO 6133147, Analysis of multi-peak traces obtained in determinations of tear strength and adhesion strength. 

Wash trials are carried out by the use of soiled test pieces, eg, commonly used stains for protease evaluation are milk, blood, and grass. Commercial pre-soiled test pieces also may contain particulate matter, eg, carbon black, as part of the stain matrix. Test materials are available ready-to-use from a number of research and testing institutes in Europe and the United States, eg, Center for Testmaterials, Vlaardingen, Holland Wascherei Forschungs Institut, Krefeld, Germany EMPA, St. Gallen, Switzedand Institut voor Reinigingstechnieken TNO, Delft, Holland and Testfabrics, Middlesex, New Jersey. Alternatively, enzyme manufacturers can supply preparation procedures. 

ISO 34 (BS903, Part A3) contains as many as five test methods for tear strength, a reflection not only of the general importance of the property but also of the difficulty of matching laboratory tear tests to product behavior. The methods comprise the trouser, crescent. Delft, and nicked and unnicked angle test pieces, none of which gi es comparable results to another. ASTM D624 specifies crescent test pieces with and without tab ends (Dies A and B respectively), the unnicked angle test piece (Die C). and the trouser test piece (Die T). 

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