Influence of Specimen Size on the Tear Strength of Fabrics by the Trapezoid Procedure

Tear strength is an important fabric characteristic used to evaluate the serviceability of textile materials and their suitability for particular end uses such as protective clothing. In this study, the effect of test specimen size on tear strength was analyzed. The aim was to determine whether smaller specimens could be used to perform tear strength tests without significantly affecting the test results. The ASTM D5587-15, Standard Test Method for Tearing Strength of Fabrics by Trapezoid Procedure, was followed using the standard test specimen size and three smaller sizes. The geometrical characteristics, i.e., trapezoid angle, length of smaller base, and notch length, were unchanged in the smaller specimens, and only the tearing distance through the specimen became shorter as the specimen size was reduced. The test was performed on three fabrics with different structures: plain weave, ripstop, and ripstop with a laminated polymer membrane. Statistical analysis based on the analysis of variance and multiple comparison tests were used to interpret the data. For the plain weave, and ripstop fabrics tested in the warp direction, the results showed no difference in the mean tear strength between the standard-sized specimens and smaller specimens as long as the specimen size did not fall below 55 by 110 mm. Below this size, the distance over which the tear strength was measured became too short for enough high peaks to be recorded and used in calculating the average tearing strength of each specimen. For the laminated fabric tested in both the warp and weft directions, and for the plain weave and ripstop fabrics tested in the weft direction, there were no statistical differences in the mean tear strength between the four specimen sizes, including the smallest size (45 by 90 mm). These results support the use of smaller specimens to accurately determine the trapezoidal tear strength of fabrics when the amount of material available for testing is limited.