1、 The following commercial specification is an original Parachute Industry Association specification. TEAR STRENGTH, SELVEDGE, GEOTEXTILE The Parachute Industry Association makes this document available for use by Industry and Government organizations that wish to apply this specification to their pr
2、oducts. 1. SCOPE 1.1 Scope. This method is intended for determining the tear strength of the selvedge of geotextile woven materials. 2. TEST SPECIMEN 2.1 Specimen. The specimen shall be cut 3 x 8 inches, from the selvedge, inclusive of all selvedge yarns, with the long dimension parallel to the warp
3、 (machine) direction. Specimens shall be marked with an isosceles trapezoid, centered on the sample, with the 1” side of the trapezoid located on the selvedge edge (see FIGURE A). FIGURE A 3. NUMBER OF DETERMINATIONS PIA-TEST METHOD-502 04 July 2011 DISTRIBUTION STATEMENT: All Rights Reserved. No Pa
4、rt of this publication may be reproduced without prior written permission from Parachute Industry Association. Additional copies may be purchased on-line from the PIA Store at: . PIA-TEST METHOD-502 Page 2 of 3 3.1 Number of Determinations. Unless otherwise specified in the procurement document, six
5、 determinations shall be tested from each sample unit. At least three specimens shall be excised from each selvedge. 4. APPARATUS 4.1 Tensile Testing Machine. A tensile testing machine with a constant rate of extension (CRE) and a load recording mechanism shall be used. 4.2 Clamps. The clamps shall
6、have a flat surface capable of gripping the specimen and preventing slippage. The clamps shall measure 2 by no less than 3 inches, with the longer dimension installed perpendicular to the direction of application of the load. 5. PROCEDURE 5.1 Preparation of specimen. Unless otherwise specified in th
7、e procurement document, material testing shall be performed under standard conditions as specified in ASTM D 1776. 5.2 The specimen. The specimen shall be placed in the clamps of the machine with the long dimension parallel to the application of the load. The distance between the clamps (gage length
8、) at the start of the test shall be 1 .005”. The upper clamps shall be supported by a free swivel or universal joint which allows the clamp to rotate in the plane of the fabric. Secure the specimen in the machine, clamping along the nonparallel sides of the trapezoid. The end edges of the clamps mus
9、t be in line with the 1” long side of the trapezoid. When secured, the short finished selvedge is taut and the remaining fabric of the specimen lies in folds. 5.3 Operation Speed. The machine shall be set to operate at a speed of 12 .5 inches per minute (in/min). 5.3 Tear Strength. Start the machine
10、 and ensure the tearing forces will be recorded. Force shall be applied to the specimen so the upper clamp, through which the force is applied, moves at a rate of 12 in/min until the specimen has torn across. After completion, record the maximum force obtained in pounds force (lbf). 5.4 Slippage. Te
11、ars in or at the edges of the clamps or for any reason are attributable to faulty technique, shall be discarded and another specimen tested. If slippage continues to occur, the clamps may be padded, the fabric may be coated under the clamp face area, or the clamp face may be modified. If any of thes
12、e modifications are used, state the method of modification on the report. 6. REPORT 6.1 Tear Strength. The tear strength of the sample unit shall be the average of the results obtained from 6 specimens tested and shall be reported to the nearest pound. 6.2 Calculation of average reporting. Each indi
13、vidual value used to calculate the average shall also be reported. PIA-TEST METHOD-502 Page 3 of 3 * Notices: This document is being maintained as a commercial specification by the Parachute Industry Association. Orders, inquiries, and comments should be addressed to PIA, Specification Committee via
14、 email at: or to our website at: . Adapted, with permission, from the ASTM D 4533-04(2009) Standard Test Method for Trapezoid Tearing Strength of Geotextiles, copyright ASTM International (ASTM), 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard and current revisio
15、n may be obtained from ASTM at: www.astm.org. Disclaimer: This document is published by the PIA to provide technical and engineering standards that can be used by reference by all those who may benefit from them. The use of this document is entirely voluntary, and its applicability and suitability f
16、or any particular use, including any patent or trademark infringement arising there from, is the sole responsibility of the user. The PIA reviews each technical publication periodically, at which time it may be reaffirmed, revised, or cancelled. The PIA invites your written comments and suggestions. Copyright 2011 Parachute Industry Association.
