PIA-TEST METHOD-6015-2015 STRENGTH AND ELONGATION TESTING SPECTRA CORD SPLICED SPECIMEN METHOD.pdf

1、 The following commercial specification is originally adopted from the military document. Revision A includes all known accepted revisions, amendments, notices, and Department of Defense (DoD) engineering changes previously developed for this item. Revision B and forward include changes adopted by D

2、oD and Industry to reflect technology and design evaluation. STRENGTH AND ELONGATION TESTING SPECTRA CORD; SPLICED SPECIMEN METHOD The Parachute Industry Association makes this document available for use by the Industry and Government organizations that wish to apply this specification to their prod

3、ucts. 1. SCOPE 1.1 Scope. This method is intended for determining the breaking strength and elongation of cordage that requires an eye splice to be tested. 2. TEST SPECIMEN 2.1 The test specimen shall be a single length of cordage. 2.2 The specimen shall be eye spliced at both ends with a loop big e

4、nough to go over the holding apparatus. Eye splice shall be accomplished with either a tapered buried eye splice, as per FED-STD-191 TM 6015, or a blunt end cut at a 45 degree angle. The taper shall consist of cutting out every fifth pick in right and left strands for 16, 24 and 32 strand round brai

5、ds and alternately fourth and fifth picks for 20 strand braid. For some types of cord a bartack may be used to secure the finger trap, but is not always necessary. 2.3 The specimen shall have a minimum of 6 inches of free cord (see FIGURE 2) between the ends of the finger traps. 3. NUMBER OF DETERMI

6、NATIONS 3.1 Number of determinations. Unless otherwise specified in the procurement document, five specimens shall be tested for every sample unit required per sampling method identified in PIA-C-7515. 4. APPARATUS 4.1 Apparatus. The apparatus for determining the breaking strength and elongation sha

7、ll conform to requirements identified in Section 4 of FED-STD-191 TM 6015 with the following exception; the straining mechanism shall be such, that during the test, the movement of the pulling clamp shall be at a uniform rate of 2-1/2 1/2 inches per minute. 4.2 An ink marker with a very fine tip sho

8、uld be used to mark the specimen. PIA-TEST METHOD-6015 22 January 2015 DISTRIBUTION STATEMENT: All Rights Reserved. No Part of this publication may be reproduced without prior written permission from Parachute Industry Association. Additional copies may be purchased on-line from PIA Specifications a

9、nd Products at: . Copyright Protected: Do Not Copy!PIA-TEST METHOD-6015 4.3 A pair of dividers or other suitable measuring device should be used to calculate the distance between marks on the specimen; the device should be graduated in divisions of 1/16 of an inch. 5. PROCEDURE 5.1 The specimen shal

10、l be placed within the holding devices with the long dimension parallel to the application of the load (see FIGURE 3). If elongation measurements are required, a tension of 1 percent of the minimum breaking strength shall be applied while under this tension. Two fine gage marks shall be spaced a min

11、imum of 5 inches apart on the specimen in such a manner that neither mark will be closer than 1/2 inch to the end of the finger trap. If the resultant marks are not exactly 5 inches apart, the precise measurements shall be recorded to 1/16 of an inch. This original distance is identified as “0” in t

12、he calculation. No marks shall be on the eye splice itself. 5.2 Elongation. If elongation is required, elongation shall be determined on the same specimen being tested for breaking strength. The machine shall be stopped and the distance between marks shall be measured and recorded at 75 percent of t

13、he minimum breaking strength. The use of an optical extensometer is allowed as long as all other requirements of this test method are met. This is the final distance identified as E in the calculation. The distance between the marks shall be measured to the nearest 1/16 of an inch. 5.3 Breaking stre

14、ngth. To measure breaking strength, the load is applied until the sample ruptures and the maximum break strength shall be read from the dial, scale or chart and recorded. 5.4 The test result shall only be considered valid and reportable if the break occurs in the free cord at or between the ends of

15、the finger traps. See FIGURES 2 and 3 for a diagram indicating free cord area. Examples of null and void tests are (but not limited to) breaks in the loops, breaks at cord insertion point of finger trap (points A/B in FIGURE 2), breaks near bartacks or anywhere within the finger traps, or finger tra

16、p slippage during testing. 6. CALCULATION 6.1 The elongation shall be calculated as follows: Elongation percentage = (E-0) x 100 Where: E = The distance in inches between gage marks measured at 75 percent of the specified minimum breaking strength. 0 = The distance in inches between the original gag

17、e marks when measured at 1percent of the minimum breaking strength. 7. REPORT 7.1 The elongation shall be reported as an average of the specimens tested per sample unit and reported to the nearest tenth of a percent. Each individual value used to calculate the average shall also be recorded and repo

18、rted on the test report. 7.2 Unless otherwise specified, the breaking strength shall be reported as an average of the specimen tested per sample unit and reported to the nearest pound. Each individual value used to calculate the average shall also be recorded and reported on the test report. 8. NOTE

19、S 8.1 Sample preparation notes. These details for sample preparation have been used with success on several types of Spectra cord and can be used as a starting point for new users of the method. Page 2 of 5 Copyright Protected: Do Not Copy!PIA-TEST METHOD-6015 8.1.1 Cut test specimen to 80 inches. M

20、ark specimen at 14, 20 and 35 inches from each end (see FIGURE 1). 8.1.2 Preparation of specimen ends: Standard Method - The ends of the specimen shall be cut at a 45 degree angle. Alternate Method - This method has been used with success when splices prepared using the standard method result in fin

21、ger trap slippage. Prepare tapered ends by following instructions in Paragraph 2.2 and marking alternating fifth picks (for a total of 8 ends on a 16 strand braid). Cut each pick at mark and remove each marked end by pulling the end through the cord. A pick tool or a small needle can be used to remo

22、ve the end and minimize any damage to the cord specimen. 8.1.3 Insert an insertion tool into the cord at point (C) on the diagram (see FIGURE 2). Push the insertion tool into the center of the cord exiting at point (B). 8.1.4 Place the end of the cord through tip of the insertion tool and slowly twi

23、st the tool and cord end back into point (B). Pull the tool through the cord and exit at point (C) (see FIGURE 2). 8.1.5 Remove the end of the cord from the insertion tool. Check again to ensure the end is cut to a 45 degree angle and push the tip of the cord back into the finger trap at point (C) t

24、o hide it. Smooth the outer cord braid back into position and lightly tug on the finger trap to seat it. Pulling on the loop while the end of the finger trap at point (C) should help. At this time, points (C) and (B) from FIGURE 1 should meet as shown in FIGURES 2 and 3. 8.1.6 Repeat steps on the op

25、posite side of specimen. 8.1.7 When both loops and finger traps are created, the test specimen should measure approximately 46 inches long is prepared for strength and elongation testing (see FIGURE 2). 8.1.8 Tools required to prepare specimen. Scissors, marker (size depending on the step and size o

26、f cord), insertion tool (commonly called a FID and used to pull end into splice), pick tool (used to remove ends in 8.1.2) and tape measure (8 foot minimum). Page 3 of 5 Copyright Protected: Do Not Copy!PIA-TEST METHOD-6015 FIGURE 3 Test Fixture. * Notice: This document has been adopted from the ori

27、ginal FED-STD-191 TEXTILE TEST METHOD of the same number and is being maintained as a commercial specification by the Parachute Industry Association. Orders, inquires and comments should be addressed to PIA, Specification Committee via e-mail at: or to our website at: . Page 4 of 5 Copyright Protec

28、ted: Do Not Copy!PIA-TEST METHOD-6015 Copyright 2015 Parachute Industry Association. Disclaimer: This document is published by the PIA to provide technical and engineering standards that can be used as reference by all those who may benefit from them. The use of this document is entirely voluntary,

29、and its applicability and suitability for any particular use, including any patent or trademark infringement arising there from, is the sole responsibility of the user. The original Government document was scanned. The PIA reviews each technical publication periodically, at which time it may be reaffirmed, revised, or canceled. The PIA invites your written comments and suggestions. Page 5 of 5 Copyright Protected: Do Not Copy!