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2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2012 SAE International All rights reserved. No part of this pub
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4、(outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2979_201205SURFACEVEHICLERECOMMENDEDPRACTICEJ2979 MAY2012 Issued 2012-05Test Method
5、 for Vulcanized Rubber and Thermoplastic ElastomerDetermination of Compressive Stress Relaxation (CSR) Response RATIONALEASTM and ISO procedures exist that address Compression Stress Relaxation (CSR) in general, but they do not provide specific details on several factors involved in determining the
6、CSR response, nor do they deal with the Automotive Standard (ASD) CSR Test Jig. This test method addresses those limitations along with a methodology that produces better accuracy and reproducibility. This test method and ASD fixtures have been used extensively over the past 10 years by Material or
7、MTSs TestWorks 4.X. See an example of the plot from the TestWorks software - Section 8.1 - Figure 1. 4.9 Excel File or equivalent to record data (required) (General Format noted in Appendix B)4.10 Ovens (required) The ovens should have precise cabinet temperature control obtained through air exchang
8、e and circulation uniformity (in time and space) and is critical to measurement repeatability and reproducibility at isothermal temperatures. Small units capable of obtaining 1.0 C around a set temperature are best suited for CSR measurement. Select ovens with air exchange rates based on ASTM E145 r
9、equirements should be consideredSAE J2979 Issued MAY2012 Page 7 of 18 4.11 Other Optional Accessories 4.11.1 Basket for Oil Testing - used with 1 gal Paint Can or Stainless Steel Test Containers (holds 28 ASD CSR jigs) - (Appendix A.2) 4.11.2 Pressure Vessel and Basket for Coolant Testing - 2 L Parr
10、 Pressure Vessel basket (holds 18 ASD CSR jigs) - (Appendix A.3) 4.11.3 Pressure Vessel and Stirring Hot Plate - Use device similar to that described ASTM D572 for coolant testing. Fortest mixtures requiring stirring to maintain uniformity use a stirring hot plate with temperature control. Provision
11、s for a pressure gauge and relief valve are also required. (Appendix A.4)4.11.4 Compression Stress Relaxation (CSR) Spring Test Set (Optional) - (Appendix A.5) 5. TEST SPECIMEN 5.1 Samples should be prepared using good molding procedures and equipment to achieve good consolidated void free and defec
12、t free samples with smooth parallel flat surfaces observed with normal corrected vision. (ASTM D3182 and SAE J2643) 5.2 Molded Button of diameter 12.7 mm 0.5 mm (0.500 in 0.010 in) and thickness 6.3 mm 0.3 mm (0.250 in 0.005 in) 5.3 Button thickness measurements are taken from the center of the butt
13、on 5.4 Measure thickness using a dial or digital caliper (4.4) in a central area to avoid edge effects 5.5 Number of Test Specimens - A minimum of three test specimens shall be used for each material. 6. DURATION AND TEMPERATURE OF TEST 6.1 Temperature of Test - The temperature of test shall be agre
14、ed upon by the customer and the supplier. The ambient test temperature shall be 23 C 2 C (73 F 4 F). For an ambient test temperature controlled environment, it is recommended that the counterforce measurement not be started until the jig temperature reaches 23 C 2 C (73 F 4 F).6.2 If ambient test te
15、mperature is not controlled, it is recommended that it be recorded for each measurement interval and that the counterforce measurement not be started until the jig temperature reaches 2 C (4 F) of ambient test temperature. Highlight the measurements of the CSR jig temperatures when they are not with
16、in the range of 23 C 2 C (73 F 4 F). These outliers could be a source of variation. 6.3 The time-interval between vulcanization and/or post cure of the button and the initial compression shall be at least 24 h at ambient conditions. 6.4 The measurement of the “initial sealing force” should be perfor
17、med 60 min after the samples are compressed. This is considered the initial sealing force (F0) for the % Retained Sealing Force calculation. The time period for the test evaluation begins at the time that the CSR jig containing the sample is placed in the test environment (oven or test fluid).6.5 Su
18、bsequent Test Time Intervals - Approximately 2 h are required after each time-interval, to attain ambient temperature unless the jigs are cooled with a fan, as well as perhaps 1 h to perform the sealing force measurement. This cool down and test time is included in the duration of test hours. It is
19、suggested, for reasons of consistency, that people try to perform testing within these timeframes, so that there is a period of 3 h between removal of the sample from the test environment and being placed back in that environment for additional aging. The counterforce measurement should not be start
20、ed until the jig temperature reaches 2 C (4 F) of ambient temperature. SAE J2979 Issued MAY2012 Page 8 of 18 6.6 Test Interval Considerations - For purposes of testing uniformity, test intervals are often specified that correspond to reasonable laboratory test times. Test intervals are often set up
21、so that samples can be tested at the same time of day. Since time for this kind of testing requires the samples be cooled for a given period of time before testing and also includes the time for testing, the defined test intervals do not reflect the total amount of aging to which the samples might h
22、ave been exposed. Because of this, the total amount of time the sample might have been exposed to the aging environments for longer period such as 1008 h varies with the number of intermediate test intervals the samples were tested at. The magnitude of the effects of these different exposure times c
23、an vary depending on the type of material, the environmental test conditions, and the number of intermediate intervals at which the samples were tested. 7. PROCEDURE Test Preparation 7.1 Refer to the ASD Template (Excel file) as an example for the format that is recommended for recording data and ca
24、lculations (Appendix B i.e., 4 materials, 3 test buttons for each material requires 12 jigs to be assembled. 7.6 Place the CSR Jig Base in the centering cup, making sure that the open section is in line with the tighter section of the centering cup and lay the 1st shim in the center. 7.7 Place the 3
25、 centering wedges in the cup to center the first shim.7.8 Apply a small amount of an appropriate lubricant (silicone lubricant, 4.5 or test lubricant, 7.29) to the sample to lightly coat the top and bottom face of the sample. Then gently wipe off excess.7.9 Place the sample on top of the first shim
26、(centered by the centering wedges). 7.10 Place the 2nd shim on top of the sample, aligning it with the centering wedges and with the sample and the 1st shim. 7.11 Position the CSR Jig Cap so that the jig labels are aligned (this ensures the Jig is assembled the same way each time).7.12 Insert the th
27、ree bolts and finger tighten to contact, then tighten down evenly with an Allen Wrench, alternating quarter turns sequentially with each bolt, until they are completely tight. (Hint: Sometimes it can be necessary to turn cap screws slightly counter clockwise to engage the treads, if they do not tigh
28、ten smoothly, and then clockwise to finger tighten.) A guideline is that all of the three bolts should be tightened in less than 1 min. SAE J2979 Issued MAY2012 Page 9 of 18 7.13 Once all of the Cap Screws are tightened, one can engage the Allen Wrench with one of the cap screws and rotate the CSR j
29、ig about 60 degrees in the centering cup. This allows the centering wedges to expand into the open portion of the centering cup; and it should be easy to remove the loaded CSR jig and wedges from the cup. The centering cup and wedges can then be reused to load and center additional CSR Jigs. 7.14 In
30、 order to sequence the relaxation and load measurement timing, it is advised to stagger the loading of the sample into the CSR jig to insure a correct time interval (60 min) between when the sample is compressed and when the initial reading is taken. Repeat for all additional samples. Measuring the
31、Sealing Force 7.15 After all the CSR Jigs have been loaded and assembled, they should be tested for their initial sealing force 60 min 5 min after they were compressed. 7.16 Measure the temperature of the CSR jigs as well as the temperature of the room using the Omega Miniature Thermocouple probe or
32、 comparable device, which have a sheath diameter of 1.6 mm (0.062 in) can be easily inserted into the CSR Jig thermocouple hole or left open to the ambient air. This is very important for the CSR Jigs after aging, since all samples must be cooled to within 2 C of the room temperature before being te
33、sted. (If additional cooling is used to cool the jig, the preferred method is to force cool the CSR Jigs with a fan using ambient air.) Record the room and jig temperature for the time interval being measured immediately preceding the measurement of sealing force (Appendix C). 7.17 Using appropriate
34、 software (4.8) enter the testing information for the samples being tested. It should include the sample test set, the CSR jig #, the test interval to appropriately identify the sample being tested. 7.18 Set up the EMUTM to run load deflection curves. 7.19 Check the load cell calibration. 7.20 Place
35、 the indenter pin centered in the top hole of the CSR Jig, and then center the CSR jig directly below the center of the plunger and axially aligned with the load cell. When placing the indenter pin in the top center hole of the CSR jig, make sure it does not touch the sides of the clamping plate. 7.
36、21 Adjust the crosshead position and plunger to be slightly higher than the contact position with the indenter pin, so that the jigs can be easily moved in and out of the test position. 7.22 Zero the crosshead position and zero the load. 7.23 Run the load deflection program. 7.24 A suggested deflect
37、ion rate is 1.3 mm (0.05 in) per min. 7.25 The amount of deflection should be enough to show the inflection region with enough points after that to allow the determination of a good linear response. (Note 8.1 Figure 1) With most samples and configurations a deflection of 0.10 mm (0.004 in) after the
38、 initial contact point should be sufficient. When there is misalignment of the sample or test configuration that can create curvature and offsets in the response, it can be necessary to use a higher deflection.SAE J2979 Issued MAY2012 Page 10 of 18 7.26 Run three deflections with at least a 10 s pau
39、se between each of them. All counterforce measurements shall be performed three (3) times for each test specimen. Three deflections are done, with the first being done to stabilize the test configuration, and then the two additional ones to insure there are no significant changes in the sealing forc
40、e values occur, due to a range of different factors such as sticking shims, indenter pin placement issues, configuration interface issues or some other items that can affect the load-deflection response. With a good system, there should be a slight drop in sealing force from the first to the second
41、deflection accompanied by a slight increase in the system stiffness, while the third deflection response should be close to the second. If this does not occur, there might be a problem with the test configuration and the CSR Jig might need to be adjusted and retested to insure a correct response. Ad
42、ditional deflections can also be run if there is too much variation between the three deflections.7.27 Determine the Sealing Force for each of the curves as noted in Section 8 and record the values on the spreadsheet noted in Appendix C. 7.28 Oven Aging and ASD CSR jig counterforce measurement. For
43、testing, place the CSR Jigs with the compressed test specimen in the oven at the specified test temperature. ASTM D573 should be referenced for testing and control of oven conditions. When making measurements of counterforce after the times specified, remove the apparatus from the oven, maintain it
44、at the standard laboratory temperature until the jig temperature is within 2 C of the recorded ambient temperature. The jig can be forced cooled with a fan if necessary. It is important that the apparatus and test specimen reach thermal equilibrium within 2 h. After determination of counterforce, re
45、turn the jig to the test environment for a further time if needed. Repeat the measurement of the counterforce after different times, according to agreed upon test intervals. Take all measurements at ambient temperature 2 C. 7.29 Liquid Immersions Testing Procedure and ASD CSR jig counterforce measur
46、ement. In some applications, retained sealing force testing under liquid immersion conditions is necessary. ASTM D471 should be referenced for this kind of testing. In this kind of testing, it might be possible or preferred to use the test fluid (oils or coolants) as the lubricant instead of the sil
47、icone fluid normally recommended when loading the samples in the CSR Jig (7.8). The test specimen/CSR Jig shall be completely immersed in liquid under consideration. The immersed test specimen shall be in the compressed condition, similar to testing in air. Care shall be taken while performing aging
48、 under liquid immersions conditions (especially at elevated temperatures) to avoid hazardous test conditions. Environmentally safe practices shall be followed while performing liquid immersion testing. For Coolant Immersion, use a pressure vessel similar to that used or described in ASTM D572 capabl
49、e of maintaining the required test fluid concentration (ratio) at higher pressures and elevated temperature for the duration of the test or change interval hours, whatever comes first. Reference Appendix A.3 or A.4 for possible coolant immersion apparatus for aging ASD CSR jigs. Reference Appendix A.2 for possible oil immersion apparatus for aging ASD CSR jigs in oil or other low volatility flu
