GMW GMW14685-2012 Determination of the Compressibility of a Cellular Elastomer at a Defined Deflection Issue 2 English.pdf

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1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14685 Determination of the Compressibility of a Cellular Elastomer at a Defined Deflection Copyright 2012 General Motors Company All Rights Reserved August 2012 Originating Department: North American Engineering Standards Page 1 of 9 1 Scope The obj

2、ect of this standard is the determination of the compressibility of a weatherstrip or other sealing or damping material of cellular elastomer at a defined deflection. The weatherstrip shall be mounted in the appropriate fixture; other sealing or damping material shall be positioned on an even surfac

3、e and deflected at a uniform speed. The deflection specified shall be comparable to that of the sealing in service. Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take pre

4、cedence. 1.1 Purpose. Not applicable. 1.2 Foreword. Not applicable. 1.3 Applicability. Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 7500-1 ISO 9513 2.2 GM Standards/Specifications. GMW16676

5、 2.3 Additional References. Statement of Requirements (SOR) 3 Resources 3.1 Facilities. Not applicable. 3.2 Equipment. 3.2.1 Test Equipment. 3.2.1.1 Test Machine. The test machine shall fulfill the following requirements: The force measuring device of the test machine shall correspond to ISO 7500-1

6、Class 1; the deflection measuring device shall correspond to ISO 9513 Class 0.2. The test machine shall be such that the test piece can be compressed between its holder and a pressure foot in a vertical direction. 3.2.1.2 Test Velocity. Pieces shall be tested at a uniform rate defined as follows: Ta

7、ble 1: Test Velocity Coding Code 1 30 3 mm/minute Code 2 100 10 mm/minute Code 3 Other agreed upon test velocities as stated on the respective part drawing and test report. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STAN

8、DARDS GMW14685 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 2 of 9 3.2.1.3 Test Piece Mounting Fixture. The test pieces of weatherstrips shall be supported by test fixtures, which shape and dimensions are defined in the respective part drawing or math data file. In spec

9、ial cases the test piece may be positioned on an even surface. The length of the test piece mounting fixture shall be at least equal to that of the test piece. The fixture must allow for secure positioning in the test machine. 3.2.1.3.1 Test Piece Mounting Fixture for Glass Run Channels. The fixture

10、 must allow the glass to be inserted into the channel at the proper depth without compressing the lip being tested. (The lip must only be compressed vertically during the test.) 3.2.1.4 Metal Pressure Foot. The shape and dimensions of the pressure foot is component dependent. Fixtures shall be made

11、of an aluminum material or steel. Shaped pressure feet shall be made using an electro discharge machining (EDM) wire burn process. Unless otherwise stated the finish of the pressure foot shall be as follows: Ra = 0.03 m Rz1max = 0.3 m Surface finish shall be measured according to GMW16676. 3.2.1.4.1

12、 The metal pressure foot shall be cleaned with a soft cloth before measurement, if necessary, using a mild solvent. 3.2.1.5 Glass Pressure Foot (Glass Run Channels). The compression foot for parts in contact with glass shall be made of tempered glass 4 mm minimum in thickness. 3.2.1.5.1 The glass sh

13、all be cleaned once at the beginning of the test, and does not have to be cleaned again between specimens. The compression foot for glass run testing shall be cleaned according to the following procedure: 3.2.1.5.1.1 Wet a lint free wipe with 2-propanol alcohol and wash the glass. 3.2.1.5.1.2 Dry th

14、e glass with a dry lint free wipe, but do not polish the glass. 3.2.1.5.1.3 Wet a third lint free wipe, and wash the glass again. 3.2.1.5.1.4 Allow the glass to air dry. 3.2.1.6 Dimensions of Pressure Foot. 3.2.1.6.1 Pressure Foot for Body Sealings. In case of an even pressure foot, the width shall

15、be 50 mm. It shall be greater than the contact surface of the seal in compressed condition. Two (2) different lengths of pressure foot are used: Table 2: Pressure Foot Length Coding Code A 200 1.0 mm Code B 100 1.0 mm 3.2.1.6.2 Pressure Foot for other Sealing and Damping Material, which is compresse

16、d for a certain percentage (25%) of its initial height, complies with Table 3 below. Table 3: Additional Pressure Foot Length Coding Code C Dimension of surface larger than the test piece surface dimensions 3.2.1.7 Supporting Table. The test piece support for determination of compressive force per u

17、nit area (Code C) shall be horizontal and coplanar to the pressure foot and larger in dimensions than the respective pressure foot. The supporting table shall contain ventilation holes ( 6 mm in diameter) spaced in regular intervals ( 20 mm from hole center to hole center) so that air can escape rap

18、idly during the test. 3.3 Test Vehicle/Test Piece. 3.3.1 Test Material. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14685 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 3 of 9 3.3.

19、1.1 Test Piece Dimensions. Test piece dimensions are defined as follows: 3.3.1.1.1 Code 1 (Non-Destructive Test). Test pieces of weatherstrips shall have a length that is at least 50 mm longer on both sides (edge effect) and can be cut from a component. (This enables to test on complete parts, which

20、 can be installed afterwards for tests in the vehicle.) If the above length cannot be obtained from a weatherstrip, a piece as long as possible shall be used. Test piece length must be agreed upon and stated in the respective test report. 3.3.1.1.2 Code 2 (Destructive Test). Test pieces of weatherst

21、rips shall have the same length as the pressure foot. Cut the weatherstrip such that it is not significantly bent or deformed during cutting. 3.3.1.1.3 Code 3. Test piece must be shorter than pressure foot in the following cases: Test pieces of weatherstrips with a length less than 100 mm, or if for

22、med corners shall be piece. If necessary, the test piece length must be specified on drawing. For other sealing and damping material, the test piece shall be the whole part or a section of it. 3.3.1.2 For initial sample approval and arbitration purposes, at least five test pieces cut from at least t

23、wo components shall be tested, for routine quality control purposes at least three test pieces, preferably from two components, shall be tested. 3.4 Test Time. Not applicable. 3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills. Not applicable. 4 Procedure Summary of Test Method. The

24、 compressibility of a cellular elastomeric component at a given deflection shall be defined as the force required obtaining the deflection following compression at a uniform given velocity. 4.1 Preparation. 4.1.1 Test Sample Preparation. For initial sample approval and arbitration purposes, the mini

25、mum time period between vulcanization and testing of elastomers shall be 72 h. The test pieces shall remain at a temperature of 23 C 5 C for at least 8 h before testing, and shall be free from strain during this period. 4.1.2 Test Procedure. The test shall be performed at a temperature of 23 C 5 C.

26、Other test temperatures shall be agreed upon in the Statement of Requirements (SOR) and stated in the respective part drawing or math data file. 4.1.3 Determination of Absolute Compressive Force at Deflection to Absolute Dimension (Characteristic Curve, Compression Load Deflection (CLD) Curve). 4.1.

27、3.1 Test Setup. 4.1.3.1.1 Fixture Attachment. Attach the Mounting Fixture and the Compression Fixture to the testing machine, so that the relation of the test piece support to the pressure foot is as specified on the respective part drawing or math data file. 4.1.3.1.2 Zero Position. 4.1.3.1.2.1 Zer

28、o Position for Weatherstrips. Position the crosshead such that the Compression Fixture is in the specified Datum position. (The pressure foot shall be allowed to contact the test piece support under a low preload of 0.5 N maximum.) Zero the positional measurement. 4.1.3.1.2.2 Specimen Installation a

29、nd Deflection Zero for Glass Run Channels. Datum position, the edge of glass inserted into the channel should be parallel to the bottom of the channel within 1 mm and should be positioned at the design nominal depth in the channel. Zero the positional measurement. 4.1.3.1.3 Specimen Installation and

30、 Force Zero. Move the crosshead to allow for installation of the specimen without deflection of the sealing feature. Install the specimen on the Mounting Fixture, make sure the specimen is not contacting the pressure foot, and zero the force measurement reading. 4.1.3.1.4 Test Procedure for Destruct

31、ive Test. 4.1.3.1.4.1 Pre-flexing. The test specimen shall be loaded and unloaded ten times to the pre-flex position. 4.1.3.1.4.1.1 For body seals, the pre-flex position is 1 mm less than the minimum sealing range. For example: if the sealing range is 15 3 mm, the pre-flex position would be 11 mm. S

32、ee Figure A2 in Appendix A. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14685 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 4 of 9 4.1.3.1.4.1.2 For glass seals, the pre-flex posi

33、tion for the inboard lip is 1 mm beyond the maximum inboard position of glass. For the outboard lip, the pre-flex position is 1 mm beyond the maximum outboard position of glass, unless this would cause a crash condition, in which case the position should be moved up in 0.5 mm increments until the cr

34、ash condition is avoided. 4.1.3.1.4.2 Measurement Cycle. During the 11th loading cycle: 4.1.3.1.4.2.1 Collect load and position data every 0.5 mm of travel, in 0.5 mm increments relative to the zero position (i.e., at whole millimeter distances from the datum, and the 0.5 mm points in between). 4.1.

35、3.1.4.2.2 Continue to load beyond the Pre-flex gap or position until the GM specified minimum gap or position is reached or the load reaches 75 N. 4.1.3.1.5 Test Procedure for Non-Destructive Test. The test piece is deflected by the pressure foot to 50 2 N and load and position data is collected eve

36、ry 0.5 mm of travel, in 0.5 mm increments relative to the zero position. Alternatively, the force-deflection-curve is recorded. The deflection will be performed three times for the same test piece. Unless otherwise stated in the drawing or test procedure, the third test curve shall be rated. 4.1.4 D

37、etermination of Absolute Compressive Force (Code A or B) at Specified Relative Deflection. 4.1.4.1 The test piece shall be inserted into the test piece support if necessary and shall then be fixed into the test machine so that the relation of the test piece to the pressure foot is as specified on th

38、e respective part drawing. The force shall be set zero. 4.1.4.2 The pressure foot shall then be allowed to contact the test piece under a steady force of 2.0 0.1 N. 4.1.4.3 While the above force is applied, the deflection measuring device shall be set to zero. The test piece is then deflected by the

39、 pressure foot through the defined distance, as specified on the respective part drawing. After obtaining the deflection, the compressive force shall be determined immediately. 4.1.5 Determination of Compressive Force per Unit Area (Code C). 4.1.5.1 The surface area of the test piece shall be determ

40、ined in square millimeter. 4.1.5.2 The pressure foot shall be mounted coplanar to the holder and the force shall be set zero. 4.1.5.3 The pressure foot shall then be allowed to contact the test piece holder under a low preload of 0.5 N maximum. The displacement point (width of slit 0 mm) shall be se

41、t zero. Then the pressure foot shall be positioned to a suitable distance from the test piece support and the test piece shall be mounted. 4.1.5.4 The pressure foot shall then be allowed to contact the test piece under a very low preload of 0.001 to 0.002 N/mm2 until the pressure foot closely contac

42、ts the surface of the test piece without any deflection. The initial height is determined at this position. The test piece is then deflected by the pressure foot about 25% of its initial height. At final height the value of the compressive force is determined immediately and divided through the area

43、 of the test piece. 4.2 Conditions. 4.2.1 Environmental Conditions. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. Not applicable. 5 D

44、ata 5.1 Calculations. Not applicable. 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. 5.3.1 Evaluation and Rating. 5.3.2 Report. 5.3.2.1 Test Description. The following information shall be reported. 5.3.2.1.1 Part information including part name, program name/vehicle program

45、name, specimen number, production or development batch number. 5.3.2.1.2 Location, date, and time of test. 5.3.2.1.3 Units of measurement. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14685 Copyright 2012 Gene

46、ral Motors Company All Rights Reserved August 2012 Page 5 of 9 5.3.2.1.4 For glass seals, report pre-flex position if different than 1 mm past the design compression range. 5.3.2.2 Data. 5.3.2.2.1 Tolerance Range Mean CLD Values (Tested to 4.1.3.1.4). For each of the specimens, report the 11th cycle

47、 CLD values for the nominal gap or position and the sealing range tolerance gaps or positions. Calculate and report the mean values for each position. 5.3.2.2.2 CLD Plot (Tested to 4.1.3.1.4). Plot out the CLD curve for the specimen which is most representative, i.e., the one whose CLD values are cl

48、osest to the means reported in 5.3.2.2.1. Plot this curve in the format shown in Figure A3 in Appendix A. 5.3.2.2.3 Characteristic Curve (Tested to 4.1.3.1.5). The compressibility at deflection to absolute dimension shall be expressed as characteristic curve (See Figure A1, Appendix A) or as the ran

49、ge of the values determined, in N, rounded to the nearest whole number, and expressed with reference to this test procedure. This range or the characteristic curve shall be wholly within the tolerance range of values as specified on the relevant part drawing or math data file, and represent the production variation found within the test pieces examined. 5.3.2.2.4 Range of Values (Tested to 4.1.4). The compressibility of a cellula