GMW-14739-2007.pdf

WORLDWIDE ENGINEERING STANDARDS Test Method Materials GMW14739 Determination of the Tensile Strength and Elongation to Failure of Elastomeric Components © Copyright 2007 General Motors Corporation All Rights Reserved September 2007 Originating Department: North American Engineering Standards Page 1 of 4 1 Scope The determination of the tensile strength and elongation to failure shown by elastomeric components used in vehicles when strained at a constant velocity within the temperature range -30 + 150°C. Note: Nothing in this standard supersedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Objectives. The determination of the tensile force and deformation to failure. These values are dependant upon the elastomer properties. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. DIN 862 ISO 7500-2 DIN 878 ISO 7500-3 DIN 51220 ISO 7500-4 ISO 7500-1 ISO 7500-5 2.2 GM Standards/Specifications. None 3 Test Equipment 3.1 A universal testing machine, capable of stressing elastomeric components to a force of 50 kN maximum at a constant velocity deviation ± 10% maximum, hereafter referred to as “the testing machine“. The testing machine shall comply with DIN 51220 and ISO 7500-1, ISO 7500-2, ISO 7500-3, ISO 7500-4, ISO 7500-5 and also comply with the following requirements: Table 1: Accuracy of Test Machine The force measuring equipment: ±1.5% of the measured value Displacement measuring equipment: ± 0.05 mm 3.2 Environmental Chamber for Use on the Testing Machine. The environmental chamber shall be of the air-circulating type, and comply with the following requirements: Table 2: Requirements for Test Chamber Temperature range: -30 to +150°C continuously adjustable Temperature variation: ± 2°C Temperature change rate: 1.5°C/minute for empty cabinet (recommended) 3.3 Preconditioning Chamber for Test Samples. The preconditioning chamber shall be of the air- circulating type and comply with the following requirements: Table 3: Requirements for Preconditioning Chamber Temperature range: -30 to +150°C continuously adjustable Temperature variation: ± 2°C Temperature change rate: 1.5°C /minute for empty cabinet (recommended) 3.4 Suitable fixtures for locating and attaching the elastomeric components to the testing machine. 3.5 Timer with a recording range of 168 h and a reading accuracy of 1 minute. 3.6 Dimensional Measuring Equipment. 3.6.1 Dimensional change measuring equipment, e.g., a linear dial gauge to DIN 878, with a range of 10 mm an accuracy of ± 0.01 mm, and exerting a relatively constant force of 2 N over its range of travel. 3.6.2 Dimensional measuring equipment, e.g., gauge blacks to DIN 862. GMW14739 GM WORLDWIDE ENGINEERING STANDARDS © Copyright 2007 General Motors Corporation All Rights Reserved Page 2 of 4 September 2007 3.6.3 Dimensional measuring equipment, e.g., precision height vernier accurate to 0.1 mm, height 500 mm maximum. 3.7 Inspection of Test Equipment. The test equipment shall be calibrated at intervals not exceeding one year, and certification retained. 4 Test Material 4.1 Test Sample Form. The test samples shall be elastomeric components, as assembled into the vehicle. 4.2 Test Sample Quantity. Three test samples minimum shall be tested. 5 Test Method 5.1 Summary of Test Method. 5.2 Test Sample Preparation. For initial sample approval and arbitration purposes, the time period between vulcanization and testing shall be seven days minimum. 5.2.1 For quality control purposes the period shall be 72 h minimum. The test samples shall remain at a temperature of +23 ± 5°C for 8 h minimum before testing, and shall be free from strain during this period. 5.3 Test Procedure. 5.3.1 General. The test sample shall be tested according to the data shown on the test specifications and the relevant component drawings for the elastomeric component regarding method of assembly, direction of stressing, etc., in addition to this test method. 5.3.1.1 All measurements on the test samples shall be made during the initial stress application. 5.3.1.2 If the force Fji, or the force indicating device on the testing machine is influenced by the weight of the test sample and/or its fixtures, compensation shall be made prior to the commencement of the test. 5.3.2 Conditioning. The test samples shall be conditioned to one of requirements specified in 5.3.4, and subsequently tested at that temperature as follows. 5.3.3 Test Method. Set the force and deflection measuring equipment to zero, and then proceed in accordance with the diagram in Appendix A. Stress the test sample from Fji = 0 to Fji = FjRi, i.e., until failure, at a velocity of vi. 5.3.4 Conditioning and Test Temperatures. One of the following conditioning periods shall be applied, as specified on the relevant component drawing, test specification or material specification. The test shall then be carried out at the conditioning temperature. 5.3.5 Deviations. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. Table 4: Storage Period and Temperatures Conditioning Code Letter Conditioning Time Hours Conditioning at Test Temperature °C None 8 minimum +23 ± 5 A 168 0/-2 -30 ± 3 B 72 0/-2 -30 ± 3 C 3 0/+1 -30 ± 3 D 168 0/-2 -20 ± 3 E 72 0/-2 -20 ± 3 F 3 0/+1 -20 ± 3 G 168 0/-2 -10 ± 3 H 72 0/-2 -10 ± 3 I 3 0/+1 -10 ± 3 K 3 0/+1 +23 ± 3 L 3 0/+1 +50 ± 3 M 3 0/+1 +70 ± 3 N 3 0/+1 +80 ± 3 O 3 0/+1 +100 ± 3 P 3 0/+1 +125 ± 3 Q 3 0/+1 +150 ± 3 6 Evaluation and Rating Record the initial curve of Fji = f (sji) of the force - deflection curve. 7 Report In addition to reference being made to this test method, the test report shall also include the following data: Part name, part or drawing number, test spec., number, additional identification, grade of elastomer, manufacturerer, date of manufacture, test sample number, date of test. -,-,- GM WORLDWIDE ENGINEERING STANDARD GMW14739 © Copyright 2007 General Motors Corporation All Rights Reserved September 2007 Page 3 of 4 Table 5: Report Details Velocity vi (m s-1) Force FjRi (N) Ultimate deflection sjRi (mm) Force-deflection curve Fji = f(sji) Any specific observations on the test sample, e.g., cracks, splits, other visible defects. 8 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of the standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 9 Notes 9.1 Glossary. Alphabetical Subscripts: Shall be used to identify the type of force or dimension, e.g., FRTensile force. Alphabetical Suffixes: Shall be used to identify the test conditions as defined in 5.3.4, Table 4, generally designated by j.j may take the form A,B,CQ, e.g. Definition S: The deflection s is the distance through which the force-application point moves under the force F during deformation of the elastomeric component. It is measured in the direction of application of the force F. FG: Denotes a force F given under the conditions denoted by test type G. Force-application Point: The force-application point is the position (taken as a point) on the moving head of the universal testing machine to which the elastomeric component or test fixture is attached. The force-application point is located along the direction of application of the force F, and may be, e.g., a thread, a thrust plate or a test fixture. Numerical Sequences: Shall be used to identify the direction, in which a force is applied, and shall be generally designated by index i, where index i may take the form 1,2,3,.n. The numerical subscripts shall follow the alphabetical subscript, e.g., FGR1, sR1. If there is only one direction of force application, the numerical subscript one (1) can be excluded, e.g., FGR, sR. Suffixes: To identify the forces or dimensions being applied or determined, and their directions, alphabetical and numerical suffixes shall be used. Ultimate Deflection sR: The ultimate deflection sR is the displacement, which the force-application paint covers when the force FR is applied during deformation of the elastomeric component. It is measured in the direction of the deflection s. Velocity V: The velocity v is the constant velocity with which the force-application point moves in the direction of application of the force F. 9.2 Acronyms, Abbreviations, and Symbols. Not applicable. 10 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW14739 The requirements for the tensile strength and elongation characteristics of elastomeric components shall be specified on component drawings, test and material specifications, reports, etc., as follows, e.g., Tensile Strength Designation GMW 14739 Test Method FAR2 = .N sAR2 = .mm FA2 = f(sA2) v2 = m s-1 etc. Test conditions and requirements 11 Release and Revisions 11.1 Release. This standard originated in October 2005. It was first approved by the Global Elastomers Team in December 2006. It was first published in September 2007. It supersedes all regional material specifications for elastomer parts for use on Global Engineered materials including but not limited to GME60238. -,-,- GMW14739 GM WORLDWIDE ENGINEERING STANDARDS © Copyright 2007 General Motors Corporation All Rights Reserved Page 4 of 4 September 2007 Appendix A Typical mapping (not to scale) obtained during test procedure for determination of Fji = f (sji). Refer also to 5.3 and section 6 of this test method Figure A1: Example Force-Deflection Curve -,-,-