1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW16192 Static Coefficient of Friction Test Copyright 2011 General Motors Company All Rights Reserved August 2011 Originating Department: North American Engineering Standards Page 1 of 7 1 Scope Note: Nothing in this standard supercedes applicable law
2、s and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. The purpose of this procedure is to determine the force required to slip one component of an assembled joint relative to another, and determine the st
3、atic coefficient of friction. 1.2 Foreword. Not applicable. 1.3 Applicability. This procedure applies to bolted joints on all vehicles. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 9000 TS 9000 ISO 17025 2
4、.2 GM Standards/Specifications. None 2.3 Additional References. x Data Acquisition System Manufacturers Operating Procedure. x Unigraphics (UG) Part Assembly Number TLA00269. 3 Resources 3.1 Facilities. 3.1.1 Approved GM Laboratory. 3.1.2 Testing may also be performed at the following locations. Tes
5、ting may be performed at locations other than the ones listed, with prior GM approval. 3.1.2.1 GM Vehicle or Component Plants. 3.1.2.2 GM Engine or Transmission Plants. 3.1.2.3 Satellite General Motors Facilities. 3.1.2.4 A supplier or supplier laboratory that is accredited to ISO 17025 or ISO 9000
6、or is TS 9000 certified. 3.2 Equipment. 3.2.1 Fixture of suitable strength to rigidly secure one side of the joint under test and permit application of the expected slip load to the other, with minimal deflection. For bolted joints use fixture TLA00269 (see Appendix C) (file located in Pontiac Datab
7、ase). 3.2.2 Test machine of the constant rate-of-crosshead-movement type. 3.2.3 Load actuator and controls with sufficient capacity to generate the anticipated force to slip. 3.2.4 Load cell with sufficient capacity to measure the anticipated friction (slip) force. The load cell shall indicate the l
8、oad with an accuracy of 1% at the indicated value, or better. 3.2.5 Instrumented fastener or load cell with sufficient capacity to measure fastener normal (clamp) force, with an accuracy of 1% at the indicated value, or better. Copyright General Motors Company Provided by IHS under license with Gene
9、ral Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16192 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 2 of 7 3.2.6 Displacement transducer to measure displacement in the direction of
10、 the friction force. Displacement transducer shall indicate displacement with an accuracy of 3% at the indicated value, or better. 3.2.7 Surface roughness gauge (if required) to measure surface roughness of the tested samples. 3.2.8 Coating thickness gauge (if required) to measure coating thickness
11、of the tested samples. 3.2.9 Amplifiers and signal conditioning equipment to monitor applied load, relative motion between joint members, and joint clamping force, if applicable. 3.2.10 Multi-channel data acquisition device capable of making permanent records of all acquired data. Note: All instrume
12、ntation is to be calibrated as required; record instrumentation details and date of calibration on data sheet unless the information is otherwise preserved in the testing laboratory records. 3.3 Test Vehicle/Test Piece. 3.3.1 The number of test samples shall be specified by the Test Engineer, unless
13、 specific requirements are set by the test requestor. 3.3.2 Test components are to be selected and assembled per the applicable design layout or drawing(s) (see file TLA00269). 3.3.3 Instrumented fasteners, if used for the measurement of joint clamp load, can be re-used if they were not damaged by p
14、rior testing. Instrumented fasteners should not be used if tightened to a specified torque. 3.4 Test Time. Not applicable. Calendar time: days Test hours: hours Coordination hours: hours 3.5 Test Required Information. The test request and/or critical data sheet(s) shall outline specific information
15、and test parameters. 3.6 Personnel/Skills. Test Engineer or Technician skill level. 4 Procedure 4.1 Preparation. 4.1.1 Prepare the test components as required to permit secure attachment to the fixture. 4.1.2 Measure and record the surface roughness and coating thickness (if required) of the test pa
16、rts. 4.1.3 Verify that sufficient clearance is present for the parts to move relative to one another in the direction which load(s) will be applied and allow measurable displacement to occur between the components. 4.1.4 Connect all instrumentation and controls. Calibrate full scale values which are
17、 relevant to the expected test conditions. 4.1.5 The applied friction (slip) force, relative displacement, and normal (clamp) force are to be monitored and recorded during all testing. 4.1.6 Fasteners are not to be retightened during the course of testing each sample. 4.1.7 Loads used for testing sh
18、ould be high enough to ensure slip between tested components. 4.2 Conditions. 4.2.1 Environmental Conditions. Test temperatures should range from 18 to 27 C and shall be recorded on the data sheet. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon.
19、Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Assemble the test components and install them in the test fixture. 4.3.1.1 Fixture the displacement transducer to measure displacement between the components. 4.3.2 Tighten the thread
20、ed fasteners to the tension specified by the test requestor. If tension is not specified, tighten the fasteners to the specified torque and record the fastener tension value. 4.3.3 Apply a load at the rate specified by the test requestor or Test Engineer until slip is observed. Copyright General Mot
21、ors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16192 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 3 of 7 4.3.4 When the joint h
22、as slipped, suspend testing of the sample. Inspect test components during disassembly and document any observed deformation(s) and/or other damage with log entries and photographs. Retain test samples for inspection by the Test Engineer and the test requestor. 4.3.5 Repeat 4.3.1 through 4.3.4 for th
23、e desired number of samples. 4.3.6 Analyze the relationships between the applied friction (slip) force, displacement, and normal (clamp) force signals to determine the static coefficient of friction between the tested components. 4.3.7 Friction (Slip) Force. Record the friction (slip) force for each
24、 test sample. 4.3.8 Normal (Clamp) Force. Record the normal force at the time slip occurs for each test sample. 4.3.9 Document all test equipment and instrumentation used. Include photographs of the test fixture and setup. 5 Data 5.1 Calculations. 5.1.1 Coefficient of Friction. 5.1.1.1 Single Shear.
25、 The static coefficient of friction is equal to the friction (slip) force divided by the bolt normal (clamp) force. = ( (5EJCHA 5 D A=N ) Where: = 5P=PE? %KABBE?EAJP KB (NE?PEKJ ( = (NE?PEKJ (5HEL )(KN?A ( = 0KNI=H (%H=IL )(KN?A 5.1.1.2 Double Shear. The static coefficient of friction is equal to th
26、e maximum friction force divided by 2X bolt normal force. = ( 2( e.g., nut and bolt or screw. Friction (Slip) Force: The maximum shear force between surfaces before sliding/slipping begins (Fmax). See Appendix B. Normal (Clamp) Force: The force compressing mating and parallel surfaces in the directi
27、on perpendicular to those surfaces (FN). See Appendix B. Slip: A change in the relationships between the following variables: maximum friction force, displacement, and/or normal force. Static Coefficient of Friction (s): The ratio of the maximum friction force contacting parallel surfaces to the nor
28、mal force expressed as a unit-less number. 7.2 Acronyms, Abbreviations, and Symbols. UG Unigraphics 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW16192 9 Release and Revisions This standard was originated in February 2009. It was first a
29、pproved by Material Standards in July 2011. It was first published in August 2011. Issue Publication Date Description (Organization) 1 AUG 2011 Initial publication. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking p
30、ermitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16192 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 5 of 7 Appendix A Data Sheet A1: Example Test Information Worksheet Example Test Information Worksheet Test Title: _ Test Request No.: _ Reques
31、tor/Phone: _ Single/Double Shear: _ Sample No. Material Finish Surface Roughness (If required) Coating Thickness (If required) Normal (Clamp) Force Friction (Slip) Force Coefficient of Friction Notes Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for Re
32、saleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16192 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 6 of 7 Appendix B Figure B1: Typical Friction (Slip) Force vs. Displacement and Normal (Clamp) Force vs. Dis
33、placement Graph Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16192 Copyright 2011 General Motors Company All Rights Reserved August 20
34、11 Page 7 of 7 Appendix C Figure C1: Test Fixture for Measurement of Static Coefficient of Friction for Bolted Joints (TLA00269) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
