Squeak and Rattle Degradation (Subasmbly, Subsystem and
Component) Evaluation Procedure
© Copyright 2006 General Motors Corporation All Rights Rerved
November 2006 Originating Department: North American Engineering Standards
Page 1 of 4
1 Scope
Note: Nothing in the standard superdes applicable laws and regulations unless specific exemption has been obtained.
Note: In the event of conflict between the English and domestic language, the English language shall take precedence.
1.1 Purpo. To provide a means of performing Squeak & Rattle (S&R) diagnostics or subjectively evaluating subasmblies, subsystems or components for squeak and rattle performance relative to vibration degradation over normal life expectancy. A subjective evaluation per GMW7293 is recommended but not required.
This procedure is intended for Development work only and not for Validation.
1.2 Foreword. This degradation test is bad on MIL Standard 810 which states the total test time may be exponentially reduced relative to a linear increa in test load. The relationship between test time and load is governed by the equation explained in Appendix A.
This test is limited to degrading a subasmbly, subsystem or component due to random simulated road vibration inputs only. It does not address environmental effects, static load effects or customer actuated inputs.
Plea refer to the Squeak and Rattle Website for the “Complete Multi-axis Vibration Tables“, to find the vibration test profiles.
All evaluations called for in this procedure are documented in GMW7293 and GMW14264 and should be performed in accord with GMW7293 and GMW14264.
For additional background information, refer to the following sources: “Subsystem Squeak & Rattle Degradation Test” by Robert S. Brines, GM Noi & Vibration Center, and “Automotive Component Vibration: A Practical Approach to Accelerated Vibration Durability Testing” by George Shinkle, Delco Remy.
1.3 Applicability. This procedure is applicable to any automotive subasmbly, subsystem or
component where squeaks and rattles are a concern and the vibration environment can be simulated.
2 References
Note: Only the latest approved standards are applicable unless otherwi specified. 2.1 External Standards/Specifications. MIL Standard 810
2.2 GM Standards/Specifications.
GMW7293 GMW14264 GMW14011
2.3 Additional References.
Evaluation Report entitled “Subsystem Squeak & Rattle Degradation Test“, by Robert S. Brines, document number 05072002-OT14-BQAC.
猜字谜S.A.E. paper 840501, “Automotive Component Vibration: A Practical Approach to Accelerated Vibration Durability Testing”, by George Shinkle (Delco Remy)
3 Resources
3.1 Facilities. Information wholly contained in GMW7293.
3.2 Equipment. Information wholly contained in GMW7293.
建筑制图3.3 Test Vehicle/Test Piece. Information wholly contained in GMW7293. 3.4 Test Time. Calendar time: 1 to 12 days Test hours: 4 to 96 hours Coordination hours:
1 to 8 hours
3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills. Information wholly contained in GMW7293.
4 Procedure
4.1 Preparation.
4.1.1 Fixturing Part. Information wholly contained in GMW7293.
GMW14188 GM WORLDWIDE ENGINEERING STANDARDS
© Copyright 2006 General Motors Corporation All Rights Rerved
Page 2 of 4 November 2006
4.1.2 Random Controller Set-up. Information wholly contained in GMW7293.
4.1.3 Determining Test Level Multiplier. Determine the test level multiplier and test time from Appendix A. Caution must be exercid to avoid choosing too high of a test level multiplier which may cau an unrealistic failure. Experience has shown that instrument panels should not be tested at an incread level.
4.2 Conditions. Information wholly contained in GMW7293.
4.2.1 Environmental Conditions. The pre-degradation and post-degradation evaluations, as well as the degradation testing, shall be performed at ambient unless otherwi specified. Instructions for evaluating a subasmbly, subsystem or component at non-ambient environmental conditions are wholly contained in GMW7293 and GMW14264.
4.2.2 Test Conditions. Deviations from the requirements of the procedure shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc.
化淡妆4.3 Instructions. It is recommended, but not required, that a subjective evaluation, per GMW7293, be conducted prior to testing to establish a baline performance level. U the vibration profile specified in the “Complete Multi-Axis Vibration Tables” on the Squeak and Rattle Website.
Select the test level multiplier and test time per ction 4.1.3. Multiply the vibration Power Spectral Density (PSD) acceleration levels from the vibration test profile by the test level multiplier (this means that Root Mean Square (RMS) level will increa by a factor of the square root of the multiplier).
Perform the degradation test for 100% of the total test time. Conduct an objective evaluation at the end of test per GMW14011.
The prence of witness marks or wear marks may assist in locating the source of Squeak and Rattle Issues.
5 Data
马祖龙5.1 Calculations. Not applicable.
5.2 Interpretation of Results. Not applicable.
5.3 Test Documentation. Document the results of all evaluations per the instructions in GMW7293, also noting the test level and the elapd test time for each evaluation.
6 Safety
This procedure may involve hazardous materials, operations, and equipment. This method does not propo to address all the safety problems associated with its u. It is the responsibility of the ur of the method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to u.
7 Notes
7.1 Glossary. Not applicable.
7.2 Acronyms, Abbreviations, and Symbols. PSD Power Spectral Density RMS Root Mean Square S&R Squeak and Rattle
8 Coding System
This standard shall be referenced in other documents, drawings, VTS, CTS, etc. as follows: Test to GMW14188
9 Relea and Revisions
9.1 Relea. This test procedure originated in June 2005, replacing GMN5160. It was first approved by the Global N&V Squeak & Rattle IDSR Harmonization Team in May 2005. It was first published in June 2005. 9.2 Revisions. Rev
Approval Date
Description (Organization)
A MAR 2006 Revision to reference in
Section 2.2 (Noi & Vibration) B
OCT 2006 Revision to ctions 1.1 and
4.3 (N&V Global S&R Harmonization Team)
GM WORLDWIDE ENGINEERING STANDARDS GMW14188
© Copyright 2006 General Motors Corporation All Rights Rerved
November 2006 Page 3 of 4
Appendix A
Table A1: Test Level Multiplier versus Test Time
Test Level Multiplier
Test Time
Test Level Multiplier
Test Time
1.00 103
超越对手
1.80 11.7
1.05 86 1.85 10.6
1.10 7
2.4 1.90 9.6
1.15 61.4 1.95 8.7
1.20 5
2.4 2.00 7.9
1.25 45.1
2.05 7.2
1.30 39.0
2.10 6.6
1.35 33.9
2.15 6.0
1.40 29.6
2.20 5.6
红参的作用1.45 26.0
2.25 5.1
1.50 2
2.9 2.30 4.7
1.55 20.3
2.35 4.4
1.65 16.1
2.40 4.0
1.70 14.4
2.45
3.7
1.75 13.0
2.50
3.5
Figure A1: Squeak and Rattle Degradation Testing
GMW14188 GM WORLDWIDE ENGINEERING STANDARDS
© Copyright 2006 General Motors Corporation All Rights Rerved
Page 4 of 4 November 2006
Appendix A - Continued
A1 Test Time and Level Determination
the plotted results):
on-accelerated test time el (PSD level) for l - vibration test level for non-lated to slope of fatigue curve and es in load is ltiply the PSD test level, the degradation The higher the test input level, the shorter time the degradation test takes. Without increasing the PSD level, the degradation test would take 103 h. The degradation time is calculated by the following equation (reference Appendix A, Table A1 and Figure A1 for a solution table to the equation and application_time - n test_time - accelerated test time
lab_test_level - vibration test lev accelerated test
application_leve accelerated test
s - scale factor re stress level of material being tested. The value often ud for “normal” engineering materials is 0.27. The scale factor can be adjusted to correlate the test to field failure experience.
Normally a factor of 2 increas recommended, which would result in a 7.9 h degradation test. However, experience has shown that it may not be practical to increa the test level for instrument panels, which means the degradation test time would need 103 h. Instrument panels have a very large number of parts some with non-linear resonant respons. In fact it is highly recommended that the test level not be incread for instrument panels.
To increa the test level, simply mu acceleration levels by the factor you want to increa the test level by (this means that the RMS acceleration will increa by a factor of the square root of the multiplier).
Without increasing the test would take 103 h. Increasing the test level by a factor of 2 would result in a 7.9 h degradation test. Caution must be exercid, so as not to increa the test level to the extent where a non-reprentative type failure will be caud. This can easily occur when localized component stress increas more rapidly than the increa in test level, often in a non-linear fashion. A non-linear increa in stress can occur when a part is being yielded or perhaps when a resonance with a high non-linear gain occurs. Non-reprentative failures can also occur when localized component stress is forced below the fatigue transition life. The fatigue transition life reprents the crossover point between the predominance of elastic type behavior versus plastic typ
e behavior. Where plastic strain behavior predominates, ductility will control behavior. Where elastic strain predominates, strength will control behavior.
Cycles to Failure
Stress or Strain
⎟⎟⎠
⎞⎜⎜⎝⎛=⎟⎟⎠⎞⎜⎜⎝⎛level n applicatio level test lab time test time n applicatio S
_____Figure A2: General Fatigue Life Curve
It should also be noted that the basis for accelerating Component Vibration Durability testing is fatigue theory. Degradation of a component for squeaks and rattles may or may not be fatigue related. Other possible mechanisms for squeak and rattle degradation may include: • Fastener looning • Creep
• Thermal cycling
• Repositioning of cables, wires, connectors &
护眼小常识other looly restrained parts • Wear (repeated adjustments, operation, etc.) •
Slams (door, hood, deck lid, etc.)
人物线描
• Body twist (occupant entry/exit, twist ditches,
etc.)
Despite the many possible mechanisms, the fatigue bad Vibration Durability appears to be our best option for a squeak and rattle degradation test.
If fatigue, fracture or other type failures occur during this test, engineering judgment (considering part availability) should be exercid to determine the next cour of action. Options may include: • Continuing the test with the broken part • Replacing the part • Repairing the part
•
Continuing the test without the part
