WORLDWIDE GM ENGINEERING Test Procedure GMW7293 STANDARDS Subjective Subsystem/Component Squeak and Rattle Test 1 Introduction Note: Nothing in this standard supercedes applicable laws and regulations. precedence. 1.1 Purpose.To perform subjective component and subsystem level validation for squeak and rattle noises whensubjectedtoavibrationspectrumcomparabletoinvehicle"vibration. 1.2Applicability.Thisprocedure is applicabletoanyautomotivecomponent or subsystem where squeaksand 1.3 Remarks. This test is limited to detecting vibration induced noises, excited by inputs >8 Hz. Squeaks or itches excited only by slow body twist (cross ditches or driveways) will not be addressed by this test. Additionally, impact type vibrations caused by a door, hood or rear compartment lid slam cannot be addressed by this test. Referto the Squeak and Rattle (S&R) SSTS/CTS for the vibration test criteria and subjective evaluation criteria. This procedure is used for Subjective evaluation when conducting the subsystem/component degradation test referenced in GMW14188.For the Objective S&R evaluation refer to GMW14011. 2References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1ExternalStandards/Specifications. None 2.2 GM Standards/Specifications. GMW7294 GMW8518 GMW14188 GMW14264 GMW7880 2.3Additional References. ·Component Technical Specification (CTS),S&R specific .MB Dynamics equipment,available from www.mbdynamics.com/Vibration-Solutions.php. :Subsystem Technical Specification (SSTS),S&R specific 3Resources 3.1 Facilities. 3.1.1 Calibration. The test facilities and equipment shall be in good working order and shall have a valid calibrationlabel. 3.1.2 Alternatives. Alternative test facilities and equipment may also be used. However, all measuring variables 3.1.3 The facility must be free of: : Any vibrations, which may affect the test specimen. Facility vibration levels should not exceed 5% of the test specified input vibration level, at any frequency. .Noise which may limit the detection or evaluation of squeaks or rattles. GM Confidential @Copyright 2016 General Motors Company All Rights Reserved July 2016 Page 1 of 7 GMW7293 GMWORLDWIDEENGINEERINGSTANDARDS 3.1.4 When the S&R SSTS/CTS calls for hot or cold temperature conditions, a walk-in environmental room or evaluation of any product noise. It is acceptable to perform subjective evaluations between the Chamber Ventilation/Environmental system cycles, providing there is adequate time between cycles. 3.2 Equipment. 3.2.1 Shaker.A quiet shaker or actuator capable of replicating the specified vibration spectrum into the component or subsystem is required. Dynamic stroke should be at least 2.5 cm in order to meet the vibration profile requirements.The shaker must be sufficiently quiet so as not to mask any squeaks and/or rattles. A larger shaker or hydraulic actuator may be required for larger subsystems such as instrument panels,doors and seats. Larger shakers and hydraulic actuators are usually noisier and may require an acoustic cover or treatment Solutions.php. 3.2.2 Fixture. Fixtures should be rigid, free of resonances in the 0 Hz to 20o Hz range and free from rattles. creaksandotherpotentiallyconflictingnoises.Fixture resonances,whenexcited,cancontributetobackground noise levels, alter the vibration input to the component, and potentially make test control very difficult. To avoid using up the travel and dynamic capability of the shaker, the fixture should also be as light as possible. Magnesium is the material of choice because of its low mass, high degree of stiffness and damping characteristics.Aluminum is often an acceptable substitute. If noise measurements are being made on larger subsystems, airbag supports may be used to support the static weight of the component and fixture. A smaller and quieter electromagnetic shaker may then be used to provide thedynamicforcetothesubsystem. Recommend: MB Dynamics Universal Test Fixture for testing instrum