Multi_Axis Sequential SR for GMW14011 and GM7293TP 2007.06.30

Multi-Axis S&R Turnkey Solutions

GMW14011 and GMW 7293TP

GM has worldwide test procedures GMW14011

and GMW 7293TP for performing Objective

Subsystem/Component Squeak and Rattle Tests.

The purpose of these procedures is to provide

instructions for subjecting the subsystem or

component to vibration profiles comparable to

in-vehicle vibration and objectively measuring

the Squeak and Rattle performance.

GM explicitly recommends MB Dynamics’ Energizer Series Shakers, Multi-directional Universal Test Fixtures and horizontal moving tables in these worldwide Test Procedures. MB delivered more than 100 turnkey squeak and rattle (S&R) solutions that meet GM’s Background N10 Loudness level of 1.5 sones and that fully conform to GM Standards. MB provides engineering services, test process development, and training to fulfill such demanding S&R requirements.

Why Multi-Axis, Sequential Test Systems for Finding & Fixing S&Rs?

Road-induced vibration causes buzzes, squeaks & rattles (S&R) inside the vehicle’s interior. Such annoying noises come from the cockpit (instrument panel), seats, door modules, console, headliner, sunroof, HVAC, steering

columns and numerous components such as seat belt retractors, audio/entertainment/navigation systems, and

cargo/sun shades. There are more than 1,000 contact points in these interior subsystems and components that could be the sources of friction-induced and impact-induced annoying noises. A systematic process is needed to troubleshoot and detect root causes of S&Rs, to identify their location, to understand the transmission path (s) (air-borne and/or structure-borne) from source to radiator to occupant, and to understand the physics of why they occur so that design, material, supplier or manufacturing process changes can be made to reduce if not eliminate them. Multi-axis sequential vibration systems that excite these subsystems and components in their vertical, fore-aft (or longitudinal), and lateral directions one axis at a time have been proven to be effective means of diagnosing root causes, paths, etc. Oftentimes the physics of why such noises occur are so complicated and not intuitive that it is helpful to excite one direction at a time to diagnose root causes. Exciting with road-measured vibration levels separately in each direction helps in this process to detect and correct.

What are some examples of multi-axis test systems?

What are important specifications for the MB Multi-Axis S&R Test Systems?

Parameter Specification

Subsystems & Components Tested Cockpits (instrument panel), seats, door modules, consoles, headliners, sunroofs, HVAC, steering columns, ? bucks, ? bucks and numerous components such as seat belt retractors, audio/entertainment/navigation systems, cargo/sun shades, clusters, etc.

Noise levels without payload 1.5 sones N10 Loudness running a typical S&R PSD profile Payload weights No practical limit; typical masses of above payloads; 150kg Payload sizes No practical limit with universal fixture tubes; attach above

payloads to arrangement of universal fixture tubes, using

brackets between payload’s vehicle connect points and tubes Vibration excitation, each axis Road-measured PSD random and time histories; sine

Max. vibration amplitudes 0.75 gRMS and 3 g’s peak instantaneous during PSD random

or time history replication (typical S&R degradation levels are

100% higher); 1.0 g pk sine

Number of Quiet Energizers with Force-Multiplying Lever Arms 1 or 2 Energizer BLACKs or SILVERs, uncooled; 1 BLACK can

perform above vibration amplitudes without forced air cooling

for payloads less than 75kg; 2 Energizers are useful for heavier payloads or larger test items or with tests requiring

higher S&R degradation amplitudes on heavier payloads

Fixture-specific conditions No head expander because those large flat surfaces radiate

noise and pump air causing higher Background Noise

readings; universal fixture tubes have small surface areas;

tubes are stiff but lightweight, having many inserts for bolting

together any payload at its vehicle connect points Environmental conditioning All equipment can operate at -40 to + 80 C, with options Frequency range GM’s S&R frequency range of 8 Hz - 100 Hz is easily attained Mobility and Positioning Energizers and universal fixture pedestals are mounted on

base masses with air casters for moving over smooth lab

floors for positioning for vertical, fore-aft and lateral

excitation; can also be bolted to floor or T-slot table Turnkey System Deliverables Includes Energizer (s) with lever arms in 3-axis base (s) with

Universal Fixture System having tubes and pedestals –

configurable for vertical, fore-aft and lateral vibration; 19”

cabinet; S&R Controller with rack-mount PC; brackets for 1st

test item; accelerometers, S&R Metrics for measuring S&Rs;

installation, training, start-up

What is S&R Metrics?

S&R Metrics is software and acoustic data acquisition

hardware dedicated to measuring buzzes, squeaks and rattles.

Sound quality packages are often used to quantify S&Rs, but

contain extra and unneeded features, including: Sharpness,

Tonality, Articulation, and Roughness. S&R Metrics is the

COST EFFECTIVE S&R detection system. Easy to use

modules make it suitable for any setting from R&D facilities to

factory installations where technicians have little time for

intricate setups and complex options. It includes Instationary

Loudness, SPL, and other audio functions necessary for S&R.