Transcript Squeak and Rattle NVH Literacy

Squeak and Rattle 101
Martin Trapp
Ford Motor Company
NVH S&R Department
5-18-06
Martin Trapp, Ford Motor
Company, 5-18-06
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Objective : To assure that the vehicle exhibits robust S&R
preventative strategies.
The most effective way to cut warranty costs and eliminate
squeaks and rattles from a vehicle is to design component,
subsystems, and systems that will resist the inputs and
excitations of the road and powertrain. These designs need
to be incorporated early enough in the vehicle line program
in order to be both feasible and cost effective.
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Company, 5-18-06
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Or the Elimination of Squeak
Squeak, Squeak
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S&R are subset of all customer Unexpected Noises (UN). These noises are generally
random and transient (short time). They can be categorized by physical phenomena
• Squeak: frictional stick/slip caused by rubbing contact of adjacent parts i.e.,
door vinyl trim squeaks against to sheet metal
• Rattle: impact contact of adjacent parts i.e., glovebox latch rattles against
striker
• Buzz: noise radiated from part undergoing resonance vibration i.e., windshield
molding buzzes
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Causes of Squeak and Itch
 Shear Movements as Small as 1mm Between Surfaces
Can Generate Noise
 Many Parts Can Move 5mm – 10mm (body twist)
 Static Coefficient of Friction Creates a Storage/Release of
Energy Event (single event, Single Stick Slip, SSS = tick)
 Multiple Adjacent Storage/Release Events Cause
Unacceptable Noise (multi event, Multiple Stick Slip,
MSS = squeak)
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Examples for Friction Stick-Slip
Stradivari
Middle armrest
Objectionable Stick-Slip
Pleasant Stick-Slip
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Methods of Evaluation
• Road Testing (Proving Grounds or End-ofLine) With “Trained” Ears
• 4-Post Test Equipment (Fixed or Portable)
• Component Lab Testing With Controlled
Parameters
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Test methods – S&R (Proving Grounds)
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What are we Listening for?
Characteristics:
• Amplitude
• Frequency
• Continuity (continuous or intermittent)
• Direction
• Recognition – familiar sound?
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S&R is rarely masked
Low amplitude - rarely masked out - heard
through noise from wind, road, engine and
exhaust
[dB]
Road
S&R
[Hz]
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Squeak and Rattle: Test Track Layout Rationale
• The test tracks are designed to provide the desired
input energy (frequency range and amplitude) to excite
specific squeak & rattle concerns.
– Interior squeaks & rattles
– Body creak
– Chassis clunk / pop / other noise (suspension noise)
– Loose stock
• The surface lengths are optimized to allow sufficient
time for the track to excite concerns and for the driver to
recognize and locate the source.
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Squeak and Rattle: Generic Best Practice S&R Test Track
Layout
Cobblestone
Washboard
Vienna Block
Rope
Raised
Vienna Block
Angle Iron
DPG RB / EB
Body Twist
Straight
Body Twist
on Turn
Speed
Transition
400’
See following slide for details.
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Squeak and Rattle: Generic Best Practice S&R Test Track
Layout
Distance
(ft)
Speed
(mph)
Time
(sec)
Maintain steady 5 mph
30
5
4.1
COBBLESTONE
Suspension, Frame, Mounts
Speed 5 mph
Interior trim S&R
Accelerate smoothly to 20 mph
100
5 -> 20
5.7
VIENNA BLOCK
Specific by veh: e.g., "Door 12 mph"
Speed 5 -> 20
mph
Interior trim S&R
Maintain steady 20 mph
100
20
3.4
RAISED VIENNA
Interior
Speed 20 mph
Interior trim S&R (Truck)
Interior trim S&R (Car)
Not applicable
Maintain steady 20 mph
100
20
3.4
Speed 20 mph
Decelerate to 5 mph
30
20 -> 5
1.7
ROUGH BRICK: Interior
EUROPEAN BRICK: Interior
DECELERATE
6. Body Twist on Turn Body creak, chassis clunk and Maintain steady 5 mph
pop
70
5
9.5
TURN & TWIST
Body, Frame, Suspension, Mounts
Speed 5 mph
7. Transition
Not applicable
Straighten vehicle out
20
5
2.7
8. Washboard (4)
Specific interior trim S&R
frequencies
Accelerate smoothly to 20 mph
100
5 -> 20
5.7
WASHBOARD
Specific by veh: e.g. "IP 18 mph"
Speed 5 -> 20
mph
9. Ropes
Interior trim S&R noticeable
Maintain steady 20 mph
with lighter impact force inputs
100
20
3.4
ROPES
Interior
Speed 20 mph
10. Angle Iron
Interior trim S&R requiring
greater impact force inputs
Maintain steady 20 mph
100
20
3.4
Angle Iron
Interior
Speed 20 mph
11. Transition
Not applicable
Decelerate to 5 mph
30
20 -> 5
1.7
DECELERATE
Speed 5 mph
12. Body Twist
Body creak, chassis clunk and Maintain steady 5 mph
pop, loose stock
40
5
5.5
BODY TWIST
Body, Frame, Suspension, Mounts
Speed 5 mph
EXIT
YIELD
Section
Concerns Identifiable
Driver Actions
1. Cobblestone (1)
Chassis clunk and pop, loose
stock
2. Vienna Block (2)
3. Raised Vienna
Block (2)
4. Rough Brick (3)
European Brick
5. Transition
(3)
13. EXIT
Total:
820 ft
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Signs
Speed Signs
Speed 20 -> 5
mph
Speed 5 mph
50.2 sec
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Squeak and Rattle: Environmental Four Poster
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Squeak and Rattle Component Testing
• Isolate the specific component
• Evaluate under controlled conditions
• Ease of Root Cause Analysis
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Squeak and Rattle Testing
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Squeak and Rattle
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Upfront Design Process
Objective : S&R Engineer reviews new product content descriptions and
program timing dates to be used in the development of test plans and
quality roadmaps.
Look For:




New product content in highly sensitive S&R subsystems
(ie. seats, I/P, suspension, body structure, closures
hardware).
Models, option content, and body styles offered.
Build timing (AA, CP, IB, etc.....)
Development milestones (Engineering sign-off, DVP&R
requirements).
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Subsystems that are not carry over should be checked for rattle.
Prioritize based on engineering judgement of rattle risk.
Historic Areas of Concern:
• IP
• Console
• Seat
• Door System (latches, surfaces,…)
Improved Through:
• Increased Design Clearance
• Strengthened Areas
• Verification Testing of Alternatives
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FRONT DOOR WIRING AND CABLES
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RH SIDE OF IP, BEHIND GLOVE BOX.
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Need flock tape. Interface between center console.
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Foam block needed to be added to 6” behind DVD attachment bracket.
Foam block is 60mmx44mm by 50mm
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Door trim bezel switch wire needs to be
wrapped in foam sleeve
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Well Protected Wire Harness
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Add Flock tape (or increase retention) to prevent vinyl to sheet metal squeak
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Tools: Material Pair Testing
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Hard Plastic Compatibility Matrix
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End of Presentation
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Enjoy the Conference
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Questions?
“Ask a question and you’re
a fool for a minute.
Do not ask the question and
you're a fool for the rest of your life.”
(Chinese proverb)
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Company, 5-18-06
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