0. NVH METHODOLOGY FLOWCHARTS
DECEMBER 4, 2006
Detroit Diesel Standard Template.ppt

1. ENGINE MOUNT VIBRATION OPERATING ENGINE VIBRATION EVALUATION
SELECT TEST VEHICLE
INSTALL TRIAXIAL ACCELEROMETER ON ACTIVE (ENGINE) SIDE AND PASSIVE (FRAME) SIDE OF EACH MOUNT
SETUP TRUCK ON CHASSIS ROLLS DYNO
RUN THE VEHICLE AT THE FOLLOWING
OPERATING CONDITIONS:
FULL LOAD SWEEP
NO LOAD SWEEP
IDLE
1200 RPM WOT
1500 RPM WOT
1800 RPM WOT
2100 RPM WOT
COLLECT ACCELERATION DATA AT EACH RESPONSE POINT IN THE X,Y,Z DIRECTIONS
FOR EACH MOUNT CALCULATE TRANSMISSIBILITY:
DIVIDE ACCELERATION OF FRAME SIDE BY ACCELERATION OF ENGINE SIDE IN X,Y,Z DIRECTIONS NO
PLOT TRANSMISSIBILITY (X,Y,Z DIRECTIONS) AS A FUNCTION OF FREQUENCY (0-500 Hz)
YES
ISOLATORS EFFECTIVE AT VIBRATION ATTENUATION
IS TRANS. > 0.5 ABOVE 1.4 x NAT. FREQ. OF ISOLATOR?
MODIFY:
-MOUNT STIFFNESS (i.e. LOWER DUROMETER)
-ALTER MOUNT DESIGN (COMPRESSION VS. SHEAR)
RE-INSTALL ON VEHICLE
Detroit Diesel Standard Template.ppt

2. TRUCK CABIN NOISE OPERATING TRUCK SOUND LEVEL EVALUATION
SELECT TEST VEHICLE
INSTALL MICROPHONE AT DRIVER’S RIGHT EAR LOCATION
SETUP TRUCK ON SMOOTH ROAD
RUN THE VEHICLE AT THE FOLLOWING
OPERATING CONDITIONS:
OVER THE ROAD, 60 MPH, 7TH GEAR (WITH LOADED TRAILER)
FULL THROTTLE ACCELERATION 1000RPM-2100RPM
STATIONARY (IDLE, 1200RPM, 1800RPM, 2100RPM)
COLLECT A-WEIGHTED SOUND PRESSURE LEVEL AT EACH CONDITION
FOR EACH CONDITION CALCULATE:
-ONE THIRD OCTAVE SPECTRA
-SOUND QUALITY METRICS (LOUDNESS, SHARPNESS)
CROSS-PLOT:
-OVERALL SPL
-THIRD OCTAVES
-SQ METRICS
VS.
FTL TARGET CURVES
BEST-IN-CLASS CURVES
YES
INTERIOR SOUND LEVELS MEET OR EXCEED TARGET VALUES AND/OR BEST IN CLASS
MODIFY:
-MOUNT STIFFNESS (i.e. LOWER DUROMETER)
-REDUCE STRUCTURAL VIBRATION LEVELS
-REDUCE GEAR RATTLE
-ADD C.L.D. TREATMENTS, BARRIERS
DO ANY METRICS EXCEED TARGET VALUES OR B.I.C? NO
Detroit Diesel Standard Template.ppt

3. TRUCK CABIN VIBRATION OPERATING TRUCK VIBRATION EVALUATION
SELECT TEST VEHICLE
INSTALL TRIAXIAL ACCELEROMETER ON STEERING WHEEL AND SEAT FRAME
SETUP TRUCK ON CHASSIS ROLLS DYNO
RUN THE VEHICLE AT THE FOLLOWING
OPERATING CONDITIONS:
FULL LOAD SWEEP
NO LOAD SWEEP
IDLE
1200 RPM WOT
1500 RPM WOT
1800 RPM WOT
2100 RPM WOT
COLLECT ACCELERATION DATA AT EACH RESPONSE POINT IN THE X,Y,Z DIRECTIONS
FOR EACH MEASUREMENT LOCATION, CALCULATE THE RESULTANT RMS ACCELERATION NO
CROSS-PLOT RESULTANT STEERING WHEEL RMS ACCELERATION VS. ISO 5349 CURVES AND RESULTANT SEAT RMS ACCELERATION VS. ISO 2631 CURVES
YES
INTERIOR VIBRATION ACCEPTABLE
DOES RMS ST. WHEEL ACCEL. LIE BELOW THE 8-HR ISO 5349 EXPOSURE CURVE?
MODIFY:
-MOUNT STIFFNESS (i.e. LOWER DUROMETER)
-STEERING COLUMN THICKNESS INCREASE
-REDUCE STRUCTURAL VIBRATION LEVELS
DOES RMS SEAT
ACCEL. LIE BELOW THE 8-HR ISO 2631 EXPOSURE CURVE?
Detroit Diesel Standard Template.ppt

4. VEHICLE PASSBY NOISE LEVEL OPERATING TRUCK PASSBY NOISE EVALUATION
SELECT TEST VEHICLE
RUN VEHICLE AS PER SAE J366 PROCEDURE
SETUP TRUCK ON EPA APPROVED PASSBY SITE NO
YES
TRUCK COMPLIANT TO EPA CFR 205
IS PEAK SOUND PRESSURE LEVEL
< 80 dBA?
MODIFY:
-MECHANICAL FEATURES OF ENGINE (GEARS, STIFFENERS, COVERS, TREATMENTS)
-CALIBRATION FEATURES (TORQUE LIMITING/ACCELERATION RATE)
Detroit Diesel Standard Template.ppt

5. VEHICLE STATIONARY NOISE LEVEL NEUTRAL ENGINE RUN-UP NOISE EVALUATION
SELECT TEST VEHICLE
RUN VEHICLE AS PER SAE J1096 PROCEDURE
SETUP TRUCK ON EPA APPROVED PASSBY SITE NO
YES
TRUCK COMPLIANT TO EPA CFR 325
IS PEAK SOUND PRESSURE LEVEL
< 85 dBA?
MODIFY:
-MECHANICAL FEATURES OF ENGINE (GEARS, STIFFENERS, COVERS, TREATMENTS)
-CALIBRATION FEATURES (TORQUE LIMITING/ACCELERATION RATE)
Detroit Diesel Standard Template.ppt

6. ENGINE DYNO STAND RADIATED NOISE OPERATING ENGINE SOUND LEVEL EVALUATION
SELECT ENGINE FOR TEST
OPERATE ENGINE AS PER SAE J1074
SETUP ENGINE ON DYNO STAND IN A SEMI-ANECHOIC CHAMBER NO
DYNO STAND SOUND LEVELS MEET OR EXCEED TARGET VALUES AND/OR BEST IN CLASS
IS ANY ONE MIC. POSITION SPL OR 4-MIC AVERAGE SPL > BEST IN CLASS?
MODIFY:
-REDUCE STRUCTURAL VIBRATION LEVELS
-ADD STIFFENING TO BLOCK
-REDUCE GEAR RATTLE
-ADD C.L.D. TREATMENTS, BARRIERS
-REDUCE COMBUSTION NOISE
YES
Detroit Diesel Standard Template.ppt

7. COMPONENT VIBRATION STATIC ENGINE VIBRATION EVALUATION
SELECT ENGINE COMPONENT
SELECT ACCELEROMETER RESPONSE POINT(S)
SELECT IMPULSE HAMMER EXCITATION POINT(S)
IMPACT THE EXCITATION POINT(S)
5 TIMES IN EACH DIRECTION (X,Y,Z)
COLLECT DATA AT EACH RESPONSE POINT, AVERAGE OF 5 IMPACTS IN EACH DIRECTION (X,Y,Z)
PLOT FREQUENCY RESPONSE FUNCTION (FRF) FOR EACH RESPONSE POINT
DETERMINE THE LOWEST NATURAL FREQUENCIES
ARE ANY NAT. FREQ. BELOW 210 Hz?
FLAG THESE AS CRITICAL FREQUENCY COMPONENTS REQUIRING FURTHER ANALYSIS
YES
RESONANCES ABOVE 6TH ORDER FORCING FUNCTIONS NO
CHECK COMPONENTS IN THE OPERATING ENGINE DATA
HIGH AMPLITUDE AT CRIT. FREQ. COMP’S?
ENGINE FORCING FUNCTIONS NOT SUFFICIENT TO EXCITE RESONANCES
CHANGE COMP. FEATURES OR
ADD SUPPORT (BRACKET, CLIP)
ADD ISOLATION
DOES CHANGE SHIFT
NAT. FREQ. > 210 Hz?
SHAKER TEST AT LOWEST NAT. FREQ. & PEAK DISPLACEMENT FOR 10E06 CYCLES
DOES COMPONENT FAIL IN FATIGUE?
COMPONENT NOT LIKELY TO FAIL DUE TO HIGH VIBRATION
Detroit Diesel Standard Template.ppt

8. COMPONENT VIBRATION OPERATING ENGINE VIBRATION EVALUATION
SELECT ENGINE COMPONENT
SELECT ACCELEROMETER RESPONSE POINT(S)
(SAME AS FRF MEAS.)
START ENGINE AND BRING UP TO OPERATING TEMPERATURE
CONDUCT FULL LOAD (100% THROTTLE) SWEEP, 1050 RPM TO 1850 RPM, 90 SECONDS
COLLECT TRI-AXIAL (X,Y,Z) DATA AT EACH RESPONSE POINT
CONDUCT NO LOAD (0% THROTTLE) SWEEP, IDLE TO 2100 RPM, 90 SECONDS
LINES OF CONSTANT ORDER WITH HIGH AMPL?
LINES OF CONSTANT FREQ. WITH HIGH AMPL?
HIGH AMPL.
< 210 Hz?
COMPONENT NOT LIKELY TO FAIL DUE TO HIGH VIBRATION NO
YES
DATA ANALYSIS:
3D CAMPBELL PLOT
1. PK ACCEL. (0-500 Hz)
2. PK-TO-PK DISPL. (0-250 Hz)
2D PK HOLD SPECTRUM
*** NO
Detroit Diesel Standard Template.ppt

9. COMPONENT VIBRATION (CONTINUED) OPERATING ENGINE VIBRATION EVALUATION
CHANGE COMP. FEATURES OR
ADD SUPPORT (BRACKET, CLIP)
ADD ISOLATION
ORDER AMPL. LEVELS NORMAL?
YES NO
IDENTIFY AND CORRECT ENGINE ORDER RELATED ISSUES, RE-MEASURE COMPONENT VIBRATION
SHAKER TEST AT LOWEST NAT. FREQ. & PEAK DISPLACEMENT FOR 10E06 CYCLES
DOES CHANGE REDUCE AMPL. OR SHIFT FREQ?
DOES COMPONENT FAIL IN FATIGUE?
***
COMPONENT NOT LIKELY TO FAIL DUE TO HIGH VIBRATION
Detroit Diesel Standard Template.ppt

10. ENGINE TORSIONAL VIBRATION OPERATING ENGINE VIBRATION EVALUATION
SELECT ENGINE FOR TEST
MOUNT MAGNETIC PICKUP IN FLYWHEEL HOUSING AND AT FRONT OF CRANKSHAFT
SETUP ENGINE ON DYNO STAND (PERFORMANCE RM. OR DURABILITY STAND) NO
ENGINE EXHIBITS ACCEPTABLE TORSIONAL VIBRATION LEVELS
IS THE ANGULAR DISPLACEMENT AT THE FLYWHEEL > 5 DEGREES?
MODIFY:
-MASS, DAMPING OR STIFFNESS OF ROTATIONAL COMPONENTS
-PROVIDE ADDITIONAL STIFFENING TO CRANK CASE
YES
PERFORM FULL LOAD & NO LOAD ENGINE SWEEPS
Detroit Diesel Standard Template.ppt

11. Detroit Diesel Standard Template.ppt