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NVH Category. NVH CharacteristicFrequency (Hz) Steady State Frequency Response Ride< 5 Shake5 - 40 Boom20 - 100 Moan100 - 150 Structural Borne Noise150 – 500 Air Borne Noise> 500 Transient Response Harshness20 - 100. Control by Damping. Control by Dynamic - PowerPoint PPT Presentation

Transcript of NVH Category

  • NVH CategoryNVH CharacteristicFrequency (Hz)Steady State Frequency ResponseRide< 5Shake5 - 40Boom20 - 100Moan100 - 150Structural Borne Noise150 500Air Borne Noise> 500

    Transient ResponseHarshness20 - 100

  • Single Degree of Freedom

  • Dynamic StiffnessDynamic Stiffness: (K - m 2) j C K* = ----------------------------------(K - m 2)2 + (C )2Mass MDamping CStiffness K = 2* *f

    f is the frequency

  • Pure ToneSound at a single frequencySound PressureObjective measurementdBLogarithmic of sound pressuredBAA-Weighted to adjust for ear sensitivity

  • Human SensitivityMore constant across frequency range with velocityHearing range 20 2000 HzDepends on overall levelSound at one frequency may mask by other frequenciesDepends on age, sex and other factors

  • Tactile ResponseSubjective-Objective

  • Tactile ResponseSubjective-Objective (2)

  • Sound Pressure Level and A Weighting

  • NVH ClassificationOperating ConditionIdle, Low Speed, Cruising, POT, WOTSubjective EvaluationShake, Boom, Noise, HarshnessObjective MeasurementSound Pressure, AccelerationFrequency RangeSourcePowertrain, Road, Exhaust

  • NVH Subjective RatingMostTargetsNo Sale

  • NVH ObjectivesAssess vehicle responses relative to design targets:Tactile responsesSeat trackSteering columnToe panAcoustic responsesDrivers earFront Passengers earRear passengers ear

  • Shake5 40 HzIdle ShakeIsolated Road ShakeRough Road ShakeSmooth Road ShakeWheel/Tire ImbalanceTire Force Variation

  • Design For ShakeBody vertical, lateral bending and torsion modesFront end bending and torsion modesFront floor modesSteering column modesSeat modesAvoid stickiness of the shock and CV joints that causes high force input and resonance in smooth road shake

  • Design For Shake (2)Mode separation and mode shape management of engine bounce, roll, pitch and yaw rigid body modes

  • Boom20 - 100 HzIdle BoomIsolated Road BoomRough Road Boom

  • Body Design for Boom

    1st and 2nd fore-aft acoustic modesBody 1st and 2nd order vertical bendingFront floor vertical bendingDash panel fore-aft bendingQuarter panel bendingFuel tank bounceSpare tire tub bounceDecklid, liftgate or lower back panel pumping

  • Structural Borne Noise100 - 500 HzPowertrain NoiseRough Road NoiseGear Whine

  • Design For NoiseMost of the vibration energy imparted to the vehicle is below 150 Hz. Below 150 Hz:Body structure is important for controlling noise and vibration Lack of structure usually results in costly design and tooling changesAbove 150 Hz:Can be resolved with relatively simple structure modifications, such as bead patterns, or damping treatments.

  • Design For Noise (2)

    Powertrain Bending IsolationPowertrain Bracket Isolation

  • 05101520253035404550CHASSIS/POWERTRAIN MODESRide ModesPowertrain ModesSuspension Hop and Tramp ModesSuspension Longitudinal ModesExhaust Modes05101520253035404550BODY/ACOUSTIC MODESBody First Bending (22Hz)Body First Torsion (25Hz)Steering Column First Vertical Bending (29Hz)05101520253035404550EXCITATION SOURCESInherent Excitations (General Road Spectrum, Reciprocating Unbalance, Gas Torque, etc.)Process Variation Excitations (Engine, Driveline, Accessory, Wheel/Tire Unbalances)First Order Wheel/Tire Unbalance (5-75MPH)V8 Idle (500-550RPM)Hot ColdHzHzHzFirst F/A Acoustic Modes (48Hz)Modal Chart

  • Body-in-White TargetsStatic StiffnessBendingTorsionNormal ModesVertical bendingTorsionLateral bending

  • Trimmed Body TargetsNormal ModesVertical bendingTorsionLateral bendingFront end bendingFront end torsion

  • Instrument Panel/Column TargetsNormal ModesVertical bendingLateral bending

  • Seat TargetsNormal ModesOn BedplateFore aftLateralIn VehicleFore aftLateral

    Different row may have different target

  • Idle Load

  • Idle Torque

  • Piston Displacement

  • Trigonometric Derivatives

  • Piston Velocity

  • Piston Acceleration

  • Smooth Road Shake

  • Wheel/Tire Imbalance DefinitionSimulationShake caused by the unbalanced inertia forces from the high speed rotation of the unbalanced wheel in vehicle cruisingLoad1.0 oz-inch (Sensitivity) unbalanced force at the spindlesBoth vertical and fore-aft loads with vertical load trailing fore-aft load by 90 degreesApplicationsFront wheel in-phase, Front wheel out-of-phase, Rear wheel in-phase and Rear wheel out-of-phase

  • Wheel/Tire Imbalance CalculationF = mr2F is imbalance Force (N)m is imbalance mass (Mg)r is imbalance radius (mm) is rotation speed (rad/sec)F = 1.0 oz-in = 1.0 * 28.3 * 10-6 (Mg/oz) * 25.4 (mm/inch) * 4 * 2 * f2 = 0.0284 * f2 (N)f is frequency (cycles/sec)

  • Wheel/Tire ImbalanceSpeed MapThe wheel/tire speed map (frequency v.s. vehicle speed) is dependent on the wheel/tire size, the wheel/tire stiffness and the payloadV = 2 * * Tire Effective Radius * FrequencyHowever, the Frequency/Vehicle Speed(MPH) is typically around 0.2Based on the above assumption, the frequency range of interest from 25 MPH to 125 MPH is 5 Hz to 25 Hz

  • Tire Force Variation DefinitionSimulationShake caused by the variation of the radial stiffness of the tiresLoad1.0 lbf (Sensitivity) variation force at the spindlesVertical load onlyApplicationsFront wheel in-phase, Front wheel out-of-phase, Rear wheel in-phase and Rear wheel out-of-phase

  • Tire Force VariationSpeed MapThe wheel/tire speed map (frequency v.s. vehicle speed) is dependent on the wheel/tire size, the wheel/tire stiffness and the payloadV = 2 * * Tire Effective Radius * FrequencyHowever, the Frequency/Vehicle Speed(MPH) is typically around 0.2Based on the above assumption, the frequency ranges of interest from 25 MPH to 125 MPH areFirst Order : 5 Hz to 25 HzSecond Order : 10 Hz to 50 Hz

  • Rough Road Noise

  • Spatial PSD Road ProfileSpatial Frequency ( Cycles / mm)Wave number1 / wavelengthPSD Amplitude (mm^2 / (cycles / mm))Power Regression Analysis (Y = 1.7872 * X-0.6729)

    7-1-512-psd

    Abscissa512

    0.00E+005.90E+01

    3.91E-041.40E+02

    7.81E-044.40E+02

    1.17E-032.29E+02

    1.56E-031.02E+02

    1.95E-037.07E+01

    2.34E-036.07E+01

    2.73E-031.00E+02

    3.13E-036.72E+01

    3.52E-033.80E+01

    3.91E-035.25E+01

    4.30E-031.05E+02

    4.69E-038.90E+01

    5.08E-037.84E+01

    5.47E-035.03E+01

    5.86E-033.99E+01

    6.25E-036.26E+01

    6.64E-032.82E+01

    7.03E-032.99E+01

    7.42E-036.29E+01

    7.81E-037.07E+01

    8.20E-032.08E+01

    8.59E-034.63E+01

    8.98E-035.04E+01

    9.38E-034.11E+01

    9.77E-032.53E+01

    1.02E-026.24E+01

    1.05E-026.04E+01

    1.09E-023.10E+01

    1.13E-021.67E+01

    1.17E-021.12E+01

    1.21E-022.49E+01

    1.25E-026.43E+01

    1.29E-029.36E+01

    1.33E-023.83E+01

    1.37E-022.50E+01

    1.41E-024.34E+01

    1.45E-026.33E+01

    1.48E-023.22E+01

    1.52E-023.38E+01

    1.56E-025.99E+01

    1.60E-028.06E+01

    1.64E-025.16E+01

    1.68E-021.96E+01

    1.72E-021.42E+01

    1.76E-024.53E+01

    1.80E-025.40E+01

    1.84E-024.55E+01

    1.88E-023.17E+01

    1.91E-022.66E+01

    1.95E-021.86E+01

    1.99E-022.58E+01

    2.03E-023.76E+01

    2.07E-025.60E+01

    2.11E-025.25E+01

    2.15E-022.41E+01

    2.19E-028.15E+00

    2.23E-021.38E+01

    2.27E-022.70E+01

    2.30E-021.96E+01

    2.34E-021.70E+01

    2.38E-025.80E+01

    2.42E-024.41E+01

    2.46E-022.30E+01

    2.50E-022.86E+01

    2.54E-022.46E+01

    2.58E-022.49E+01

    2.62E-022.85E+01

    2.66E-022.12E+01

    2.70E-021.48E+01

    2.73E-023.11E+01

    2.77E-023.50E+01

    2.81E-023.45E+01

    2.85E-021.89E+01

    2.89E-026.24E+00

    2.93E-029.50E+00

    2.97E-028.62E+00

    3.01E-026.90E+00

    3.05E-021.92E+01

    3.09E-021.75E+01

    3.13E-021.70E+01

    3.16E-022.85E+01

    3.20E-025.27E+01

    3.24E-022.59E+01

    3.28E-021.62E+01

    3.32E-021.55E+01

    3.36E-022.39E+01

    3.40E-022.58E+01

    3.44E-022.83E+01

    3.48E-022.11E+01

    3.52E-022.25E+01

    3.55E-022.62E+01

    3.59E-024.06E+01

    3.63E-024.43E+01

    3.67E-022.01E+01

    3.71E-021.85E+01

    3.75E-021.69E+01

    3.79E-021.14E+01

    3.83E-021.24E+01

    3.87E-028.44E+00

    3.91E-028.79E+00

    3.95E-021.06E+01

    3.98E-021.04E+01

    4.02E-021.20E+01

    4.06E-022.45E+01

    4.10E-022.75E+01

    4.14E-021.46E+01

    4.18E-021.36E+01

    4.22E-022.12E+01

    4.26E-022.89E+01

    4.30E-022.47E+01

    4.34E-022.38E+01

    4.38E-021.00E+01

    4.41E-021.75E+01

    4.45E-022.20E+01

    4.49E-021.10E+01

    4.53E-022.05E+01

    4.57E-022.42E+01

    4.61E-022.03E+01

    4.65E-022.36E+01

    4.69E-021.25E+01

    4.73E-028.94E+00

    4.77E-028.13E+00

    4.80E-029.17E+00

    4.84E-026.36E+00

    4.88E-027.93E+00

    4.92E-026.84E+00

    4.96E-021.23E+01

    5.00E-021.49E+01

    5.04E-021.32E+01

    5.08E-021.53E+01

    5.12E-021.21E+01

    5.16E-029.62E+00

    5.20E-028.89E+00

    5.23E-028.74E+00

    5.27E-028.35E+00

    5.31E-021.00E+01

    5.35E-022.11E+01

    5.39E-022.03E+01

    5.43E-021.37E+01

    5.47E-022.04E+01

    5.51E-021.53E+01

    5.55E-026.57E+00

    5.59E-025.44E+00

    5.63E-027.11E+00

    5.66E-021.11E+01

    5.70E-029.38E+00

    5.74E-029.26E+00

    5.78E-021.05E+01

    5.82E-021.73E+01

    5.86E-023.07E+01

    5.90E-021.92E+01

    5.94E-029.15E+00

    5.98E-021.37E+01

    6.02E-021.60E+01

    6.05E-029.29E+00

    6.09E-026.65E+00

    6.13E-021.07E+01

    6.17E-021.27E+01

    6.21E-021.1