Lecture-01-16-08 - MECH 668 Vehicle Noise, Vibration and...

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Unformatted text preview: MECH 668 Vehicle Noise, Vibration and Harshness (NVH) Vehicle Interior Noise Winter 2008 2 Interior Noise Sources Interior Noise Engine noise Road noise Intake noise Exhaust noise Wind noise Component noise Brake noise Squeak & rattle Source Structural modes Acoustic cavity modes Filter effects 3 Common Methods to Quantify Excitations & Response ¡ Excitations : ¡ Dynamic Force F(t) (Newton, Lbf) or Torque (Nm or lbf-in) 9 Engine, spindle, wind, electric motor, squeak & rattle, brake ¡ Base Excitation x(t) (mm, inch) 9 Road, squeak & rattle ¡ Transmission error e(t) ( μ m, μ-inch) 9 Gears, cams, components ¡ Volumetric velocity Q(t) (m 3 /s, in 3 /s) 9 Intake, exhaust, engine, wind ¡ Response : ¡ Structural motion (x - m or in; v - m/s or in/s; a - m/s 2 or in/s 2 ) ¡ Reaction force (Newton, lbf) or torque fluctuation (Nm, lbf-in) ¡ Sound pressure (Pa=N/m 2 , Psi=lbf/in 2 ) Displacement type 4 Control of Excitations ¡ Steady-state or repeated dynamics : ¡ Reduce excitation level (F(t), e(t), Q(t) ¡ Avoid high excitation near structural or acoustic resonances ¡ Change excitation frequencies ¡ Transients : ¡ Avoid impulsive excitations ¡...
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This note was uploaded on 10/13/2010 for the course MECH 668 taught by Professor Lim during the Winter '08 term at University of Cincinnati.

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Lecture-01-16-08 - MECH 668 Vehicle Noise, Vibration and...

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