mechanical vibration rao
TRANSCRIPT
1
MEEM 3700 1Lecture 1-Introduction
MEEM 3700MEEM 3700Mechanical VibrationsMechanical Vibrations
Mohan RaoChuck Van Karsen
Mechanical Engineering-Engineering MechanicsMichigan Technological University
Copyright 2003
MEEM 3700 2Lecture 1-Introduction
No Forces Forces
No Motion
Motion
2
MEEM 3700 3Lecture 1-Introduction
Harmonic Motion
Mechanical Vibrations
Sound (Acoustics)
Force
MotionLinearNon-Linear
Arbitrary motion
MEEM 3700 4Lecture 1-Introduction
Dynamics and Kinematics (MEEM 2700)
Strength of Materials (MEEM 2150)
Thermodynamics (MEEM 2200)
Differential Equations (MA3521)
3
MEEM 3700 5Lecture 1-Introduction
Our heart beat, our lungs oscillate, we hear because our ear drum vibrates…Vibration even makes us snore!!
The light waves which permit us to see & sound waves through which we hear entail vibration
We move by oscillating our legs
We cannot even say “Vibration” without vibration of larynges, vocal cord
We limit out discussion to “MECHANICAL VIBRATION”… i.e. Vibration of Dynamic Systems
What is a Dynamic System??? Any System that contain Mass and Elasticity.
MEEM 3700 6Lecture 1-Introduction
FriendFriend
•Conveyors, Hoppers, Compactors, Pneumatic Drills, etc.
•Opening of a cork from a wine bottle
•Washing Machine
•Mechanical Shakers, Mixers, Sieves, Sorters, etc.
•Musical Instruments
•Clocks, Watches
•Medical Field – Massagers, etc.
FoeFoe•RESONANCE – RESONANCE – RESONANCE
Tacoma Narrows BridgeTacoma Narrows Bridge
•Similar problems in machine tools, vehicles, turbines, pumps, compressors, buildings, aircraft & spacecraft systems
•Excessive vibration leads to loosening on parts, noise & eventual failure
•Effects of vibration on human body: Discomfort, Fatigue, Loss of Efficiency
•Sound quality in products
4
MEEM 3700 7Lecture 1-Introduction
Vibrations in Machinery
MEEM 3700 8Lecture 1-Introduction
Vibrations in Recreation
5
MEEM 3700 9Lecture 1-Introduction
Vibrations in Defense
MEEM 3700 10Lecture 1-Introduction
Vibrations in Transportation
6
MEEM 3700 11Lecture 1-Introduction
Vibrations in Aerospace
MEEM 3700 12Lecture 1-Introduction
Vibrations in Automobiles
NVH (Noise, Vibration, & Harshness) is a Top Priority for the BIG 3 Auto Industry.
Several hundred million dollars have been invested in infrastructure & human resource development in this area over the past 10 years.
7
MEEM 3700 13Lecture 1-Introduction
Sound/Noise in Automobiles
MEEM 3700 14Lecture 1-Introduction
Research in the Dynamic Systems Laboratory
Damping Characterization
8
MEEM 3700 15Lecture 1-Introduction
Research in the Dynamic Systems Laboratory
Nobeyama 45m Radio Telescope
MEEM 3700 16Lecture 1-Introduction
9
MEEM 3700 17Lecture 1-Introduction
MEEM 3700 18Lecture 1-Introduction
M
Mass
Spring
K
Damper
C
Inertia (Kinetic Energy)
Storage (Potential Energy) Dissipative (Energy Loss)
10
MEEM 3700 19Lecture 1-Introduction
TorsionalSpring
Kt
RotatingInertia
J
TorsionalDamper
Ct
MEEM 3700 20Lecture 1-Introduction
M
XK
11
MEEM 3700 21Lecture 1-Introduction
M
K X2X1Kc c
Rear Suspension Front Suspension
MEEM 3700 22Lecture 1-Introduction
M
KK
Mt Mt
c cX1 X2
X3 X4K K
Wheels/tires
12
MEEM 3700 23Lecture 1-Introduction
M
KK
Mt Mt
c c
Ms
K
K
KX4X3
X2X1
X5
Seat
MEEM 3700 24Lecture 1-Introduction
M
KK
Mt Mt
c c
Ms
K
K
KX4X3
X2X1
X5
M
θ
X6
Seat
13
MEEM 3700 25Lecture 1-Introduction