Mechanical Vibrations Notes

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  • Topic: Wave, Torsional vibration, Vibration
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MEEM 3700 Mechanical Vibrations
Mohan Rao Chuck Van Karsen
Mechanical Engineering-Engineering Mechanics Michigan Technological University Copyright 2003

MEEM 3700
Lecture 1-Introduction

1

No Forces No Motion

Forces

Motion

MEEM 3700
Lecture 1-Introduction

2

1

Force Linear Non-Linear Arbitrary motion Harmonic Motion Motion

Mechanical Vibrations Sound (Acoustics)
MEEM 3700
Lecture 1-Introduction

3

Dynamics and Kinematics (MEEM 2700) Strength of Materials (MEEM 2150) Thermodynamics (MEEM 2200) Differential Equations (MA3521)

MEEM 3700
Lecture 1-Introduction

4

2

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 cannot even say “Vibration” without vibration of larynges, vocal cord We move by oscillating our legs 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
Lecture 1-Introduction

5

Friend
•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.

Foe
•RESONANCE – RESONANCE – RESONANCE

Tacoma 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 MEEM 3700 6

Lecture 1-Introduction

3

Vibrations in Machinery

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Lecture 1-Introduction

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Vibrations in Recreation

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Lecture 1-Introduction

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4

Vibrations in Defense

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Lecture 1-Introduction

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Vibrations in Transportation

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Lecture 1-Introduction

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5

Vibrations in Aerospace

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Lecture 1-Introduction

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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.

MEEM 3700
Lecture 1-Introduction

12

6

Sound/Noise in Automobiles

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Lecture 1-Introduction

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Research in the Dynamic Systems Laboratory

Damping Characterization

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Lecture 1-Introduction

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7

Research in the Dynamic Systems Laboratory

Nobeyama 45m Radio Telescope

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Lecture 1-Introduction

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Lecture 1-Introduction

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8

MEEM 3700
Lecture 1-Introduction

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M K
Mass
Inertia (Kinetic Energy)

C

Spring
Storage (Potential Energy)

Damper
Dissipative (Energy Loss)

MEEM 3700
Lecture 1-Introduction

18

9

Ct J Kt
Torsional Spring Rotating Inertia Torsional Damper

MEEM 3700
Lecture 1-Introduction

19

M

K

X

MEEM 3700
Lecture 1-Introduction

20

10

M

X1

c

K

c

K X 2

Rear Suspension
MEEM 3700
Lecture 1-Introduction

Front Suspension
21

M X1 X2

c Mt X3
K

K

c
Wheels/tires

K

Mt
K

X4
22

MEEM 3700
Lecture 1-Introduction

11

Ms X5
K

Seat

M X1 X2

c Mt X3
K

K

c Mt

K

K
MEEM 3700

X4
23

Lecture 1-Introduction

Ms X5
K

Seat

θ

M X1
K K

c Mt X3
K

X6

c Mt

X2

K
MEEM 3700

X4
24

Lecture 1-Introduction

12

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Lecture 1-Introduction

25

13

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