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Transcript of scanfield/ME 4370 dropbox/notes... · Web viewMechanics of Materials: Hookes Law; σ=eϵ Stress:...
Mechanical Systems Review for ECE Students:
1) Materials
Metal Specific Gravity
Young's Modulus
(E)
Shear Modulus
(G)Bulk
ModulusPoisson's Ratio
Thermal Conductivi
ty0 deg.C
Linear Expansio
n Coefficie
nt
Melting Point
Proof/Yield
Stress
Ultimate.
Stress
Electrical
Resistivity
20 deg.C
- GPa GPa GPa W / ( m K ) x10-6/ deg C Deg K x 107Pa x 107Pa x10-8
ohm.mAluminium 2,7 68,95 26 75. 0,33 237 25 933 3-14 6-14 2,655Copper 8,96 117,2 46 130 0,36 398. 16,6 1357 4,7-32 20-35 1,673Gold 19,32 74,46 28. 167 0,42 315 14,2 1336 0-21 11-23 2,35
Iridium 22,42 517,1 147 6 2723 5,3
Iron 7,87 196,5 76 0,3 80,3 12 1809 16 35 9,7
Lead 11,35 13,79 6 0,43 35,2 29 600,7 1,5-1,8 20,6
Magnesium 1,74 44,13 0,35 156 25 923 4,45
Manganese 7,34 158,6 22 1517 185
Molybdenum 10,22 275,8 0,32 138 5 2893 5,2
Nickel 8,9 213,7 79. 176 0,31 90,5 13 1726 14-66 48-73 6,85Silver 10,50 72,39 28. 100 0,37 427 19 1234 5,5-30 14-38 1,59
Sodium 0,97 134 70 370,98 4,2
Steel (Mild) 7,8 210 80 0,3 50 12 1630-1750 20-40 30-50 10
Tin 7,31 41,37 17. 52 0,33 67 20 505 0,9-1,4 1,5-20 11,0Titanium 4,54 110,3 41. 110 0,3 22 8,5 1943 2-50 25-70 43
Tungsten 19,3 344,7 140 0,28 178 4,5 3673 100-400 5,65
Table 1: Tensile strength and Young’s modulus for selected materialsmaterial tensile strength MPa modulus of elasticity GPa304 stainless steel 500 200
copper 270 12096% alumina 200 340aluminium 90 70Sn63 solder 35 30epoxy resin 40 3silicone rubber 10 0.003
Figure 7: The block slip model, showing behaviour of metals under stress
Mechanics of Materials:
1) Hookes Law; σ=eϵ2) Stress:
a. σ=FA axial
b. τ=FA shear
c. τ=TrJ torsion
d. σ=MyI bending
3) Combined Stresses
4) Shear and Moment
5) Allowable stress in design
a. σ a=SFS
Kinematics and Dynamics:
Particle Motion:s=∫ v (t )dt=∬a (t )dt
For constant accelerations
1-D constant Acceleration equations:
Describing MotionCartesian Coordinates Polar Coordinates:
Motion composed of two components:
Translation Rotation
Kinematics of Multi BodiesLinks Joints
Degrees of Freedom / Mobility
Linkages:
4-bar Slider-crank
Notes:
1) Nonlinear2) Toggle positions3) Mulitple solutions4) Forces governed by5)
Cam systems:Automotive, manufacturing, rocking chairs, garage doors, door latches
Constant-velocity transmissions:Most common:Gear trains, belts & pulleys, gears & sprockets
Governing equation: θ1θ2
=−N 2
N1