Essentials of Mechanical Stress Analysis

Essentials of Mechanical Stress Analysis
اسم المؤلف
Amir Javidinejad
التاريخ
المشاهدات
393
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Essentials of Mechanical Stress Analysis
Second Edition
Amir Javidinejad
Contents
Preface xi
Author xiii
Chapter 1 Basics of Engineering Materials 1
1.1 Introduction . 1
1.2 The Fundamental Terms . 1
1.3 The Material Properties 7
1.4 Material Selection . 11
References . 12
Chapter 2 Stress and Strain Relationship . 13
2.1 Introduction . 13
2.2 Stress . 13
2.3 2-D Stresses on an Inclined Angle 14
2.4 Principal Stresses 14
2.5 Mohr’s Circle 15
2.6 Strain . 23
2.7 Plane Stress and Strain . 24
2.8 Principal Strains 25
2.9 Stress Based on the Measured Strains . 25
2.10 Stress State in Polar Coordinates . 27
2.11 Stress Field around Circular Holes in Thin Plates 29
2.12 Stress due to Thermal Expansion and Axial
Pre-loading 31
References . 35
Chapter 3 Stresses due to Various Loading Conditions 37
3.1 Introduction . 37
3.2 Contact Stresses 37
3.3 Thin-Walled Spherical Pressure Vessels . 42
3.4 Thin-Walled Cylindrical Pressure Vessels 43
3.5 Thick-Walled Cylinder . 51
3.6 Stress on Hydraulic Actuators . 52
3.7 Stress due to Various Combined Loadings . 53
3.8 Stresses due to Rotational Loadings 55
References . 58
viiChapter 4 Failure Criteria . 59
4.1 Introduction . 59
4.2 Material Failure 59
4.2.1 Ductile Failure 59
4.2.2 Brittle Failure 59
4.3 Maximum-Shearing-Stress Criterion
(Ductile Material) . 60
4.4 Maximum-Distortion-Energy Criterion
(Ductile Material) . 61
4.5 Maximum-Normal-Stress Criterion
(Brittle Material) . 62
4.6 Coulomb-Mohr’s Criterion (Brittle Material) 63
4.7 Factor of Safety Calculations . 63
References . 67
Chapter 5 Beam Analysis Theory . 69
5.1 Introduction . 69
5.2 Boundary Conditions and Loading 69
5.3 Shear and Moment Diagrams . 70
5.4 Deflection of the Beams . 74
5.5 Bending of the Beams 82
5.6 Shear of the Beams 83
5.7 Guide to Beam Design and Analysis . 85
5.8 Torsion of the Beams . 88
5.9 Curved Beam Theory . 89
References . 98
Chapter 6 Plate Analysis Theory 99
6.1 Introduction . 99
6.2 Circular Plates Uniformly Loaded . 99
6.3 Circular Plates Loaded at the Center . 102
6.4 Uniformly Loaded Rectangular Plates . 107
References . 110
Chapter 7 Elastic Stability and Buckling . 111
7.1 Introduction . 111
7.2 Column Buckling Instability 111
7.3 Column Buckling under Combined Axial
and Bending Loads . 117
7.4 Multiple Column System Buckling . 119
7.5 Buckling of Plates 121
References . 124
viii ContentsChapter 8 Energy Methods . 125
8.1 Introduction . 125
8.2 Strain Energy 125
8.3 Castigliano’s Theory . 127
8.4 Stress due to Impact by Potential Energy . 130
References . 137
Chapter 9 Fatigue Analysis . 139
9.1 Introduction . 139
9.2 Stress-Life S-N Curve . 139
9.3 Fatigue Crack Growth 141
Reference 144
Chapter 10 Numerical and Finite Element Methods 145
10.1 Introduction . 145
10.2 Stress on Truss Elements . 145
10.3 Stress on Beam Members . 157
10.4 Accurate Finite Element Analysis of Plates 164
10.5 Finite Element Analysis Results Correlations . 175
10.6 Determination of Fastener Stiffness for FEA 176
References . 179
Chapter 11 Composite Analysis Theory . 181
11.1 Introduction . 181
11.2 Orthotropic Lamina 181
11.3 Orthotropic Layers Oriented at an Arbitrary Angle 182
11.4 Analysis of Laminate . 185
11.5 Effective Modulus of the Laminate . 193
References . 194
Chapter 12 Fasteners and Joint Connections 195
12.1 Introduction . 195
12.2 Fastener-Connection Failure . 195
12.3 Welded-Connection Failure 198
12.4 Eccentric Loading of Fasteners 199
12.5 Inter-Coupling Loading of Fasteners and Inserts 202
12.6 Fastener Properties . 203
References . 204
Contents ixChapter 13 MathCAD® Stress Analysis Simulations . 205
13.1 Introduction . 205
13.2 Section Property Calculations 205
13.3 Stress Transformation and Principal Stresses 210
13.4 Hooke’s Law (Stress and Strain Conversations) . 212
13.5 Contact Stresses 214
13.6 Pressure Vessels . 215
13.7 Shear and Moment Diagrams . 216
13.8 Curved Beam Theory . 219
13.9 Deflection of Circular Plates 222
13.10 Deflection of Rectangular Plates 228
13.11 Column Buckling 230
13.12 Plate Buckling . 233
13.13 Truss System Analysis . 234
13.14 Composite Laminate Lay-up Analysis . 238
13.15 Eccentric Loading of the Fasteners 244
References . 245
Index . 247
Index
2-D stresses on an inclined angle, 14–15
Airy stress function, 29–31, 164
Allowable strength, 8–9
ANSYS, use of for finite element analysis of
plates, 166–171
Axial strain deformation, 1
Beam members, finite element analysis of stress
on, 144–157
Beams
bending, 82
boundary conditions for, 69
curved beam theory and deformation of,
89–96
deflection of, 74–82
loading, 70
shear and moment diagrams, 70–73
shear stresses in, 83–85
torsion of, 88
use of MathCAD to determine shear and
moment diagram of, 216–218
Bending
beams, 82
curved beam under, 89
laminates, 186
Bending moments
central-loaded plates, 102–104
fastener failure, 196
uniformly loaded circular plates, 99–102
Bolted and riveted connection failure, 195–198
Boundary conditions
beams, 69
center-loaded plates, 102–104
column buckling instability, 111–116
edge, 85–88
plate buckling, 121
shear–moment diagrams, 70–73
Buckling
column instability, 111–116
combined loading, 117–119
multiple column systems, 119–121
plates, 121–123
use of MathCAD to determine in columns,
230–232
use of MathCAD to determine in plates, 233
Cantilevered beams, 76–80
deflection of, 74–76
stress due to impact by potential energy on,
130–131
Cartesian coordinates, representation of stress
in, 27
Castigliano’s theory, 127–130
Central-loaded circular plates, analysis of,
102–104
Circular holes, stress field around in thin plates,
29–30
Circular plates
center loaded, 102–104
uniformly loaded, 105–106
use of MathCAD to determine deflection of,
222–229
Columns
buckling instability, 111–16
buckling under combined axial and bending
loads, 117–118
multiple system buckling, 119–120
use of MathCAD to determine buckling in,
230–232
Combined loading, column buckling under,
117–18
Composite analysis
effective modulus of laminate, 193
orthotropic lamina, 181–182
orthotropic layers oriented at an arbitrary
angle, 182–184
Composite laminates, use of MathCAD for layup analysis, 222–227
Composite materials
properties of, 10
stress analysis of, 181
Concentrated loading, 69
Contact stresses, 37–41
calculation of using MathCAD, 214
Couple loading, 69
Cracks
fatigue crack growth, 142–144
material failure due to, 59
Curvature representation theory, 74–75
Curved beam theory deformation and, 89–96
use of MathCAD to determine stresses,
219–221
Cyclic loading, fatigue analysis under, 141–142
Cylindrical pressure vessels determination of
stress on thick-walled, 51–52
determination of stress on thin- walled,
43–50
247Deflection
beam members, 74–75
circular center-loaded plates, 102–104
material failure due to, 59
multiple column system buckling, 119–120
uniformly loaded circular plates, 99–101
uniformly loaded rectangular plates,
107–109
Deformation
curved beam theory and, 89–96
multiple column system buckling, 119–120
Displacement, analysis of laminate, 185
Eccentric loading of fasteners, 199–203
use of MathCAD for analysis of, 230–233
Edge boundary conditions, plate analysis of
circular plates, 99–100
Effective modulus, 193–194
Elastic bodies
contact stresses in, 36–42
displacement and rotation of, 125–127
stress due to impact by potential energy on,
130–136
use of Castigliano’s theory for, 127–129
Endurance limit, 140–141
Engineering material properties, 7
Equivalent spring force, 132
Factor of safety, calculations for, 63–66
Failure analysis
fastener connections, 195–197
maximum distortion energy criterion, 59
maximum normal stress criterion, 59
maximum shear stress criterion, 60
Mohr’s criterion, 63
welded connections, 199–200
Failure criteria, 59
factor of safety based on, 63
Fastener failure, analysis of, 195–203
Fasteners
eccentric loading of, 199–203
intercoupling loading of, 20
properties of, 203–204
use of MathCAD for analysis of eccentric
loading of, 244–245
Fatigue analysis
crack growth, 139–140
stress-life S–N curve, 139–140
Fillet weld connections, failure, 198–199
Final stresses, 199
Finite element analysis
stress on beam members, 157–163
stress on truss elements, 145–156
use of ANSYS for accurate analysis of stress
on plates, 164–175
use of MathCAD for in truss systems,
234–237
Fixed beams, 69–70
Fracture failure criteria, 59
maximum normal stress, 62
Mohr’s criterion, 63
Free mesh, use of in finite element analysis of
plate stress, 166–175
Free-body diagrams
beam, 70–71
cylindrical pressure vessels, 43–46
fasteners, 200–201
Fundamental terms, 1–5
Gradual loading, 69
Gyration ratio, 111
High-aspect-ratio mapped mesh, use of for finite
element analysis of plates, 153–167
High-density free mesh, use of for finite element
analysis of plates, 153–167
Hooke’s law, 1, 19
MathCAD, 208–209
Impact loading, 131–135
Inclined angle, 2-D stresses on, 14–15
Inserts, intercoupling loading of, 202
Joint failure, 195, 197–198
Knock-down factors, 7
Lamina
analysis of composites, 185–186
analysis of layers oriented at an arbitrary
angle, 182–185
properties of, 10
properties of composites, 11
Laminates
composite analysis of, 185–192
effective modulus of, 193–194
material properties, 9–111
use of for composite lay-up analysis,
185–192
Lateral strain deformation, 2
Loading
beams, 69–82
buckling of plates, 121–124
column buckling, 111–119
column buckling under axial and bending
loads, 117–119
composite analysis of laminate, 185
determination of stress on truss elements,
145–156
eccentric, 199
248 Indexfastener failure and, 195–196
intercoupling, 202
shear and moment diagrams, 70–73
Long columns
buckling instability, 111–116
definition of, 111
Low-aspect-ratio mapped mesh, use of for finite
element analysis of plates, 166–167
Low-density free mesh, use of for finite element
analysis of plates, 166–167
Mapped mesh, use of in finite element analysis
of plate stress, 166–167
Material coefficient of thermal expansion, 7
Material constants, 1–8
Material failure, factors in, 55
Material properties, 9–11
MathCAD
calculation of contact stresses using, 214
plate buckling analysis using, 233
section property calculations using, 206–209
stress and strain conversations, 210–213
use of for analysis of eccentric loading of
fasteners, 244–245
use of for composite lay-up analysis,
238–244
use of for finite element analysis of truss
systems, 234–237
use of for principal stresses and Mohr’s
circle, 210
use of to calculate wall stresses on pressure
vessels, 215
use of to determine deflection of circular
plates, 222–227
use of to determine deflection of rectangular
plates, 228–229
use of to determine shear and moment
diagram of a beam, 216–218
use of to determine stresses for curved beam
members, 219–221
Maximum contact pressure, 37–33
determination of for spherical contacts,
33–42
Maximum distortion energy criterion, 61
Maximum normal stress criterion, 62
beam bending, 82
Maximum shear stress
determination of using Mohr’s circle, 15–19
fastener failure and, 195
Maximum shear stress criterion, 60
Metallic materials, stress analysis of, 9
Modulus of elasticity, 1
Mohr’s circle, 15–19
construction of using MathCAD, 210
Mohr’s criterion, 63
Moment diagrams, 70–73
use of MathCAD to determine for beams,
216–218
Moment loading, 55
Neutral axis location, 89, 90, 92
Normal stress, beam bending, 82
Number of residual life cycles, material failure
due to, 60
Numerical analysis
stress on beam members, 158–161
stress on truss elements, 145–156
One-side fixed beams, 69–70
One-side simply supported beams, 69–70
Orthotropic composite materials, 8, 181–182
analysis of layers oriented at arbitrary
angles, 182–183
Planes, stress and strain for, 24–25
Plate analysis assumptions for, 99
central-loaded circular plates, 102–103
uniformly loaded circular plates, 99–102
uniformly loaded rectangular plates,
107–109
Plates
accurate finite element analysis of, 165–175
buckling of, 121–122
use of MathCAD for determination of
buckling in, 230
Poisson’s ratio, 1
Polar coordinates, stress state in, 13–14
Potential energy, stress due to impact by,
130–132
Pressure vessels
thin-walled cylindrical, 43–50
thin-walled spherical, 42
use of MathCAD to calculate wall stresses
on, 215
Principal strains, 25
Principal stresses, 14–15
calculating using MathCAD, 210
determination of using Mohr’s circle, 14–18
factor of safety, 59
Quasi-isotropic laminates, 193
Rectangular plates
analysis of uniformly loaded, 107–109
use of MathCAD to determine deflection in,
228–229
Rod truss members, analysis of stress on, 145–156
S–N curve, 139–140
Safety factor, calculations for, 63–65
Index 249Section property calculations using MathCAD,
206–208
Shear
components of stress, 15
free body diagrams, 70–73
use of MathCAD to determine diagram for
beams, 216–218
Shear modulus, 3
Shear strength, 3
Shear stresses beams, 83–84
torsion and, 88–89
Simply supported beams, 55–56
deflection of, 74–81
Slenderness, 97
Spherical contacts, contact stresses for, 38
Spherical pressure vessels, determination of
stress on thin-walled, 43
Steel, stress-life S–N curve, 139–140
Stiffness
beam members, 146
determination of for truss elements, 146–153
laminate, 185–1192
orthotropic lamina, 181
plate buckling and, 233
Strain
definition of, 1
material failure due to, 47
plane, 25–26
Strain deformation, 3
Strain energy
definition of, 125
displacement and rotation of elastic bodies,
125–126
Strain transformation, 20–26
composite analysis of orthotropic lamina,
183–185
use of MathCAD to perform, 213
Strains
composite analysis of orthotropic lamina,
181–182
laminates, 185–192
principal, 25–26
stress based on measured, 25–26
Strength of a material, 2
Stress
based on measured strains, 25
beam bending, 82
definition of, 1
determination of on beam members, 157–163
determination of on thin-walled pressure
vessels, 43–47
field of around circular holes in thin
plates, 29
impact by potential energy, 130–134
material failure due to, 37–58
plane, 24
shear components of, 13–14
state of in polar coordinates, 27–28
use of finite element analysis for plates,
164–174
use of finite element analysis to determine,
164–174
Stress analysis, fundamental terms, 1–11
Stress concentration factor, 5
Stress riser, 5
Stress state transformation
determination of using Mohr’s circle, 15–19
Stress transformation, use of MathCAD for
calculating, 210
Stress-life S–N curve, 139–140
Stress–strain relations, 23–24
laminates, 182
representation of in polar coordinate system,
25–28
Stresses
2-D on an inclined angle, 14
analysis of in central-loaded circular plates,
102–105
analysis of in uniformly loaded circular
plates, 99–101
composite analysis of orthotropic lamina,
182–185
contact, 214–215
principal, 14–15
T-beams, shear stress distribution in, 85
Tension tear-out, 197–198
Thermal expansion
material coefficient of, 7
strain due to, 31
Thick-walled pressure vessels
determination of stress on, 51–52
Thin plates definition of, 99
stress field around circular holes in, 29–30
Thin-walled pressure vessels, determination of
stress on, 42–43
Timoshenko approach to plate analysis, 99–107
Torsion loading, 69, 162
beam members, 88
Truss elements
determination of strain energy in, 125–126
determination of stress on using finite
element analysis, 164–174
use of MathCAD for finite element analysis
of, 234–237
Ultimate strength of a material, 1
Uniformly distributed loading, 69
Uniformly loaded circular plates, analysis of,
99–102
250 IndexUniformly loaded rectangular plates, analysis of,
107–109
Unity deflection, 158
Unity displacement, 160
von Mises criterion, 61
stress field on plates, 164
Welded connections, failure of, 198–199
Winkler method, 89–96
Yield failure criteria, 59
maximum distortion energy, 61
maximum shear stress, 60
Yield strength, 3

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