FATIGUE
by Kelly
All images scanned by T. Schmierer
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Visual example of axial stress
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Visual example of torsional stress
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Visual example of flexural stress
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An S-N plot for an aluminum alloy
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A diagram showing location of the three steps in a fatigue fracture under axial stress
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A diagram showing the surface of a fatigue fracture.
The rough surface indicates brittle failure, while the smooth surface represents crack propagation
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An example of beachmarks or "clamshell pattern" associated with stress cycles that vary in magnitude and time as in factory machinery
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An example of the striations found in fatigue fracture.
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Equation 1
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Equation 2
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Equation 3
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Equation 4
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A case hardened steel gear
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Example of pits formed by corrosion on the surface of LiF
STRESS INTENSITY
by Kim
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Schematic representations of
(a) an interior crack in a plate of infinite width, and
(b) an edge crack in a in a plate of semi-infinite width
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Schematic representation showing the effect of plate thickness on fracture toughness
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Basic modes of loading involving different crack surface displacements
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Graph showing distribution of stresses in vicinity of crack tip
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Picture of the Liberty Bell
STRESS CONCENTRATION
by Noble
All images scanned by T. Schmierer
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Diagram showing
(a)The geometry of surface and internal cracks.
(b) Schematic stress profile along the line X-X' in (a),
demonstrating stress amplification at crack tip positions
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Equation 1
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Equation 2
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Diagrams showing stress concentration factor plots for three different macroscopic flaw situations
ENERGY METHODS
by Yue
All images scanned by M. Gallagher
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Diagram of a plate with a crack growing with an applied stress
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Fractograph of ductile cast iron showing a transgranular fracture surface
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Fractograph of an intergranular fracture surface
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Three modes of crack surface displacements
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A cracked body with a force (F) and (a) is the crack length
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A graph of the increase of growth rate with crack size
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Illustration of Charpy and Izod Impact Tests
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A graph of the temperature dependence on the Charpy V-notch impact energy
(curve A) and percent shear fracture (curve B)
NUMERICAL
THEORY
by Midkiff
All images scanned by J. Midkiff
midkiff1.jpg
Structure of a three-member truss
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Single truss member
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Equation 1
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Equation 2
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Force diagram of single truss member
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Equation 3
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Equation 4
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Equation 5
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Three member truss
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diagram showing displacements and external forces
on a three member truss
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Equation 6
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Equation 7
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Equation 8
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Nodal forces on a three member truss
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Equation 9
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Equation 10
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Equation 11
EXAMPLES
by Schultz
All images preprocessed in Patran and processed in
Abaqus by J. Schultz on an ESM workstation
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FEA results of stresses in a plate with an elliptical crack
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FEA results of stresses in a plate with an elliptical crack
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FEA results of stresses in a plate with a circular crack
mesh.gif
Mesh with boundary conditions for one of the models
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Geometry of FEA drawn in Autocad
SIMPLE COMPUTER PROBLEM
by Tingler
All images scanned by T. Schmierer
Tingler8-1.jpg
Equation 8.1
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Equation 8.2
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Equation 8.5 a,b,c
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Equation 8.6
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Equation 8.7
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Equation 8.8
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Equation 8.9
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Equation 8.10
HISTORY/INTRODUCTION
by Widas
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Figure 1 from http://www.noraneng.com
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Mesh diagram of a van
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Figure 3 from http://umass.edu/mie/labs/mda/fea/fealib/goldstein/PROJECT.html
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Non-linear model of a bicycle frame
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Fatigue analysis of a train
EXPERIMENTAL
DUCTILE FRACTURE
by Bailey
All images scanned by T. Schmierer
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A tensile stess-strain curve
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A scanning electron fractograph of ductile cast iron, examining a transgranular fracture surface
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Figure showing the macroscopic differences between two ductile specimens(a,b)
and the brittle specimen (c)
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Figure demonstrating the microscopic qualities of ductile fracture surfaces
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Figure demonstrating the microscopic qualities of ductile fracture surfaces
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Sheared aluminium specimen showing cup and cone, and brittle fracture
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Graph that determines brittle to ductile transition
through an impact test for a 1018 hot-rolled steel
BRITTLE FRACTURE
by Ballard
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Chevron fracture surface
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Diagram showing intergranular fracture
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Radiating ridge fracture surface
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Diagram showing transgranular fracture
DESIGN
by Gordon
All images scanned by T. Schmierer
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Graph showing aluminum oxide's modulus of elasticity as a function of porosity
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Graph showingaluminum oxide's modulus of rupture as a function of porosity
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Diagram of a ceramic material before sintering
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Diagram of a ceramic material during sintering
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Diagram of a ceramic material after sintering
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Equation showing the minimum fiber length for a continuous fiber composite
pe-2.jpg
Equation showing the tensile strength of a discontinous
fiber composite with fiber length greater than lc
pe-3.jpg
Equation showing the tensile strength of a discontinous
fiber composite with fiber length less than lc
rf-1.jpg
Figure showing the tenile and compressive stress on tempered glass
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Equation for factor of safety
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A poor design that will create a stree concentration
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A good design that will minimise stress concentration
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Equation for the minimum thickness of material before plane strain behavior occurs
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Equation for the fracture toughness of a material with a thickness less than B
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Equation for the fracture toughness of a material with a thickness equal to or greater than B;
when it fractures in mode I
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Equation for the critical applied stress required to cause failure in a material
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Equation for the critical crack length required to cause failure in a material
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Diagram of a mode I fracture
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Diagram of a mode II fracture
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Diagram of a mode III fracture
Graph showing composite performance in relation to stress alignment
FRACTOGRAPHY
by Halahan and Mutter
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Stainless steel showing transgranular cleavage
Scanned by M. Gallagher
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TiB2 showing cleavage
Scanned by M. Gallager
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Ni base alloy showing cleavage
Scanned by M. Gallagher
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Silicon carbide showing small cleavage
Scanned by M. Gallagher
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Obvious decohesion
Scanned by R. Halahan
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Stainless steel showing hydrogen embrittlement
Scanned by R. Halahan
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Stainless steel showing decohesive rupture
Scanned by M. Gallagher
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Carbon-Magnesium steel showing stress corrosion cracking
Scanned by M. Gallagher
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Low carbon steel with a layer of oxide
Scanned by R. Halahan
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Low carbon steel with a layer of oxide
Scanned by R. Halahan
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Nickel based alloy with fatigue striations
Scanned by M. Gallagher
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Enlarged picture of fatig1.jpg
Scanned by M. Gallagher
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Nickel based alloy with jagged fatigue striations
Scanned by M. Gallagher
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Titanium alloy with fatigue striations
Scanned by M. Gallagher
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High carbon steel with an elongated dimple
Scanned by M. Gallagher
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AISI 10B21 Steel with well defined microvoid coalescence
Scanned by M. Gallagher
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Aluminum alloy with microvoids
Scanned by M. Gallagher
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Titanium alloy with equiaxed and elongated dimples
Scanned by M. Gallagher
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Nitralloy 135 M with microvoid coalescence
Scanned by M. Gallagher
FRACTURE TOUGHNESS
by McMurtry
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A specimen with an internal crack
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A specimen with a through-thickness crack
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A specimen with a half circle surface crack
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A fracture toughness vs. thickness graph
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Three modes of crack surface displacement
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Two ASTM standard compact specimen of different b sizes
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Graph of fracture toughness vs. temperature for different steels
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A graph of fracture toughness vs. temperature for various strain rates
applied to A572 steel
EXPERIMENTAL FATIGUE
by Meyer
All images scanned by C. Meyer
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Fracture appearances of fatigue failures in bending
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Typical fatigue zone with identifying marks
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Graph showing the effect of hardness on the fatigue life
of threads rolled before and after heat treatment
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Graph of bending fatigue test results on sections from crankshafts:
endurance limit versus surface treatment
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Typical fatigue life curve
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Bending angle guide
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Graph of experimental data: angle vs. cycles to failure
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Graph of crack growth rates obtained from adjacent pairs of a vs. N data points
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figure showing completely reversed controlled strain test and
two possible stress responses, namely cycle-dependent
hardening and softening
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Diagram of a stable stress-strain hysteresis loop
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Elastic, plastic, and total strain vs. Life curves
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A tension fatigue failure of a helicopter rotor blade flapping link
MOVIES
by Luszcz and Mix
cyclic.mpgand cyclic2.mpg
Fracture of a Hercules Graphite fiber/vinyl ester matrix composite resulting from a completely reversed load
controlled fatigue test
(performed by Nikhil Verghese - Tech graduate student)
brittle.mpg
shows brittle fracture of a class 20 gray iron sample
resulting from a constant strain tensile test (performed by J. Luszcz and J. Mix)
ductile.mpg
shows ductile fracture of a 4 wt% Cu in Al sample resulting
from a constant strain tensile test (performed by J. Luszcz and J. Mix)
fractures.jpg
shows resulting fractures of gray iron (brittle fracture,
round specimen), 4 wt% Cu in Al (ductile fracture, flat specimen), and
polyethylene (extremely ductile fracture, white specimen) (taken by J. Luszcz and J. Mix)
