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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term811.gif
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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img00001.gif
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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img00004.gif
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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img00001.gif
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
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midkiff1.jpg
Structure of a three-member truss
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midkiff2.jpg
Single truss member
midkiff3.jpg
Equation 1
midkiff4.jpg
Equation 2
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Force diagram of single truss member
midkiff6.jpg
Equation 3
midkiff7.jpg
Equation 4
midkiff8.jpg
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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midkif14.jpg
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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rmin.gif
FEA results of stresses in a plate with an elliptical crack
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rmed.gif
FEA results of stresses in a plate with an elliptical crack
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circle.gif
FEA results of stresses in a plate with a circular crack
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mesh.gif
Mesh with boundary conditions for one of the models
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geom.gif
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
Tingler8-8.jpg
Equation 8.8
Tingler8-9.jpg
Equation 8.9
Tingler8-10.jpg
Equation 8.10
HISTORY/INTRODUCTION
by Widas
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widas1.jpg
Figure 1 from http://www.noraneng.com
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widas2.jpg
Mesh diagram of a van
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widas3.jpg
Figure 3 from http://umass.edu/mie/labs/mda/fea/fealib/goldstein/PROJECT.html
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widas4.jpg
Non-linear model of a bicycle frame
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widas5.jpg
Fatigue analysis of a train
EXPERIMENTAL
DUCTILE FRACTURE
by Bailey
All images scanned by T. Schmierer
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bailey1.jpg
A tensile stess-strain curve
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bailey2.jpg
A scanning electron fractograph of ductile cast iron, examining a transgranular fracture surface
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bailey3.jpg
Figure showing the macroscopic differences between two ductile specimens(a,b)
and the brittle specimen (c)
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bailey4.jpg
Figure demonstrating the microscopic qualities of ductile fracture surfaces
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bailey5.jpg
Figure demonstrating the microscopic qualities of ductile fracture surfaces
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bailey6.jpg
Sheared aluminium specimen showing cup and cone, and brittle fracture
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bailey7.jpg
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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chevrons.gif
Chevron fracture surface
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intergran.gif
Diagram showing intergranular fracture
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radiate.gif
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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cf-1.gif
Graph showing aluminum oxide's modulus of elasticity as a function of porosity
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cf-2.gif
Graph showingaluminum oxide's modulus of rupture as a function of porosity
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cf-3.gif
Diagram of a ceramic material before sintering
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Diagram of a ceramic material during sintering
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cf-5.gif
Diagram of a ceramic material after sintering
pe-1.jpg
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
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rf-1.gif
Figure showing the tenile and compressive stress on tempered glass
se-1.jpg
Equation for factor of safety
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sf-1.gif
A poor design that will create a stree concentration
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sf-2.gif
A good design that will minimise stress concentration
te-1.jpg
Equation for the minimum thickness of material before plane strain behavior occurs
te-2.jpg
Equation for the fracture toughness of a material with a thickness less than B
te-3.jpg
Equation for the fracture toughness of a material with a thickness equal to or greater than B;
when it fractures in mode I
te-4.jpg
Equation for the critical applied stress required to cause failure in a material
te-5.jpg
Equation for the critical crack length required to cause failure in a material
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tf-2.gif
Diagram of a mode I fracture
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tf-3.gif
Diagram of a mode II fracture
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Diagram of a mode III fracture
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Graph showing composite performance in relation to stress alignment
FRACTOGRAPHY
by Halahan and Mutter
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clev1.jpg
Stainless steel showing transgranular cleavage
Scanned by M. Gallagher
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clev2.jpg
TiB2 showing cleavage
Scanned by M. Gallager
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clev3.jpg
Ni base alloy showing cleavage
Scanned by M. Gallagher
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clev4.jpg
Silicon carbide showing small cleavage
Scanned by M. Gallagher
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cohesive1.jpg
Obvious decohesion
Scanned by R. Halahan
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Stainless steel showing hydrogen embrittlement
Scanned by R. Halahan
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cohesive3.jpg
Stainless steel showing decohesive rupture
Scanned by M. Gallagher
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cohesive4.jpg
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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Gray cast iron with sulfate deposites
Scanned by R. Halahan
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fatig1.jpg
Nickel based alloy with fatigue striations
Scanned by M. Gallagher
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fatig2.jpg
Enlarged picture of fatig1.jpg
Scanned by M. Gallagher
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fatig3.jpg
Nickel based alloy with jagged fatigue striations
Scanned by M. Gallagher
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fatig4.jpg
Titanium alloy with fatigue striations
Scanned by M. Gallagher
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void1.jpg
High carbon steel with an elongated dimple
Scanned by M. Gallagher
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void2.jpg
AISI 10B21 Steel with well defined microvoid coalescence
Scanned by M. Gallagher
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void3.jpg
Aluminum alloy with microvoids
Scanned by M. Gallagher
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void4.jpg
Titanium alloy with equiaxed and elongated dimples
Scanned by M. Gallagher
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void5.jpg
Nitralloy 135 M with microvoid coalescence
Scanned by M. Gallagher
FRACTURE TOUGHNESS
by McMurtry
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fig1.jpg
A specimen with an internal crack
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fig2.jpg
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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fig5.jpg
Three modes of crack surface displacement
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Two ASTM standard compact specimen of different b sizes
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fig7.jpg
Graph of fracture toughness vs. temperature for different steels
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fig8.jpg
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)