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
img1.jpg
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
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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
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
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Equation showing the tensile strength of a discontinous
fiber composite with fiber length greater than lc
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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.mpg and 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)
