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22 Cards in this Set
- Front
- Back
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Where is the center of gravity located at the level of the pelvis in the sagittal plane?
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Anterior to the body of S2
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What is the principal determinant of the magnitude of the JRF (joint
reaction force)? |
Muscle activity around the joint
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Define stress and strain
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Stress = force/area (measure of internal strain)
Strain = change in length/original length (measure of deformability) |
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How is strain energy represented on the stress-strain diagram?
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Area under the curve
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Strain energy is a measure of what material property?
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Toughness
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What is the definition of toughness?
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Ability of a material to absorb energy before it fails
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What is the definition of stiffness?
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Resistance of a material to deformation from an applied load
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Compare the stress-strain curve appearances of brittle and ductile materials.
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Brittle materials have linearly perfect stress-strain curves; no plastic deformation
Ductile materials allow for a large amount of plastic deformation |
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If cortical bone is the midline, working away from the midline in the direction of increasing elastic modulus are what four materials?
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Titanium
Stainless steel Cobalt chrome Ceramic/alumina |
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Working away from the midline in the direction of decreasing elastic modulus are what three materials?
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Polymethylmethacrylate
Polyethylene Cancellous bone |
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What is the definition of fatigue failure?
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Failure after many cycles of repetitive submaximal load
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Fatigue failure will never occur if what condition is met?
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Force is below the endurance limit of the material
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As the strain rate increases, viscoelastic materials become more what?
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Stiff (higher elastic modulus)
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What is the definition of hysteresis?
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Hysteresis refers to energy dissipation such that unloading and loading does not follow the same path
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Stress relaxation of a liquid is essentially the same as what?
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Creep
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What formula determines the bending rigidity of a rectangle?
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Base * height3
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What formula determines the bending rigidity of a cylinder?
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Radius4
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The area moment of inertia is a measure of what?
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Resistance to bending
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What is the mass moment of inertia?
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Measures resistance to rotation
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What is the polar moment of inertia?
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Measures resistance to torsion
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Pitting and crevice corrosion are most likely with what material?
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316L stainless steel is most likely to be associated with pitting and crevice corrosion
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There is a classically increased risk of galvanic corrosion between what two metals?
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316L stainless steel cobalt chrome
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