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49 Cards in this Set
- Front
- Back
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What is structural behavior? |
Global response depending on size, shape, number of components, their organization, and their material properties |
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What is material behavior? |
Intrinsic properties of a material independent of size and shape (colligative properties) |
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What does load mean in the context of biomechanics? |
force |
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What is deformation in the context of biomechanics? |
change in length |
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What is stiffness in the context of biomechanics? |
resistance to deformation |
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What is failure load in biomechanics? |
Force required to fracture a material |
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What is stress in biomechanics? |
Force / Area = Stress |
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What is strain in biomechanics? |
Deformation / Length = Strain |
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What is the modulus in biomechanics? |
Stiffness / geometry = modulus |
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What is strength in biomechanics? |
The ultimate amount of force a material can withstand before fracturing |
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In what direction is a shear force to a surface of an object? |
Parallel to the surface |
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What is eccentric loading on an object? |
Applying a force to just one side of the object |
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What is axial loading? |
Applying a force along the lines of an axis as in compression. |
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What is elastic behavior? |
material returns to original state after being loaded |
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What is plastic behavior? |
material is permanently altered after being loaded |
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What is viscoelastic behavior? |
Behavior of the material depends on the rate at which a force is applied |
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What is a monotonic load? |
Apply a load and increase the force until it breaks |
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What is fatigue? |
load applied cyclically until material breaks |
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What is creep? |
constant load applied over time until material either equilibrates or fails |
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Which of the following terms relates to a structural property?
(b) strain (c) stiffness (d) strength (e) modulus |
(c) stiffness |
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What equation denotes stress? |
Force / Area = Stress
(in N/m^2 or Pascals) |
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What equation denotes strain?
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dL/L = strain (dL = change in length) |
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What is Young's modulus?
What does it mean? |
Stress/Strain = Modulus
It is the ability to resist deformation |
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What is the Yield point of a material? |
The point at which a material transitions from elastic to plastic deformation.
(also called proportional limit) |
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What is the ultimate strength? |
The maximum strength obtained by a material before failure |
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What does the area under the plastic deformation region of a curve signify? |
Plastic deformation - change in length after removing the load |
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What is all the area under the stress/strain curve signify? |
Strain energy: capacity of a material to absorb energy |
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How is modulus determined in a stress vs strain graph? |
It is the slope |
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What stress to failure ratio does a strong material have? |
High (sharp slope) |
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What is resilience? |
Material's ability to absorb energy without permanent (plastic) deformation
(area under the elastic part of the curve) |
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What is toughness? |
Material's capacity to undergo plastic deformation
(area under the plastic region of the curve) |
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If the strain rate (speed at which force is applied) is high for a viscoelastic material, how will this affect its modulus and resilience? |
Higher modulus, lower resilience (bc it will break) |
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A material's modulus of elasticity: (a) is a structural property (b) is the capacity of a material to absorb energy (c) can be compressive or tensile (d) is the slope in the elastic range of the stress-strain curve (e) changes with the direction of the force |
D |
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Resilience is... (a) A material's ability to absorb energy without plastic deformation (b) The area under a stress-strain curve in the plastic region (c) A material's ability to absorb energy with plastic deformation (d) The total area under the stress-strain curve |
A |
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What is an isotropic material? |
It has the same mechanical properties no matter how that material is loaded (compression, tension, and shear) |
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A viscoelastic material...
(a) Has a higher modulus with a lower strain rate (b) Is less elastic at a higher strain rate (c) is more elastic at a higher strain rate (d) is ductile when tension is applied |
B |
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What determines bending stiffness in a rectangular structure? |
The height
(rigidity depends on height cubed) |
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How is radius of an object affect rigidity |
Rigidity is proportional to the fourth power of the radius |
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Of what materials is bone a composite structure? (3) |
Collagen, water, and calcium hydroxyapatite |
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How does the angle of a loaded force affect the modulus of bone? |
The modulus increases the more parallel the load is.
(Cannot be easily compressed but very weak in shear and torsion) |
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What kind of fracture is caused by tension force? |
transverse fracture |
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What kind of fracture is applied by compression force? |
Oblique fracture |
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What kind of fracture is caused by bending force? |
Butterfly fracture |
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What kind of fracture is caused by torsion force? |
Spiral fracture |
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On what side of a butterfly fracture are 2 breaks? (compression side or tension side?) |
Compression side |
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Tubular bones demonstrate different types of fracture patterns that differ with the applied load; this is referred to as... (a) Viscoelasticity (b) Young's modulus (c) Load-deformation curve (d) Anisotropy |
D |
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What are joint reactive forces? |
Forces generated in a joint due to external forces |
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What is joint congruence? |
Fit of articular surfaces
(Less contact area leads to degeneration) |
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How does a patient reduce the load weight on a hip joint? |
Move the center of gravity over it by leaning when they walk |
