9. SIMPLE HARMONIC MOTION (SHM) (PART 2) Flashcards

1
Q
  1. Are many biological materials anisotropic or isotropic?
    Give 2 examples.
A
  • they are anisotropic

EG: oesophagus, small intestine

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2
Q
  1. Which bones in the body are most resistant to any form of stretching?
A
  • the bones in the leg
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3
Q
  1. Which formula for stress (σ) is valid until the stress reaches its maximum capacity before a fracture occurs?
A
  • σ = Yε
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4
Q
  1. What is the Ultimate Compressive Stress (UCS)?
A
  • it is the amount of stress a bone can withstand before it fractures
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5
Q
  1. What is the ultimate compressive stress for a compact bone?
A
  • 170 MPa
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6
Q
  1. How do we work out how much the bone has shortened by?
A
  • ▵L = σ. L original / Y
  • ▵L = change in length
  • σ= stress
  • Lo/Loriginal= the original length of the bone before
    the applied stress
  • Y = Young’s Modulus
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7
Q
  1. Up until when is the Hookean Stress- Strain relation valid in tension and compression?

Hookean Stress- Strain: Y = σ/ε

A
  • it is valid up until a limiting stress
  • this is where a fracture happens
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8
Q
  1. Up until which point is there Elastic Hookean Behaviour?
A
  • up until Point P
  • this is the Proportional limit
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9
Q
  1. What can be said about the slope up until Point P?
A
  • it is constant
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10
Q
  1. What happens at higher stresses?
A
  • the stress-strain relationship becomes nonlinear
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11
Q
  1. What can the object do up until the elastic limit?
A
  • the object an return to its initial length when the stress is removed
  • it does no go through deformation
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12
Q
  1. What happens for stresses beyond the elastic limit?
A
  • there is permanent or plastic deformation
  • this is irreversible
  • the object can no longer return to its initial length after the stress has been removed
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13
Q
  1. What is the yield point?
A
  • it is a stress higher than the elastic limit
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14
Q
  1. What can occur after the Yield point?
A
  • much elongation can occur
  • without much increase in the load
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15
Q
  1. What can the material do up until the Ultimate Tensile Stress (UTS)?
A
  • the material can remain intact for larger stresses up until this point
  • the larger the breaking point:
    - the stronger the material
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16
Q
  1. What does the application of stress result in at point F?
A
  • a fracture in the material/object
  • this occurs at a strain called the Ultimate Strain
  • this is also known as the Ultimate Percent Elongation (UPE)
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17
Q
  1. Why do the stress -strain relations look qualitatively different for ceramics, metals and elastomers?
A
  • each of these has very different microscopic structures
  • they have different Young Moduli
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18
Q
  1. What kind of stress-strain relationship do ceramics have?
A
  • they have a linear stress-strain relationship
  • it has a large Young Modulus slope
  • this means it is a tough material
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19
Q
  1. What can be said about the fracture point of ceramics?
A
  • it appears only a little into the nonlinear elastic region
  • it appears for smaller values of strain
    (values less than 0.1)
20
Q
  1. Is bone similar to ceramic?
A
  • yes
21
Q
  1. What can be said about the properties of metals?
A
  • they have a smaller Young Modulus
  • they are less tough than ceramics
  • they have a larger non-elastic and plastic region
  • they have a larger Ultimate Percent Elongation
22
Q
  1. What can be said about the properties of elastomers?
A
  • they distort greatly
  • even when small stresses are placed on them
  • it takes much larger stresses to increase the strain further after a certain point
  • they have a very large ultimate percent elongation
    ( it is usually greater than 1)
23
Q
  1. What are some examples of Elastomers?
A
  • rubber, polymers, blood vessels
24
Q
  1. What can be said about the plastic deformation phase of ductile materials?
A
  • it is extensive
25
Q
  1. Give 4 examples of ductile metals?
A
  • modelling clay
  • chewing gum
  • plastic
  • most metals
26
Q
  1. What can be said about the plastic deformation phase of brittle materials?
A
  • they have a limited or essentially no plastic phase
27
Q
  1. What are 5 examples of brittle materials?
A
  • glass
  • ceramics
  • cast iron
  • bone
  • teeth
28
Q
  1. What resists tension in cartilage?
A
  • solid components
29
Q
  1. What resists compression in cartilage?
A
  • solid and liquid components
30
Q
  1. In ligaments and tendons, is there resistance to both tension and compression?
A
  • no
  • there is only resistance to tension
31
Q
  1. Where do fractures occur?
A
  • at the ultimate compressive stress (UCS)
  • this is different from the Ultimate Tensile Stress
32
Q
  1. What does compact bone (cortical/dense bone) have with regards to its Young’s Modulus?

What does this mean with regards to resistance to compression and tension?

A
  • it has a large Young’s Modulus
  • this is comparable to that of other strong materials
  • it can withstand more stress in compression than in tension
33
Q
  1. What can be said about the Young’s Modulus of spongy or cancellous bone?
A
  • it is more porous
  • it has a very small Young’s Modulus
34
Q
  1. Which aspects of the human body are hard materials with similar stress-strain curves that are ceramic like?
A
  • bones
  • teeth
  • nails
35
Q
  1. Which aspects of the human body have more elastomer like properties?
A
  • tendons
  • cartilage
  • resting muscles
  • skin
  • arteries
  • intestines
36
Q
  1. Name 6 body materials that cannot be modelled as Hookean springs?
A
  • collagenous tissues
  • tendons
  • mesentery
    (the folds attached to intestines and the dorsal
    abdomen)
  • sclera
  • cartilage
  • resting skeletal muscles
37
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
38
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
39
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  1. Read through this summary.
    Does everything make sense?
A
  • yes
40
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
41
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
42
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
43
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
44
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
45
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
46
Q
  1. Read through the summary.
    Does everything make sense?
A
  • yes