Biomechanics Exam One Flashcards

1
Q

Stress (σ)

A

Force applied to an area
Measured in N/m^2 or pascals
σ = F/A

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2
Q

Strain (ε)

A

Deformation caused by applied stress

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3
Q

Tension

A

the act or action of stretching

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4
Q

Compression

A

the state of being compressed

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5
Q

Shear

A

unaligned forces acting on one part of a body in a specific direction, and another part of the body in the opposite direction.

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6
Q

Torsion

A

the twisting of an object due to an applied torque.

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7
Q

Bending

A

to turn or force from straight or even to curved or angular.

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8
Q

Stress/Strain Curve

A

Slope is Young’s Modulus/Stiffness
Elastic region which can go back to how the object was once stress is removed
After elastic region is yield point before plastic region
Plastic region is permanent deformation
After the plastic region the specimen fails
a type of test where a load is continuously applied to a test specimen until it fractures

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9
Q

Young’s modulus

A

Stiffness for material
Y=σ/ε=F/A=L/ ∆L

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10
Q

Residual Strain

A

Difference between original length and length resulting from stress into the plastic region

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11
Q

Stiffness

A

Resistance to deformation

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12
Q

Strength

A

Resistance to failure
expressed as force required to produce:
a permanent deformation: yield strength
a fracture: fracture strength

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13
Q

Metal vs glass

A

Metal: ductile-large plastic region
Glass: brittle-fracture and yield at the same time

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14
Q

Elastic material

A

Linear between stress and strain
Mechanical energy is fully recovered (provided it stays in elastic region)

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15
Q

Viscoelastic

A

Same definitions for elastic materials apply
Exhibits non-linear stress strain characteristics
Ex. Bone. Has these characteristics because of the liquid in bone

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16
Q

Hysteris

A

Loss of energy into the material and time dependent delay

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17
Q

Stress relaxation

A

Time dependent decrease in load or force or stress required to maintain a constant deformation
The deformation is temporary until the stress is removed

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18
Q

Creep

A

Time dependent increase in deformation while under constant load/force/stress

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19
Q

Bone tissue

A

connective tissue

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20
Q

short bones

A

square, triangular shape

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21
Q

Flat bones

A

flat
scapula, skull

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22
Q

irregular bones

A

irregular in shape

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23
Q

Long bones

A

has one dimension longer than another dimension

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24
Q

facet

A

small, smooth area

25
Q

foramen

A

a hole in a bone
For blood vessels/nerves to attach to it

26
Q

Condyle

A

rounded process
Articulates with other bone to form a joint

27
Q

Fossa

A

A large smooth area

28
Q

Process

A

Bony promiscue
Does not have clearly distinct role

29
Q

Tuberosity

A

Like a process but has a very specific process

30
Q

Regions of long bone

A

Diaphysis
Metaphysis

31
Q

diaphysis

A

shaft of long bone
ends are epiphysis

32
Q

metaphysis

A

two areas in-between diaphysis and the epiphysis

33
Q

Compact bone

A

hallow center
is arranged in units called osteons

34
Q

osteons

A

are aligned by lines of stress
not cells! Units!

35
Q

periosteum

A

outside layer of bone
dense irregular CT

36
Q

what is the compact bone made out of

A

osteons
Is the periosteum

37
Q

endosteum

A

inner most layer of bone

38
Q

central canal

A

space in center of osteons
space for blood vessels and nerves

39
Q

what is the primary stress for bones?

A

Compressive stress

40
Q

concentric lamellae

A

rings around central canal

41
Q

Lucnae (lucuna is one)

A

one type of bone cell resides

42
Q

Canaliculi

A

connects lucnae to allow communication between cells

43
Q

Histology of bone

A

20% water
30% collagen fibers
50% mineral salts –> calcium phosphate

44
Q

spongy bone or cancellous bone or trabecular bone tissue

A

consists of red and yellow bone marrow
osteocytes get nutrients directly from circulating blood

45
Q

osteocytes

A

bone cell
retired
maintain and no other role
before retirement they are osteoblasts

46
Q

osteoblasts

A

produce collagen fibers

47
Q

osteogenic

A

mitotically active
help make more cells

48
Q

osteoclast

A

break down bone
could be for nutrition
ex. If there is low Ca2+ in the blood, the body will break down bone tissue in order for the heart to function

49
Q

How does bone ocify?

A

Bone oficies from middle to ends
replaces cartilage to bone

50
Q

Wolff’s law

A

shape of bone reflects its function
Bone is laid down where needed and reabsorbed where not needed
Regular exercise provides stimulation to maintain bone throughout the body

51
Q

Which bone is more adaptive, trabecular or cortical?

A

Trabecular because it is less stiff than cortical bone
Cortical bone is more stiff than trabecular
Cortical does well under compression dur to gravity

52
Q

Viscoelastic load vs deformation graph

A

A fast, higher load is going to cause more deformation and when it fails will have a bad fracture
A slow, lower load is going to make a stress fracture and it will be tiny in comparison with the fast, higher load

53
Q

What forces are involved with bending?

A

compression, tension, shear

54
Q

Compression forces

A

necessary force for proper development
Stiffness of bone resists compression
excessive compression force can lead to compression fractures

55
Q

Tensile loading rate

A

Main source is muscle contraction

56
Q

Avulsion fracture

A

occurs when a ligament or other soft tissue attachment to bone overcomes the stress capacity of the bony attachment and tears off a portion of the bone.

57
Q

Osgood-Schlatter’s

A

pulling of the patellar tendon away from its insertion point on the tibial tuberosity
When tendon is pulled it can cause mini fractures around the tibial tuberosity
an overuse condition or injury of the knee that causes a painful bump and swelling on the shinbone below the knee
Typically affects growing kids

58
Q

anisotropic

A

Properties depend on direction
exhibiting properties with different values when measured in different directions
Bone is strongest and stiffest in the direction that bears the most load, while keeping bone mass low.
Bone’s elastic deformation is anisotropic, meaning it’s different when measured parallel to the bone’s long axis, and when measured perpendicular to it.
Trabecular bone’s orientation can change depending on mechanical load, and it can become anisotropic.