Intro Flashcards Preview

Tissue Biomechanics > Intro > Flashcards

Flashcards in Intro Deck (29)
Loading flashcards...
1
Q

The amount of force on an object

A

Load

2
Q

Load divided by the cross sectional area

A

Stress

Ex: stepping on a foot in flat shoes vs high heels

3
Q

A change in length in response to a a load

A

Deformation

4
Q

The amount of deformation - change in length divided by the original length

A

Strain

5
Q

Shear strain is the angle of deformation expressed in _____

A

Radians

6
Q

The ability of a substance or material to return to its original form following the removal of a deforming load With no loss of energy.

A

Elasticity

7
Q

The property of a material to permanently deform if loaded beyond its elastic range - original form is lost and material energy is lost.

A

Plasticity

8
Q

A measure of resistance offered to external loads by a material as it deforms.

A

Stiffness = the amount of stress (load)/the amount of strain (deformation)

9
Q

A stiffer material needs _____ stress to

deform

A

MORE

10
Q

A measure of compliance offered to external loads by a material as it deforms.

A

Flexibility = the amount of strain (deformation)/the amount of stress (load)

11
Q

A flexible material needs _______ stress to

deform

A

LESS

12
Q

The quality whereby a material exhibits little plastic deformation before FAILURE.

A

Brittleness

FAILURE < 5% total elongation of
material

13
Q

The quality whereby a material exhibits large plastic deformation before FAILURE.

A

Ductility

FAILURE > 5% total elongation of
material

14
Q

The property of a material that links how it will deform to how the load is applied.

A

Viscoelasticity

15
Q

A viscoelastic material will deform differently depending on what (4) properties of loading?

A
  • rate of loading
  • speed
  • quantity
  • duration
16
Q

How does the term stiffness differ when used in biomechanical terms vs. rheumatologic terms?

A

Biomechanical stiffness can be good (bones are stiff and spinal stiffness = stability)
Rheumatologic stiffness is a symptom that suggests inflammation

17
Q

Material can respond in a variety of characteristic ways

A
  • creep
  • relaxation
  • hysteresis
  • fatigue
  • damping
  • thixotropy
18
Q

A deformation of a viscoelastic material

with time, when the load remains constant.

A

Creep

Ex: Disc loss of height during the day. (Creep is
much faster with a degenerated disc.)
Ex: shortening of muscles (hip flexors) with prolonged sitting

19
Q

Tissue adapting to newl unethical such that a decrease of load over time is required to maintain a fixed deformation.

A

Relaxation

Ex: Force needed to hold down the branch of a
tree decreases over time

20
Q

Loss of energy during a loading cycle, despite returning to its original form.

A

Hysteresis

21
Q

The process of plastic deformation or failure of a material from repeated loading.

A

Fatigue

Ex: Bending a paper clip repeatedly until failure.

22
Q

Resistance to speed, i.e. the faster the loading, the greater the load
necessary to deform an object a given amount.

A

Damping

Ex: Disc compression: Slow loading causes fluid to come out,
squishes or deflates. Fast loading - fluid can’t come out, good shock
absorber

23
Q

The reduction in the viscosity of a fluid

following movements

A

Thixotropy

Ex: ketchup, synovial fluid, muscles

24
Q

The turnover of collagen is accelerated when?

A
  • in young/growing
  • in injured tissue
  • in immobilized tissue
26
Q

What are the 5 types of injuries?

A

1- high load (single trauma)
2 - repetitive loads (end range)
3 - sustained loads (end range) e.g. postural syndromes
4 - sudden unguarded moment
5 - normal activity coupled with failure of segmental coordination (especially unstable joint)

27
Q

3 type of loads

A

Tensile
Compression
Shear

28
Q

Example of tensile load vs compressive load

A

Pulling on a patients neck vs pressing down on their head

Both tensile and compression strain are measured by the % length change (and for comparison: shear strain is the angle of deformation in radians)

29
Q

What are 5 types/modes of injury?

A
  • high load (single traumatic event)
  • repetitive load (end range)
  • sustained load (end range, postural syndromes)
  • sudden unguarded movement
  • normal activity couples with a failure of segmental coordination, especially in unstable joint
30
Q

What are the factors that affect how a viscoelastic material will deform?

A
  • rate of loading
  • speed of loading
  • quantity of loading
  • duration of loading