Kinesiology- Biomechanics Of Soft Tissue- Part 2

Front 1

Normal Force

Back 1

Normal force-force applied perpendicular to a surface of, or plane whithin an, object

(or you can have a normal axial force, or normal axial compression force)

Front 2

Axial force

Back 2

Axial force- force applied along a long axis

(or you can have a normal axial force, or normal axial compression force)

Front 3

Compression

Back 3

compression- pressing together

(or you can have a normal axial force, or normal axial compression force)

Front 4

Tension

Back 4

tension-stretching or pulling an object apart

Front 5

bending

Back 5

bending- loading a structure at an area where there is no direct support

Front 6

torsion-

Back 6

torsion-twisting an object

Front 7

shear force

Back 7

shear force- force applied parallel to the surface of, or along a plane within, the object

Front 8

stress

Back 8

stress- intermolecular resistance within an object to the deforming action of an outside force

sigma

Front 9

strain

Back 9

strain- measure of deformation, describing the change in the dimension of an object as a result of an outside force

epsilon symbol is used

Front 10

Compression stress and strain

Back 10

compression stress and strain
-object tends to shorten and widen
-stress and strain within the object
-also produces shear forces

Front 11

Tension stress and strain

Back 11

tension stress and strain

object tends to narrow and elongate
-stress and strain within the object
-also produces shear forces

Front 12

bending stress and strain

Back 12

bending stress and strain
-compression on concave side
-tension on convex side
-no forces at central axis

Front 13

Torsion Stress and Strain

Back 13

Torsion Stress and Strain
-shear over entire object, perpendicular to axis of rotation

-compression and tension on diagonal to axis of rotation

(can have shear, compression and tension)

Front 14

Force

Back 14

Force-action that tends to change the shape, size, or state of inertia or motion of an object

Front 15

load

Back 15

load- force external to an object

Front 16

load and deformation

look at load deformation curve p. 28 in biomech. soft tissue

Back 16

load deformation curve:
-applicable to a single object
-not applicable to a type of material

example: you would used this to study a single tendon

Front 17

Load Deformation Curve: Elastic Region

Back 17

Load Deformation Curve: Elastic Region
-straight line
-slope indicates stiffness

(deformation occurs but when load is released the object returns to its original shape)

elastic=temporary deformation

Front 18

Load Deformation Curve: Plastic Region

Back 18

Load Deformation Curve: Plastic region
-permanent deformation

-when load is released object returns to new shape-perminent deformation of the object

plastic=permanent deformation

some return of shape is parallel to plastic point of deformation.
-rebounds a little, once load is resolved-->measure the permanent deformation parallel to elastic line.

Front 19

Load Deformation Curve: components

Back 19

Load Deformation Curve: components

Elastic region
yield point
plastic region
failure

Front 20

Stress and Strain: Stress-Strain Curve

Back 20

Stress and Strain: Stress-Strain Curve

-applicable to a type of material
-represents mechanical behavior of a material
-provides standardization of testing conditions and size and shape of specimens

Front 21

Stress and Strain: Stress-Strain Curve

Stress

Back 21

Stress and Strain: Stress-Strain Curve

Stress: load divided by cross-sectional area of material

Front 22

Stress and Strain: Stress-Strain Curve

Strain

Back 22

Stress and Strain: Stress-Strain Curve

Strain: deformation divided by original length of material

Front 23

Stress and Strain: Stress-Strain Curve

Demonstrates

Back 23

Stress and Strain: Stress-Strain Curve

demonstrates
-degree of stiffness of material
--resistance offered to deformation
--slope of elastic region

-strength of material
--ultimate failure point

-energy
--area under the curve
--energy is released at failure

Front 24

Stress and Strain: Stress-Strain Curve

Material properties

Back 24

Stress and Strain: Stress-Strain Curve

material properties: response to load varies over time
elasticity- large elastic region
----------returns to original form following large stress

plasticity- small elastic regions
-----------material is permanently deformed with light stress

Front 25

ductility

Back 25

ductility-large plastic region
-----large amount of deformation before failure

Front 26

Stress and Strain: Stress-Strain Curve

Material properties- pasticity

Back 26

plasticity- small elastic regions
-----------material is permanently deformed with light stress

Front 27

Stress and Strain: Stress-Strain Curve

Material properties-elasticity

Back 27

elasticity- large elastic region
----------returns to original form following large stress

Front 28

Brittleness- stress and strain

Back 28

brittleness- small plastic region
---minimal deformation before failure

Front 29

Material properties-
Viscoelasticity

Back 29

Material properties- Viscoelasticity

-a material's variable response to a constant load or a constant deformation
-------relaxation
----------decrease in stress under constant deformation

-------creep
-------------increase in strain constant load; progressive deformation over time, constant load on strain-time curve

Front 30

Stress and Strain-
Relaxation

Back 30

Relaxation- decrease in stress under constant deformation

Stress-time curve- stress decreases over time; constant deformation

(decrease in resistance to deformation under constant deformation. resistance to being deformed goes away)

example: serial casting-constant load into deformation

serial casting the leg provides resistance on the back of the knee cap-->leads to more motion

Front 31

Material properties: Viscosity

Back 31

Material properties: Viscosity- delay in strain under stress

-material does not deform immediately

--depends on rate loading

Front 32

Stress and Strain-
Resilience

Back 32

Resilience- ability of an object to rebound from a surface of from another object

-quick return to original shape-bouncy ball

Front 33

damping

Back 33

damping-opposite of resiliance
-slow return to original shape

Front 34

Material properties- Necking

Back 34

Material properties- necking
-decrease in cross-sectional area as material lengthens during tensile deformation

-distinct area that becomes narrower
-not all materials have this.
-decrease in cross sectional area will absorb some of the force

Front 35

Material properties- hysteresis

Back 35

material properties- hysteresis-

energy loss during repetitive cycles of loading and unloading
--clinically-several oscillations to heat up joint followed immediately by sustained stretch

-in soft tissue this release of energy is in the form of heat.

Front 36

Load deformation curve- yield point

Back 36

Yield point-

elastic -->plastic

Front 37

Stress and strain-

creep

Back 37

increase in strain under constant load

strain-time curve
-progressive deformation over time
-constant load
-constant push that follows deformation into new deformation