chapter 9

Question 1

mechanical responses of structures are related to

Answer 1

injury

Question 2

when external forces imposed are resisted by internal forces it causes

Answer 2

deformation of the body

Question 3

external applied load: stress
deformation caused: ___

Answer 3

strain

Question 4

mechanical stress

Answer 4

how an applied force is distributed over the body it acts on

Question 5

cross-sectional area: the force is the resultant of the

Answer 5

intermolecular bond forces

Question 6

the cross-sectional area of the imaginary plane is the area over which ____ force is applied

Answer 6

internal

Question 7

3 principal stresses depending on applied loading

Answer 7

tension, compression, shear

Question 8

axial stress

Answer 8

external forces act perpendicular to the analysis plane

Question 9

uniaxial load

Answer 9

external forces are colinear

Question 10

tensile stress occurs at the _____ as a result of a force or load pulling the molecules apart at that plane

Answer 10

analysis plane

Question 11

tension causes body to deform by

Answer 11

stretching (elongating)

Question 12

bone cross-sectional area depends on

Answer 12

plane of analysis

Question 13

larger cross-sectional area=___stress

Answer 13

lower

Question 14

smaller cross-sectional area=___stress

Answer 14

higher

Question 15

cross sectional area: 1cm^2
tensile force applied: 700,000N
what is the max tensile stress

Answer 15

7GPa

Question 16

compressive stress occurs at the analysis plane as a result of ______ at that plane

Answer 16

a load squeezing the molecules together at that plane

Question 17

compression causes body to deform by shortening or elongating

Answer 17

shortening

Question 18

shear stress is a ____ stress

Answer 18

transverse

Question 19

shear stress acts parallel to____as a result of non-collinear forces sliding molecules at that plane

Answer 19

analysis plane

Question 20

sprains are in ____
strains are in ____

Answer 20

ligaments/tendons
muscle/cartilage

Question 21

compression is

Answer 21

bruises of soft tissue, crushing fracture of bone

Question 22

shear is

Answer 22

blisters on skin, joint dislocation

Question 23

when external forces are not uniaxial more complex loading occurs as (3)

Answer 23

bending, torsion, combined loads

Question 24

complexity of loading reflects ___, ___ and ___ of external forces imposed

Answer 24

number, direction and location

Question 25

bending load

Answer 25

nonaxial tension and compression produced at the analysis plane from 3 or more forces creating force couples at opposite ends of the object

Question 26

bending loads cause the body to deform by

Answer 26

curving

Question 27

torsion load

Answer 27

nonaxial shear stress acts parallel to the analysis plane as a result of opposing torques applied about the long axis of the body

Question 28

torsion causes body to deform by

Answer 28

twisting

Question 29

what resists torsion

Answer 29

tubular and hollow cross-section of bone

Question 30

combined loading

Answer 30

bones under complex loading from gravity, tendons ligament and other bones, contact forces

Question 31

sustained loading a combination of

Answer 31

tension, compression, simple shear loads, bending, torsion

Question 32

strain quantifies the materials ____

Answer 32

deformation

Question 33

linear strain

Answer 33

change in an objects length

Question 34

linear strain produced by

Answer 34

tensile or compressive stress

Question 35

change in orientation of an objects molecules

Answer 35

shear strain

Question 36

shear strain produced by

Answer 36

shear stress

Question 37

liner strain deformation by

Answer 37

tensile or compressive stress (change in length)

Question 38

linear strain reported in ____ terms, describing change in length

Answer 38

absolute

Question 39

linear strain reported in ____ as proportional length change

Answer 39

relative

Question 40

unit of linear strain

Answer 40

dimensionless; is a ratio

Question 41

poissons ratio

Answer 41

width of an object also changes as it lengthens or shortens

Question 42

poissons ratio range

Answer 42

.1 to .5

Question 43

stress-strain relationship describes

Answer 43

behavior of material under load

Question 44

elastic behavior

Answer 44

material deforms and returns to original length when unloaded

Question 45

plastic behavior

Answer 45

material deforms but doesn't return to original length permanent deformation

Question 46

slope of the stress-strain curve

Answer 46

elastic modulus

Question 47

stiff material: ___ strain per unit of stress (___ E)

Answer 47

less, large

Question 48

pliant material: ___ strain per unit of stress (___ E)

Answer 48

more, low

Question 49

elastic limit

Answer 49

the yield point for a material on the o/e curve

Question 50

stress above the elastic limit causes

Answer 50

permanent deformatin

Question 51

example of plastic behavior

Answer 51

ankle sprain; ligaments get stretched and dont hold the bones together as closely as they once did

Question 52

mechanical strength of a material

Answer 52

max stress a material can withstand before failure

Question 53

yield strength

Answer 53

stress at the elastic limit disruption of internal organization

Question 54

max stress material can withhold material starts to give away

Answer 54

ultimate strength

Question 55

stress level where total failure occurs breakage or complete rupture of materialfailure strength

Answer 55

failure strength

Question 56

strain exhibited when ____ occurs

Answer 56

total failure

Question 57

ductile material exhibits a ____ failure strain

Answer 57

large

Question 58

brittle material

Answer 58

exhibits a low failure strain deforms minimally before giving away

Question 59

toughness

Answer 59

ability of a material to absorb energy before failure

Question 60

are bones or ligaments/tendons tougher

Answer 60

ligaments/tendons

Question 61

active element of connective tissue

Answer 61

muscle

Question 62

passive elements of connective tissue

Answer 62

bone, cartilage, ligament, tendon

Question 63

____ is very stiff while ___ is pliant

Answer 63

collagen, elastin

Question 64

failure strain of collagen

Answer 64

8-10%

Question 65

failure strain of elastin up to ___%

Answer 65

160

Question 66

isotropic

Answer 66

stiffness similar in different directions

Question 67

stiffness dependent on load direction

Answer 67

ansiotropic

Question 68

bone: ___% mineral, ____% collagen, ___% water

Answer 68

45, 30-35, 20

Question 69

strongest and stiffest material in musculoskeletal system

Answer 69

bone

Question 70

bone strength affected by rate of

Answer 70

loading

Question 71

cartilage: ___% water, ___%collagen

Answer 71

60-80, 10-30

Question 72

what cartilage covers bone ends at joints

Answer 72

hyaline (articular) cartilage

Question 73

fibrous connective tissue specialized in

Answer 73

joints

Question 74

tendons and ligaments: ___% water, ___%collagen

Answer 74

70, 25

Question 75

do ligaments or tendons have more elastin

Answer 75

ligaments

Question 76

what determines muscle stiffness

Answer 76

active component, sarcomere

Question 77

tendons and ligaments collagen fibers in bindles aligned with

Answer 77

functional axis