Stress Analysis

Question 1

Name 5 ways a material can be stressed?

Answer 1

tension 
compression 
bending 
shear 
torsion

Question 2

How is axial stress calculated?

Answer 2

force per unit area

stress = force/area

Question 3

How is axial strain calculated?

Answer 3

amount of elongation or shortening

change in length/original length

Question 4

What is young’s Modulus?

Answer 4

a measure of the ability of a material to resist elongation and compression (stiffness)

E = stress/strain

Question 5

how are shear stresses caused?

Answer 5

forces acting in opposite directions to planes within a material

Question 6

How is shear stress calculated?

Answer 6

shear force/shear area

Question 7

What is shear strain?

Answer 7

angular deformation (angle sheared)

Question 8

What is angular deformation measured in?

Answer 8

radians

Question 9

What is the equation for sheer strain?

Answer 9

angle sheared (r) = distance sheared/distance between shearing forces

Question 10

What is shear strength?

Answer 10

the maximum shear strength a material can withstand before fracture

shear force to fracture/ sheared area

Question 11

What is another name for the shear modulus?

Answer 11

the modulus of rigidity

Question 12

How is the modulus of rigidity calculated?

Answer 12

shear stress/shear strain

Question 13

Which letter represent the modulus of rigidity?

Answer 13

G

Question 14

Where does the largest shear stress occur?

Answer 14

at 45 degrees to the axial loading

Question 15

what is equal to the largest shear stress?

Answer 15

half the axial stress

Question 16

How does bending stress occur?

Answer 16

when a material is acted on by forces or moments that tend to bend or curve it

Question 17

What are 2 common types of bending?

Answer 17

cantilever

3 point

Question 18

When a material is bent, what is in between the compressed side and the elongated side?

Answer 18

neutral axis of no stress

Question 19

In a complex shape like a bone, is the neutral axis always at its geometric centre?

Answer 19

Depends on the shape of the bone

Question 20

What happens to stress the further a material is bent from the neutral axis?

Answer 20

increases

Question 21

Where does maximum stress occur in bending?

Answer 21

the surface of the beam

Question 22

Where will a material being bent, fail?

Answer 22

at the surface

Question 23

What is the equation M = F x L used for?

Answer 23

bending moment calculation

Question 24

What is second moment of area?

Answer 24

a measure of the distribution of a materials mass from the neutral axis

Question 25

Which type of beam has the highest bending strength?

Answer 25

the “I-section” beam

Question 26

What equation group is used to calculate second moment of area?

Answer 26

MIsyEr

M - maximum bending moment
I - second moment of area
s - maximum bending stress
y - distance from the neutral plane
E - Young’s Modulus of the beams material
r - radius of the circle containing the neutral axis

Question 27

What is the equation for calculating second moment of area in a rectangular cross section?

Answer 27

I = bd*3/12

Question 28

What is the equation for calculating the second moment of area in a circular cross section?

Answer 28

I = pi x d*4/64

Question 29

What is the equation for calculating the second moment of area in a hollow circular cross section?

Answer 29

I = pi/64 x (d4outer - d4inner)

Question 30

Name a scenario whee a bone is subject to bending stress and could fracture?

Answer 30

boot top ski fracture