stress analysis Unit 2

Question 1

isotropic material?

Answer 1

when they are loaded they exhibit uniform mechanical properties in all directions

Question 2

axial stress arises when a material is subjected to tensile or compressive forces along a geometric axis

Answer 2

axial stress is defined as the force per unit area

Question 3

equation for maximum shear stress?

Answer 3

tmax = axial stress6/2

Question 4

the largest shear stress occurs in the planes at 45degrees to the axial loading and is equal to half of the loading stress

Answer 4

y

Question 5

units of maximum shear stress?

Answer 5

Pa

Question 6

what distinguishes the neutral axis from any other axis in a bent beam?

Answer 6

the neutral axis maintains the same length when the beam is bent - it is neither elongated or compressed

Question 7

how to convert degrees to radians?

Answer 7

radians = degrees x Pi/180

Question 8

equation for MIS….

Answer 8

MISYER bent

Question 9

how to calculate I for rectangle?

Answer 9

bd3/12

Question 10

CIRCULAR?

Answer 10

pi d 4/64

Question 11

hollow circular?

Answer 11

pi ( outer d 4 - inner d 4) / 64

Question 12

unit of shear strain?

Answer 12

radian

Question 13

modulus of rigidity?

Answer 13

shear stress/shear strain

Question 14

to calculate maximum shear stress?

Answer 14

find stress and divide by 2

Question 15

units for maximum shear stress?

Answer 15

Pa

Question 16

ski boot fracture - what kind of bending causes this?

Answer 16

3 point

Question 17

a bar is sad to be in pure torsion wen its cross section is?

Answer 17

retaining its shape

Question 18

sheer stress in torsional stress?

Answer 18

G theta r AB/L

Question 19

what is G?

Answer 19

modulus of rigidity

Question 20

for a solid circular cross section, it can be shown that J=

Answer 20

pi d 4/32

Question 21

for a hollow circular cross section?

Answer 21

j= pi(d4 outer - d4 inner) / 32

Question 22

what is J?

Answer 22

polar second moment of area

Question 23

when are bones strongest?

Answer 23

in compression

Question 24

what can muscles do to reduce chance of fracture?

Answer 24

contract to produce compressive loading on the bone and because bones are stronger in compression than in tension, this reduces likelihood of a fracture

Question 25

why is it sometimes desireable for muscles to contact even when its not to produce movement?

Answer 25

muscle contraction can put compressive load on a bone, bones are stronger in compression than tension

Question 26

what role to microscopic voids play in ductile fracture?

Answer 26

microscopic voids are small holes at the centre of the bar. they are formed when a high stress causes a separation of the metal at grain boundaries. as the local stresses increase, the microscopic voids start to join together and produce larger cavities. eventually the metal contact is reduced and a fracture occurs, at an angle of 45 degrees to the applied tensile load.

Question 27

what is the difference in the fracture surface in a brittle fracture?

Answer 27

the fracture surface is flat, rather than 45 degrees in a ductile fracture. it has a granular appearance