week 5

Question 1

what is ductility

Answer 1

plastic deformation before fracture

Question 2

what is toughness

Answer 2

energy absorbed before

Question 3

what is brittleness

Answer 3

little plastic deformation and low toughness

Question 4

what are the 3 main chatacteristics of a ductile fracture

Answer 4

high amount of plastic deformation
final shear de-cohesion
rough and fibrous fracture surface

Question 5

what is the step by step cup and cone fractrue (5 steps)

Answer 5

initial necking 
small cavity formation
cavities start to form a crack
crack propagation
final shear fracture at 45 degree angle

Question 6

what are the chatacteristics of a brittle fracture (4 things)

Answer 6

when it snaps it creates a flat surface
no to small deformation
shiny surface where its snapped
no warning when failed

Question 7

how is stress transmitted through a material

Answer 7

Stress is transmitted through “ lines of force”

Question 8

what happens if there is a discontinuity (due to crack) on the line of force

Answer 8

the stress concentrate will be at the tip of the discontinuity

Question 9

what does the severity of the stress concentration depend on (3 things)

Answer 9

applied stress
size of the crack
shape of the crack

Question 10

what does plastic deformation reduce

Answer 10

the effect of stress concentration