week 2

Question 1

what are the 4 key info’s a stress/strain graph is able to provide

Answer 1

Elastic behaviour
Yielding
Strain hardening
Necking

Question 2

what is poisson’s ratio

Answer 2

When a material is stressed in one direction, it
will deform (strain) in the direction of the load

Question 3

what is deformation also known as?

Answer 3

strain

Question 4

what 2 ways are materials tested

Answer 4

tensile strength test and destruction test

Question 5

what is devleoped on the elastic limit

Answer 5

strain is developed directly proportional to the applied stress

Question 6

what happens beyond the stress limit

Answer 6

plastic deformation

Question 7

what is yield stress

Answer 7

stress at which noticeable plastic deformation has occured

Question 8

what test is used for a material that is unable to provide a clear yield point

Answer 8

proof stregnth

Question 9

what is ductility

Answer 9

the extend of plastic deformtion

Question 10

what does a ductile material go through prior to failure

Answer 10

large plastic deformation

Question 11

what is fracture

Answer 11

this is the last stage of tensile test, when the material fails and breaks into 2 pieces

Question 12

what is brittle fracture

Answer 12

this is when fracture occurs elastic deformation, but with no plastic strain

Question 13

what is ductile fracture

Answer 13

occurs after plastic deformation

Question 14

what is toughness

Answer 14

Toughness is the ability of a material to absorb energy prior to failure

Question 15

what does toughness measure

Answer 15

• It is measures as energy to break a unit volume of material.

Question 16

what 3 parameters affect toughness

Answer 16

strain rate
temperature
notch effect

Question 17

what 2 things decrease temperature is lowered on a material

Answer 17

toughness and ductility decreases when temperaturre is lowered

Question 18

what is the notch effect and how can it effect toughness

Answer 18

this is the flaws, cracks and defects in the material which are able to decrease the toughness of the material.

Question 19

what is the strain rate

Answer 19

the rate of loading

Question 20

how can the strain rate effect toughness and ductility

Answer 20

Toughness and ductility decrease as the rate of loading increases

Question 21

what is hardness

Answer 21

this is the resistance of a material to surface indentation