lecture 2

Question 1

physical properties

Answer 1

mechnial
electrical
thermal

Question 2

stress

Answer 2

internal reaction to the external force
stress = force per unit area N/m^2
(megapascal MPa)

Question 3

type of stress

Answer 3

tension
compressive
shear

Question 4

1. tension (elongation)

Answer 4

2 forces are directed away from each other in straight line.
It stretches (elongates) the body

Question 5

2. compression

Answer 5

shrinkage

internal resistance is compressive stress

Question 6

tension and compression of glass

Answer 6

glass does well in tension but not in compression

Question 7

3. shear

Answer 7

forces toward each other not in straight line.

ex: marginal ridges

Question 8

strain

Answer 8

change in length of body when a stress is applied

body undergoes deformation when a force is applied to it.

Question 9

strain equation

Answer 9

Deformation / original length

Question 10

stress-strain curve

Answer 10

strain on x-axis, stress on y-axis

survivaility, breathability

Question 11

elastic deformation

Answer 11

stress is proportional to strain
no permanent deformation is expected
area of curve before proportional limit

Question 12

straight line on stress-strain curve

Answer 12

no permanent deformation

Question 13

proportional limit (elastic limit)

Answer 13

maximum stress that a material will withstand before permanent deformation. (X-AXIS)
stress level where elastic deformation to plastic deformation
stress level where straight line to curve

Question 14

plastic deformation

Answer 14

curve is not longer straight

material will not return to its original shape

Question 15

Yield point

Answer 15

measure of point of deformation

Question 16

what is the difference between yield point and proportional limit?

Answer 16

??

Question 17

failure point

Answer 17

the point at which the material fractures

point where curve to straight

Question 18

ultimate tensile strength

Answer 18

maximum stress required to fracture a structure

Question 19

strength

Answer 19

ability of material to resist change

Question 20

total strain

Answer 20

total amount material stretches

sum of elastic deformation, plastic deformation.

Question 21

elasticity

Answer 21

property of having a constant ratio of stress to strain

stiff or flexible

Question 22

plasticity

Answer 22

when the proportional limit is exceeded, the material exhibit plastic behavior

Question 23

Ductile

Answer 23

exhibit large amount of plastic behavior

Question 24

Brittle

Answer 24

exhibit no plastic behavior

Question 25

Resilience

Answer 25

area under the elastic portion of SS curve | elastic recovery is the most important component

Question 26

formability (ductability)

Answer 26

ability to bend material ability of a material to withstand permanent deformation under a tensile load without rupture Gold>Silver>Platinum

Question 27

formability in graph

Answer 27

area under the curved side | plastic side of graph

Question 28

malleability

Answer 28

ability of material to withstand permanent deformation under a compressive load without rupture same graph as formability, same sht but compression

Question 29

toughness

Answer 29

area under elastic and plastic portion of SS curve

Question 30

Springiness

Answer 30

strain that occurs when the material is stressed to its proportional limit Springiness = 1/Stiffness

Question 31

Fatigue strength

Answer 31

materials may fail due to fatigue at stress below Ultimate Tensile Strength (strength when it causes to fail)

Question 32

range

Answer 32

the distance that the wire will bend elastically before permanent deformation occurs (Y-AXIS)

Question 33

Springback (elastic recovery)

Answer 33

if the wire is deflected beyond its yield point, it will not return to its original shape but clinically useful springback will occur unless the failure point is reached (Y-AXIS)

Question 34

permanent deformation

Answer 34

factor of modulus of elasticity and volume of object. | the energy can be stored without permanent deformation

Question 35

Impact strength

Answer 35

energy required to fracture the material under an impact for force.