Mechanical Properties

Question 1

application is determined by? general

Answer 1

property

Question 2

instron is what? testing?

Answer 2

a type of mechanical testing machine– UNDER COMPRESSIVE FORCES
- trying to break it

if material can last high stress/ high load –> should be a good material

Question 3

load is a what? - very general

Answer 3

a force

how much force you apply

Question 4

unit of force

Answer 4

newton

Question 5

how do we standardize the load?

Answer 5

load per unit material

Question 6

how do we standardize the load?

Answer 6

load per unit material

• units are pascal and it is what STRESS not what load it breaks at

Question 7

stress is?

Answer 7

load divided by the certain area

Question 8

if have higher stress what does that mean?

Answer 8

it is stronger

Question 9

describe the load deformation curve

Answer 9

any material / solid material when squeeze there is a dimensional change

it is SIZE AND SHAPE DEPENDENT

Question 10

test with failure load?

Answer 10

no

Question 11

force is

Answer 11

newton

Question 12

deformation change is measured how

Answer 12

in mm

- shows deformation or displacement change

Question 13

stress definitino

Answer 13

INTENSITY of the internal force acting on a specific AREA passing through a point

Question 14

stress equation

Answer 14

Force / Area

Force is measures in load (newton) and area is meters squared (m2)

Question 15

units SI?

Answer 15

1N/m2 = 1 pascal

Question 16

1 megapascal uquals how many pascals?

Answer 16

1,00,000

Question 17

hookes law is?

Answer 17

a linear representation of load and deformation

Question 18

describe normal stress? what type

Answer 18

the intensity of the force acting normal to A

- compressive, tensile

Question 19

what is shear stress

Answer 19

the intensity force acting TANGENT TO A

Question 20

strain definition

Answer 20

used to describe the deformation of a body by changes in LENGTH OF LINE SEGMENTS (and the changes in the angle between them)

Question 21

units of strain

Answer 21

unitless - expressed as a percentage

Question 22

equation for strain

Answer 22

(length - L0) / L0

LO - original length

Question 23

how do units change in strain

Answer 23

newton – megapascal

Question 24

ideal elastic material

Answer 24

Isotropic

Strain (deformation) is proportional to the stress applied to it

When unloaded the deformation fully recovers immediately

Question 25

deformation also called

Answer 25

strain

Question 26

does zirconia follow elastic deformation?

Answer 26

yes | - dont really see the deformation - but if too high of a load it can fracture

Question 27

what does bisacrylic follow?

Answer 27

plastic deformation

Question 28

plastic deformation

Answer 28

it deviates from the linear curve | - so starts to taper off

Question 29

applying load should be maintained within what?

Answer 29

the elastic deformation load range to keep the proper shape

Question 30

three points that occur in the elastic region and order

Answer 30

1. proportional limit 2. elastic limit 3. yield stress

Question 31

parts of the plastic behavior

Answer 31

1. yielding 2. strain hardening 3. necking

Question 32

true fracture stress?

Answer 32

the load at fracture divided by cross-sectional area

Question 33

ultimate stress and true fracture stress are where on curve?

Answer 33

in plastic behvior

Question 34

ultimate stress

Answer 34

stress material can handle before being broken

Question 35

plastic deformation definition

Answer 35

when unloaded, the deformation cannot fully recover - so get permanent deformation

Question 36

definition of malleability

Answer 36

whereby a material can be plastic deformed and shapes WHEN COLD

Question 37

ductility

Answer 37

whereby a material can be plastic deformed by elongation without fracture

Question 38

brittleness definition

Answer 38

whereby a material will fracture without appreciable prior plastic deformation

Question 39

if a material fractures without plastic deformation what do we characterize it as?

Answer 39

brittle

Question 40

strain hardening

Answer 40

aka work hardening and is characteristic of ductile materials like metal - occurs through plastic deformation - after this period you see necking

Question 41

why is a conventional stress-strain diagram important?

Answer 41

it provides a means for obtaining data about a materials tensile or compressive strength WITHOUT regard for the materials physical size or shape

Question 42

points on diagram in stress / strain | - which in which section

Answer 42

ELASTIC Portion 1. proportional limit 2. elastic limit 3. yield limit PLASTIC 1. ultimate stress 2. fracture stress

Question 43

what determines a ductile material?

Answer 43

any material that can be subjected to LARGE STRAINS before it fractures is a ductile material

Question 44

four distinct behaviors of a ductile material as it is loaded

Answer 44

1. elastic behavior 2. yielding 3. strain hardening 4. necking

Question 45

if have low yield?

Answer 45

can fracture suddenly

Question 46

example of ductile

Answer 46

mild steel

Question 47

example of brittle

Answer 47

gray cast iron, ceramic

Question 48

brittle materials have?

Answer 48

very little or no yielding and so they can fracture suddenly

Question 49

modulus of elasticity is represented by what on the stress-strain curve?

Answer 49

THE SLOPE -- it is the slope of the proportional stress-strain curve

Question 50

poisoon ratio? what value is ideal

Answer 50

ratio is transverse strain divided by the axial strain - if a test piece is loaded in tension or compression, then in directions perpendicular to the load axis - so compressive - shrinks but gets wider (expands if compressive) - tensile - elongates but gets skinny (contraction if tensile) CORRESPONDING LATERAL STRAINS WILL APPEAR A CONTRACTION IF THE LOAD IS TENSILE , AN EXPANSION IF IT IS COMPRESSIVE 0 to 0.5 (0.5 is ideal)