Week 2: Mechanical Properties Flashcards

1
Q

classification of mechanical properties

A

1st classifications: bulk/surface

2nd classifications: sub-classifications of bulk properties (fundamental, applied)

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2
Q

force per unit area from externally applied forces

A

stress

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3
Q

unit of stress

A

Pa/MPa

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4
Q

fundamental types of stress

A

tension, compression, shear

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5
Q

force perpendicular to resisting area

A

tension

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6
Q

force perpendicular to resisting area, sense of load opposite to that of tension

A

compression

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7
Q

force parallel to resisting area

A

shear

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8
Q

combined types of stress

A

torsion, flexure/bending

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9
Q

where does stress concentrate?

A

notches, grooves, cracks, surface irregularities

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10
Q

describes relative deformation or change in shape and size with respect to initial length under applied forces (stresses)

A

strain

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11
Q

strain that is recoverable

A

elastic

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12
Q

strain that is permanent

A

plastic

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13
Q

high modulus equals what type of material?

A

rigid material

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14
Q

low modulus equals what type of material?

A

less rigid material

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15
Q

Stresses _______ than the

elastic limit produce permanent/plastic deformation in the material.

A

equal to or higher

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16
Q

Stress at which material changes from elastic to plastic strain

A

elastic

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17
Q

ductility/malleability is measured by what

A

% of elongation

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18
Q

high % ductility/malleability equals what?

A

ductile material

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19
Q

low % ductility/malleability equals what?

A

brittle material

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20
Q

stress at which material breaks, last point in stress-strain curve

A

Ultimate Tensile Strength (UTS)

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21
Q

Maximum stress the material undergoes during stress-strain test

A

maximum stress

22
Q

Amount of energy a material can absorb without permanently deforming

A

resilience

23
Q

Total amount of energy a material can absorb until fracture

A

toughness

24
Q

ability for material to resist indentations, resistance to be scratched

A

hardness

25
Q

loss of anatomic form from surface or restoration, results in wear

A

abrasion

26
Q

Repeated low forces (below elastic limit) that bring the material to an unexpected fracture

A

fatigue stress

27
Q

a key note about viscoelasticity, or combination of viscous and elastic behavior, is that it is __ _____

A

time dependent

28
Q

slow deformation with time under constant stress

A

creep

29
Q

material constantly deformed, may show drop in stress to keep deformation with time

A

stress relaxation

30
Q

laboratory tests (__ _____) ____ predict ___ ______ behavior

A

in vitro, cannot, in vivo

31
Q

consideration of the whole mass of material

A

bulk properties

32
Q

examples of bulk properties

A

strength, elasticity, etc.

33
Q

examples of surface properties

A

hardness, wear, etc.

34
Q

sub-classification of bulk properties

A

fundamental properties, applied properties

35
Q

stress is applied from…

A

external forces

36
Q

calculations of stress

A

Force (F) / cross-sectional area (A)

37
Q

strain is…

A

dimensionless

38
Q

in stress-stain graph…
y axis =
x axis =

A

y axis = stress AND strength

x axis = strain

39
Q

area under curve of stress-strain graph is…

A

values of force per displacement (work)

40
Q

linear part of the graph is…

A

elastic strains

41
Q

flexibility (is/is not) a fundamental property

A

is NOT

42
Q

change from elastic to plastic strain points

A

“PEY”
proportional limit
elastic limit
yield point

43
Q

if you go above ___ ____, restorations will fail

A

elastic limit

44
Q

maximum strength is found at the _______

A

highest point of the graph

45
Q

malleability: ability of a material to be formed into a ____

A

sheet

46
Q

ductility: ability of a material to be formed into a ____

A

wire

47
Q

in stress-strain graph, area underneath linear slope of graph is _____

A

modulus of resilience

48
Q

in stress-strain graph, total area under graph = ____

A

toughness (has units of energy)

49
Q

area under graph energy units

A

J/m^3

50
Q

in stress-strain graph, linear slope is ________

A

modulus of elasticity