Dent 1.1

Question 1

how is stress measured

Answer 1

Ratio of force per area (or stress)

Question 2

Tension

Answer 2

Elongation forces directed away from each other in the same straight line (molecules resist being pulled apart)

Question 3

Compression

Answer 3

shrinkage forces directed toward eachother in the same straight line (molecules resist being forced more closely together)

Question 4

Shear

Answer 4

Forces paralle NOT along the same straight line (one portion resists sliding past the other

Question 5

Torsion

Answer 5

twisting forces

Question 6

Bending

Answer 6

results from a bending moment

Question 7

Define strain

Answer 7

Deformation caused by stress

Question 8

what is the proportional limit

Answer 8

The greatest sustained stress with out deviation from the linear proportionality of the stress strains

Question 9

at what point does irreversible stain occur, and what is this region called

Answer 9

Once the Curve is no longer linear, Plastic region

Question 10

what is the Elastic Limit

Answer 10

The greatest stress sustained without permanent deformation

Question 11

when would Proportional limit and elastic limit represent the same stress within the same structure

Answer 11

In Linearly Elastic Materials

Question 12

the stress at which the material begins to function in a plastic manner (permanent strain of about 0.2%)

Answer 12

yield strength

Question 13

_____ _____ is slightly higher then _____ _____ because it include a slight amount of permanent deformation.

Answer 13

Yield strength, proportional limit

Question 14

what are the two types of permanent defomration

Answer 14

Destructive - filling, crowns ect.

Constructive - ortho wires, partial clasps

Question 15

Ultimate strength

Answer 15

The Highest point on the graph, the stress that a material can withstand.

Question 16

which is more important, Yield strenght of Ultimate strength

Answer 16

Yield strength

Question 17

Fracture strength

Answer 17

stress at which a brittle material fractures

Question 18

for most dental alloys and ceramics subjected to tension, , the US and Sf will be _______

Answer 18

Similar

Question 19

Elongation

Answer 19

Deformation that results from the application of tensile force, indicates the workability of alloy

Question 20

Elastic modulus

Answer 20

the measure of elastisity, represents the stiffness of the material with in the elastic region. E=stress/strain

Question 21

The _____ the value of E, the more stiff or rigid the material

Answer 21

Higher

Question 22

resistance of material to permanent deformation is known as

Answer 22

Resilience (the area under the Elastic portion)

Question 23

the resistance of material to fracture

Answer 23

Toughness

Question 24

the combination of what three things increases toughness

Answer 24

combination of
yield strength
Ultimate strength
Strain

Question 25

what are fracture Mechanics

Answer 25

Characterizes the behavior of materials with cracks or flaws

Question 26

what is used to measure the strength of brittle materials

Answer 26

Diametral compression test

Question 27

fatugue strength

Answer 27

the stress at which the material fails under repeated loading

Question 28

endurance limit

Answer 28

stress at which the material can be loaded an infunuite number of times with out failing

Question 29

fatigue depends on the ______ of the load and the ________ of loadings

Answer 29

Magnitude, Number

Question 30

materials with mechanical properties dependant on loading rate are termed

Answer 30

Viscoelastic

Question 31

the resistance of a fluid to flow

Answer 31

Viscosity

Question 32

CREEP

Answer 32

increase in strain in material under constant stress

Question 33

resistance to tearing forces are known as

Answer 33

Tear strength