NAME: ________________________

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of 71 available terms

5 Matching Questions

1. Shear stress
2. Units of Modulus of elasticity
3. diametral compression test
4. Why do prostheses sometimes fail under a very small force, even though the strength of the prosthetic material is relatively high?
5. fatigue failure
1. a
Repeated stresses resulting in fractures. the fracture due to fatigue occurs at stress levels well below tensile strength.
2. b
a test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation (brittle).
3. c Ratio of force to the original cross-sectional area parallel to the direction of the force applied to a test specimen.
4. d Flaws (could be microscopic)
5. e Giganewtons per square meter (GN/m²), or gigapascals (<b>GPa</b>)

5 Multiple Choice Questions

1. Plastic deformation occurs when the <b>elastic stress limit (proportional limit)</b> within the prosthesis is exceeded.
2. 1. <b>strain rate</b>
2. the shape of the test speciment
3. the surface finish (control flaws)
4. the environment in which material is tested
3. Compressive <b>stress</b> within a compression test specimen at the point of fracture.

note: compressive stress -Ratio of compressive force to cross-sectional area perpendicular to the axis of applied force.
4. The area bounded by the elastic region is a measure of <b>resilience</b>, and the total area under the stress-strain curve is a measure of<b> toughness</b>.
5. Force per unit area of a material subjected to flexural loading.

5 True/False Questions

1. A value of 0.3 for Poisson's ratio is typical. Thus, the shear modulus is usually about ___% of the elastic modulus.composites followed by porcelain, PMMA, amalgam and alumina.

2. StressForce per unit area within a structure subjected to an external force or pressure (See Pressure).

3. Shear stress is calculated by dividing the force by the area ________ to the force direction.

a. perpendicular
b. parallel
b. parallel

brackets for braces is a good example

4. As the interatomic spacing increases, the internal energy increases. As long as the stress is <b>not greater than the proportional limit</b>, this <u>energy</u> is known as__________.Toughness increases with increases in strength and ductility.

5. which of the dental restorative materials have the highest resilience?composites followed by porcelain, PMMA, amalgam and alumina.