5 Written questions
5 Matching questions
- Yield strength
- average biting force
- A _______ stress is caused by a load that tends to stretch or elongate a body.
- The area bounded by the elastic region is a measure of ________, and the total area under the stress-strain curve is a measure of ____________.
- Strength depends on what factors: (4)
- a 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
- b b. tensile
- c 756 N
• The <b>stress</b> at which a test specimen exhibits a specific amount of plastic strain (0.2%)
• The YS at 0.2% strain offset from the origin is 1536 MPa in this case.
- e 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 Multiple choice questions
- Because of the reduction in area, the force required to increase deformation actually decreases.
- Relative ability of a material to deform physically under a <b>tensile</b> stress before it fractures
- flaws on the surface are associated with higher stresses than are flaws of the same size in interior regions. Thus surface finishing of brittle materials such as ceramics, amalgams, and composites is extremely important in areas subjected to tensile stress.
- Force per unit area of a material subjected to flexural loading.
- Ratio of force to the original cross-sectional area parallel to the direction of the force applied to a test specimen.
5 True/False questions
Proportional limit →
Maximum stress at which stress is proportional to strain and above which plastic deformation occurs.
in this case: PL= 1020 MPa
Toughness → Relative inability of material to deform plastically
Hardness → Ability of a material to absorb elastic energy and to deform plastically before fracturing; measured as the total area under a plot of tensile stress vs. tensile strain.
fatigue failure →
Repeated stresses resulting in fractures. the fracture due to fatigue occurs at stress levels well below tensile strength.
which tooth structure has the hgiher <b>propotional limit</b> and <b>modulus of elasticity</b>?
b. dentin → a. increases
although ductility of the metal ↓↓