5 Written Questions
5 Matching Questions
- Which one is tougher?
- the stress above which stress is no longer proportional to strain.
- When stress is induced in a two-unit cantilever bridge, where you would expect the tensile and compressive stress develop?
- How can resilience of two materials be compared?
- which tooth structure has the hgiher <b>propotional limit</b> and <b>modulus of elasticity</b>?
- a b. dentin is tougher!
the more flexible material is the tougher it is. enamel is brittle
Tension would develop on the occlusal half where as compression would develop in the gingival half.
- c Proportional limit
by comparing the <b>area</b> underneath the elastic region.
↑ the area = ↑ resilience
5 Multiple Choice Questions
- they could have either. they are independent of each other.
- a. increases
although ductility of the metal ↓↓
- 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.
Area or point of significantly higher stress associated with a structural discontinuity such as a crack or pore or a marked change in dimension of a structure.
a test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation (brittle).
5 True/False Questions
Two important aspects of microscopic flaws in brittle materials: → 1. tensile stress
2. shear stress
3. compressive stress
Poisson's ratio →
Change in length per unit initial length.
Units are in %
Proportional limit →
Maximum stress at which stress is proportional to strain and above which plastic deformation occurs.
in this case: PL= 1020 MPa
Plastic deformation occurs when the ______________ within the prosthesis is exceeded. → Plastic deformation occurs when the <b>elastic stress limit (proportional limit)</b> within the prosthesis is exceeded.
endurance limit → Relative ability of a material to deform physically under a <b>tensile</b> stress before it fractures