5 Written questions
5 Matching questions
- diametral compression test
- Elastic strain
- True stress
- a Ratio of applied force to the actual cross-sectional area; however, for convenience stress is often calculated as the ratio of applied force to the initial cross-sectional area.
a test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation (brittle).
- c Deformation that is recovered upon removal of an externally applied force or pressure.
- d The relative amount of elastic energy per unit volume released on unloading of a test specimen.
- e 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.
5 Multiple choice questions
- 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.
• 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.
- Plastic deformation occurs when the <b>elastic stress limit (proportional limit)</b> within the prosthesis is exceeded.
is a property that represents the stress value at which a small amount (0.1% or 0.2%) of plastic strain <b>has occurred</b>.
Does not exist for very brittle materials
5 True/False questions
Shear strength → Maximum shear stress at the point of fracture of a test specimen.
Which of the following has more resistence?
a. Dental porcelain
c. Resin-based composite
e. Alumnia ceramic →
dentin → 50 MPa
enamel → 10 MPa
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__________. → resilience
the term resilience is associated with 'springiness'
For brittle materials that exhibit only elastic deformation and can sustain no plastic deformation, stresses at or slightly above the ________________ result in fracture. →
maximum elastic stress (proportional limit)
Maximum stress that a structure can withstand without sustaining a specific amount of plastic strain (yield strength) or stress at the point of fracture (ultimate strength).