5 Written questions
5 Matching questions
- Shear stress is calculated by dividing the force by the area ________ to the force direction.
- Units of Modulus of elasticity
- Two important aspects of microscopic flaws in brittle materials:
- a Relative ability of a material to deform physically under a <b>tensile</b> stress before it fractures
- b b. parallel
brackets for braces is a good example
- c Force per unit area within a structure subjected to an external force or pressure (See Pressure).
- d 1. the stress intesntiy at these flaws increases with the length of the flaw, specially when it is oriented prependicular to the direction of tensile stress
2. flaws on the surface are associated with higher stresses than are flaws of the same size in interior regions.
- e Giganewtons per square meter (GN/m²), or gigapascals (<b>GPa</b>)
5 Multiple choice questions
- Ratio of compressive force to cross-sectional area prependicular to the axis of applied force.
- 1. most restorations have rough, <b>curved</b> surfaces
2. tensile strength is <b>below</b> shear strength value
3. force must be applied exactly adjacent to the
Tension would develop on the occlusal half where as compression would develop in the gingival half.
- Maximum amount of plastic strain a tensile test specimen can sustain before it fractures (See Ductility).
- ↑ elastic modulus
5 True/False questions
average biting force →
Stress = Force / area
stress units - MPa
Materials with a high elastic modulus have:
a. high strength values.
b. low strength values. → they could have either. they are independent of each other.
Poisson's ratio → the ratio of horizontal extension to vertical compression.
Most engineering materials have values of approximately <b>0.3</b>
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).
diametral compression test →
a test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation (brittle).