DMS Glossary Flashcards
What is compressive strength?
the stress required to cause fracture, making a material no longer fit for purpose
What is elastic modulus?
- the stress requires to cause a change in shape
- rigidity
- stress/strain ratio
- Young’s ratio
What are brittleness and ductility?
the dimensional change experienced before fracture occurs
- brittle materials experience minimal dimensional change before fracture
- ductile materials can experience considerable dimensional change before fracture
What is hardness?
the resistance of a material’s surface to indentation or abrasion
What is the initial gradient on a stress-strain curve indicative of?
- elastic modulus
- steeper the gradient the more rigid the material
What is the change in gradient on a stress-strain curve indicative of?
proportional limit
What is the end point on a stress strain curve indicative of?
fracture stress
- the point at which a material fails
What is creep?
the gradual increase in permanent strain experienced under prolonged application of stress beyond the elastic limit
What is stress?
The deforming force measured across a given area
- can be tensile, compressive, shear or torsional
- stress = F/A
What is a stress concentration point?
An abrupt change in the geometric shape of a material that leads to higher stress at that point
- common in endodontic files
What is strain?
The response of a material to stress
- the amount of deformation a material undergoes
- strain = ^L/L
What is elastic limit
a set value representing the maximal strain that can be applied to a material allowing the material to return to its original dimensions
What is elastic deformation?
reversible deformation that does not exceed the elastic limit
What is plastic deformation?
permanent bond displacement occurring when the elastic limit is exceeded
What is plastic limit?
the point at which a plastic deformed material breaks
What is cyclic fatigue?
the generation of tension/compression cycles in a material freely rotating in a curvature
- experiences both tension and compression
- results in work hardening
- ultimately ends with failure of material
What is torsional fatigue?
the generation of strain within a material when different areas are subjected to varying rotational stresses
What is shape memory?
alloys which can be deformed at one temperature but when heated or cooled they return to their original shape
What is viscosity?
a measure of a material’s ability to flow
- determines a material’s potential for making close contact with tissues
