It is the maximal stress required to fracture a structure.
The three basic types of strength are:
1- Tensile strength.
2- Compressive strength.
3- Shear strength.
It is the maximal tensile stress the structure will
withstand before rupture.
Tensile strength is measured by
subjecting a rod, wire or dumbbell
shaped specimen to a tensile loading
(unilateral tension test).
Brittle materials are difficult to test by using the unilateral tension test.
Instead, an indirect tensile test called diametral compression test is used.
In this method, a compressive load is placed on the diameter of a short
cylindrical specimen.
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It is the deformation that results from the application of a tensile force.
The flexural strength of a material is obtained when one
loads a simple beam, simply supported (not fixed) at each
end, with a load applied in the middle, such a test is
called (three-point bending test).
Flexural strength test is especially useful in comparing denture base
materials in which a stress of this type is applied to a specimen of denture
acrylic with masticatory loads.
It is the resistance to motion of one material body over another. If an
attempt is made to move one body over the surface of another, a
restraining force to resist motion is produced; this restraining force is the
(static) frictional force and results from the molecules of the two objects
bonding where their surfaces are in close contact.
Figure (1-20): Microscopic area of contact between two objects. The
frictional force, which resists motion, is proportional to the normal force
and the coefficient of friction.
It is a loss of material resulting from removal and relocation of materials
through the contact of two or more materials
Tooth brushing with a dentifrice may cause wear of teeth.
Adhesion is the force which causes two different substances to attach
when they are brought in contact with one another. When the molecules of
the same substance hold together; the forces are said to be cohesion.