TOPIC 4: MECHANICAL TEST
TOPIC 4: MECHANICAL TEST4.1 Material testing.
4.1.1 Explain the purpose and types of material testing
deformation:
Materials are tested /inspected for one more of the following
purposes.To assess numerically the fundamentals mechanical
properties of the materials e.g. Ductility, Malleability, hardness,
toughness, brittleness etc.To determine data that is stress values
(deformation force) which break the specimen upon which engineer
can base his design.To check chemical composition and structure of
products.To determine the surface and sub-surface defects in raw
material and products.To determine suitability of material/products
for a particular application
4.1 Material testing.
4.12 Define mechanical properties in material testinga)
StrengthStrength is the property that enables a metal to resist
deformation under load. The ultimate strength is the maximum strain
a material can withstand.
b) Hardness Hardness is the property of a material to resist
permanent indentation.c) ElasticityElasticity is the ability of a
material to return to its original shape after the load is
removed.d) PlasticityPlasticity is the ability of a material to
deform permanently without breaking or rupturing.
4.1 Material testing.
4.12 Define mechanical properties in material testinge)
DuctilityDuctility is the property that enables a material to
stretch, bend, or twist without cracking or breaking.
f) ToughnessToughness is the property that enables a material to
withstand shock and to be deformed without rupturing. Toughness may
be considered as a combination of strength and plasticity.g)
BrittlenessTendency of a material to fracture or fail upon the
application of a relatively small amount of force, impact, or
shock.
