Mechanical Properties of Metals Flashcards
Key mechanical
design properties
stiffness, strength, hardness, ductility, and toughness
Factors to be considered in performing designed laboratory experiments that replicate as nearly as possible the service conditions.
nature of the
applied load and its duration, environmental conditions
It can be used to ascertain
several mechanical properties of materials that are important in design.
Tension Test
conducted in a manner
similar to the tensile test, except that the force is compressive and the
specimen contracts along the direction of the stress
Compression Test
more common because they are easier to perform; also, for most
materials used in structural applications, very little additional
information is obtained from compressive tests
Tensile tests
used when a material’s behavior under large and permanent (i.e.,
plastic) strains is desired, as in manufacturing applications, or when the
material is brittle in tension.
s. Compressive tests
computed as Ƭ = F/A
shear stress
is the load or
force imposed parallel to the upper and lower faces, each of which has
an area of A
F in the formula
defined as the tangent of the strain
angle.
shear strain
units of stress
N/m2 or lb/in2
Stresses that are
computed from the tensile, compressive, shear, and torsional force
states.
Geometric Consideration of the Stress State
The degree to which a structure deforms
or strains depends on the magnitude of an
imposed stress
Elastic Deformation
For most metals that are
stressed in tension and at relatively low levels,
stress and strain are __________ to each other
through the relationship
proportional
For most typical metals
the magnitude of this modulus ranges between ___________ for magnesium and ___________
45 GPa (6.5x106
psi), 407 GPa (59x106
psi)
Deformation in which stress and strain are proportional
elastic
deformation
elastic means
reversible
plastic means
permanent
time-dependent elastic behavior
anelasticity
Maximum stress on engineering stress-strain curve
Tensile Strength, TS
It is a measure of
the degree of plastic deformation that has been sustained at fracture.
Ductility
A metal
that experiences very little or no plastic deformation upon fracture
brittle
capacity of a material to absorb energy when it is
deformed elastically and then, upon unloading, to have this energy recovered.
Resilience
the strain
energy per unit volume required to stress a material from an unloaded state
up to the point of yielding.
modulus of resilience
the ability of a material to absorb energy and
plastically deform before fracturing
Toughness
a property
that is indicative of a material’s resistance to fracture when a crack
Toughness
a measure of a material’s resistance to localized plastic
deformation (e.g., a small dent or a scratch)
hardness
material property and Critical properties depend
largely on sample flaws (defects, etc.)
Elastic modulus
the instantaneous applied load divided by the
instantaneous cross-sectional area.
True stress