Mechanical Properties Of Metals Flashcards
The mechanical behavior of a material refects its______________ in relation to an applied load or force.
response or deformation
mechanical design properties are
stiffness, strength, hardness, ductility, and
toughness
ascertained by perorming carefully designed laborator experiments that replicate as nearly as possible the seice conditions.
Mechanical Properties
three principal ways in which a load
may be applied:
tension, compression, and shear
is designed to elongate the specimen at a constant rate and to continuously and simultaneously measure the instantaneous
applied load and the resulting elongation.
tensile testing machine
is used in ductility computations
Gauge length
typically takes several minutes to perform and is destructive;
stress–strain test
the test specimen is permanently deformed and usually fractured.
stress–strain test
strain tests may be conducted if in-service forces are of this type.
Compression stress
conducted in a manner that the force is compressive and the specimen contracts
along the direction of the stress.
Compression stress
is taken to be negative, which yields a negative stress.
compressive force
are used when a material’s behavior under large and permanent (i.e., plastic) strains is desired
Compressive tests
is a variation of pure shear, wherein a structural
member is twisted
Torsion
produce a rotational motion about the longitudinal axis of one end of the member relative to the other end.
Torsional forces
Stresses that are computed from the tensile,
compressive, shear, and torsional force states act either ________________ to planar faces of the bodies.
parallel or perpendicular
Torsional tests are normally performed on
cylindrical solid shafts or tubes
function of the orientations of the planes upon which the stresses are taken to act
Stress state
The degree to which a structure deforms or strains independent on the magnitude of an imposed stress.
False (dependent)
Deformation in which stress and strain are proportional
elastic deformation
This modulus may be thought of as stiness, or a material’s resistance to elastic deformation.
Modulus of elasticity
an
important design parameter for computing elastic deflections
Modulus
Elastic deformation is
nonpermanent
timedependent elastic strain
anelasticity
due to time-dependent microscopic and atomistic processes that are attendant to the deformation
anelasticity
parameter termed _____________ is defined as the ratio of the lateral and axial strains
Poisson’s ratio
elastic deformation persists only to strains of about ______.
0.005
stress corresponding to the intersection of this line and the stress–strain cue as it bends over in the plastic region
yield strength
the stress at
the maximum on the engineering stress–strain curve
tensile strength
corresponds to the maximum stress that can be
sustained by a structure in tension
tensile strength
measure of the degree of plastic deformation that has been sustained at fracture
Ductility
capacity of a material to absorb energy when it is deformed elastically and then, upon unloading, to have this energy recovered.
Resilience
is a property that is indicative of a material’s
resistance to fracture when a crack
Toughness
defined as the load divided by the
instantaneous cross-sectional area over which
deformation is occurring
True stress
measure of a material’s resistance to localized plastic deformation
hardness
constitute the most common method used to measure hardness because they are so simple to perform and require no special skills.
Rockwell Hardness Tests
hard, spherical indenter is forced into the surface of the metal to be tested.
Brinell Hardness Tests
For each test a very small diamond indenter having pyramidal geometry is forced into the surface of the specimen.
Knoop and Vickers Microindentation Hardness Tests
Is based on the yield strength of the material and is defined as the yield strength divided by a factor of safety
safe stress
