Engineering Materials Ch 4
Card Set Information
Engineering Materials Ch 4
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is defined as the resistance of a material to external elements such as force, load, or weight measured in pounds per square inch (PSI).
is the amount of deformation or stretch that occurs over a standard gage length (2") expressed in inches or a percentage.
Stress is equal to
Strain is equal to
The four types of stress involved in strengths of materials are:
of the tensile test is to determine the
a specimen can resist before taking a
set or before
max load, permanent, rupture
materials will neck down through the plastic range before rupture occurs.
materials do not neck down significantly; instead, they fail sharply and abruptly at the maximum load(because brittle materials do not exhibit much plasticity).
the stress value at which the elastic portion of the curve loses it's proportionality between stress and strain
the top of the elastic region, where the amount of strain increases with little increase in stress.
maximum load divided by original area.
Lf = length at fracture
Lo = length original
Percent Reduction of Area
Ao=Area of original cross section
Af=Area of final cross section
Modulus of Elasticity
is a measure of the ability of a material to withstand changes in length when under lengthwise tension or compression.
the property that allows a material to deform permanently, under tension.
the property that allows a material to deform permanently, in compression.
the ability of a metal to be deformed permanently, without failing.
The plastic deformation resulting from the application of a
is a slow, but steadily increasing
applied to a material under load.
is important in structures as
and other load-bearing structures in which the members are subjected to long-term static loads.
is generally referred to as a material's property that indicates resistance to
may be either
is measured by resistance to
Common static hardness tests:
hardness test is the oldest and most established method.
B - for testing materials of medium hardness.
C - for testing very hard materials.
hardness testers are indentation tests and depend on the calculation of energy absorbed by the specimen during the test.
The general outcome of an impact test is the determination of the energy required to
is an indication of how well a material can withstand shock loading.
is used to measure
the transfer of energy
required to break a given volume of material.
Two common forms of impact testing are:
is defined as the failure of a material due to repeated or cyclic stresses being applied to it.
is the stress at which a material fails by fatigue.
Three factors affecting fatigue are:
and structure of the material
such as surface scratches, notches, inclusions, and other defects that can help initiate cracking.
NDT stands for
NDT is typically used to identify defects such as
that might lead to the failure of the part.
voids, inclusions, cracks
Four types of NDT testing are:
is an applied force that acts in a direction parallel to the plane in which the force is applied.
occurs when parallel forces are applied in opposite directions.
forces occur along a
forces occur between
When a material is bent or flexed under a load, a portion of the cross section is under
and a portion is under
Somewhere between these two opposing forces is a
line, or axis, separating the forces. Along this axis, the specimen is
in tension nor in compression.
of a beam is the displacement of a point on the neutral surface of a beam from its original position under the action of applied loads.
tends to compact or squeeze the specimen.
uses a twisting motion to test the strength of the specimen.
does not render the part unusable for its intended purpose.
applies force perpendicular to the primary axis of the part.
measures the resistance to surface penetration.
most commonly used to determine the cross-sectional geometry for a given application.
uses repeated, cyclic motions to determine the point of failure for a given part or specimen.
conducted over a very long period of time.
tends to pull the specimen apart.
used to measure the transfer of energy required to break a specimen.