Chapter 6 Mechanical Properties Flashcards
elasticity
is the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed.
elastic deformation
the temporary change in length, volume, or shape produced in an elastic substance by a stress that is less than the elastic limit of the substance.
plastic deformation in metals
is the permanent distortion that occurs when a material is subjected to tensile, compressive, bending, or torsion stresses that exceed its yield strength and cause it to elongate, compress, buckle, bend, or twist.
* plastic deformation continued *
plastic means perminent
engineering stress
is the applied load divided by the original cross-sectional area of a material. Also known as nominal stress.
tensile stress
Tensile stress (σ) is the resistance of an object to a force that could tear it apart.
shear stress
often denoted by τ, is the component of stress coplanar with a material cross-section. It arises from the shear force, the component of the force vector parallel to the material cross-section.
engineering stress example
simple tension and torsion
tension = is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it.
torsion = the twisting or wrenching of a body by the exertion of forces tending to turn one end or part about a longitudinal axis while the other is held fast or turned in the opposite direction
states of stress example
3 other common stress states
compression
bi axial
hyrdostatic
strain
number that describes relative deformation or change in shape and size of elastic, plastic, and fluid materials under applied forces
tensile strain
the deformation or elongation of a solid body due to the application of a tensile force or stress. In other words, tensile strain is produced when a body increases in length as applied forces try to “stretch” it.
lateral strain
the ratio of the change in diameter of a circular bar of a material to its diameter due to deformation in the longitudinal direction
shear strain
amount of contortion caused by the sliding of plane layers over each other within a deformity