Chapter 4 TERMS Flashcards
define brittleness
Relative inability of a material to deform plastically before it fractures.
define compressive stress
Compressive force per unit area perpendicular to the direction of applied force.
define compressive strength
Compressive stress at fracture.
define ductility
Relative ability of a material to elongate plastically under a tensile stress. This property is reported quantitatively as percent elongation.
define elastic strain
Amount of deformation that is recovered instantaneously when an externally applied force or pressure is reduced or eliminated.
define elastic modulus
(also modulus of elasticity and Young’s modulus)—Stiffness of a material that is calculated as the ratio of elastic stress to elastic strain.
define flexural strength
force per unit area at the instant of fracture in a test specimen subjected to flexural loading.
define flexural/bending stress
orce per unit area of a material that is subjected to flexural loading.
define fracture toughness
The critical stress intensity factor at the point of rapid crack propagation in a
solid containing a crack of known shape and size.
define hardness
Resistance of a material to plastic deformation, which is typically produced by an indenta- tion force
define malleability
Ability to be hammered or compressed plastically into thin sheets without fracture.
define percent elongation
Amount of plastic strain, expressed as a percent of the original length, which
tensile test specimen sustains at the point of fracture (Ductility).
define plastic strain
Irreversible deformation that remains when the externally applied force is reduced or eliminated.
define pressure
Force per unit area acting on the surface of a material (compare with Stress).
define proportional limit
Magnitude of elastic stress above which plastic deformation occurs.
define resilience
The amount of elastic energy per unit volume that is sustained on loading and released upon unloading of a test specimen
define shear stress
Ratio of shear force to the original cross-sectional area parallel to the direction of the applied force.
define shear strength
Shear stress at the point of fracture.
define stress
Force per unit area within a structure subjected to a force or pressure (see Pressure).
define stress concentration
Area or point of significantly higher stress that occurs because of a structural discontinuity such as a crack or pore or a marked change in dimension.
define strain
Change in dimension per unit initial dimension. For tensile and compressive strain, a change in length is measured relative to the initial reference length.
define stress intensity
stress intensity factor)—Relative increase in stress at the tip of a crack of given shape and size when the crack surfaces are displaced in the opening mode (also Fracture Toughness).
define strain hardening
Increase in strength and hardness and decrease in ductility of a metal that results from plastic deformation.
define strain rate
Change in strain per unit time during loading of a structure.
define strength
Maximum stress that a structure can withstand without sustaining a specific amount of plastic strain (yield strength); (2) stress at the point of fracture (ultimate strength).
define tensile stress
Ratio of tensile force to the original cross-sectional area perpendicular to the direction of applied force.
define tensile strength
Tensile stress at the instant of fracture.
define toughness
Ability of a material to absorb elastic energy and to deform plastically before fracturing;
measured as the total area under a plot of tensile stress versus strain.
define true stress
Ratio of applied force to the actual (true) cross-sectional area; however, for convenience, stress is often calculated as the ratio of applied force to the initial cross-sectional area.
define yield strength
The stress at which a test specimen exhibits a specific amount of plastic strain.
