General Concepts and Definitions
· Strength The
ability to sustain load.
Stiffness Push per move; the ratio
of deformation to associated load level.
Stability The ability of a structure
to maintain position and geometry. Instability involves collapse that is
not initiated by material failure. External stability concerns the ability of a
structure's supports to keep the structure in place; internal stability
concerns a structure's ability to maintain its shape.
Ductility The amount of inelastic
deformation before failure, often expressed relative to the amount of
strength is measured by a stress level at which there is a permanent and significant
change in the material's load carrying ability. For example, the yield stress,
or the ultimate stress.
stiffness is most commonly expressed in terms of the modulus of elasticity: the
ratio of stress to strain in the linear elastic range of material behavior.
Stability As it is
most commonly defined, the concept of stability applies to structural elements
and systems, but does not apply to materials, since instability is defined
as a loss of load carrying ability that is not initiated by material failure.
ductility can be measured by the amount of inelastic strain before failure compared
to the amount of elastic strain. It is commonly expressed as a ratio of the
maximum strain at failure divided by the yield strain.