1 - Structural Design - Terminologies
modulus of elasticity
a coefficient of elasticity of a material expressing the RATIO BET. UNIT STRESS and the corresponding UNIT STRAIN caused by the stress.
stress-strain diagram
is a graphic representation of the relationship between unit stress values and the corresponding unit strains for a specific material
elastic limit
maximum stress below which the material does not return to its original length but has incurred a permanent deformation we call permanent set
proportional limit
maximum stress which the material springs back to the original length when the load is released
rapture strength
stress at which material specimen breaks
malleablity
the ability of the material to regain and rebound to original shape when the load is released
strain-rate effect
the behaviour an increased rate of load application can cause in normally ductile material
temperature effect
the brittle behavior low temperatures can cause in a normally ductile material
creep
the gradual permanent deformation of a body produced by a continued application of stress or prolonged exposure to heat
permanent set
the inelastic strain remaining in the material after complete release of the stress producing deformation
ultimate strength
the maximum stress that can be attained immediately before actual failure or rapture
allowable stress
the maximum unit stress permitted for a material in the design of a structural member usually a fraction of the material's elastic limit, yield strength, or ultimate strength. also called working stress
elasticity
the property of a material that enables it to deform in response to an applied force and to recover its original size and shape upon removal of the force
ductility
the property of a material that enables it to undergo plastic deformation after being stressed beyond the elastic limit and before rupturing.
brittleness
the property of material that causes it to rapture suddenly under stress with little evident deformation. they give no warning of impending material
toughness
the property of material that enables it to absorb the energy before rapturing, represented by the area under the stress-strain curve derived from a tensile test of the material
elastic range
the range of unit stress for which a material exhibits elastic deformation
yield strength
the stress necessary to produce specific limiting permanent set in a material. it is used to determine the limit of usefulness of a material having a poorly defined poor stress
yield point
the stress wherein the deformation increases without any increase in the load. the material at some portion shows a decrease in its cross section
stress relaxation
the time-dependent decrease in stress in a constrained material under a constant load
fatigue
the weakening or failure of material at a stress below the elastic limit when subjected to a repeated series of stresses
