0- Definitions.
i) Elasticity : The property on account of which a body regains its original size and shape on removal of external deforming force is called as elasticity.
ii) Plasticity : The property on account of which a body does not regain its original size and shape on removal of applied force is called as plasticity.
iii) Rigidity : The property on account of which a body does not change its size and shape, even if large force is applied on it, is called as rigidity.
iv) Deforming force: The force applied on elastic body which is responsible for deformation (change size and shape) of the body, is called as deforming force.
v) Internal restoring force: Under deformed condition, every shifted molecule tries to achieve its original position (because of elasticity). The force which is responsible to restore original size and shape of the body is called as internal restoring force.
vi) Stress: The restoring force per unit cross-sectional area is called as stress.
vii) Strain : The change in dimensions per unit original dimensions is called as strain.
viii) Elastic limit: The stress corresponding to the limiting value of the load, which is when applied and subsequently released, does not produce permanent deformation is called as elastic limit.
ix) Hooke’s law: It states that, within elastic limit, stress is directly proportional to the strain.
x) Young’s Modulus of Elasticity (Y): It is defined as the ratio of tensile stress to tensile strain.
xi) Bulk Modulus of Elasticity (K): It is defined as the ratio of volume stress to volume strain.
xii) Modulus of Rigidity (h): It is defined as the ratio of shearing stress to shearing strain.
xiv) Factor of safety : The ratio of maximum load that the structure can bear, to the actual load on the structure.
xv) Breaking stress : The maximum stress upto which wire can be loaded or wire can bear is called as breaking stress.
xvi) Ultimate stress : The ratio of maximum load that the specimen is capable of withstanding to its original cross-sectional area.
xvii) Working stress : The ratio of actual load to the original cross-sectional area.
