Elastic Relaxation Time The time delay in restoring the original configuration after removal of deforming force is called elastic relaxation time .
For quartz and phosphor bronze this time is negligible . Elastic After Effect
The temporary delay in regaining the original configuration by the elastic body after the removal of deforming force , is called elastic after effect .
Elastic Fatigue
The property of an elastic body by virtue of which its behaviour becomes less elastic under the action of repeated alternating deforming force is called elastic fatigue .
Ductile Materials
The materials which show large plastic range beyond elastic limit are called ductile materials , e . g ., copper , silver , iron , aluminum , etc .
Ductile materials are used for making springs and sheets . Brittle Materials
The materials which show very small plastic range beyond elastic limit are called brittle materials , e . g ., glass , cast iron , etc .
Elastomers
The materials for which strain produced is much larger than the stress applied , with in the limit of elasticity are called elastomers , e . g ., rubber , the elastic tissue of aorta , the large vessel carrying blood from heart . etc .
Elastomers have no plastic range . Elastic Potential Energy in a Stretched Wire
The work done in stretching a wire is stored in form of potential energy of the wire .