Mechanical Properties of Solids Flashcards
Deforming Force
A force which changes the size or shape of a body
Elasticity
Property of body being able to regain original size and shape after the removal of deforming force
Perfectly elastic
Body regains its original size and shape completely and immediately after the removal of deforming force
Plasticity
If a body does not regain its orginal size and shape even after the removal of deforming force
Equilibrium Separation
For some particular separation (r), potential energy is minimum and interatomic force is zero
Explain elastic behaviour in terms of interatomic force
- When interatomic r is large, potential energy is negative, interatomic force is attractive
- Becomes minimum at equilibrium separation
- When separation below r, potential energy increases and interatomic force is repulsive
Strain
Ratio of change in any dimension produced in the body to original dimension
Strain = Change in dimension / Original dimension
Stress
Internal restoring force setup per unit area of cross - section of the deformed body
Stress = Applied Force / Area
Longitudinal strain
Increase in lenth per unit original length
= delta l / l
Volumetric Strain
Change in volume per unit orignal volume
= delta V / V
Shear strain
Angle theta through which a face originally perpendicular to the fixed face turned on applying tangential deforming force
= Relative displacement between 2 parallel planes / Distance between parallel planes
Elastic limit
Maximum stress within which the body completely regains its original size and shape after the removal of deforming fortce
Hooke’s Law
Extension in a wire is directly proportional to the load applied
Stress / Strain = Constant
Modulus of elasticity
Ratio of stress to the corresponding striain, within the elastic limit
E = Stress / Strain
Young’s Modulus of elasticity
Within the elastic limit, ratio of longitudinal stress to the longitudinal strain
Young’s Modulus Formula
Y = [F / pi (r^2)] * [l / delta l]