define moduls of elasticity,stress,strain and poissons ratio
Answers
1)The modulus of elasticity of a material is a measure of its stiffness. It is equal to the stress applied to it divided by the resulting elastic strain.
2)Stress
Stress is defined as the force per unit area of a material.
i.e. Stress = force / cross sectional area:
Definitions of Stress, Strain and Youngs Modulus
where,
σ = stress,
F = force applied, and
A= cross sectional area of the object.
Units of s : Nm-2 or Pa.
3)Strain
Strain is defined as extension per unit length.
Strain = extension / original length
Definitions of Stress, Strain and Youngs Modulus
where,
ε = strain,
lo = the original length
e = extension = (l-lo), and
l = stretched length
Strain has no units because it is a ratio of lengths.
We can use the above definitions of stress and strain for forces causing tension or compression.
If we apply tensile force we have tensile stress and tensile strain
If we apply compressive force we have compressive stress and compressive strain.
4)Poisson's ratio is the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force. Tensile deformation is considered positive and compressive deformation is considered negative. The definition of Poisson's ratio contains a minus sign so that normal materials have a positive ratio. Poisson's ratio, also called Poisson ratio or the Poisson coefficient, or coefficient de Poisson, is usually represented as a lower case Greek nu, n.
If your browser does not interpret Symbol font properly, Greek nu, n may instead look like a bold face Latin n.