Some of the objects you may have observed, such as a rubber band, maybe readily stretched. But can an iron rod be stretched? Isn't it impossible? In this article, we will study more about the characteristics of solids and how numbers like stress may help us comprehend the strength of solids.
Stress and strain are two words used in physics to describe the forces that cause things to deform. Deformation is the change in the shape of an item caused by the application of force. Deformation can also be caused by very tiny forces. The item feels it as a result of external forces, such as squeezing, squashing, twisting, shearing, ripping, or pushing the objects apart.
In mechanics, stress is the force delivered per unit area. It is represented by the formula below.
σ=FA
where,
Stress is defined as the ratio of internal force F generated when a substance gets deformed to area A wherein force is applied. At equilibrium, the internal force equals the amount of the applied external force.
Strain is the ratio of the amount of deformation experienced by the body in the direction of force applied to the body's original sizes. The solid's deformation in terms of length is provided below.
ϵ=δlL
Where,
ϵ is the strain caused by the imposed tension
l represents a length change
L is the material's original length.
Strain is the ratio of form or size change to original shape or size. It is stated numerically since it has no dimensions.
Because strain is a dimensionless term that defines the relative change in form. Depending on the tension applied, the body might feel two forms of strain.
The stress-strain curve for a material illustrates the connection between stress and strain. The strain values on the curve correspond to the stress incurred by various loads on the item.
The stress-strain diagram has the following points or regions:
While studying springs and elasticity in the nineteenth century, English scientist Robert Hooke found that numerous materials displayed a similar characteristic when the stress-strain connection was studied. Hooke's Law defined a linear area in which the force required to stretch material was proportionate to its extension.
Hooke's Law says that within the elastic limit of a material, the strain is proportional to the applied stress.
Hooke's law is usually stated mathematically as:
F = –k.x
Where F is the force, x is the extension length, and k is the proportionality constant known as the spring constant in N/m.