Stress and strain are physical properties of a material when it is subjected to pressure or a load. A solid has the ability to deform when under pressure. The pressure per unit area of the solid is referred to as stress, while the deformation caused by this stress is called the resulting strain. Strain and stress are closely related, with strain occurring only because of stress. This article will discuss the differences and the relationship between stress and strain.
It is difficult to imagine that a substance as hard as rocks can bend and break under constant pressure. However, once students understand the concepts of stress and strain, they can comprehend how rocks give way and form new rocks. Three words, all beginning with “S” (stress, strain, and structure) and used in geology, are often a source of confusion among geology students. Although stress and strain are used in everyday English, this discussion focuses on their meaning in structural engineering and geology.
Consider being put under pressure—wouldn’t you feel stressed? This is a helpful way to remember the meaning of stress in geology. Students are given Play-Doh to create imaginary rocks and then apply pressure (stress) on them to see if they deform (strain) and observe the resulting structure. While using putty or Play-Doh provides an idea of what happens when significant stress (pressure per unit area) is applied to rocks, it is important to understand that deformities in rocks occur due to thousands of years of continuous stress.
Key Takeaways
- Stress is the pressure per unit area applied to a rock or solid.
- Strain is the deformation or change in dimension of the rock as a proportion of the original dimension, making it a dimensionless quantity.
- Both stress and strain are essential properties of rocks that explain deformation in rocks and the formation of new layers of rocks over a long time scale.
