In materials science, what does the term 'stress' refer to?

The term 'stress' in materials science specifically refers to the internal resisting force per unit area when an external load or force is applied. Stress is quantified as the force exerted on an object divided by the area over which that force is distributed, typically measured in Pascals (Pa) or pounds per square inch (psi). This concept is critical in understanding how materials behave under various loading conditions, as it helps predict whether a material will deform, yield, or fracture.

Understanding stress is essential for engineers and material scientists when designing components that must withstand specific loads without failing. For instance, in structural applications, knowing the stress experienced by a beam can aid in determining the appropriate material and dimensions necessary to ensure safety and functionality.

The other definitions—tendency to deform, change in size or shape, and total energy applied—are related concepts but do not accurately define 'stress' in the context of materials science. Deformation is a result of stress, rather than a description of stress itself. Therefore, identifying stress as the internal resisting force per unit area provides clarity and precision in the study of material behavior under load.