The tensile strength is governed by the intensity of force on a normal cross-section of a wire, and not by the total force.
Fig: Tensile stress
Consider a uniform bar of cross sectional area A subjected to an axial tensile force P. The stress at any section x-x normal to the line of action of the tensile force P is specifically called tensile stress pt . Since internal resistance R at x-x is equal to the applied force P, we have,
pt = (internal resistance at x-x)/(resisting area at x-x)
Under tensile stress the bar suffers stretching or elongation.
- Tensile Stress is the stress state leading to expansion, that is, the length of a material tends to increase in the direction of the force / stress while the volume of the material stays constant. Generally, tensile stress occurs when a material is subjected to pulling or stretching force.
- Stress is defined as a force applied over a cross-sectional area, with typical units of pounds per square inch (psi) or Newton’s per square meter, also known as Pascals (Pa). The type of stress that a material is exposed to will always depend on how the force is being applied.
- An understanding of tensile stress is essential in selecting materials for mechanical engineering and design applications.