What type of stress occurs when external tensile forces act parallel but not in line?

When external tensile forces act parallel but not in line, the type of stress that occurs is shear stress. Shear stress arises when forces are applied in opposite directions, causing layers of material to slide against one another. This is often visualized with two parallel pieces of material where one is pushed in one direction while the other is pulled in the opposite direction.

In this scenario, the forces create an internal resistance within the material, typically leading to a distortion rather than a change in length. The result is that parts of the material try to slide past each other, which characterizes shear stress as distinct from tensile or compressive stress, which involve stretching or compressing a material along the same line of force. Working stress, on the other hand, refers to the stress under which a material is designed to safely operate, but does not specifically address the orientation of the forces involved.