Fasteners are subjected to ___________ stress when forces try to pull the assembly apart or push it together along its axis.

The situation described involves forces acting along the axis of a fastener, which leads to a specific type of stress. When discussing fasteners in assembly mechanics, the term that accurately reflects the stress occurring when forces pull the assembly apart is tensile stress. Tensile stress occurs when a material is subjected to a pulling force, causing it to elongate and potentially reach its failure point.

In contrast, compressive stress would occur when forces are pushing an assembly together, which is the opposite of what is being described. Strain is a measure of deformation and is a result of stress but does not describe the type of stress itself. Static stress generally refers to forces that are constant and unchanging, but does not specify the directional nature relevant to the pull or push along the axis. Therefore, the correct characterization of the forces described in the question is tensile stress.