Stress analysis is an engineering discipline that determines the stress (physics) in materials and structures subjected to static or dynamic forces or loads (see statics and dynamics). The aim of the analysis is usually to determine whether the element or collection of elements, usually referred to as a structure, can safely withstand the specified forces. This is achieved when the determined stress from the applied force(s) is less than the ultimate tensile strength or ultimate compressive strength the material is known to be able to withstand, though ordinarily a safety factor is applied in design.
Most often the term stress analysis is applied to mathematical or computational methods applied to structures that do not yet exist, such as a proposed aerodynamic structure, or to large structures such as a building, a machine, a reactor vessel or a piping system.
A stress analysis can also be made by actually applying the force(s) to an existing element or structure and then determining the resulting stress using sensors, but in this case the process would more properly be known as testing (destructive or non-destructive). In this case special equipment, such as a wind tunnel, or various hydraulic mechanisms, or simply weights are used to apply the static or dynamic loading.
When forces are applied, or expected to be applied, repeatedly, nearly all materials will rupture or fail at a lower stress than they would otherwise. The analysis to determine stresses under these dynamically forced conditions is termed fatigue analysis and is most often applied to aerodynamic structural systems.