Strength of materials

Strength of materials is the study of strength and elastic behaviour of engineering materials. Strength is considered in terms of compressive strength, tensile strength, and shear strength.

Tensile stress is a loading that tends to produce stretching on a material by the application of axially directed pulling forces. Materials can withstand some tensile loading, but if enough force is applied, they will eventually break into two parts. Steel is an example of a material with high tensile strength.

Compressive strength is the capacity of a material to withstand axially directed pushing forces. When the limit of compressive strength is reached, materials are crushed. Concrete can be made to have high compressive strength.

Shear stress is caused when a force is applied to produce a sliding failure of a material along a plane that is parallel to the direction of the applied force.

Ultimate strength is an attribute directly related to a material, rather than just specific specimen of the material, and as such is quoted force per unit of cross section area (). For example, Ultimate Tensile Strength (UTS) of mild steel is . It is useful to remember that .

Factor of Safety is a designed constraint that an engineered component or structure must achieve. FS = UTS/f. For example to achieve a factor of safety of 4, a the allowable stress on a mild steel component can be worked out as .