Metals - Cambridge OCREnsuring structural integrity

Metals can be reinforced or stiffened to improve the properties of the material and its ability to resist forces.

Forces act on materials all the time - even if a material appears stationary it still has a force acting on it. There are five terms used to describe what type of force can act on a material:

• tension - a pulling force
• compression - a pushing force
• bending - forces at an angle to the material
• torsion - a twisting force
• shear - forces acting across the material

Sheet metal can be strengthened and stiffened to resist these forces using the following methods:

• bending - a fold or bend in the material will give it structural strength as the fold will give it a triangular shape, which is the strongest shape for resisting compression and tension - an effect often used on metal roofing
• hemmed edge - folding over the material at the edges will give it structural integrity and allow it to resist compression, tension, torsion and shear forces - an effect often used on the edge of car doors
• embossing - pressing ribs or similar shapes into the material alters its aesthetic and also provides structural integrity, an effect often used on the draining area of sinks for reinforcement - as well as the added function of helping drain excess water into the sink
• stretching into shape - a flat shape is weakest at its middle point and will deform under compression; stretching the material into a specific shape gives greater strength through the curved or bent shape of the item - which spreads the load out to the edges to resist compression