Elastic/Plastic Deformation

Summary

Elastic/Plastic Deformation - When designing a structure, an engineer will consider two types of deformation; elastic and plastic.

Technical Information

All materials deform elastically, although some materials only deform elastically at imperceptibly low strains. After a material has reached its elastic limit, it will begin to yield which means that it will deform more without any extra stress being added to it. This is plastic deformation.

If a material is deformed elastically, it will return to its original shape when the load is removed. If a material is deformed plastically, it is deformed permanently and will not return to its original shape when unloaded.

In a ductile material, such as steel, once it reaches the plastic limit a hinge is formed. In a brittle material, such as concrete, it simply cracks.

Elastic deformation is usually considered when calculating the deflection of an element, whilst plastic deformation is usually considered when calculating the load required for an element to fail.