The resistance of materials (RDM) may be an explicit discipline of the mechanics of continuous media permitting the computation of the stresses and deformations within the structures of the various materials (machines, engineering, building, and civil engineering).
The RDM makes it potential to cut back the study of the world behavior of a structure (relation between stresses – forces or moments – and displacements) thereto of the native behavior of the materials composing it (relation between stresses and deformations). the target is to style the structure in line with criteria of resistance, acceptable deformation, and acceptable monetary value.
When the intensity of the strain will increase, there’s 1st elastic deformation (the material is malformed proportionately to the force applied and returns to its original form once the strain disappears), typically followed (depending on the plasticity of the material) a plastic deformation (the material doesn’t come to its original form once the strain disappears, residual deformation remains), and at last rupture (the stress exceeds the intrinsic strength of the material).
In its current use, the RDM uses the subsequent assumptions:
The material is:
elastic (the material returns to its original form once a loading-unloading cycle),
linear (the deformations area unit proportional to the constraints),
homogeneous (the material is of identical nature altogether its mass),
isotropic (the properties of the fabric area unit identical altogether directions).
The problem is :
- in tiny displacements (the deformations of the structure ensuing from its loading area unit negligible and don’t have an effect on much, not its geometry),
- quasi-static (no dynamic effect),
- almost equal (no modification in temperature).
These simplifications permit straightforward and quick calculations, machine-controlled (by computer) or by hand. However, they’re generally inappropriate, in particular:
Highly heterogeneous or anisotropic materials area unit ofttimes used, like composite materials, wood, bolstered concrete;
some applications involve vital elastic deformations, particularly with versatile materials (composite materials, polymers), it’s then now not within the linear domain or that of tiny displacements.