
The following are basic definitions and equations used to calculate the strength of materials. The ultimate strength refers to the point on the engineering stress–strain curve corresponding to the stress that produces fracture. Material strength refers to the point on the engineering stress–strain curve (yield stress) beyond which the material experiences deformations that will not be completely reversed upon removal of the loading and as a result the member will have a permanent deflection. The calculated stiffness and mass distribution of the member may be used to calculate the member's dynamic response and then compared to the acoustic environment in which it will be used. The calculated buckling load of the member may be compared to the applied load. The calculated deflection of the member may be compared to a deflection criteria that is based on the member's use. The calculated stresses may then be compared to some measure of the strength of the member such as its material yield or ultimate strength. Once the state of stress and strain within the member is known, the strength (load carrying capacity) of that member, its deformations (stiffness qualities), and its stability (ability to maintain its original configuration) can be calculated. With a complete description of the loading and the geometry of the member, the state of stress and of state of strain at any point within the member can be calculated. This requires a complete description of the geometry of the member, its constraints, the loads applied to the member and the properties of the material of which the member is composed. The stresses and strains that develop within a mechanical member must be calculated in order to assess the load capacity of that member. The applied loads may be axial (tensile or compressive), or shear. Deformation of the material is called strain when those deformations too are placed on a unit basis. The stresses acting on the material cause deformation of the material in various manner. A load applied to a mechanical member will induce internal forces within the member called stresses when those forces are expressed on a unit basis. In materials science, the strength of a material is its ability to withstand an applied load without failure. Strength of materials, also called mechanics of materials, is a subject which deals with the behavior of solid objects subject to stresses and strains.

Strength of Materials Basics and Equations | Mechanics of Materials Equations
