Stress (physics)
From Simple English Wikipedia, the free encyclopedia
Stress in material science means that material is influenced in a way that may cause it to break or change its form.
Precisly spoken stress is the internal distribution of force per unit area that balances and reacts to external loads applied to a body. It is a second-order tensor with nine dimensions, but can be fully described with six dimensions due to symmetry in the absence of body moments. Stress is often broken down into its shear and normal components as these have unique physical significance. Often results from built up pressure due to the lack of an outlet.
Stress can be applied to solids, liquids and gases. Static fluids support normal stress (hydrostatic pressure) but will flow under shear stress. Moving viscous fluids can support shear stress (dynamic pressure). Solids can support both shear and normal stress, with ductile materials failing under shear and brittle materials failing under normal stress. All materials have temperature dependant variations in stress related properties.
[edit] Stress in one-dimensional bodies
All real objects occupy three-dimensional space. However, if two dimensions are very large or very small compared to the others, the object may be modelled as one-dimensional. This simplifies the mathematical modelling of the object. One-dimensional objects include a piece of wire loaded at the ends and viewed from the side, and a metal sheet loaded on the face and viewed up close and through the cross section.
