.. _materialCommands: Material Commands ----------------- Like many finite element applications, all nonlinear elements have associated with them a material. It is the material in conjunction with the element geometry that provides the force-displacement response of the element. In OpenSees materials are divided into three general types: #. **uniaxial materials** which define a uniaxial (1 dimensional) stress-strain relationship. #. **nDimensional materials** which define multi-dimensional (plane stress, plane strain, or 3d) stress-strain relationships. #. **sections** which define coupled moment-curvature and axial-deformation relationships for beam column elements. .. figure:: figures/OpenSeesMaterials.png :align: center :width: 400px :figclass: align-center OpenSees Materials .. toctree:: :maxdepth: 1 material/uniaxialMaterial material/ndMaterial .. material/section For simple investigation of material/section behavior, try the built-in material testing commands. .. toctree:: :maxdepth: 1 material/matTestCommands