The equilibrium equation, the compatibility condition, and the material law are the three fundamental concepts of the theory of structures. We have researched and understood the compatibility condition in structures as well as in elasticity. This has lead to the formulation of two direct stress calculation methods: the integrated force method (IFM) for finite element discrete structures, and the completed Beltrami-Michell formulation (CBMF) in elasticity. The benefits from the new methods are presented.

A conical bearingless motor/generator imparts torque and forces in three orthogonal axes on a body without contact between the rotating and the stationary components. The main elements are a concentric rotor and stator separated by an air gap.