Principles of flexible body general dynamic equations derivation based on the Craig–Bampton model and of their practically significant approximations

In the article dynamic equations of motion of flexible bodies' large displacement within a multibody system with small deformations are given. In the process of derivation finite element method (FEM) and the Craig–Bampton method of FEM model's matrices reduction are used. No additional approximations are involved, thus obtaining the most general equations in given problem definition. Analysis of difficulties arising in practical using of the derived general dynamic equations is conducted, and ways to overcome those are suggested. Modified equations derivation using more general approximation than is assumed in literature is presented. An example of derived flexible structures' dynamic equations software realization is given.