Obtaining the equations of motion for an element in finite element analysis (FEA) model in the analysis of a multi-body system (MBS) having component elastic elements represents an important (maybe the main) step to build a soft able to solve such a problem numerically. In use FEA in the study of a MBS with elastic elements, the method of Lagrange's equations is especially used at present. This method presents the advantages of a homogeneous writing and the possibility to follow the operations easier. However, there are also equivalent formulations, developed by analytical mechanics, for approaching such a mechanical system. The earning of these alternative forms will be presented, by comparison.

在具有组件弹性元件的多体系统（MBS）的分析中，获得有限元分析（FEA）模型中元素的运动方程式是构建能够解决此类问题的软件的重要（也许是主要的）步骤。数字上的问题。在有限元法用于具有弹性单元的MBS研究中，目前特别使用拉格朗日方程式。此方法具有均质写入的优点，并且可以更轻松地进行操作。但是，也存在由分析力学开发的等效公式，用于接近这种机械系统。通过比较将显示这些替代形式的收入。