DEVELOPMENT OF A NEW MULTI-FLEXIBLE BODY DYNAMICS (MFBD) PLATFORM : A RELATIVE NODAL DISPLACEMENT METHOD FOR FINITE ELEMENT ANALYSIS

摘要

Recently the analysis of multi flexible body dynamics has been a hot issue in the area of the computational dynamics research. There have been two main streams of research. One is the extension of conventional FEA theory for the multi flexible body systems, using either the total Lagrangian or updated Lagrangian method. The other is the extension of the multi body dynamics theory. The latter is the topic of this research. One essential requirement of a shape function in FEA theory is ability to represent the rigid body motion. This research proposes to use the moving reference frame to represent the rigid body motion. Therefore, the shape function does not need to have ability to represent the rigid body motion. The moving reference frame covers the rigid body. Since the nodal displacements are measured relative to its adjacent moving nodal reference frame, they are still small for a truss structure undergoing large deformations if the element sizes are small. As a consequence, many element formulations developed under small deformation assumptions are still valid for structures undergoing large deformations, which significantly simplifies the equations of equilibrium. Several numerical examples are analyzed to demonstrate the efficiency and validity of the proposed method.