Development of New Generation of Multibody System Computer Codes

Multibody system (MBS) computer codes currently being used are based on three-decade old technology that is failing to respond to new modeling challenges. Modern and complex ground vehicle models, for example, include significant details that cannot be captured using existing MBS software technology. This paper discusses a new Department of Defense (DoD) initiative focused on the development of new generation of MBS computer codes that have capabilities and features that are not provided by existing MBS software technology. This old technology fails to meet new challenges of developing more detailed models in which the effects of significant changes in geometry and large deformations cannot be ignored. New applications require accurate continuum mechanics based vehicle/soil interaction models, belt and chain drive models, efficient and accurate continuum based tire models, cable models used in rescue missions, models that accurately capture large deformations due to thermal and excessive loads, more accurate bio-mechanics models for ligaments, muscles, and soft tissues (LMST), etc. Addressing these modeling and virtual prototyping challenges is necessary in order for industries and federal laboratories to have a new generation of MBS software that will serve their mission. The development of such a new software technology will require a successful integration of computational geometry (CG), FE, and MBS algorithms. Existing MBS algorithms have a structure and formulations that do not allow for such a successful CG/FE/MBS integration. The kinematic description used in existing finite element formulations is not consistent with CG methods (B-spline and NURBS) used in CAD, that is, the geometry of CAD models is not preserved when these models are converted to a FE mesh for performing the analysis. Furthermore, the use of CG methods as analysis tools is also not recommended for MBS applications that require certain treatments of the joints and constraints. For this reason, a fundamentally different FE approach is required for the new integration of CG, large displacement FE, and MBS algorithm. This will be accomplished in the DoD initiative using the nonlinear FE absolute nodal coordinate formulation (ANCF) that has many desirable features. This paper discusses the feasibility of developing such a new software technology that is required for accurate virtual prototyping of vehicles, machines, and equipment.