Multi-field Coupling Dynamics For Multi-body System

With the development of industrial technology, multi-field coupling problem ofthe multi-body system has become a key problem in the field of aerospace, vehicles andso on, which includes the rigid-flexible coupling, rigid-liquid coupling,rigid-liquid-flexible coupling, rigid-flexible-thermal coupling. In this dissertation,dynamic modeling methods for multi-body system considering multi-field coupling areinvestigated. Combining the dynamic equations for the two-dimensional liquid-filledrectangular tank and the dynamic equations for the flexible beams, the dynamic modelfor the rigid-liquid-flexible coupling multi-body system is established. Furthermore,combining the heat conduction equations and dynamic equations for the flexible beamsincluding thermal effect, the dynamic model for the rigid-flexible-thermal couplingmulti-body system is also established. Kinematic constraint equations are led into thedynamic equations to derive the Lagrange equations of the first kind for multi-fieldcoupling multi-body system. The main content of this thesis include the followingaspects:In chapter1, the recent research on the multi-field coupling dynamics issummarized and then the objective of the investigation is proposed.The dynamic model for multi-body system considering the rigid-liquid coupling isestablished in chapter2. Based on the theorem of momentum and the theorem ofmoment of momentum, and combined with the fluid dynamics equations andsolid-fluid boundary conditions, the continuum dynamic equations for thetwo-dimensional liquid-filled rectangular tank are derived. Selecting the appropriatevelocity potential function, the dynamic equations are discretized into ordinarydifferential equations by using Galerkin method. Kinematic constraint equations are ledinto the dynamic equations to derive the Lagrange equations of the first kind for the rigid-liquid coupling multi-body systems composed of several liquid-filled rectangulartanks. As an example, the rigid-liquid coupling dynamics are analyzed for the tanktrucks. The effect of baffle on the reduction of the liquid sloshing is also investigated.The dynamic model for multi-body system considering the rigid-liquid-flexiblecoupling is established in chapter3. Based on continuum mechanics theory and finiteelement theory, and using the hybrid-coordinate formulation, the variational dynamicequations for the planar beam undergoing large overall motion are derived.Furthermore, combining dynamics equations of the flexible beam and dynamicsequations of the liquid-filled tank, kinematic constraint equations are led into thedynamic equations to derive equations for rigid-liquid-flexible coupling multi-bodysystems. Through the numerical simulations of the liquid-filled tank attached with aflexible beam, the characteristics of the rigid-Liquid-flexible coupling dynamicperformance and the transformation of energy for conservative system are analyzed.The dynamic model for the rigid-flexible-thermal coupling multi-body system isestablished in chapter4. Based on strain-displacement relationship with the inclusion ofthe thermal effect and considering the relation between the heat flux and the rotationalangle as well as the angular deformation, the heat conduction equations and thedynamic equations for the flexible beam are derived using finite element method andvirtual work principle. Constraint equations are led into the equations to derive the heatconduction equations and dynamic equations of the first kind for the rigid-flexible-thermal coupling multi-body systems. The numerical simulations of thethermally included hub-beam system applied with solar heat flux are carried out toinvestigate the rigid-flexible-thermal coupling performance. The influence of theradiation angle, damping coefficient, the ratio of the moment of inertia and the responsetime ratio on the instability of the system is investigated, and the stability region iscalculated. Furthermore, considering the relation between the heat flux and the spatialdisplacement, the thermally induced vibration performance of the beam is studied incase of the sudden change of the heat environment.