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A condensed algorithm for adaptive component mode synthesis is proposed to compute the dynamics of viscoelastic flexible multibody systems efficiently and accurately. As studied, the continuous use of modes derived from the initial configuration will lead to poor convergence when dealing with geometric nonlinearity caused by large deformations and overall rotations. The modal reduction at a series of quasi‐static equilibrium configurations should be updated accordingly. According to the loss rate of system energy in the updating process of modal bases, an adaptive mode selection is proposed to reserve the optimal modal bases with their modal number automatically so as to achieve a high‐accuracy simulation. In the proposed condensed iteration algorithm, the order of reduced dynamic equations in the Newton‐Raphson is far less than the number of the unknowns to be discrete in generalized‐α scheme. Using an analytical mapping between the two parts of unknowns, the new algorithm solves a small part of the unknowns iteratively and solves the others noniteratively. Therefore, the saving of time cost comes not only from the proposed adaptive component mode synthesis, but also from the proposed condensed iteration algorithm. The modal bases of subsystems are updated by a series of frame‐like quasi‐static equilibrium configurations independently, in conjunction with the Craig‐Bampton method. Thus, the challenges in the model reduced of extensive ranges of stiffness and damping are removed via the successively updated modal bases. Finally, three numerical tests are made to illuminate the high accuracy and efficiency of the new algorithm proposed. [ABSTRACT FROM AUTHOR]

Abstract An efficient and explicit topology optimization approach is initially proposed for eigenfrequencies of a rotating thin plate in this study. First of all, an accurate dynamic model of the rotating thin plate is established via the thin plate elements of the absolute nodal coordinate formulation (ANCF). When performing the modal characteristic analysis of the rotating thin plate at a prescribed angular velocity, the linear perturbation analysis is employed, during which the coupling between the membrane and bending deformations is considered. The coupling term makes the dynamic model established in the study more accurate than conventional models, especially in the case of large deformations. Then, the moving morphable components (MMC) are used to describe the topology of the plate. In the frame of MMC-based topology optimization, explicit geometrical parameters, positions, and orientations of the components are taken as the design variables so that the total number of the design variables can be greatly reduced. For the topology optimization, the sensitivities of a simple eigenfrequency and multiply repeated eigenfrequencies with respect to a design variable are analytically derived. During the optimization, in order to remove the localized modes in the low-density areas, the mass and stiffness matrices of the thin plate elements of ANCF are carefully penalized. Finally, four numerical examples are presented to validate the proposed topology optimization approach and to demonstrate its effectiveness for two objectives, i.e., maximizing either the first eigenfrequency or the gap between two consecutive eigenfrequencies of a rotating thin plate. Highlights • A new topology optimization approach for eigenfrequencies is proposed. • An accurate dynamic model for a rotating thin plate is established. • The eigenfrequency optimization design of the rotating thin plate is studied. • Two objectives are considered for the topology optimization of the thin plate. [ABSTRACT FROM AUTHOR]

Summary: An efficient method of model order reduction is proposed for the dynamic computation of a flexible multibody system undergoing both large overall motions and large deformations. The system is initially modeled by using the nonlinear finite elements of absolute nodal coordinate formulation and then locally linearized at a series of quasi‐static equilibrium configurations according to the given accuracy in dynamic computation. By using the Craig‐Bampton method, the reduced model is established by projecting the incremental displacements of the locally linearized system onto a set of local modal bases at the quasi‐static equilibrium configuration accordingly. Afterwards, the initial conditions for the dynamic computation for the reduced model via the generalized‐α integrator can be determined from the modal bases. The analysis of computation complexity is also performed. Hence, the proposed method gives time‐varying and dimension‐varying modal bases to elaborate the efficient model reduction. Finally, three examples are presented to validate the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

This paper introduces a new computational multibody system framework for developing accurate tire models using the finite element absolute nodal coordinate formulation (ANCF). Absolute nodal coordinate formulation finite elements are used to create the geometry and perform the finite element/multibody system analysis of the tires. The computational procedure used in this study allows for modeling composite tires and for using a continuum-based air pressure and contact tire force models. The absolute nodal coordinate formulation tire mesh, which allows for high spinning speed, has a constant inertia matrix and zero Coriolis and centrifugal forces. The concept of the absolute nodal coordinate formulation reference node, introduced recently, is used to develop linear connectivity conditions between the tire tread and rim, thereby allowing for imposing these linear conditions at a preprocessing stage. Using this approach, the dependent variables are eliminated at a preprocessing stage before the start of the simulation. The reference node, which is not associated with a particular finite element, is used to define the inertia of the rigid rims. The inertia coefficients associated with the rim reference nodes are first developed in terms of the absolute nodal coordinate formulation position and gradient coordinates. The rigidity of each rim is enforced during the dynamic analysis using six nonlinear algebraic constraint equations that are combined with the dynamic differential equations of motion using the technique of Lagrange multipliers. It is shown in this investigation that the concept of the absolute nodal coordinate formulation reference node can be used to develop a complete vehicle model using one absolute nodal coordinate formulation mesh in which the redundant variables are systematically eliminated at a preprocessing stage, and consequently, the number of differential and algebraic equations that need to be solved is significantly reduced. The use of the new approach proposed in this paper is demonstrated using a vehicle model described by one absolute nodal coordinate formulation mesh. [ABSTRACT FROM AUTHOR]

Abstract: A computational methodology for analysis of spatial flexible multibody systems, considering the effects of the clearances and lubrication in the system spherical joints, is presented. The dry contact forces are evaluated through a Hertzian-based contact law, which includes a damping term representing the energy dissipation. The frictional forces are evaluated using a modified Coulomb’s friction law. In the case of lubricated joints, the resulting lubricant forces are derived from the corresponding Reynolds’ equation. An absolute nodal formulation is utilized in flexible body formulation. The generalized-α method is used to solve the resulting equations of motion. The effectiveness of the methodology is demonstrated by two numerical examples. [Copyright &y& Elsevier]

• A novel computation and optimization methodology is proposed for studying a space antenna assembly dynamics. • An efficient particle swarm optimization algorithm is used to optimize the assembly manipulator joint trajectories. • The oriented bounding box contact detection method is used to avoid contact problems. • After completing assembly the satellite base attitude disturbance is minimized by using the optimized trajectories. The autonomous assembly technology can be used to construct large space structures such as space telescopes, satellite antennas and space stations. A novel computation methodology to study the assembly dynamics of a large space modular satellite antenna is proposed. The system rigid body and flexible body are respectively described by the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). A parameterized inverse kinematics resolution method is used to evaluate the arm joint rotation angles of a rigid assembly manipulator with 7 degree-of-freedom (DOF). To minimize the disturbance of the floating satellite base attitude, an efficient particle swarm optimization (PSO) algorithm with Latin hypercube sampling skill (LHS-PSO) is used to find the optimized arm joint trajectories of the assembly manipulator arms. In the optimization process the oriented bounding box (OBB) contact detection method is also embedded to eliminate the trajectories which may lead to the arm-satellite or arm-arm impact problems. Finally, two numerical examples are provided to validate the proposed computation methodology. The results show that the satellite base attitude almost return back to its initial state after completing the assembly process by using the optimized joint trajectories. [ABSTRACT FROM AUTHOR]