Flexible Multibody System Model of a Spider Crane with two Extendable Booms

2021 ◽  
Author(s):  
Anja Patricia Regina Lauer ◽  
Boris Blagojevic ◽  
Otto Lerke ◽  
Volker Schwieger ◽  
Oliver Sawodny
Keyword(s):  
Multibody System ◽  
System Model ◽  
Flexible Multibody System ◽  
Flexible Multibody

Parametric Flexible Multibody Model for Material Removal During Turning

2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Achim Fischer ◽  
Peter Eberhard ◽  
Jorge Ambrósio
Keyword(s):  
Material Removal ◽  
Degrees Of Freedom ◽  
Multibody System ◽  
Parametric Model ◽  
System Model ◽  
Flexible Multibody System ◽  
Multibody Model ◽  
Input And Output ◽  
Flexible Multibody ◽  
Output Behavior

This work presents a flexible multibody system model for the inside turning of thin-walled cylinders. The model accounts for the varying input and output behavior of the workpiece due to workpiece rotation and tool feed, as well as the changing workpiece dynamics due to material removal. A parametric approach is used to incorporate the effect of material removal. Hereby, a number of systems are precalculated for different machined states that are then interpolated to obtain the model for the desired machined state. As different systems typically have different vectors of degrees of freedom, a preprocessing step must be added to guarantee compatibility and thus a meaningful interpolation. In this work, two ways of obtaining a parametric model are presented that lead to similar results. The parametric model is then used to analyze stability of an inside turning operation. By taking into account the varying workpiece dynamics, an improved tool feed is suggested that would allow to greatly reduce the cycle time.

Flexible Multibody Dynamics Formulation by Hamilton’s Equations

2010 ◽  
Author(s):  
Martin M. Tong
Keyword(s):  
Multibody Dynamics ◽  
Multibody System ◽  
Mass Matrix ◽  
Equations Of Motion ◽  
Flexible Multibody Dynamics ◽  
Flexible Body ◽  
Flexible Multibody System ◽  
Generalized Coordinates ◽  
Flexible Multibody ◽  
The Matrix

Numerical solution of the dynamics equations of a flexible multibody system as represented by Hamilton’s canonical equations requires that its generalized velocities q˙ be solved from the generalized momenta p. The relation between them is p = J(q)q˙, where J is the system mass matrix and q is the generalized coordinates. This paper presents the dynamics equations for a generic flexible multibody system as represented by p˙ and gives emphasis to a systematic way of constructing the matrix J for solving q˙. The mass matrix is shown to be separable into four submatrices Jrr, Jrf, Jfr and Jff relating the joint momenta and flexible body mementa to the joint coordinate rates and the flexible body deformation coordinate rates. Explicit formulas are given for these submatrices. The equations of motion presented here lend insight to the structure of the flexible multibody dynamics equations. They are also a versatile alternative to the acceleration-based dynamics equations for modeling mechanical systems.

Model reduction of a flexible multibody system with clearance

2015 ◽  
Vol 85 ◽  
pp. 106-115 ◽  
Author(s):  
Dongyang Sun ◽  
Guoping Chen ◽  
Yan Shi ◽  
Tiecheng Wang ◽  
Rujie Sun
Keyword(s):  
Model Reduction ◽  
Multibody System ◽  
Flexible Multibody System ◽  
Flexible Multibody

Multiple Dynamic Response Patterns of Flexible Multibody Systems With Random Uncertain Parameters

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Zhe Wang ◽  
Qiang Tian ◽  
Haiyan Hu
Keyword(s):  
Dynamic Response ◽  
Multibody System ◽  
Uncertain Parameters ◽  
Response Patterns ◽  
Algebraic Equations ◽  
Flexible Multibody System ◽  
Random Parameters ◽  
Collocation Points ◽  
Nonlinear Algebraic Equations ◽  
Flexible Multibody

The mechanisms with uncertain parameters may exhibit multiple dynamic response patterns. As a single surrogate model can hardly describe all the dynamic response patterns of mechanism dynamics, a new computation methodology is proposed to study multiple dynamic response patterns of a flexible multibody system with uncertain random parameters. The flexible multibody system of concern is modeled by using a unified mesh of the absolute nodal coordinate formulation (ANCF). The polynomial chaos (PC) expansion with collocation methods is used to generate the surrogate model for the flexible multibody system with random parameters. Several subsurrogate models are used to describe multiple dynamic response patterns of the system dynamics. By the motivation of the data mining, the Dirichlet process mixture model (DPMM) is used to determine the dynamic response patterns and project the collocation points into different patterns. The uncertain differential algebraic equations (DAEs) for the flexible multibody system are directly transformed into the uncertain nonlinear algebraic equations by using the generalized-alpha algorithm. Then, the PC expansion is further used to transform the uncertain nonlinear algebraic equations into several sets of nonlinear algebraic equations with deterministic collocation points. Finally, two numerical examples are presented to validate the proposed methodology. The first confirms the effectiveness of the proposed methodology, and the second one shows the effectiveness of the proposed computation methodology in multiple dynamic response patterns study of a complicated spatial flexible multibody system with uncertain random parameters.

Nonlinear Formulation for Flexible Multibody System Applied With Thermal Load

2007 ◽  
Author(s):  
Jinyang Liu ◽  
Hao Lu
Keyword(s):  
Heat Conduction ◽  
Thermal Load ◽  
Multibody System ◽  
Thermal Strain ◽  
Sudden Change ◽  
Dynamic Equations ◽  
Flexible Beam ◽  
Flexible Multibody System ◽  
Beam System ◽  
Flexible Multibody

In this paper, temperature variation and dynamic performance of flexible multibody system applied with thermal load are investigated. Considering thermal strain and geometric nonlinear terms, heat conduction equations and dynamic equations for a flexible beam are derived, and then the system heat conduction equations and dynamic equations of flexible multibody system are assembled, and temperature, kinematic and driving constraint equations are used to obtain Lagrange’s equations of the first kind with Lagrange multipliers. Simulation of a rotating hub-beam system with simply-supported boundary condition is carried out to show the softening effect of the beam with temperature increase. Finally, thermal bending of flexible beam system applied with heat flux at upper surface is investigated. Coupling between rotational motion and transverse deformation as well as sudden change of constraint forces and axial stresses are shown to reveal the characteristics of thermal shock.

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