scholarly journals Reduction of Coupling Interface Degrees of Freedom in Mixed-Interface Component Mode Synthesis

2020 ◽  
Vol 10 (8) ◽  
pp. 2759
Author(s):  
Yu Tang ◽  
Hui Qin
Keyword(s):  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Eigenvalue Problems ◽  
Numerical Models ◽  
Optimal Number ◽  
Component Mode Synthesis ◽  
Computational Accuracy ◽  
Structural Dynamic ◽  
Dam Foundation ◽  
Rectangular Beam

A new coupling interface degrees of freedom (DOFs) reduction technique for the mixed-interface component mode synthesis (MCMS) method is proposed, which referred to as the MCMS-rid method. This approach employs a set of shape functions via the linear interpolation (LI) in finite element method (FEM) to realize interface nodal coordinate transformations for each substructure, and then only a small number of interpolation basic nodes (IBNs) will be involved in mode synthesis and the following dynamic analysis. Unlike the majority of available CMS methods that retain a full dimension of the coupling interface DOFs, the MCMS-rid method allows to reduce the coupling interface DOFs significantly and enhance the computational efficiency. Three numerical models, including a rectangular beam with two ends fixed, a non-rectangular beam with the button fixed and a simplified dam-foundation system with different material properties, are presented to demonstrate the computational accuracy and efficiency of the proposed method. The results indicate that favourable accuracy with a least number of retained DOFs involved in mode synthesis can be obtained for solving eigenvalue problems when compared with other MCMS methods. The optimal number and distribution of the IBNs are discussed on structural dynamic analysis as well. It is shown that the more the IBNs are involved in mode synthesis, the better the precision that will be received. Furthermore, when the sub-regions are nearly square, the precision is best.

Selection of Degrees of Freedom for Dynamic Analysis

1987 ◽  
Vol 109 (1) ◽  
pp. 65-69 ◽  
Author(s):  
K. W. Matta
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
General Purpose ◽  
Component Mode Synthesis ◽  
Complex Structures ◽  
Large Complex ◽  
Static Condensation ◽  
Basis Vectors ◽  
Selection Of

A technique for the selection of dynamic degrees of freedom (DDOF) of large, complex structures for dynamic analysis is described and the formulation of Ritz basis vectors for static condensation and component mode synthesis is presented. Generally, the selection of DDOF is left to the judgment of engineers. For large, complex structures, however, a danger of poor or improper selection of DDOF exists. An improper selection may result in singularity of the eigenvalue problem, or in missing some of the lower frequencies. This technique can be used to select the DDOF to reduce the size of large eigenproblems and to select the DDOF to eliminate the singularities of the assembled eigenproblem of component mode synthesis. The execution of this technique is discussed in this paper. Examples are given for using this technique in conjunction with a general purpose finite element computer program GENSAM[1].

Dynamic Analysis of 6-DOF Large Displacement Composite Simulation Platform

2012 ◽  
Vol 233 ◽  
pp. 181-185 ◽  
Author(s):  
Xiang Ming Liu ◽  
Hong Yi Yan
Keyword(s):  
Optimal Design ◽  
Dynamic Analysis ◽  
Dynamic Equation ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Lagrange Equation ◽  
Stewart Platform ◽  
Simulation Platform ◽  
Structural Dynamic ◽  
Depth Analysis

For the problem of Typical Stewart Platform with small workspace and poor flexibility, the paper proposed a new 6-DOF simulator platform. The simulator platform compounds the three-bar parallel mechanism with moving degrees of freedom and the three-axis turntable with rotating degrees of freedom, it can repeat any attitude of 6-DOF in space. Effectively solve the problem of Typical Stewart Platform with small workspace and poor flexibility. Using Lagrange equation establish dynamic equation of the simulator platform, and using MATLAB in-depth analysis its dynamics. It can provide a reference for the optimal design of structural dynamic of the simulation platform.

A Simplified Finite Element Riveted Lap Joint Model in Structural Dynamic Analysis

2014 ◽  
Vol 1016 ◽  
pp. 185-191
Author(s):  
Marco Daniel Malheiro Dourado ◽  
José Filipe Bizarro de Meireles
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Numerical Models ◽  
Element Model ◽  
Lap Joints ◽  
Mode Shapes ◽  
Lap Joint ◽  
Structural Dynamic ◽  
Riveted Lap Joints

This paper proposes a simplified finite element model to represent a riveted lap joint in structural dynamic analysis field. The rivet is modeled byspring-damperelements. Several numerical models are studied with different quantities of rivets (1, 3 and 5) andspring-damperelements (4, 6, 8, 12, 16 and 20) per rivet. In parallel, samples of two aluminum material plates connected by different quantities of rivets (1, 3 and 5) are built and tested in order to be known its modal characteristics – natural frequencies and mode shapes. The purpose of the different settings is to get the best numerical riveted lap joint representation relatively to the experimental one. For this purpose a finite element model updating methodology is used. An evaluation of the best numerical riveted lap joint is carried out based on comparisons between the numerical model after updating and the experimental one. It is shown that the riveted lap joints composed by eight and twelvespring-damperelements per rivet have the best representation. A stiffness constant valuekis obtained for the riveted lap joints in study.

Interfacing FEA and Multibody Simulation Through Component Mode Synthesis

2005 ◽  
Author(s):  
Hassan N. Bayoumi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Multibody Systems ◽  
Simulation Software ◽  
Component Mode Synthesis ◽  
Multibody Simulation ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Systems Software

Many of the currently available commercial multibody systems simulation packages are limited to rigid bodies linked by joints. Accurate dynamic analysis of multibody systems might require consideration of the flexibility of some components. Finite element analysis is generally the method of choice for structural dynamic analysis. Implementation of a fully featured reliable finite element capability within well-established commercial multibody systems software is not an easy task. A practical solution is to interface commercial finite element analysis software with commercial multibody systems software. This paper describes the theory and implementation aspects of such an interface. The interface is based on the Craig-Bampton method of component mode synthesis. The power of this technique is that it presents customers of commercial multibody simulation software with a practical and reliable tool to address component flexibility. The technique has been implemented to interface two major commercial simulation packages. Two practical applications, a flexible connecting rod and a flexible hard disk drive head-stack assembly, are discussed.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

Dynamic Analysis of Cage Stress in Tapered Roller Bearings Using Component-Mode-Synthesis Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Tomoya Sakaguchi ◽  
Kazuyoshi Harada
Keyword(s):  
Rigid Body ◽  
Dynamic Analysis ◽  
Boundary Point ◽  
Axial Load ◽  
Synthesis Method ◽  
Load Condition ◽  
Component Mode Synthesis ◽  
Analysis Model ◽  
Tapered Roller ◽  
Tapered Roller Bearings

In order to investigate cage stress in tapered roller bearings, a dynamic analysis tool considering both the six degrees of freedom of motion of the rollers and cage and the elastic deformation of the cage was developed. Cage elastic deformation is equipped using a component-mode-synthesis (CMS) method. Contact forces on the elastically deforming surfaces of the cage pocket are calculated at all node points of finite-elements on it. The location and pattern of the boundary points required for the component-mode-synthesis method were examined by comparing cage stresses in a static condition of pocket forces and constraints calculated by using the finite-element and the CMS methods. These results indicated that one boundary point lying at the center on each bar is appropriate for the effective dynamic analysis model focusing on the cage stress, especially at the pocket corners of the cages, which are actually broken. A behavior measurement of a polyamide cage in a tapered roller bearing was conducted for validating the analysis model. It was confirmed in both the experiment and analysis that the cage whirled under a large axial load condition and the cage center oscillated in a small amplitude under a small axial load condition. In the analysis, the authors discussed the four models including elastic bodies having a normal eigenmode of 0, 8 or 22, and rigid-body. There were small differences among the cage center loci of the four models. These two cages having normal eigenmodes of 0 and rigid-body whirled with imperceptible fluctuations. At least approximately 8 normal eigenmodes of cages should be introduced to conduct a more accurate dynamic analysis although the effect of the number of normal eigenmodes on the stresses at the pocket corners was insignificant. From the above, it was concluded to be appropriate to introduce one boundary point lying at the center on each pocket bar of cages and approximately 8 normal eigenmodes to effectively introduce the cage elastic deformations into a dynamic analysis model.

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