High-Fidelity Flexibility-Based Component Mode Synthesis Method with Interface Degrees of Freedom Reduction

AIAA Journal ◽  
2016 ◽  
Vol 54 (11) ◽  
pp. 3619-3631 ◽  
Author(s):  
Jin-Gyun Kim ◽  
Damijan Markovic
Keyword(s):  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Component Mode Synthesis ◽  
High Fidelity

The Application of Modal Synthesis Method in the Processing Center Dynamics Analysis

2012 ◽  
Vol 163 ◽  
pp. 207-210
Author(s):  
Peng Liu ◽  
Chun Jie Wang ◽  
Ru Sun
Keyword(s):  
Computational Efficiency ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Vibration Mode ◽  
Synthesis Method ◽  
Component Mode Synthesis ◽  
Dynamics Analysis ◽  
Full Model ◽  
Modal Synthesis ◽  
Five Axis

Modal synthesis method is a method which can reduce structural degrees of freedom, it is applicable for analysis and calculations of Machining centers and other large-scale structure. In this paper, the dynamical performance of Five-axis boring and milling processing center was studied with component mode synthesis technology . Compared with full model FEM, component mode synthesis technology could meet the accuracy requirements and have higher computational efficiency. Modal characteristics of processing center in different positions was studied, the result showed that each frequency of processing center in different position was different while the vibration mode remained unchanged.

Modeling of Flexible Robot-Payload Systems Through Component Synthesis

1998 ◽  
Vol 122 (2) ◽  
pp. 381-386 ◽  
Author(s):  
T. Zhou, ◽  
J. W. Zu, and ◽  
A. A. Goldenberg
Keyword(s):  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Modeling Method ◽  
Component Mode Synthesis ◽  
Flexible Robot ◽  
Computationally Efficient ◽  
Efficient Manner ◽  
Robot Gripper ◽  
Coupling Dynamics ◽  
Rigid Body Motions

In this paper, a new modeling method is developed for analyzing the dynamic behavior of a system consisting of a rigid robotic manipulator and a flexible sheet metal payload. The component mode synthesis method is applied to reduce the degrees of freedom of the payload and to model the interfaces between the robot gripper and the payload. Using nonlinear compatibility functions, the method is modified to synthesize the dynamics of the entire robot-payload system. Exact models are developed capable of describing both large and small rigid-body motions. A modular form is derived and the coupling dynamics is formulated in a computationally efficient manner. Numerical examples are presented to demonstrate the effectiveness of the modeling method. [S0022-0434(00)01102-3]

Component Mode Synthesis of a Vehicle System Model Using the Fictitious Mass Method

2006 ◽  
Vol 129 (1) ◽  
pp. 73-83 ◽  
Author(s):  
M. Karpel ◽  
B. Moulin ◽  
V. Feldgun
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Synthesis Method ◽  
Normal Modes ◽  
Low Frequency ◽  
Component Mode Synthesis ◽  
Response Analysis ◽  
Element Analysis ◽  
Local Boundary

A new procedure for dynamic analysis of complex structures, based on the fictitious-mass component mode synthesis method, is presented. Normal modes of separate components are calculated by finite-element analysis with the interface coordinates loaded with fictitious masses that generate local boundary deformations in the low-frequency modes. The original fictitious-mass method is extended to include three types of component interconnections: displacement constraints, connection elements, and structural links. The connection elements allow the introduction of springs and dampers between the interface points without adding structural degrees of freedom. The structural links facilitate the inclusion the discrete finite-element representation of typically small components in the coupling equations. This allows a convenient treatment of loose elements and the introduction of nonlinear effects and parametric studies in subsequent analyses. The new procedure is demonstrated with the structural model of a typical vehicle with four major substructures and a relatively large number of interface coordinates. High accuracy is obtained in calculating the natural frequencies and modes of the assembled structure and the separate components with the fictitious masses removed. Dynamic response analysis of the vehicle travelling over a rough road, performed by modal coupling, is in excellent agreement with that performed for the full model.

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.

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].

Interface Reduction in Craig-Bampton Component Mode Synthesis by Orthogonal Polynomial Series

2017 ◽  
Author(s):  
Luigi Carassale ◽  
Mirko Maurici
Keyword(s):  
Degrees Of Freedom ◽  
Axial Compressor ◽  
Component Mode Synthesis ◽  
Reduction Techniques ◽  
Interface Reduction ◽  
Reduction Methods ◽  
Interface Displacement ◽  
Polynomial Series ◽  
Efficient Representation

The component mode synthesis based on the Craig-Bampton method has two strong limitations that appear when the number of the interface degrees of freedom is large. First, the reduced-order model obtained is overweighed by many unnecessary degrees of freedom. Second, the reduction step may become extremely time consuming. Several interface reduction techniques addressed successfully the former problem, while the latter remains open. In this paper we tackle this latter problem through a simple interface-reduction technique based on an a-priory choice of the interface modes. An efficient representation of the interface displacement field is achieved adopting a set of orthogonal basis functions determined by the interface geometry. The proposed method is compared with other existing interface reduction methods on a case study regarding a rotor blade of an axial compressor.

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