A Method for Substructural Sensitivity Synthesis

1991 ◽  
Vol 113 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Joo Ho Heo ◽  
K. F. Ehmann
Keyword(s):  
Dynamic Characteristics ◽  
Computational Efficiency ◽  
Synthesis Method ◽  
Simple Calculation ◽  
Component Mode Synthesis ◽  
New Method ◽  
Eigenvalues And Eigenvectors ◽  
Modal Data ◽  
Entire Structure ◽  
Design Variables

A new method, termed the substructural sensitivity synthesis method, which utilizes the computational merits of the component mode synthesis technique was proposed for the simple calculation of design sensitivities of the dynamic characteristics of substructurally combined structures. It has been shown that the modal sensitivities of the entire structure can be obtained by synthesizing the substructural modal data and the sensitivities of the modal data for the design variables of the modifiable substructure. For a truss structure, as an example, the sensitivities of the eigenvalues and eigenvectors obtained by the new method were compared with exact solutions in terms of accuracy and computational efficiency.

ELABORATE STRUCTURAL DAMAGE DETECTION USING AN IMPROVED GENETIC ALGORITHM AND MODAL DATA

2013 ◽  
Vol 13 (06) ◽  
pp. 1350024 ◽  
Author(s):  
S. S. NASERALAVI ◽  
S. GERIST ◽  
E. SALAJEGHEH ◽  
J. SALAJEGHEH
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Structural Damage ◽  
Structural Damage Detection ◽  
Improved Genetic Algorithm ◽  
Eigenvalues And Eigenvectors ◽  
Damage Functions ◽  
Element Mesh ◽  
Modal Data ◽  
Design Variables

This paper addresses a proficient strategy for detection of structural damages in details using the variations of eigenvalues and eigenvectors. There are two concerns in this study. First, the severity of damage can vary within the damaged elements; second, it is possible that the damage extents do not exactly match the pre-generated finite element mesh. The first concern forms the motivation for employing the proper damage functions to model the elemental damages, and the second for considering the nodal positions as design variables. To obtain the design variables, an improved genetic algorithm is introduced in which two new operators are embedded. This strategy is applied to a beam and a plate structure as the cases of study. The results demonstrate the applicability and efficiency of the proposed algorithm in elaborate damage detections.

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.

Component Mode Synthesis Method Using Partial Interface Modes: Application to Tuned and Mistuned Bladed Disk With Local Non-Linearity

2009 ◽  
Author(s):  
Duc-Minh Tran
Keyword(s):  
Synthesis Method ◽  
Normal Modes ◽  
Component Mode Synthesis ◽  
New Method ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Generalized Coordinates ◽  
Bladed Disk ◽  
Static Condensation ◽  
Fixed Interface

A new fixed interface component mode synthesis method using partial interface modes is presented. Partial interface modes are the structure normal modes which result from the static condensation of the structure to the interface between the substructures and which are clamped at a part of this interface. This method is the generalization of the classical component mode synthesis method which keeps all the interface physical displacements in the assembled reduced system and the method using interface modes which eliminates all of them. It allows one to reduce the number of the interface generalized coordinates and at the same time to keep some of the physical displacements at the interface. This latter capability is very useful to build reduced order models in which the presence of physical displacements are essential, for example in order to impose prescribed motions or to take into account local non-linearities. The new method is applied to a bladed disk in both tuned and mistuned cases.

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.

Reduction of Forced Vibration Response by Optimum Balance of Linkage and Optimum Design of System

1997 ◽  
Author(s):  
She-min Zhang ◽  
Nobuyoshi Morita ◽  
Takao Torii
Keyword(s):  
Objective Function ◽  
Root Mean Square ◽  
Forced Vibration ◽  
Vibration Response ◽  
New Method ◽  
Mean Square ◽  
Design Variables ◽  
Calculation Results ◽  
Angular Velocities ◽  
Optimum Balance

Abstract This paper proposes a new method to reduce the forced vibration response of frame of linkage. It is that the root-mean-square (RMS) value of binary maximum (Bmax) of forced vibration response at a series of angular velocities is taken as the objective function, and the counterweight mass parameters of links and the stiffness factors are used as design variables. Then, it is found out that the responses are related not only to the Bmax value of shaking forces, but also to the shape of curve of shaking forces. The calculation results are compared with those of two other methods used in the reduction of forced vibration response by optimized balance of linkages, and it is shown that the new method can significantly reduce the responses of frame of linkage.

A New Method for Detection of Graph Isomorphism Based on the Quadratic Form

2003 ◽  
Vol 125 (3) ◽  
pp. 640-642 ◽  
Author(s):  
P. R. He and ◽  
W. J. Zhang ◽  
Q. Li and ◽  
F. X. Wu
Keyword(s):  
Quadratic Form ◽  
Graph Isomorphism ◽  
New Method ◽  
Eigenvalues And Eigenvectors ◽  
Kinematic Chains ◽  
Quadric Surfaces

This paper proposes a new method for detection of graph isomorphism using the concept of quadratic form. Graphs/kinematic chains are represented first by quadratic form, and the comparison of two graphs is thus reduced to the comparison of two quadratic form expressions. If both the lengths and the directions of the semiaxes of quadric surfaces, which are characterized by the eigenvalues and eigenvectors, are the same, the associated graphs/kinematic chains are isomorphic. An algorithm is developed based on this idea, and tested for the counter-examples known to other methods.

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