Dynamic Beam Modification Using Dimples

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
W. N. Cheng ◽  
C. C. Cheng ◽  
G. H. Koopmann
Keyword(s):  
Natural Frequencies ◽  
Design Method ◽  
Frequency Equation ◽  
Search Method ◽  
The Other ◽  
Impedance Method ◽  
Dimple Size ◽  
Straight Beam ◽  
Novel Method ◽  
Force Equilibrium

In this paper, a design method to modify the vibration characteristics of a beam by creating cylindrical dimples on its surface is investigated. In particular, the vibration response of a beam with several dimples is formulated using the impedance method. The dimpled beam is divided into two kinds of structural segments: one, a curved beam that is modeled as the dimple and the other, a straight beam. The frequency equation is derived by assembling the impedance of each structure segment based on conditions of force equilibrium and velocity compatibility. Then a novel method for shifting the natural frequencies of a beam to preassigned values by creating cylindrical dimples on this structure is introduced. The dimple size and its location on the structure can be determined analytically, so the time consuming process using the traditional optimal search method is thereby avoided. Several examples using this technique are demonstrated.

A Study on Flange Lathe of Double-Tool Holder Based on Optimization Design Method of FE

2011 ◽  
Vol 48-49 ◽  
pp. 118-122
Author(s):  
Fu Qiang Ying ◽  
Yi Wang ◽  
Ling Dong Wu ◽  
Liang Yi Li
Keyword(s):  
Sensitivity Analysis ◽  
Optimization Design ◽  
Natural Frequencies ◽  
Design Method ◽  
Dynamic Performance ◽  
The Other ◽  
Design Parameters ◽  
Fe Model ◽  
Tool Holder ◽  
Dynamic Performances

With the optimization design method of FE,the FE model of vertical flange lathe beam of double-tool holder was established,the sensitivity analysis of dynamic performance for the machine tool was performed based on presented modal analysis and probability analysis.The influence rules of the first four natural frequencies affected by the design parameters of the lathe beam were confirmed and the weaknesses of it were indicated as well.Then, the structure of the lathe beam was optimized.As a result ,the dynamic performances of the lathe beam are improved and it offers the basis for the optimization design of the other lathe parts.

Design Optimization of Beams With Multi-Layers of Corrugations

2015 ◽  
Author(s):  
W. N. Cheng ◽  
C. C. Cheng
Keyword(s):  
Dynamic Characteristic ◽  
Frequency Equation ◽  
Optimal Number ◽  
Modeling Technique ◽  
Original Design ◽  
Reduction System ◽  
Straight Beam ◽  
Impedance Modeling ◽  
Corrugated Beam ◽  
Force Equilibrium

Optimal designs of beams with multi-layers of corrugations are introduced in this paper. The dynamic characteristic of corrugated structures is investigated firstly using the impedance modeling technique. The dynamic response of a beam with layers of corrugations is formulated by dividing a corrugated beam into two kinds of structural segments: one, the corrugation modeled as a curved beam using finite element method and the other, the liner treated as a straight beam formulated analytically. Then the frequency equation is derived by assembling the impedance of each structure segment based on conditions of force equilibrium and velocity compatibility. The accuracy of the impedance modeling technique are compared to different existing methods, e.g. FEM, Guyan reduction, improved reduction system (IRS), improved reduction system (DIRS), and iterative improved reduction system (IIRS). Finally, examples of optimal design of corrugated beams are presented. Results further show that with an optimal number of corrugated layers and optimal thickness of liner and medium of each layer, the corrugated beam has a desirable dynamic characteristic, e.g. the first bending natural frequency may increase 40% as compared to that of the original design.

Natural Frequency Tuning Using Structural Patches

2005 ◽  
Vol 127 (1) ◽  
pp. 28-35 ◽  
Author(s):  
P. W. Wang ◽  
C. C. Cheng
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Frequency Tuning ◽  
Search Method ◽  
Optimal Search ◽  
Novel Method ◽  
Host Structure

A novel method for shifting the natural frequencies of a structure to specific values using structural patches is introduced. When a host structure is bonded with multiple structural patches, its natural frequencies can be shifted to the desired values by tuning the patch thickness and the patch location on the host structure. These parameters can be analytically determined using the methodology proposed in this paper. The time consuming process produced using the traditional optimal search method is thereby avoided. The results show that multiple natural frequencies can be changed simultaneously to the desired values. The number of natural frequencies shifted requires using the same number of structural patch pairs. Several examples using this technique are demonstrated and the results are experimentally validated.

Free Vibrations of Thin Cylindrical Shells Having Finite Lengths With Freely Supported and Clamped Edges

1955 ◽  
Vol 22 (4) ◽  
pp. 547-552
Author(s):  
Yi-Yuan Yu
Keyword(s):  
Natural Frequencies ◽  
Cylindrical Shells ◽  
Free Vibrations ◽  
Frequency Equation ◽  
The Other ◽  
Lateral Vibration ◽  
Normal Functions ◽  
First Case ◽  
End Conditions ◽  
Good Agreement

Abstract Free vibrations of thin cylindrical shells having finite lengths are investigated on the basis of a set of three differential equations which are derived in a similar manner as Donnell obtained his equations for the bending and buckling problems. The equations can be solved readily after a simplifying assumption is introduced. In this manner the frequency equations are obtained for cylindrical shells with both edges freely supported, with both edges clamped, and with one edge freely supported and the other edge clamped. It is found that the lowest frequency given by the frequency equation is the smallest in the first case, larger in the third, and the largest in the second. The other two frequencies yielded by the frequency equation are approximately the same in all cases. As a result of the approximations, the characteristic equations for the three cases are found to be similar to the frequency equations for the lateral vibration of beams with similar end conditions. For the case of freely supported edges the normal functions obtained are identical in form with those assumed by Flügge and by Arnold and Warburton. For the same case, natural frequencies of one numerical example are computed by means of the present method, and the results are in good agreement with those obtained by these previous authors.

scholarly journals Spectral Dynamic Analysis of Torsional Vibrations of Thin-Walled Open Section Beams Restrained Against Warping at One End and Transversely Restrained at the Other End

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Chellapilla Kameswara Rao 1 ◽  
Lokavarapu Bhaskara Rao 2
Keyword(s):  
Dynamic Analysis ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Frequency Equation ◽  
The Other ◽  
Graphical Form ◽  
Open Section ◽  
Torsional Frequency ◽  
Thin Walled ◽  
Spectral Frequency

The present paper deals with spectral dynamic analysis of free torsional vibration of doubly symmetric thin-walled beams of open section. Spectral frequency equation is derived in this paper for the case of rotationally restrained doubly-symmetric thin-walled beam with one end rotationally restrained and transversely restrained at the other end. The resulting transcendental frequency equation with appropriate boundary conditions is derived and is solved for varying values of warping parameter and the rotational and transverse restraint parameter. The influence of rotational restraint parameter, transverse restraint parameter and warping parameter on the free torsional vibration frequencies is investigated in detail. A MATLAB computer program is developed to solve the spectral frequency equation derived in this paper. Numerical results for natural frequencies for various values of rotational and transverse restraint parameters for various values of warping parameter are obtained and presented in both tabular as well as graphical form showing the influence of these parameters on the first fundamental torsional frequency parameter.

scholarly journals A Study on the Variable Inductor Design by Switching the Main Paths and the Coupling Coils

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1856
Author(s):  
Yen-Chung Chiang ◽  
Juo-Chen Chen ◽  
Yu-Hsin Chang
Keyword(s):  
Design Method ◽  
The Other ◽  
Cmos Process ◽  
Mos Transistors ◽  
Quality Factors ◽  
Process Technology ◽  
Variation Versus ◽  
Variable Inductor ◽  
Metal Layers ◽  
Coupled Coils

In a radio frequency (RF) system, it is possible to use variable inductors for providing tunable or selective frequency range. Variable inductors can be implemented by the microelectromechanical system (MEMS) process or by using transistors as switches to change the routing of coils or coupling quantities. In this paper, we investigated the design method of a variable inductor by using MOS transistors to switch the main coil paths and the secondary coupled coils. We observed the effects of different metal layers, turn numbers, and layout arrangements for secondary-coupled coils and compared their characteristics on the inductances and quality factors. We implemented two chips in the 0.18 m CMOS process technology for each kind of arrangement for verification. One inductor can achieve inductance values from about 300 pH to 550 pH, and the other is between 300 pH and 575 pH, corresponding to 59.3% and 62.5%, respectively, inductance variation range at 4 GHz frequency. Additionally, their fine step sizes of the switched inductances are from 0.5% to 6% for one design, and 1% to 12.5% for the other. We found that both designs achieved a large inductance tuning range and moderate inductance step sizes with a slight difference behavior on the inductance variation versus frequency.

Design and Evaluation of Usable Systems

2002 ◽  
Vol 46 (3) ◽  
pp. 367-371
Author(s):  
John F. McGrew
Keyword(s):  
Genetic Algorithm ◽  
Change Management ◽  
Management System ◽  
Design Method ◽  
The Other ◽  
Design Team ◽  
Style Analysis ◽  
Decision Style ◽  
Parallel Design

This paper discusses a case study of a design and evaluation of a change management system at a large Telecommunications Corporation. The design and evaluation were done using the facilitated genetic algorithm (a parallel design method) and user decision style analysis. During the facilitated genetic algorithm the design team followed the procedure of the genetic algorithm. Usability was evaluated by applying user decision style analysis to the designed system. The design is compared with an existing system and with one designed by an analyst. The change management system designed by the facilitated genetic algorithm took less time to design and decision style analysis indicated it would be easier to use than the other two systems.

Vibrations of Spinning Rings With Radial and Circumferential Displacement Constraints

1991 ◽  
Author(s):  
Shyh-Chin Huang ◽  
Chen-Kai Su
Keyword(s):  
Natural Frequencies ◽  
Point Contact ◽  
Frequency Equation ◽  
Mode Shapes ◽  
Complex Conjugate ◽  
Constrained System ◽  
Form Complex ◽  
Circumferential Displacement ◽  
On The Road ◽  
Displacement Constraints

Abstract The frequencies and mode shapes of rolling rings with radial and circumferential displacement constraints are investigated. The displacement constraints practically come from the point contact, e.g., rolling tire on the road, or other applications. The proposed approach to analysis is calculating the natural frequencies and modes of a non-contacted spinning ring, then employing the receptance method for displacement constraints. The frequency equation for the constrained system is hence obtained, and it can be solved numerically or graphically. The receptance matrix developed for the spinning ring is surprisingly found not symmetric as usual. Moreover, the cross receptances are discovered to form complex conjugate pairs. That is a feature that has never been described in literature. The results show that the natural frequencies for the spinning ring in contact, as expected, higher than those for the non-contacted ring. The variance of frequencies to rotational speeds are then illustrated. The analytic forms of mode shapes are also derived and sketched. The traveling modes are then shown for cases.

Buckling Design of Axially Compressed Cylindrical Shells Based on Energy Barrier Approach

2021 ◽  
pp. 2150165
Author(s):  
Haigui Fan ◽  
Wenguang Gu ◽  
Longhua Li ◽  
Peiqi Liu ◽  
Dapeng Hu
Keyword(s):  
Experimental Data ◽  
Energy Barrier ◽  
Thin Shell ◽  
Design Method ◽  
Lightweight Design ◽  
Cylindrical Shells ◽  
Design Criterion ◽  
The Other ◽  
Shell Structures ◽  
Buckling Loads

Buckling design of axially compressed cylindrical shells is still a challenging subject considering the high imperfection-sensitive characteristic in this kind of structure. With the development of various design methods, the energy barrier concept dealing with buckling of imperfection-sensitive cylindrical shells exhibits a promising prospect in recent years. In this study, buckling design of imperfection-sensitive cylindrical shells under axial compression based on the energy barrier approach is systematically investigated. The methodology about buckling design based on the energy barrier approach is described in detail first taking advantage of the cylindrical shells whose buckling loads have been extensively tested. Then, validation and discussion about this buckling design method have been carried out by the numerical and experimental analyses on the cylindrical shells with different geometrical and boundary imperfections. Results in this study together with the available experimental data have verified the reliability and advantage of the buckling design method based on energy barrier approach. A design criterion based on the energy barrier approach is therefore established and compared with the other criteria. Results indicate that buckling design based on energy barrier approach can be used as an efficient way in the lightweight design of thin-shell structures.

scholarly journals A novel method of sintering hybrid steels in an improved semiclosed container system

2013 ◽  
Vol 45 (3) ◽  
pp. 379-383 ◽  
Author(s):  
A. Cias
Keyword(s):  
Mechanical Properties ◽  
Structural Steels ◽  
Laboratory Scale ◽  
The Other ◽  
Reduction Reactions ◽  
High Affinity ◽  
Conventional Sintering ◽  
Superior Mechanical Properties ◽  
Novel Method

Conventional sintering techniques for structural steels have been developed principally for Cu and Ni containing alloys. Applying these to Cr and Mn steels (successful products of traditional metallurgy) encounter the problem of the high affinity for oxygen of these elements. A solution is employing a microatmosphere in a semiclosed container which favours reduction reactions. This has already proved successful on a laboratory scale, especially with nitrogen as the furnace gas. Further modifications to the system, now described, include the use of two sintering boxes, one inside the other. Superior mechanical properties, even using air as the furnace gas, are attainable.

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