Optimal Design of Elastic Linkage Mechanisms With Multi-Frequency Constraints

1994 ◽  
Author(s):  
Zhang Xianmin ◽  
Shen Yunwen ◽  
Liu Hongzhao ◽  
Cao Weiqing
Keyword(s):  
Optimal Design ◽  
Minimum Weight ◽  
Design Sensitivity ◽  
Stability And Convergence ◽  
Bound Constraints ◽  
Frequency Constraints ◽  
Design Algorithm ◽  
Design Variables ◽  
Weight Design ◽  
Flexible Mechanisms

Abstract The paper presents a finite element method for minimum weight design of flexible mechanisms with multiple frequency constraints and upper and lower bound constraints on the design variables. The design algorithm developed in this paper is formulated in terms of the Kuhn-Tucker optimality criterion, in which two damping factors are introduced to guarantee the algorithm possesses good stability and convergence. The first and second order design sensitivity analysies of eigenvalues are presented and the values of the damping factors α and β are recommended. Results of three numerical examples show that the algorithm is stable and the optimal design can be obtained in lsee than fifteen iterations.

scholarly journals Design Optimization of Composite Laminated Tube Based on Improved Niching Evolutionary Algorithm

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Sen Ma ◽  
Qilin Zhao ◽  
Darong Pan
Keyword(s):  
Optimal Design ◽  
Evolutionary Algorithms ◽  
Objective Function ◽  
Evolutionary Algorithm ◽  
Minimum Weight ◽  
Local Optimum ◽  
Optimal Result ◽  
Minimum Weight Design ◽  
Design Variables ◽  
Weight Design

A minimum weight design is developed for a composite laminated tube considering the number of plies as one of the design variables. The objective function is found to be complex, and more than one optimal design point may exist with different numbers of plies. Existing methods based on evolutionary algorithms tend to become trapped around a local optimum and can find no more than one optimal result per calculation. Aiming at the characteristics of the objective function, an improved evolutionary algorithm (INDE for short) is established based on niching technology. The formula for calculating the distance between individuals in the niching technology is improved to satisfy the minimum weight design for the composite laminated tube. As a result, the improved niching evolutionary algorithm offers better global search ability and can find more than one optimal result per calculation for different numbers of plies.

Minimum Weight Design of a Rotor Bearing System With Multiple Frequency Constraints

1988 ◽  
Vol 110 (4) ◽  
pp. 592-599 ◽  
Author(s):  
Ting Nung Shiau ◽  
Jon Li Hwang
Keyword(s):  
Minimum Weight ◽  
Optimization Techniques ◽  
Multiple Frequency ◽  
Minimum Weight Design ◽  
Feasible Directions ◽  
Frequency Constraints ◽  
Design Algorithm ◽  
Rotor Bearing ◽  
Weight Design ◽  
Bearing System

The objective of the present study is to develop an efficient design algorithm for minimum weight design of a rotor bearing system under the requirements of operational speed range, i.e., multiple frequency constraints, to increase the performance of an existent rotor system. The system is modeled as an assemblage of rigid disks, shaft elements with distributed mass and stiffness, and discrete bearings. The system design variables are the inner radius of shaft elements and the stiffnesses of bearings. The optimization techniques employed to compare the results are method of exterior penalty function, method of feasible directions, and method of modified feasible directions. The parameter sensitivity analysis of the system is also presented. Three examples are used to demonstrate the merits of the design algorithm. The results indicate that the weight of the rotor bearing system can be significantly reduced at the optimum stage.

Minimum Weight Design Problems of Fiber-Reinforced Beam Subjected to Uniform Bending

1985 ◽  
Vol 107 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Juhachi Oda
Keyword(s):  
Minimum Weight ◽  
Bending Moment ◽  
Material Strength ◽  
Sequential Linear Programming ◽  
Volume Percent ◽  
Fiber Volume ◽  
Minimum Weight Design ◽  
Design Problems ◽  
Design Variables ◽  
Weight Design

Problems considered here are that of minimizing the weight of beams, which are subjected to a uniform bending moment and reinforced by the fibers distributed in the direction of beam axis. The beam is simplified as a multilaminate structure, of which the fiber volume percent Vfi of each lamina is considered as the design variables. To formulate this design problem the bending theory of multilaminate beam and the law of mixture for the composite material strength are applied. Furthermore, the sequential linear programming and the sequential unconstrianed minimization techniques are used to obtain the design solutions numerically.

Minimum-Weight Design of Stiffened Cylinders Under Hydrostatic Pressure

1977 ◽  
Vol 21 (04) ◽  
pp. 217-224
Author(s):  
G. J. Simitses ◽  
M. Aswani
Keyword(s):  
Hydrostatic Pressure ◽  
Objective Function ◽  
Failure Modes ◽  
Minimum Weight ◽  
Minimum Weight Design ◽  
Design Charts ◽  
Design Variables ◽  
Weight Penalty ◽  
Weight Design ◽  
Two Stages

A methodology is developed by which one may design a stiffened cylinder of specified material, radius and length such that it can carry safely a given hydrostatic pressure with minimum weight. The solution is accomplished in two stages. First, design charts based on a simplified formulation of the objective function are obtained. Second, these design charts are used to evaluate the design variables. Such an approach enables the designer to introduce needed changes or avoid interaction of failure modes by paying the least weight penalty. Design examples are presented and the results are compared with those obtained by other investigators.

Minimum Weight Design of Symmetric Angle-Ply Laminates With Incomplete Information on Initial Imperfections

1997 ◽  
Vol 64 (1) ◽  
pp. 90-96 ◽  
Author(s):  
S. Adali ◽  
A. Richter ◽  
V. E. Verijenko
Keyword(s):  
Minimum Weight ◽  
A Priori ◽  
Initial Deflection ◽  
Initial Imperfections ◽  
Design Variables ◽  
L2 Norm ◽  
Weight Design ◽  
Laminate Thickness ◽  
Favorable Conditions ◽  
Multiple Load

An angle-ply laminated plate is optimized with the objective of minimizing its weight subject to maximum deflection and buckling constraints. The plate has an initial deflection the shape of which is not known a priori, i.e., the initial deflection is not specified in a “deterministic” manner and as such it is “uncertain.” The weight is proportional to the laminate thickness which is minimized taking the ply angles as design variables and under the least favorable conditions of initial imperfections. The convex modeling approach is employed to analyze the uncertain initial deflection with the uncertain quantities allowed to vary arbitrarily around their average values subject to the requirement that these variations are bounded in L2 norm. The results are given for both single load and multiple load cases and the effect of uncertainty on the optimal design is investigated. It is shown that the minimum weight increases with increasing level of uncertainty and the optimal ply angles also depend on the level of uncertainty.

Fail-Safe Optimal Design of Complex Structures With Substructures

1982 ◽  
Vol 104 (4) ◽  
pp. 861-868 ◽  
Author(s):  
D. T. Nguyen ◽  
J. S. Arora
Keyword(s):  
Optimal Design ◽  
Design Sensitivity ◽  
Structural Systems ◽  
Complex Structures ◽  
Design Problems ◽  
Design Algorithm ◽  
Analysis And Design ◽  
Computational Advantage ◽  
Complex Structural ◽  
Fail Safe

In this paper, the problem of fail-safe design of complex structural systems is considered. A substructural formulation for this class of design problems is presented. Constraints are imposed on stresses, deflections, natural frequency, and member sizes. It is shown that a structure can be designed to withstand the projected future damage. It is also shown that the substructural formulation offers computational advantage for both structural analysis and design sensitivity analysis parts of an optimal design algorithm. Fail-safe designs of open truss and closed helicopter tailbooms are obtained using a program developed based on the substructural formulation.

Minimum Weight Design of a Car Trunk Deck-Lid Subject to Overall Stiffness Constraints

1982 ◽  
Vol 104 (4) ◽  
pp. 831-836 ◽  
Author(s):  
H. A. Du ◽  
S. C. Tang
Keyword(s):  
Minimum Weight ◽  
Optimization Technique ◽  
Design Procedure ◽  
Optimization Techniques ◽  
Structural Components ◽  
Minimum Weight Design ◽  
Design Constraints ◽  
Design Variables ◽  
Practical Design ◽  
Weight Design

A design procedure for a car trunk deck-lid using an approximate optimization technique is presented. Selecting the deck-lid gages and deck-lid inner panel configuration as design variables and overall stiffnesses as constraints, a possible weight reduction of 20 percent is demonstrated, compared with the base production deck-lid design. Although other practical design constraints might not allow one to achieve this goal, the potential value of optimization techniques is clearly demonstrated by this study. It is concluded that it could be useful to develop and apply such a procedure to components such as hoods, deck-lids, doors, and fenders, which are isolatable as structural components.

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