Multiobjective Design of an Antisymmetric Angle-Ply Laminate by Nonlinear Programming

1983 ◽  
Vol 105 (2) ◽  
pp. 214-219 ◽  
Author(s):  
S. Adali
Keyword(s):  
Nonlinear Programming ◽  
Pareto Optimality ◽  
Performance Index ◽  
Fiber Orientation ◽  
Design Problem ◽  
Natural Frequencies ◽  
Interactive Process ◽  
Design Variables ◽  
Present Design ◽  
Multiobjective Design

An antisymmetrically laminated angle-ply plate is optimized with the objectives of minimizing the maximum dynamic deflection, maximizing the natural frequencies and/or maximizing the buckling load. The design variables are the fiber orientation and the thickness of individual layers and are computed by using the methods of nonlinear programming. The concept of Pareto optimality is used in formulating the design problem and in reducing the multiple objectives into a single performance index. Numerical results are presented in the form of optimal tradeoff curves which allow the designer to assess the various possibilities open to him before deciding on a certain design. In this sense, the present design is an interactive process.

Multiobjective Optimization of a Pin-Fin Heat Sink Using Evolutionary Algorithms

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Siwadol Kanyakam ◽  
Sujin Bureerat
Keyword(s):  
Evolutionary Algorithms ◽  
Heat Sink ◽  
Incremental Learning ◽  
Design Problem ◽  
Population Based ◽  
Design Approach ◽  
Mixed Integer ◽  
Pin Fin ◽  
Design Variables ◽  
Multiobjective Design

This paper presents the use of multiobjective evolutionary algorithms for the optimal geometrical design of a pin-fin heat sink. The multiobjective design problem is posed to minimize two conflicting objectives: the junction temperature and the fan pumping power of the heat sink. The design variables are mixed integer/continuous. The encoding/decoding process for this mixed integer/continuous design variables is detailed. The multiobjective optimizers employed to solve the design problem are population-based incremental learning, strength Pareto evolutionary algorithm, particles swarm optimization, and archived multiobjective simulated annealing. The approximate Pareto fronts obtained from using the various optimizers are compared based upon the hypervolume and generational distance indicators. From the results, population-based incremental learning (PBIL) outperforms the others. The new design approach is said to be superior to a classical design approach. It is also illustrated that the proposed multiobjective design process leads to better design compared to the current commercial pin-fin heat sinks.

scholarly journals The Sensitivity Analysis for Life Estimation of Turbine Blades

1997 ◽  
Author(s):  
O. Repetski ◽  
K. Zainchkovski
Keyword(s):  
Vibration Analysis ◽  
Dynamic Stress ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Stress Sensitivity ◽  
Life Estimation ◽  
Sensitivity Coefficients ◽  
Sensitivity Distribution ◽  
Design Variables ◽  
Forced Vibration Analysis

The proposed algorithm permits one to determine the sensitivity coefficients of natural frequencies and dynamic displacements and stresses in the free- and forced vibration analysis. This algorithm is presented in a computer program with the help of finite element method (FEM). The design variables is the thickness of the blades. Usually a maximum resonance accounts more than half the damage and deterioration of machine components. The analysis of dynamic stress sensitivity distribution for this resonance permits us to control for both the endurance of machines and their components based on the thickness. In this study the sensitivity coefficients for both free vibration, dynamic resonances are investigated by acceleration and braking the regimes.

Design for Latitude Using TOPT

1988 ◽  
Author(s):  
K. L. d’Entremont ◽  
K. M. Ragsdell
Keyword(s):  
Nonlinear Programming ◽  
Design Problem ◽  
Thrust Bearing ◽  
Taguchi Methods ◽  
Quality Loss ◽  
Variance Minimization ◽  
Minimization Problems ◽  
Bearing Design

Abstract An enhanced nonlinear programming code has been developed and applied to a turbogenerator hydrostatic thrust bearing design problem. The original code was OPT. It is augmented by a pre- and post-processor which addresses the performance variance minimization problems posed by Japan’s Genichi Taguchi. The new code TOPT is formed by adapting Taguchi’s external design influence and quality loss concepts to OPT. TOPT’s results are compared to an optimization using traditional Taguchi methods which are introduced to the reader. These two approaches yield comparable results.

scholarly journals A Nonlinear Inverse Design Problem for a Pipe Type Heat Exchanger Equipped with Internal Z-Shape Lateral Fins and Ribs

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6424
Author(s):  
Cheng-Hung Huang ◽  
Chih-Yang Kuo
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Design Problem ◽  
Direct Problem ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Design Variables ◽  
Non Linear ◽  
Inverse Design Problem ◽  
Η Value

A non-linear three-dimensional inverse shape design problem was investigated for a pipe type heat exchanger to estimate the design variables of continuous lateral ribs on internal Z-shape lateral fins for maximum thermal performance factor η. The design variables were considered as the positions, heights, and number of ribs while the physical properties of air were considered as a polynomial function of temperature; this makes the problem non-linear. The direct problem was solved using software package CFD-ACE+, and the Levenberg–Marquardt method (LMM) was utilized as the optimization tool because it has been proven to be a powerful algorithm for solving inverse problems. Z-shape lateral fins were found to be the best thermal performance among Z-shape, S-shape, and V-shape lateral fins. The objective of this study was to include continuous lateral ribs to Z-shape lateral fins to further improve η. Firstly, the numerical solutions of direct problem were solved using both polynomial and constant air properties and then compared with the corrected solutions to verify the necessity for using polynomial air properties. Then, four design cases, A, B, C and D, based on various design variables were conducted numerically, and the resultant η values were computed and compared. The results revealed that considering continuous lateral ribs on the surface of Z-shape lateral fins can indeed improve η value at the design working condition Re = 5000. η values of designs A, B and C were approximately 13% higher than that for Z-shape lateral fins, however, when the rib numbers were increased, i.e., design D, the value of η became only 11.5 % higher. This implies that more ribs will not guarantee higher η value.

scholarly journals Optimization of Laminated Composite Plates for Maximum Biaxial Buckling Load

2020 ◽  
Vol 36 (2) ◽  
Author(s):  
Pham Dinh Nguyen ◽  
Quang-Viet Vu ◽  
George Papazafeiropoulos ◽  
Hoang Thi Thiem ◽  
Pham Minh Vuong ◽  
...  
Keyword(s):  
Fiber Orientation ◽  
Orientation Angle ◽  
Laminated Composite ◽  
Optimization Procedure ◽  
Composite Plates ◽  
Buckling Load ◽  
Biaxial Compression ◽  
Laminated Composite Plates ◽  
Design Variables ◽  
Fiber Orientation Angle

This paper proposes an optimization procedure for maximization of the biaxial buckling load of laminated composite plates using the gradient-based interior-point optimization algorithm. The fiber orientation angle and the thickness of each lamina are considered as continuous design variables of the problem. The effect of the number of layers, fiber orientation angles, thickness and length to thickness ratios on the buckling load of the laminated composite plates under biaxial compression is investigated. The effectiveness of the optimization procedure in this study is compared with previous works.

Multiobjective Design Optimization of Microchannel Cooling System Using High Performance Thermal Vias in LTCC Substrates

2013 ◽  
Vol 10 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Aparna Aravelli ◽  
Singiresu S. Rao ◽  
Hari K. Adluru
Keyword(s):  
Heat Transfer ◽  
Design Optimization ◽  
High Performance ◽  
Cooling System ◽  
Optimization Technique ◽  
Optimization Theory ◽  
Thermal Design ◽  
Design Variables ◽  
Microchannel Cooling ◽  
Multiobjective Design

Increased heat generation in semiconductor devices for demanding applications leads to the investigation of highly efficient cooling solutions. Effective options for thermal management include passing of cooling liquid through the microchannel heat sink and using highly conductive materials. In the author's previous work, experimental and computational analyses were performed on LTCC substrates using embedded silver vias and silver columns forming microchannels. This novel technique of embedding silver vias along with forced convection using a coolant resulted in higher heat transfer rates. The present work investigates the design optimization of this cooling system (microheat exchanger) using systems optimization theory. A new multiobjective optimization problem was formulated for the heat transfer in the LTCC model using the log mean temperature difference (LMTD) method of heat exchangers. The goal is to maximize the total heat transferred and to minimize the coolant pumping power. Structural and thermal design variables are considered to meet the manufacturability and energy requirements. Pressure loss and volume of the silver metal are used as constraints. A hybrid optimization technique using sequential quadratic programming (SQP) and branch and bound method of integer programming has been developed to solve the microheat exchanger problem. The optimal design is presented and sensitivity analysis results are discussed.

A Model-Based Formulation of Robust Design

2005 ◽  
Vol 127 (3) ◽  
pp. 388-396 ◽  
Author(s):  
Khalid Al-Widyan ◽  
Jorge Angeles
Keyword(s):  
Covariance Matrix ◽  
Robust Design ◽  
Design Problem ◽  
Engineering Systems ◽  
Design Environment ◽  
Design Task ◽  
Model Based ◽  
Functional Relations ◽  
Design Variables ◽  
Environment Parameters

Laid down in this paper are the foundations on which the design of engineering systems, in the presence of an uncontrollable changing environment, can be based. The changes in environment conditions are accounted for by means of robustness. To this end, a theoretical framework as well as a general methodology for model-based robust design are proposed. Within this framework, all quantities involved in a design task are classified into three sets: the design variables (DV), grouped in vector x, which are to be assigned values as an outcome of the design task; the design-environment parameters (DEP), grouped in vector p, over which the designer has no control; and the performance functions (PF), grouped in vector f, representing the functional relations among performance, DV, and DEP. A distinction is made between global robust design and local robust design, this paper focusing on the latter. The robust design problem is formulated as the minimization of a norm of the covariance matrix of the variations in PF upon variations in the DEP, aka noise in the literature on robust design. Moreover, one pertinent concept is introduced: design isotropy. We show that isotropic designs lead to robustness, even in the absence of knowledge of the statistical properties of the variations of the DEP. To demonstrate our approach, a few examples are included.

A Pareto-Based Genetic Algorithm Search Approach to Handle Damped Natural Frequency Constraints in Turbo Generator Rotor System Design

2004 ◽  
Vol 126 (3) ◽  
pp. 619-625 ◽  
Author(s):  
Anders Angantyr ◽  
Jan Olov Aidanpa¨a¨
Keyword(s):  
Genetic Algorithm ◽  
Natural Frequencies ◽  
Design Criterion ◽  
Rotor System ◽  
Design Tool ◽  
Generator Rotor ◽  
System A ◽  
Turbo Generator ◽  
Design Variables ◽  
Search Approach

The detailed design of a turbo generator rotor system is highly constrained by feasible regions for the damped natural frequencies of the system. A major problem for the designer is to find a solution that fulfills the design criterion for the damped natural frequencies. The bearings and some geometrical variables of the rotor are used as the primary design variables in order to achieve a feasible design. This paper presents an alternative approach to search for feasible designs. The design problem is formulated as an optimization problem and a genetic algorithm (GA) is used to search for feasible designs. Then, the problem is extended to include another objective (i.e., multiobjective optimization) to show the potential of using the optimization formulation and a Pareto-based GA in this rotordynamic application. The results show that the presented approach is promising as an engineering design tool.

Multiobjective Weighting Selection for Optimization-Based Control Design

1997 ◽  
Vol 122 (3) ◽  
pp. 567-569 ◽  
Author(s):  
Ricardo H. C. Takahashi ◽  
Juan F. Camino and ◽  
Douglas E. Zampieri ◽  
Pedro L. D. Peres
Keyword(s):  
Control Design ◽  
Active Suspension ◽  
Pareto Optimal ◽  
Pareto Optimal Solutions ◽  
Optimal Solutions ◽  
Cost Functional ◽  
Design Variables ◽  
Optimal Controllers ◽  
Selection For ◽  
Multiobjective Design

A methodology for the multiobjective design of controllers is presented, motivated by the problem of designing an active suspension controller. This problem has, as a particular feature, the possibility of being defined with two design variables only. The multiobjective controller is searched inside the space of “optimal controllers” defined by a weighted cost functional. The weightings are taken as the optimization variables for the multiobjective design. The method leads to (local) Pareto-optimal solutions and allows the direct specification of controller constraints in terms of some primary objectives which are taken into account in the multiobjective search. [S0022-0434(00)01403-9]

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