Search results

1 – 10 of over 22000
To view the access options for this content please click here
Article
Publication date: 30 August 2021

Mohamed L. Shaltout and Hesham A. Hegazi

In this work, the design problem of hydrodynamic plain journal bearings is formulated as a multi-objective optimization problem to improve bearing performance under…

Abstract

Purpose

In this work, the design problem of hydrodynamic plain journal bearings is formulated as a multi-objective optimization problem to improve bearing performance under different operating conditions.

Design/methodology/approach

The problem is solved using a hybrid approach combining genetic algorithm and sequential quadratic programming. The selected state variables are oil leakage flow rate, power loss and minimum oil film thickness. The selected design variables are the radial clearance, length-to-diameter ratio, oil viscosity, oil supply pressure and oil supply groove angular position. A validated empirical model is adopted to provide relatively accurate estimation of the bearing state variables with reduced computations. Pareto optimal solution sets are obtained for different operating conditions, and secondary selection criteria are proposed to choose a final optimum design.

Findings

The adopted hybrid optimization approach is a random search algorithm that generates a different solution set for each run, thus a different bearing design. For a number of runs, it is found that the key design variables that significantly affect the optimum state variables are the bearing radial clearance, oil viscosity and oil supply pressure. Additionally, oil viscosity is found to represent the significant factor that distinguishes the optimum designs obtained using the implemented secondary selection criteria. Finally, the results of the proposed optimum design framework at different operating conditions are presented and compared.

Originality/value

The proposed multi-objective formulation of the bearing design problem can provide engineers with a systematic approach and an important degree of flexibility to choose the optimum design that best fits the application requirements.

Details

Industrial Lubrication and Tribology, vol. 73 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 2003

Y.J. Lin and R. Farahati

This paper presents a versatile and economical knowledge‐based assembly design of blade and shell assemblies by employing behavioral modeling concepts. Behavioral modeling…

Abstract

This paper presents a versatile and economical knowledge‐based assembly design of blade and shell assemblies by employing behavioral modeling concepts. Behavioral modeling is a new generation CAD concept aimed at achieving ultimately optimum results with the efforts made in the early stage of the product development cycle. As a result, the assembly process of any odd‐configured parts such as torque converter blades, can be accurately planned, and made adaptable to all potential in‐process alterations due to either changes of components design or that of the assembly kinematics. Optimum assembly design is achieved when the volumetric interference meets a desired value based on an expert's determination. Experimental verification of the proposed optimum assembly design conducted in Luk, Inc. with two different blades' assemblies demonstrates satisfactory results.

Details

Assembly Automation, vol. 23 no. 2
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 2002

Nielen Stander and K.J. Craig

This paper evaluates a Successive Response Surface Method (SRSM) specifically developed for simulation‐based design optimization, e.g. that of explicit nonlinear dynamics…

Abstract

This paper evaluates a Successive Response Surface Method (SRSM) specifically developed for simulation‐based design optimization, e.g. that of explicit nonlinear dynamics in crashworthiness design. Linear response surfaces are constructed in a subregion of the design space using a design of experiments approach with a D‐optimal experimental design. To converge to an optimum, a domain reduction scheme is utilized. The scheme requires only one user‐defined parameter, namely the size of the initial subregion. During optimization, the size of this region is adapted using a move reversal criterion to counter oscillation and a move distance criterion to gauge accuracy. To test its robustness, the results using the method are compared to SQP results of a selection of the well‐known Hock and Schittkowski problems. Although convergence to a small tolerance is slow when compared to SQP, the SRSM method does remarkably well for these sometimes pathological analytical problems. The second test concerns three engineering problems sampled from the nonlinear structural dynamics field to investigate the method's handling of numerical noise and non‐linearity. It is shown that, despite its simplicity, the SRSM method converges stably and is relatively insensitive to its only user‐required input parameter.

Details

Engineering Computations, vol. 19 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 3 April 2017

Krishna Kumar Singh and Mrityunjay K. Sinha

The purpose of this paper is to present a way to determine the optimum values of design parameters in a cylindrical heat sink with branched fins. Investigations into the…

Abstract

Purpose

The purpose of this paper is to present a way to determine the optimum values of design parameters in a cylindrical heat sink with branched fins. Investigations into the effect of design parameters, such as the number of fins, length of fin, height of fin and outer diameter of the heat sink on heat transfer are reported here. In this analysis, branch angle (α = 10°) is considered.

Design/methodology/approach

The Taguchi method, a powerful tool to design optimization, is applied for the tests and standard L9 orthogonal array with three factors, and three levels for each factor are selected. Nine test samples are analyzed in which the total heat transfer rate for each test sample is found. Contribution ratios for each parameter are also found. The results obtained from this analysis are used to find the optimum design parameter values relating to the heat sink performance.

Findings

The optimum design parameters are analyzed in this paper. The reliability of the optimum test samples is verified. Also, the variation of the average heat transfer rate of optimum sample is reported when it is compared with the reference sample.

Practical implications

Effective design of a cylindrical heat sink has been reported for cooling light-emitting diode (LED) lights, which have recently attracted the attention of the illumination industry. In this analysis, the contribution ratios have an important role to set out the performance characteristics of a heat sink.

Originality/value

The reliability of the optimum test samples is verified. Also, the variation of the average heat transfer rate of optimum sample is reported when it is compared with the reference sample.

Details

Journal of Engineering, Design and Technology, vol. 15 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

To view the access options for this content please click here
Article
Publication date: 1 January 2006

R. Balamurugan, C.V. Ramakrishnan and N. Swaminathan

The structural design problem can be viewed as an iterative design loop with each iteration involving two stages for topology and shape designs with genetic algorithm (GA…

Abstract

Purpose

The structural design problem can be viewed as an iterative design loop with each iteration involving two stages for topology and shape designs with genetic algorithm (GA) as the optimization tool for both.

Design/methodology/approach

The topology optimization problem, which is ill posed, is regularized using a constraint on perimeter and solved using GA. The problem is formulated as one of compliance minimization subject to volume constraint for the single loading case. A dual formulation of this has been used for the multiple loading cases resulting in as many behavioral constraints as there are loading cases. The tentative topology given by the topology optimization module is taken and the domain boundary is approximated using straight lines, B‐splines and cubic spline curves and design variables are selected among the boundary defining points. Optimum boundary shape of the problem has been obtained using GA in two different ways: without stress constraints; and with stress constraints.

Findings

The proposed two stage strategy has been tested on benchmark structural optimization problems and its performance is found to be extremely good.

Practical implications

The strategy appears to be eminently suitable for implementation in a general purpose FE software as an add‐on module for structural design optimization.

Originality/value

It has been observed that the integrated topology and shape design method is robust and easy to implement in comparison with other techniques. The computing time requirements for the GA does not appear daunting in the present scenario of high performance parallel computing and improved GA techniques.

Details

Engineering Computations, vol. 23 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 1 May 1999

M.R. Ghasemi, E. Hinton and R.D. Wood

This paper demonstrates the use of genetic algorithms (GAs) for size optimization of trusses. The concept of rebirthing is shown to be considerably effective for problems…

Downloads
1305

Abstract

This paper demonstrates the use of genetic algorithms (GAs) for size optimization of trusses. The concept of rebirthing is shown to be considerably effective for problems involving continuous design variables. Some benchmark examples are studied involving 4‐bar, 10‐bar, 64‐bar, 200‐bar and 940‐bar two‐dimensional trusses. Both continuous and discrete variables are considered.

Details

Engineering Computations, vol. 16 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 3 October 2016

Jun Zheng, Zilong Li, Liang Gao and Guosheng Jiang

The purpose of this paper is to efficiently use as few sample points as possible to get a sufficiently explored design space and an accurate optimum for adaptive…

Abstract

Purpose

The purpose of this paper is to efficiently use as few sample points as possible to get a sufficiently explored design space and an accurate optimum for adaptive metamodel-based design optimization (AMBDO).

Design/methodology/approach

A parameterized lower confidence bounding (PLCB) scheme is proposed in which a cooling strategy is introduced to guarantee the balance between exploitation and exploration by varying weights of the predicting error and optimum of a metamodel. The proposed scheme is investigated by a set of test functions and a structural optimization problem, in which PLCB with four kinds of cooling control functions are studied. Moreover, other infill criteria (such as expected improvement and its extension versions) are taken into comparison.

Findings

Results show that the proposed PLCB (especially PLCB with the first cooling control function) based AMBDO method can find the optimum with fewer evaluations and maintain good accuracy, which means the proposed PLCB contributes to the excellent efficiency and accuracy in finding global optimal solutions.

Originality/value

The parameterized version of the lower confidence bound metric is proposed for AMBDO, typically used in the context of adaptive sampling in efficient global optimization.

Details

Engineering Computations, vol. 33 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 1 May 1995

C. Huang and B. Kröplin

This paper deals with the optimum design of composite laminated plates.Both ply orientation angles and ply thicknesses of the composite plate areused as design variables…

Abstract

This paper deals with the optimum design of composite laminated plates. Both ply orientation angles and ply thicknesses of the composite plate are used as design variables. The optimum design process is divided into two sublevels. In the first sublevel, the strain energy of the plate is minimized by changing the ply orientation angles while the ply thickness distributions remain unmodified. In the second sublevel, with the angle values obtained in the first sublevel, the optimum thickness distribution of each ply is obtained by minimizing the structural weight while satisfying stiffness and gauge constraints. The final optimum design is achieved by iterating between these two sublevels. The stiffness analysis is performed by the finite element method in which a triangular element is used that is suitable for from thin to thick plates and includes the transverse shear effects. All the derivative analysis is performed analytically. The mathematical programming method called Constrained Variable Metric is used to solve the optimum problem. An example is provided for a rectangular laminated plate with good results to show the effectiveness of the method.

Details

Engineering Computations, vol. 12 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 14 August 2020

Sadik Lafta Omairey, Peter Donald Dunning and Srinivas Sriramula

The purpose of this study is to enable performing reliability-based design optimisation (RBDO) for a composite component while accounting for several multi-scale…

Abstract

Purpose

The purpose of this study is to enable performing reliability-based design optimisation (RBDO) for a composite component while accounting for several multi-scale uncertainties using a large representative volume element (LRVE). This is achieved using an efficient finite element analysis (FEA)-based multi-scale reliability framework and sequential optimisation strategy.

Design/methodology/approach

An efficient FEA-based multi-scale reliability framework used in this study is extended and combined with a proposed sequential optimisation strategy to produce an efficient, flexible and accurate RBDO framework for fibre-reinforced composite laminate components. The proposed RBDO strategy is demonstrated by finding the optimum design solution for a composite component under the effect of multi-scale uncertainties while meeting a specific stiffness reliability requirement. Performing this using the double-loop approach is computationally expensive because of the number of uncertainties and function evaluations required to assess the reliability. Thus, a sequential optimisation concept is proposed, which starts by finding a deterministic optimum solution, then assesses the reliability and shifts the constraint limit to a safer region. This is repeated until the desired level of reliability is reached. This is followed by a final probabilistic optimisation to reduce the mass further and meet the desired level of stiffness reliability. In addition, the proposed framework uses several surrogate models to replace expensive FE function evaluations during optimisation and reliability analysis. The numerical example is also used to investigate the effect of using different sizes of LRVEs, compared with a single RVE. In future work, other problem-dependent surrogates such as Kriging will be used to allow predicting lower probability of failures with high accuracy.

Findings

The integration of the developed multi-scale reliability framework with the sequential RBDO optimisation strategy is proven computationally feasible, and it is shown that the use of LRVEs leads to less conservative designs compared with the use of single RVE, i.e. up to 3.5% weight reduction in the case of the 1 × 1 RVE optimised component. This is because the LRVE provides a representation of the spatial variability of uncertainties in a composite material while capturing a wider range of uncertainties at each iteration.

Originality/value

Fibre-reinforced composite laminate components designed using reliability and optimisation have been investigated before. Still, they have not previously been combined in a comprehensive multi-scale RBDO. Therefore, this study combines the probabilistic framework with an optimisation strategy to perform multi-scale RBDO and demonstrates its feasibility and efficiency for an fibre reinforced polymer component design.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 6 July 2012

Goutam Saha and Dilip Roy

Grounded theory, supported by leading designers, argues for an integrated approach covering end users and designers. However, no substantial work on apparel design has…

Abstract

Purpose

Grounded theory, supported by leading designers, argues for an integrated approach covering end users and designers. However, no substantial work on apparel design has been done so far where a balance is maintained by combining the opinions of consumers and the designers. The purpose of this paper is to provide an analytical framework for designing apparel considering both consumers’ opinions and fashion designers’ views.

Design/methodology/approach

An algorithm is proposed for reducing attributes and their levels to carry out conjoint analysis and assign utilities to different attributes and their levels. After selecting the best three design combinations based on their utilities, the authors have arrived at optimum design combinations. Through Delphi method, the opinions of a few fashion designers about these selected design combinations have been collected for matching with optimum design.

Findings

An optimum design is suggested for a formal office shirt, for North Indian women, by integrating opinions of designers and consumers.

Originality/value

Attribute and level reduction technique is an original contribution to the literature. Further, the authors’ approach to apparel design may provide a guideline to apparel manufacturers when designing their products. Knowledge of optimum design combinations gained through this approach may help apparel manufacturers and retailers in bringing efficiency in stock keeping unit management by keeping more stocks of apparel with optimum design combinations and thus ensuring a better return on investment made on their stocks.

Details

Journal of Fashion Marketing and Management: An International Journal, vol. 16 no. 3
Type: Research Article
ISSN: 1361-2026

Keywords

1 – 10 of over 22000