• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.683-691
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• 2010

In this paper, using an adjoint variable method, we develop a design sensitivity analysis(DSA) method applicable to heat conduction problems in steady state. Also, a topology design optimization method is developed using the developed DSA method. Design sensitivity expressions with respect to the thermal conductivity are derived. Since the already factorized system matrix is utilized to obtain the adjoint solution, the cost for the sensitivity computation is trivial. For the topology design optimization, the design variables are parameterized into normalized bulk material densities. The objective function and constraint are the thermal compliance of structures and allowable material volume respectively. Through several numerical examples, the developed DSA method is verified to yield very accurate sensitivity results compared with finite difference ones, requiring less than 0.25% of CPU time for the finite differencing. Also, the topology optimization yields physical meaningful results.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.128-137
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• 1998

A numerical approach for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. Compared with the conventional analytical methods, which require explicit derivation of sensitivity equations, the proposed numerical method can be applied to any type of suspension systems without obtaining sensitivity equations, once any kinematic analysis procedure is established. To obtain sensitivity equations, a numerical differentiation algorithm that uses the third order Lagrange polynomial is developed. The algorithm efficiently and accurately computes the sensitivity of various vehicle static design factors with respect to kinematic design variables. Through a suspension design problem, the validity and usefulness of the method is demonstrated.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.38-48
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• 1997

A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

• Journal of the Korean Home Economics Association
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• v.44 no.4 s.218
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• pp.133-144
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• 2006

The contemporary period is called "the age of sensibility" in which each individual consumer seeks to have her or his own products. Businesses are in need of design developments with an emphasis on customer sensitivity, and at the same time consumers must understand their own sensitivity to acquire information on designs that suit them. This research established a sensitivity and configuration database on designing men's jackets using the sensitivity engineering approach to clothing design information. The user interface was created on the Internet. Sixty-seven sensitivity terms of vocabulary appropriate for the assessment of men's jacket design were selected, and the different designs were classified into six items and 24 categories. Thirty men's jackets with different designs were produced for sensory testing and the results were analyzed in accordance with general linear I statistics. A sensitivity database was established for each category. My-sql, PHP, Java Script, and Html were used for the configuration database work. The configuration of items/categories, with the most appropriate sensitivity database information assigned to the selected sensitivity vocabulary, was programmed for display on the computer screen. The sensitivity vocabulary of a customer's choice for each factor was selected for the program to run, while the category and product configuration of the men's jacket most suitable for the search was displayed based on the user interface.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.247-259
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• 1996

Kinematic design sensitivity analysis for vehicle in suspension systems design is performed. Suspension systems are modeled using composite joins to reduce the number of the constraint equations. This allows a semi-analytical approach that is computerized symbolic manipulation before numerical computations and that may compensate for their drawbacks. All the constraint equations including design variables are derived in symbolic equations for sensitivity analysis. By directly differentiating the equations with respect to design variables, sensitivity equations are obtained. Since the proposed method only requires the hard point data, sensitivity analysis is possible in suspension design stage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.81-87
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• 1998

In this paper, a global acoustic design sensitivity analysis (DSA) of field point pressure with respect to structural sizing design variables is developed. Firstly acoustic sensitivity is formulated and implemented numerically. And it is combined with continuum structural sensitivity to obtain the global acoustic, design sensitivity. For this procedure, GASA (global acoustic design sensitivity analyzer) has been developed. A half scale of automobile cavity model is considered in this paper. In order to confirm accuracy of the results of global acoustic DSA obtained by GASA, it is compared with the result of central finite difference method. In order to reduce computation time, Rayleigh approximated solution is evaluated and compared with the solution which used every nodal velocities. Also the acoustic optimization procedure is performed using design sensitivities. From these numerical studies, it can be shown that global acoustic DSA is a useful tool to improve acoustic problems.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.746-752
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• 2001

Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.62-68
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• 2000

Optimization technique to find a path of an inner reinforcement of an automobile hood is proposed by using design sensitivity informations. The strength and modal characteristics of the automobile hood are analyzed and their design sensitivity analyses with respect to the thickness are carried out using MSC/NASTRAN. Based on the design sensitivity analysis, determination of design variables and response functions is discussed. Techniques improving design from design sensitivity informations are suggested and the double-layer method is newly proposed to optimize the path of stiffener for a shell structure, Using the suggested method, we redesign a new inner reinforcement of an automobile hood and compare the responses with the original design. It is confirmed that new design improved in the frequency responses without the weight increasement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1852-1860
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• 1991

A shape design sensitivity of the elastic deformation due to a change of traction boundary condition is presented. The solution of governing equations for a linear elasticity problem is obtained by finite element method and the traction boundary is defined by design variables. The performance functional to be considered involves both the domain and boundary integral. Variations of geometry can be defined as design velocity. Using material derivative concept and adjoint equations, the design sensitivity is derived by Lagrange multiplier method. For a given geometry of a structure, the change of traction boundary is described by the tangential component of the design velocity only. The final result for the shape design sensitivity is formulated as the boundary integral form, the integrand is defined by tangential component of design velocity and first order derivatives of parameters. Numerical implementation of design sensitivity is discussed and is compared with the difference of the actual values.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.205-210
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• 2000

An optimum design algorithm of PSC box girder bridges using design sensitivity analysis is proposed in this paper. For the efficiency of the proposed algorithm, approximated reanalysis techniques using design sensitivity analysis are introduced. And also to save the numerical efforts, an efficient reanalysis technique through approximated structural responses is proposed. A design sensitivity analysis of structural response is executed by automatic differentiation(AD). The efficiency and robustness of the proposed algorithm, compared with conventional algorithm, is successfully demonstrated in the numerical example.