Subproblem Approximation Method Research Articles

Layout Optimization of Mooring Base of the Ship-Based Helicopter Based on FEM

The ship-based helicopter is always dangling in the sea because of winds and waves. It is necessary to analyze and calculate the mooring of helicopter. In order to void the complex derivation of mathematical formulas, the parameterized finite element method (FEM) model about the ship-based helicopter body, mooring cable and mooring base is established with the software ADAMS. This model is used to calculate the mooring tension and optimize the locations of the mooring bases. In the various layouts of the mooring bases, the minimal mooring tension is the layout optimization object. After some added constraint conditions are considered, the mooring point coordinates are searched and calculated in the standard and nonstandard parking positions with subproblem approximation method. Through the comparison and analysis of the relative changing ratio of the position coordinates, the final optimization layout scheme is obtained.

Thermo-mechanical simulation and parameters optimization for beam blank continuous casting

The objective of this work is to optimize the process parameters of beam blank continuous casting in order to ensure high quality and productivity. A transient thermo-mechanical finite element model is developed to compute the temperature and stress profile in beam blank continuous casting. By comparing the calculated data with the metallurgical constraints, the key factors causing defects of beam blank can be found out. Then based on the subproblem approximation method, an optimization program is developed to search out the optimum cooling parameters. Those optimum parameters can make it possible to run the caster at its maximum productivity, minimum cost and to reduce the defects. Now, online verifying of this optimization project has been put in practice, which can prove that it is very useful to control the actual production.

Closed Die Forging Geometrical Parameters Optimization for Al-MMC

Demand for lighter and stiffer products has been increasing in the last few years especially in automobile manufacturing. The closed die forging process of Metal Matrix Material (MMC) is presented as possible solution, since it produces parts with good mechanical properties and lighter weight. A computational modeling of closed die forging process using finite element method and optimization techniques makes the design optimization faster and more efficient, decreasing the use of conventional trial and error methods. In this study, the application of commercial finite element software (ANSYS) has been used to model cold closed die forging process. The model has been developed using ANSYS Parametric Design Language (APDL) to simulate a single stage axi-symmetry closed die forging process for H cross sectional shape. The material used is AlMgSi matrix with 15% SiC particles. Its flow curve and fractural strain are obtained from the literature. ANSYS Optimizer is used to obtain the maximum height in which the material can flow in the rib by changing Design Variables (DV) and State Variables (SV). Normally design variables are geometrical parameters such as, rib height to width ratio, web height to rib height ratio, fillet radii, draft angle and billet radius. State Variables (SV) are some parameters that depend on the design variables such as, the equivalent strain which must be below the fracture strain of the MMC material, and an acceptable contact gap (within the allowable tolerances range). Optimization method called Sub-Problem Approximation Method was used to find out the optimal design set. The technique used in this study can be used for newly developed materials to investigate its forgeability for much complicated shapes in closed die forging process.

Optimal Placement of Multi Circular Heat Sources of HANARO Irradiation Test

During fuel irradiation tests of material and fuel rods, all parts of cylindrical shells with multiple holes act as heat sources due to fission heat and γ-flux. The thermal stress is induced by a temperature difference among the heat sources. In this study, the thermal stress of the cylindrical structure is minimized by using an optimization method about the geometric variables. The circular shapes of the multi-specimens are investigated. For the thermal analysis of the structure, the finite element method code, ANSYS 8.1 is used. A sub-problem approximation method is used for the structural design optimization.

A comparative study on optimization of constrained layer damping treatment for structural vibration control

This paper presents a comparison of optimization algorithms for constrained layer damping (CLD) patches’ layout with an objective to minimize the maximum vibration response of the odd modes, which constitutes the dominant acoustic radiation, of a simply supported beam excited by a harmonic transverse force. An analytical model developed for relating the displacement response of the beam with bonded CLD patches and their layout is adopted to formulate the optimization problem. Four different nonlinear optimization methods/algorithms, sub-problem approximation method, the first-order method, sequential quadratic programming (SQP) and genetic algorithm (GA), are then, respectively, used to optimize the CLD patches’ locations and lengths with the aim of minimum displacement amplitude at the middle beam. The efficiency of each considered optimization method is evaluated and also compared in terms of obtained optimal beam displacement and the added weight owing to damping treatment. The results show that GA is most efficient in obtaining the best optimum for this optimization problem in spite of highest computation efforts required to improve its stability.

Shape Design Optimization of the Boom System in High Ladder Vehicle

A shape design optimization of the boom system in high ladder vehicle modeled by 3-dimensional finite elements is carried out. The structural analysis is performed using 3-D FEA (Finite Element Analysis) giving the results of displacements, stresses and natural frequencies. The section height and width of the boom is controlled by the FEA result data. The subproblem approximation method is implemented for the optimal shape based on displacement and principal stress. In the meantime, Lanzcos algorithm method is implemented in order to find the natural frequency of the system. The optimal models obtained by three different optimization processes are compared with the initial model and evaluated for economic conditions respectively. It is found that the different shape optimization processes give the different shape optimization results, which suggest their unique optimal shapes under their necessary design condition.