Design optimization of a wind tunnel force balance using stepwise response surface method

A force balance measures the forces being applied to an object in a wind tunnel test. The force balance needs to be optimized to generate an acceptable gauge reading while guaranteeing no structural failure by the wind tunnel loadings. This paper proposes a stepwise response surface method (RSM) for design optimization of a force balance. Three sampling techniques were tried in the RSM study, and finite element simulation was used for functional evaluation. The first trial was based on broad sampling, followed by a second trial based on narrow sampling. The data from these trials was then utilized in a final regression, in which a quadratic model was generated to identify the final optimum point. The final design of the force balance provides satisfactory gauge readings with decreased stress values even though the roll moment is greatly increased.

     

Reliability based design optimization using response surface augmented moment method

Journal of Mechanical Science and Technology - A new approach toward reliability based design optimization (RBDO) is proposed based on the response surface augmented moment method (RSMM). In RSMM,...     

Parametric study and optimization of a food can corrugation design using a response surface method

This paper presents the parametric design and functional optimization of a thin-walled food container with a corrugated surface. The configuration of the can corrugation should be designed to minimize the use of raw material subject to the constraints of the targeted structural performance. In the present study, the failure behaviors and the buckling strengths of a commercial food can under paneling pressure and axial loading are investigated with a series of experiments and finite element analyses. Full factorial design is implemented to study the effects of the geometric parameters of the corrugation (e.g., depth, radius, spacing and number of beadings) on its strength. Parameter optimization using a rotatable central composite design is employed to identify an optimal corrugation design by approximating the response surfaces of the can strength in terms of the significant design variables. The obtained surfaces are derived through the analysis of variance, and the suitability of the response is justified. A light- weight can body is then achieved by reduction of the can body thickness according to the required strength characteristics. Finite element analysis of the optimal model is also performed to confirm the predicted results. By using the proposed procedure, the can-body weight can be reduced by up to 12% compared with the original design.     

Robotic fiber placement process analysis and optimization using response surface method

Unlike traditional materials, composites are carefully designed materials suitable for specific applications. Conventional methods of fabrication of composite structures have proven to be labor intensive and time-consuming. Robotic fiber placement is a composite fabrication technique that increases the flexibility of fiber placement process and allows for the fabrication of more complex structures. This study is aimed at analyzing and optimizing the robotic fiber placement process parameters. Many experiments have been conducted to analyze gas torch temperature, fiber laying head speed, and fiber compaction force and the process is optimized using response surface method.     

A study on the optimization method for a multi-body system using the response surface analysis

An optimization method, which minimizes the characteristic value of a system using response surface analysis, is presented. Plackett-Burman design is used as a screening method. Using the response surface analysis, second order recursive model function is estimated as an objective function. To verify the reliability of the model function, an F-test based on the analysis of variances table is used. Lastly, the sequential quadratic-programming method is used to find the value of design parameters. By applying the preceding procedure to a multi-body dynamic model, the optimization process presented in this study is verified. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Sung Pil Jung received a B.S. degree in Mechanical Engineering from Ajou University in 2006. Currently he is a Ph.D candidate at Ajou University in Suwon, Korea. Mr. Jung’s research interests are in the area of multi-body & structural dynamics, optimization and computer aided engineering. Tae Won Park received a B.S. degree in Mechanical Engineering from Seoul University. He then went on to receive his M.S. and Ph.D. degrees from the University of Iowa. Dr. Park is currently a Professor at the School of Mechanical Engineering at Ajou University in Suwon, Korea.     

A multi-objective airfoil shape optimization study using mesh morphing and response surface method

Journal of Mechanical Science and Technology - Here, a distinct procedure was adopted to optimize the shape of the NACA 0012 airfoil profile for Reynolds number, Mach number, and angle of attack...     

Flow-forming optimization based on hardness of flow-formed AISI321 tube using response surface method

Flow forming is an advanced locally plastic deformation applied to manufacture seamless tubes with thin walls and high precision dimension. One of the important mechanical properties of flow-formed tubes is hardness. In this study, after preliminary experiments for definition of effective parameters, design of experiments (DOE) is utilized to determine the influence of the parameters such as rotational speed of mandrel, feed rate, and wall thickness reduction on the hardness of flow-formed AISI 321 steel tube. Under experimental results, a mathematical model comprising effective parameters is developed to predict the optimum hardness, using response surface methodology (RSM). RSM’s Box–Behnken design is employed to specify the optimum condition caused to a minimum hardness at high optimum confidence level. The analyzed model revealed that the hardness increases with increasing of the mandrel speed and the depth of cut, and it decreases with decreasing of the feed rate. The new point of view is related to the fact that the high level of thickness reduction covers the efficiency of mandrel speed.     

Modeling and optimization of a reluctance accelerator using DOE-based response surface methodology

This paper introduces experiment-based modeling and optimization of a reduced-scale Electromagnetic launcher (EML) using the Design of experiments (DOE) technique. Response surface models describing the velocity and kinetic energy of the launched projectile were developed using the Box–Behnken method with design variable transforms, and an Analysis of variance (ANOVA) was conducted to refine the models by removing statistically insignificant terms. A bi-objective optimization problem with the maximum velocity and maximum kinetic energy as objects was considered, and a Pareto front was obtained using the generated response surfaces as the solution of the problem. Verification tests on the optimal design points were conducted to demonstrate the validity of the developed models.

     

Reliability-based design optimization via high order response surface method

To reduce the computational effort of reliability-based design optimization (RBDO), the response surface method (RSM) has been widely used to evaluate reliability constraints. We propose an efficient methodology for solving RBDO problems based on an improved high order response surface method (HORSM) that takes advantage of an efficient sampling method, Hermite polynomials and uncertainty contribution concept to construct a high order response surface function with cross terms for reliability analysis. The sampling method generates supporting points from Gauss-Hermite quadrature points, which can be used to approximate response surface function without cross terms, to identify the highest order of each random variable and to determine the significant variables connected with point estimate method. The cross terms between two significant random variables are added to the response surface function to improve the approximation accuracy. Integrating the nested strategy, the improved HORSM is explored in solving RBDO problems. Additionally, a sampling based reliability sensitivity analysis method is employed to reduce the computational effort further when design variables are distributional parameters of input random variables. The proposed methodology is applied on two test problems to validate its accuracy and efficiency. The proposed methodology is more efficient than first order reliability method based RBDO and Monte Carlo simulation based RBDO, and enables the use of RBDO as a practical design tool.     

Analysis and design of hydroformed thin-walled tubes using enhanced one-step method

This paper deals with the analysis and design of tube hydroforming parameters in order to reduce defects which may occur at the end of the forming process, such as necking and wrinkling. We propose a specific methodology based on the coupling between an enhanced one-step method for the rapid simulation of tube hydroforming process and a surrogate model based on a metamodeling technique. The basic formulation of the one-step method has been modified and adapted for the modeling of 3D tube hydroforming problems in which the initial geometry is a circular tube expanded by internal pressure and submitted to axial feeding. In the surrogate model, approximate responses are built using moving least squares method and constructed within a moving region of interest which moves across a predefined discrete grid of authorized experimental designs. Two applications of tube hydroforming of aluminum alloy 6061-T6 have been utilized to validate our methodology. The final design is validated using experiments together with the classical explicit dynamic incremental approach using ABAQUS? commercial code.     

Design optimization of magnetorheological damper geometry using response surface method for achieving maximum yield stress

Journal of Mechanical Science and Technology - Field controllable magnetorheological (MR) damper has gained prominence as a suitable vibration control device for a wide variety of applications as...     

Multiple-response optimization for micro-endmilling process using response surface methodology

In the present trend, new fabrication methods for producing miniaturized components are gaining popularity due to the recent advancements in micro-electro mechanical systems. Micro-machining differs from the traditional machining with the small size tool, resolution of x?Cy and z stages. This paper focuses RSM for the multiple response optimization in micro-endmilling operation to achieve maximum metal removal rate (MRR) and minimum surface roughness. In this work, second-order quadratic models were developed for MRR and surface roughness, considering the spindle speed, feed rate and depth of cut as the cutting parameters, using central composite design. The developed models were used for multiple-response optimization by desirability function approach to determine the optimum machining parameters. These optimized machining parameters are validated experimentally, and it is observed that the response values are in good agreement with the predicted values.     

Optimal robot placement using response surface method

This paper is concerned with a new approach for optimal placement of a prescribed task in the workspace of a robotic manipulator. The approach is resulted by applying response surface method on concept of path translation and path rotation. A robotic optimization tool based on this approach is developed as an add-in to RobotStudio. The methodology has been carefully verified by optimizing the position of several kinds of industrial robots and paths in four showcases to attain minimum cycle time. The results indicate that an increase in productivity up to 37%, compared to the admissible location with the highest cycle time, is achieved by optimally positioning the task in the robot workspace.     

A response surface based sequential approximate optimization using constraint-shifting analogy

When a traditional response surface method (RSM) is used as a meta-model for inequality constraint functions, an approximate optimal solution is sometimes actually infeasible in a case where it is active at the constraint boundary. The paper proposes a new RSM that ensures the constraint feasibility with respect to an approximate optimal solution. Constraint-shifting is suggested in order to secure the constraint feasibility during the sequential approximate optimization process. A central composite design is used as a tool for design of experiments. The proposed approach is verified through a mathematical function problem and engineering optimization problems to support the proposed strategies.     

Wind turbine airfoil design using response surface method

This paper describes the design of a wind turbine airfoil under various operating conditions through the use of a suitable combination of flow analysis and optimization techniques. The proposed method includes a parametric study on the influence of design variables and different design conditions on airfoil performance. The incompressible Navier-Stokes equations and the k-ɛ turbulence model are used to compute the aerodynamic coefficients of an airfoil. The response surface method (RSM) is applied to obtain the optimum solution of the defined objective function and the penalty term of the constraint. The influence of the design variables (change in airfoil geometry) on airfoil performance as well as the accuracy of the RSM is examined from the statistical viewpoint. Various airfoil shapes with good aerodynamic performance are obtained according to various operating conditions (change in angle of attack), objective functions (minimum of drag coefficient or maximum of lift-to-drag ratio), and constraints (the lift coefficient of a designed airfoil is higher than that of a base airfoil at a certain angle of attack).     

FMEA for the reliability of hydroformed flanged part for automotive application

Tube hydroforming technology is widely used in the automotive industries due to its advantages such as weight reduction, increased strength, improved quality, and reduced tooling cost compared to conventional manufacturing technology. The hydroformed parts often have to be structurally joined at some point. Therefore, the hydroformed automotive parts which have a localized attachment flange are useful. In many cases, the parts formed by hydroforming process are directly related with structural safety, reliability of hydroformed parts must be considered. In this study, hydroforming process of flanged rectangular parts was designed and process reliability was investigated. Finite element analysis was performed to optimize tool geometry considering process parameters such as die aspect ratio and pressure conditions with Dynaform 5.5. Hydroforming experiments to fabricate a flanged rectangular part were performed with optimized tool geometry. The relationship between process parameters and defect was analyzed by FMEA (failure modes and effects analysis). The result shows that process condition was optimized and reliability of rectangular part was increased.     

基于中心点精确响应面法的板壳结构优化

对响应面方法中两个最为关键的概念——近似函数及试验设计做了简单描述,选择线性函数作为约束条件的近似函数形式,并对位移和应力约束作不同处理,位移约束不合常数项,而应力约束含常数项。提出了一种适合建立一阶形式响应面并使结构分析次数最少的试验设计方法——中心扩展法。求解响应面时在最小二乘法的基础之上作了改进,提出中心点精确响应面法,使拟合的响应面中心点处的响应值精确等于有限元分析值。最后通过数值算例说明改进后的响应面法对于板壳结构优化的可行性和优越性。     

Modelling of extrusion force using the surface response method

Due to the complexity of bulk metal forming processes, the establishment of theoretical models for these processes is prohibitively difficult and frequently impossible. Consequently, empirical models attained by means of experimental research are habitually used to replace the theoretical models. This paper describes the application of the surface response method in an attempt to define a relationship between the maximum extrusion force and three process parameters; namely, the conical die angle γ, die land height, h and die exit diameter, d. An extensive experimental program of aluminium extrusion was undertaken in parallel with the empirical modelling. An adequacy test was made on the analysed models to determine the accuracy with which the model predicted data obtained by experimental methods.     

Modeling and optimization of burr height in drilling of Al-7075 using Taguchi method and response surface methodology

This investigation presents the use of Taguchi and response surface methodologies for minimizing the burr height and the surface roughness in drilling Al-7075. The Taguchi method, a powerful tool to design optimization for quality, is used to find optimal cutting parameters. Response surface methodology is useful for modeling and analyzing engineering problems. The purpose of this paper was to investigate the influence of cutting parameters, such as cutting speed and feed rate, and point angle on burr height and surface roughness produced when drilling Al-7075. A plan of experiments, based on L₂₇ Taguchi design method, was performed drilling with cutting parameters in Al-7075. All tests were run without coolant at cutting speeds of 4, 12, and 20 m/min and feed rates of 0.1, 0.2, and 0.3 mm/rev and point angle of 90^°, 118°, and 135°. The orthogonal array, signal-to-noise ratio, and analysis of variance (ANOVA) were employed to investigate the optimal drilling parameters of Al-7075. From the analysis of means and ANOVA, the optimal combination levels and the significant drilling parameters on burr height and surface roughness were obtained. The optimization results showed that the combination of low cutting speed, low feed rate, and high point angle is necessary to minimize burr height. The best results of the surface roughness were obtained at lower cutting speed and feed rates while at higher point angle. The predicted values and measured values are quite close to each other; therefore, this result indicates that the developed models can be effectively used to predict the burr height and the surface roughness on drilling of Al-7075.