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.     

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.     

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.     

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.     

基于响应面法的微操作平台多目标优化

为了提高微操作平台的操作空间和动态性能,基于响应面法对一种新型微操作平台进行了多目标优化设计。采用中心组合设计方法选取仿真试验点,根据试验点建立平台的参数化几何模型,应用软件ANSYS对平台进行静力学和模态分析得到其固有频率、位移放大倍数和最大应力的响应值。根据所得的仿真试验数据,采用最小二乘法和显著性检验建立反映平台性能指标的二阶多项式响应面模型。最后,计算了反映响应面拟合度的评价指标,验证了所建响应面模型的精确性。以微操作平台的放大倍数和固有频率为优化目标,强度为约束,建立了平台的多目标优化模型,采用多目标遗传算法对平台进行优化得到Pareto解集。从Pareto解集可知,固有频率与放大倍数之间是相互冲突的,故需权衡固有频率和放大倍数从Pareto解集选取最优解。比较优化前后平台的各性能指标可知,平台的固有频率增大了35.58%,放大倍数增大了2.33%,最大应力减小了38.97%,证明了提出的优化方法的有效性。     

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.     

基于响应面法的减速器行星架多目标优化研究

针对某二级行星齿轮减速器的行星架存在的强度不足、质量过大等问题,对行星架的应力分布进行了分析,对行星架进行了多目标优化.首先,采用两种不同的方案对行星架进行了强度分析(其中,方案一采用了直接加载轴承力的方法,方案二采用了行星架装配体刚柔耦合模型),得出了二种不同的应力和应力分布结果;然后,通过对其实际工况进行分析,结果...     

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.     

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).     

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.