Robust Mechanical Design Through Minimum Sensitivity

1989 ◽  
Author(s):  
A. D. Belegundu ◽  
S. Zhang
Keyword(s):  
Contact Pressure ◽  
Thermal Environment ◽  
Mechanical Design ◽  
Operating Temperature ◽  
Design Stage ◽  
Element Analysis ◽  
Uncertain Variables ◽  
Design Variables ◽  
Minimum Sensitivity ◽  
Selection Of

Abstract The problem of designing mechanical systems or components under uncertainty is considered. The basic idea is to ensure quality control at the design stage by minimizing sensitivity of the response to uncertain variables by proper selection of design variables. This formulation is applied to the design of a brass sleeve which is press fitted over a steel shaft in an uncertain thermal environment. The contact pressure is determined using finite element analysis. By optimizing the shape of the sleeve, the sensitivity of contact pressure with respect to operating temperature is reduced. The minimum sensitivity approach offers a straightforward procedure for robust design and can be implemented in a general manner. It is shown that reduction in sensitivity leads to increase in probability of safety.

Robustness of Design Through Minimum Sensitivity

1992 ◽  
Vol 114 (2) ◽  
pp. 213-217 ◽  
Author(s):  
A. D. Belegundu ◽  
Shenghua Zhang
Keyword(s):  
Optimization Problem ◽  
Probability Distributions ◽  
Uncertain Variable ◽  
Design Stage ◽  
Cross Sectional ◽  
Uncertain Variables ◽  
Design Variables ◽  
Variable Reduction ◽  
Minimum Sensitivity ◽  
Selection Of

The problem of designing mechanical systems or components under uncertainty is considered. The basic idea is to ensure quality control at the design stage by minimizing sensitivity of the response to uncertain variables by proper selection of design variables. The formulation does not involve probability distributions. It is proved, however, that when the response is linear in the uncertain variable, reduction in sensitivity implies lesser probability of failure. The proof is generalized to the non-linear case under certain restrictions. In one example, the design of a three-bar truss is considered. The length of one of the bars is considered to be the uncertain variable while cross-sectional areas are the design variables. The sensitivity of the x-displacement is minimized. The constrained optimization problem is solved using a nonlinear programming code. A criterion which can help identify some of the problems where robustness in design is critical is discussed.

Topological and Geometric Synthesis of Compliant Mechanisms

2000 ◽  
Author(s):  
Joel A. Hetrick ◽  
Sridhar Kota
Keyword(s):  
Compliant Mechanisms ◽  
Programming Algorithm ◽  
Design Stage ◽  
Stable Convergence ◽  
Ground Structure ◽  
Element Analysis ◽  
Cross Section Area ◽  
Design Variables ◽  
Section Area ◽  
Geometric Variation

Abstract Structural optimization of compliant mechanisms is a systematic and automated approach for synthesizing the topology (layout) of mechanisms given the motion requirements. Here, two optimization approaches are presented: one employing a traditional full ground structure and one utilizing a modular ground structure whose nodes are allowed to wander within specified ranges. For problems discretized by many elements, the modular ground structure effectively reduces the number of design variables and speeds design convergence. In addition, relocation of node coordinates allows for geometric variation within the topology (layout) design stage. Linear finite element analysis using truss elements is utilized along with a sequential quadratic programming algorithm to optimize the mechanisms. Derivation of an efficiency based objective formulation is presented to determine the optimal mechanism design which satisfies motion requirements while maximizing the transfer of energy through the mechanism. Calculation of design derivatives with respect to element cross-section area and node position is performed using the adjoint variable method which provides faster and more stable convergence over finite difference approaches. Design examples are presented which directly compare the performance of topology optimized designs for the fixed node full ground structure to the floating node modular ground structure.

scholarly journals Multi-Objective Optimisation of Biodiesel Synthesis in Simulated Moving Bed Reactor

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 127
Author(s):  
Nillohit Mitra Ray ◽  
Ajay K. Ray
Keyword(s):  
Design Stage ◽  
Simulated Moving Bed ◽  
Moving Bed ◽  
Multi Objective ◽  
Design Variables ◽  
Biodiesel Synthesis ◽  
Single Column ◽  
Set Up ◽  
Yield And Purity ◽  
Selection Of

In this work, multi-objective optimisation study was performed to determine the performance improvement in a simulated moving bed reactor (SMBR) for biodiesel synthesis. The selection of the operating parameters such as switching time, liquid flow rates in various sections, as well as the length and number of columns is not straightforward in an SMBR. In most cases, conflicting requirements and constraints influence the optimal selection of the decision (operating or design) variables. A mathematical model that predicts single-column experimental results well was modified and verified experimentally for multiple-column SMBR system. In this article, a few multi-objective optimisation problems were carried out for both existing set-up as well as at the design stage. A non-dominated sorting genetic algorithm (NSGA) was used as the optimisation tool for the optimisation study. Due to conflicting effect of process parameters, the multi-objective optimisation study resulted in non-dominated Pareto optimal solutions. It was shown that significant increase in yield and purity of biodiesel in SMBR was possible both for operating and at design stage.

Design and optimization of a novel rescue end-effector

2018 ◽  
Vol 233 (3) ◽  
pp. 1032-1044
Author(s):  
Chunrong Wang ◽  
Jing Zhao ◽  
Erdong Xia
Keyword(s):  
Structural Strength ◽  
Equivalent Stress ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Element Analysis ◽  
End Effector ◽  
Design And Optimization ◽  
Design Variables ◽  
Optimization Efficiency ◽  
Selection Of

This paper describes the design of a novel multi-functional rescue end-effector with tonging, shearing and grasping capabilities to meet the demands of urban catastrophe rescue applications. The tonging and shearing form and the grasping form of the end-effector are analysed. The two forms are determined using the transformations of their grasping mechanisms. Four objectives (to maximize shearing space, minimize mass, minimize the equivalent stress and minimize deformation) are proposed for selection of the optimal grasping mechanism structure. Additional objectives also involve the end-effector’s structural strength and kinematic characteristics. A nested optimization structure that is composed of the non-dominated sorting genetic algorithm II (NSGA-II) and finite element analysis is proposed to perform multi-domain and multi-objective optimization of the end-effector. To improve the optimization efficiency, a traditional synthesis technique and a sensitivity analysis are applied to reduce the outer and inner numbers of the design variables. Simulation results indicate that the values of the four target objectives are superior to those before optimization and two referenced objectives, and the end-effector mass in particular, can evidently be reduced.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

Multi-Objective Design Problem of Tire Wear and Visualization of Its Pareto Solutions2

2006 ◽  
Vol 34 (3) ◽  
pp. 170-194 ◽  
Author(s):  
M. Koishi ◽  
Z. Shida
Keyword(s):  
Inverse Problems ◽  
Conceptual Design ◽  
Dimensional Space ◽  
Design Stage ◽  
Objective Functions ◽  
Pareto Solutions ◽  
Design Problems ◽  
Multi Objective ◽  
Design Engineers ◽  
Design Variables

Abstract Since tires carry out many functions and many of them have tradeoffs, it is important to find the combination of design variables that satisfy well-balanced performance in conceptual design stage. To find a good design of tires is to solve the multi-objective design problems, i.e., inverse problems. However, due to the lack of suitable solution techniques, such problems are converted into a single-objective optimization problem before being solved. Therefore, it is difficult to find the Pareto solutions of multi-objective design problems of tires. Recently, multi-objective evolutionary algorithms have become popular in many fields to find the Pareto solutions. In this paper, we propose a design procedure to solve multi-objective design problems as the comprehensive solver of inverse problems. At first, a multi-objective genetic algorithm (MOGA) is employed to find the Pareto solutions of tire performance, which are in multi-dimensional space of objective functions. Response surface method is also used to evaluate objective functions in the optimization process and can reduce CPU time dramatically. In addition, a self-organizing map (SOM) proposed by Kohonen is used to map Pareto solutions from high-dimensional objective space onto two-dimensional space. Using SOM, design engineers see easily the Pareto solutions of tire performance and can find suitable design plans. The SOM can be considered as an inverse function that defines the relation between Pareto solutions and design variables. To demonstrate the procedure, tire tread design is conducted. The objective of design is to improve uneven wear and wear life for both the front tire and the rear tire of a passenger car. Wear performance is evaluated by finite element analysis (FEA). Response surface is obtained by the design of experiments and FEA. Using both MOGA and SOM, we obtain a map of Pareto solutions. We can find suitable design plans that satisfy well-balanced performance on the map called “multi-performance map.” It helps tire design engineers to make their decision in conceptual design stage.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

scholarly journals The research of dynamic impacts on the hydraulic structure foundation base, transformed in the process of accident recovery

2018 ◽  
Vol 251 ◽  
pp. 04040
Author(s):  
Zaven Ter-Martirosyan ◽  
Ivan Luzin
Keyword(s):  
Field Experiments ◽  
Dynamic Properties ◽  
Soil Parameters ◽  
Experimental Site ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Foundation Base ◽  
Dynamic Impacts ◽  
Scale Experiment ◽  
Selection Of

The article presents the results of a comprehensive research of the dynamic impacts on a modified base. The modified base was obtained as a result of compensatory injection at the experimental site for the accident recovery at the hydraulic engineering structure. The complex study of the dynamic impacts includes special laboratory tests to determine the soil parameters, the finite element analysis of the experimental site, taking into account the dynamic properties, the selection of the necessary equipment for field experiments based on the numerical solution results, a full-scale experiment with the measurement of the foundation sediments of the experimental site.

Color Trend Analysis using Machine Learning with Fashion Collection Images

2021 ◽  
pp. 0887302X2199594
Author(s):  
Ahyoung Han ◽  
Jihoon Kim ◽  
Jaehong Ahn
Keyword(s):  
Machine Learning ◽  
Trend Analysis ◽  
Image Data ◽  
Fashion Industry ◽  
Color Palette ◽  
Web Scraping ◽  
Design Variables ◽  
Sales Organizations ◽  
Fashion Designers ◽  
Selection Of

Fashion color trends are an essential marketing element that directly affect brand sales. Organizations such as Pantone have global authority over professional color standards by annually forecasting color palettes. However, the question remains whether fashion designers apply these colors in fashion shows that guide seasonal fashion trends. This study analyzed image data from fashion collections through machine learning to obtain measurable results by web-scraping catwalk images, separating body and clothing elements via machine learning, defining a selection of color chips using k-means algorithms, and analyzing the similarity between the Pantone color palette (16 colors) and the analysis color chips. The gap between the Pantone trends and the colors used in fashion collections were quantitatively analyzed and found to be significant. This study indicates the potential of machine learning within the fashion industry to guide production and suggests further research expand on other design variables.

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