Extension of Stress and Strength Interference Theory for Conceptual Design-for-Reliability

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Zhaofeng Huang ◽  
Yan Jin

It has been recognized that design-for-reliability (DFR) during the conceptual design stage is very challenging. There are several gaps and deficiencies hindering the DFR implementation. The first gap is due to the disconnection between the output of the conceptual design and reliability parameters needed for the reliability modeling. The second gap is between the knowledge available during the conceptual design and the information needed for reliability analysis. The state of the art design-for-reliability research and implementation are primarily based on the traditional reliability stress and strength interference theory. The research to date has mainly focused on the embodiment design-for-reliability, since they take embodiment design data as inputs and derive reliability measures of the product as results. On the other hand, the conceptual design, in general, and functional design in specific are usually nonanalytical and nonquantitative and result in little information immediately useful for a detailed reliability analysis. Our research aims to address these gaps and deficiencies and to build a bridge between the reliability research and the conceptual design research in order to realize conceptual design-for-reliability. In this paper, we first review the state of research and practice in the fields of reliability and conceptual design. Building on the previous research, we extend the traditional reliability stress and strength interference theory and develop a conceptual stress and conceptual strength interference theory (CSCSIT) that parametrizes the conceptual design space by introducing reliability related parameters into functional design. Based on CSCSIT, a practical analysis framework is proposed to support functional design-for-reliability. A functional design example is presented to demonstrate the effectiveness of CSCSIT and the proposed framework.

Author(s):  
Zhaofeng Huang ◽  
Yan Jin

Stress and Strength Interference Theory (SSIT) is a fundamental theory for reliability assessment. It has been widely used as a foundation for design-for-reliability (DFR). However, SSIT and associated methodology and tools, that require detailed definitions of constructional and form structure, are only applicable to an embodiment design. As many researchers have attempted to push DFR upfront to a conceptual and functional design stage, SSIT loses its usefulness, while other equivalent theory and tools for conceptual and functional design-for-reliability do not exist. Therefore, DFR for conceptual and function design becomes ad-hoc that lacks a systematic approach and parametric reliability quantification. In this paper, we first review the literature on stress and strength interference, and then extend the concepts of stress and strength to conceptual stress and conceptual strength that are relevant to conceptual and functional designs. Based on the conceptual stress and conceptual strength, we introduce a Conceptual Stress and Conceptual Strength Interference Theory (CSCSIT) and discuss how it can be applied to support conceptual and function design-for-reliability. We illustrate our theoretical work with a conceptual and function design example. We conclude the paper with a discussion of the future research to further define and substantiate the CSCSIT work.


Author(s):  
Rong-Yuan Jou

A freezing chucker is a clamp-less mechanism of fixture for easy broken egg-shell, clay, and other ferrous/nonferrous materials. Typical structure of this mechanism includes a top plate for freezing workpieces, a body with specially designed channels for the coolant flows, and a bottom plate to fasten on the table of other machine. Just by a small amount of liquids on the top surface and by rapidly cool down to 253K, parts can be frozen stationary on the top plate surface and can conduct precision machining on it. There are four steps to design a new freeze chucker by the engineering design process: planning and clarifying the task; conceptual design; embodiment design; detailed design. Some useful tools from the Quality Function Deployment (QFD) technique and the Theory of Inventive Problem Solving (TRIZ) method are used in this design process. Eight concept designs are generated by the conceptual design work and the final design of channel with transverse ribs is selected by decision matrix technique during embodiment design and detailed design stage. This final design is evaluated by numerical modeling of the COMSOL MULTIPHYSICS 3.2 finite-element based package. Performances such as the temperature distribution of top-plate surface temperature and the lowest temperature of a freezing chucker are shown. Numerical results show the success of the innovative channel design by this inventive design process using TRIZ methodology.


Author(s):  
Zeke Strawbridge ◽  
Daniel A. McAdams ◽  
Robert B. Stone

Design research has generated many computational tools to aid the designer over the years. Most of these tools are focused on either the preliminary steps of customer need gathering or the concluding steps of embodiment or detail design. The conceptual design phase has seen fewer computational tools even though well known methods are available such as brainstorming, intrinsic and extrinsic searches and morphological analysis. In this paper a generalized computational conceptual design tool is presented to aid designers at the conceptual design stage. It relies on storing and reusing existing design knowledge to create new concept variants. Concept variants are computed using matrix manipulations, essentially creating a mathematical morphological matrix. The concept generator produces quick concepts that can be used for concept selection or as a basis for generating additional concept variants through non-computational, creative techniques.


2006 ◽  
Vol 34 (3) ◽  
pp. 170-194 ◽  
Author(s):  
M. Koishi ◽  
Z. Shida

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.


Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Luca Bruzzone ◽  
Mario Baggetta ◽  
Shahab E. Nodehi ◽  
Pietro Bilancia ◽  
Pietro Fanghella

This paper presents the conceptual and functional design of a novel hybrid leg-wheel-track ground mobile robot for surveillance and inspection, named WheTLHLoc (Wheel-Track-Leg Hybrid Locomotion). The aim of the work is the development of a general-purpose platform capable of combining tracked locomotion on irregular and yielding terrains, wheeled locomotion with high energy efficiency on flat and compact grounds, and stair climbing/descent ability. The architecture of the hybrid locomotion system is firstly outlined, then the validation of its stair climbing maneuver capabilities by means of multibody simulation is presented. The embodiment design and the internal mechanical layout are then discussed.


Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3469
Author(s):  
Ji Han ◽  
Pingfei Jiang ◽  
Peter R. N. Childs

Although products can contribute to ecosystems positively, they can cause negative environmental impacts throughout their life cycles, from obtaining raw material, production, and use, to end of life. It is reported that most negative environmental impacts are decided at early design phases, which suggests that the determination of product sustainability should be considered as early as possible, such as during the conceptual design stage, when it is still possible to modify the design concept. However, most of the existing concept evaluation methods or tools are focused on assessing the feasibility or creativity of the concepts generated, lacking the measurements of sustainability of concepts. The paper explores key factors related to sustainable design with regard to environmental impacts, and describes a set of objective measures of sustainable product design concept evaluation, namely, material, production, use, and end of life. The rationales of the four metrics are discussed, with corresponding measurements. A case study is conducted to demonstrate the use and effectiveness of the metrics for evaluating product design concepts. The paper is the first study to explore the measurement of product design sustainability focusing on the conceptual design stage. It can be used as a guideline to measure the level of sustainability of product design concepts to support designers in developing sustainable products. Most significantly, it urges the considerations of sustainability design aspects at early design phases, and also provides a new research direction in concept evaluation regarding sustainability.


Author(s):  
B. H. de Roode ◽  
H. A. Crone

Abstract This paper describes a general design model that serves as a base for computer-support in the conceptual design stage. The model consists of a model of the artefact to be designed, design activities and knowledge. The artefact model contains multiple views, each highlighting a certain aspect of the design. Design activities are performed to create this model and knowledge describes information generated in the past that can be reused. The general design model has been used to develop a specific model for the design of production machines. This specific model has been implemented in a prototype computer-program and has been evaluated within several companies. The results are promising and show that designers gain new insights by using the model.


2000 ◽  
Author(s):  
Yusheng Chen ◽  
Satyandra K. Gupta ◽  
Shaw Feng

Abstract This paper describes a web-based process/material advisory system that can be used during conceptual design. Given a set of design requirements for a part during conceptual design stage, our system produces process sequences that can meet the design requirements. Quite often during conceptual design stage, design requirements are not precisely defined. Therefore, we allow users to describe design requirements in terms of parameter ranges. Parameter ranges are used to capture uncertainties in design requirements. Our system accounts for uncertainties in design requirements in generating and evaluating process/material combinations. Our system uses a two step algorithm. During the first step, we generate a material/process option tree. This tree represents various process/material options that can be used to meet the given set of design requirements. During the second step, we evaluate various alternative process/material options using a depth first branch and bound algorithm to identify and recommend the least expensive process/material combination to the designer. Our system can be accessed on the World Wide Web using a standard browser. Our system allows designs to consider a wide variety of process/material options during the conceptual design stage and allows them to find the most cost-effective combination. By selecting the process/material combination during the early design stages, designers can ensure that the detailed design is compatible with all of the process constraints for the selected process.


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