Design for manufacturing: application of collaborative multidisciplinary decision-making methodology

Design for manufacturing is often difficult for mechanical parts, since significant manufacturing knowledge is required to adjust part designs for manufacturability. The traditional trial-and-error approach usually leads to expensive iterations and compromises the quality of the final design. The authors believe the appropriate way to handle product design for manufacturing problems is not to formulate a large design problem that exhaustively incorporates design and manufacturing issues, but to separate the design and manufacturing activities and provide support for collaboration between engineering teams. In this article, the Collaborative Multidisciplinary Decision-making Methodology is used to solve a product design and manufacturing problem. First, the compromise Decision Support Problem is used as a mathematical model of each engineering teams’ design decisions and as a medium for information exchange. Second, game-theoretic principles are employed to resolve couplings or interactions between the teams’ decisions. Third, design-capability indices are used to maintain design freedom at the early stages of product realization in order to accommodate unexpected downstream design changes. A plastic robot-arm design and manufacturing scenario is presented to demonstrate the application of this methodology and its effectiveness for solving a complex design for manufacturing problem in a streamlined manner, with minimal expensive iterations.     

A bill of materials-based approach for end-of-life decision making in design for the environment

Re-use, recycling or remanufacturing of products and components are good alternatives for reducing the environmental problems resulting from the huge amounts of waste currently arriving at landfills. A new approach is proposed in this paper for enhancing these alternatives from the earliest stages of product design. Given the product structure (obtained from its bill of materials (BOM)) and the joining and geometrical relationships among the components (obtained from the three-dimensional, computer-aided design representation), a model is proposed that will determine the EOL (EOL) strategy, i.e. the depth of disassembly inside the structure and the final end (re-use, recycle, remanufacture or disposal) for each disassembled part leading to the highest profit. A scatter search (SS) metaheuristic is used to determine the disassembly cost at each level of the BOM. The model presents a number of major improvements with respect to previous research. It addresses the problems of simultaneously determining both the best EOL strategy and the disassembly sequence, as well as allowing removal of components not only over the two or three Cartesian axes and affording the possibility of modifying the encountered strategy in a further step so as to fulfil other business criteria (such as disassembly time, resources availability or maximum waste generation rate).     

工业设计的未来之路绿色设计

分别从以下五个方面阐述了绿色设计是工业设计未来之路,绿色设计是工业设计理我完善的必然选择;是保证人类自生存,实现可持续发展的必然选择;是21世纪绿色消费浪潮下的必然产物;是未来企业的立立之本;是消除绿色贸易壁垒的有效方法,此外,还分析了绿色设计的主要方法以及在设计中应遵循的准则,最后,本文呼呈更多的工业设计师来关注我们的环境,认识了解绿色设计,自觉地工业设计中纳入绿色要概念。     

Mapping function to failure mode during component development

When designing aerospace systems, it is essential to provide crucial failure information for failure prevention. Failure modes and effects types of analyses and prior engineering knowledge and experience are commonly used to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. In this work, we aim to enhance this process by providing design-aid tools which derive similarities between functionality and failure modes. Specifically, this paper presents the theoretical foundations of a matrix-based approach to derive similarities that exist between different failure modes, by mapping observed failure modes to the functionality of each component, and applies it to a simple design example. The function–failure mode method is proposed to design new products or redesign existing ones with solutions for functions that eliminate or reduce the potential of a failure mode. Electronic Publication     

数字时代的包装设计

介绍了数字化包装设计产生的时代背景,并从设计理念、设计服务对象、设计空间、设计调研、创意设计、设计表现、设计评价、市场验证等8个方面,阐述了数字时代包装设计的新特点与优势.     

Life cycle modeling for adaptive and variant design part 2: case study

Life cycle modeling for design (LCMD) facilitates the incorporation of life cycle modeling into product design by including consideration of uncertainty in a products final specifications. The methodology combines Life Cycle Assessment with probabilistic design methods in a way that reduces information needs. Part 1 of this article presents the basic LCMD methodology. Here, in Part 2, LCMD is used to evaluate material substitution opportunities to reduce resource consumption, reduce life cycle air emissions, and increase the recyclable mass for a Ford C-class sedan. In addition to further illustrating LCMD, the case study identifies vehicle design scenarios that offer modest improvements in environmental performance and related cost tradeoffs.

基于数量化理论I的老年人APP用户体验设计

目的 为了提升老年人APP用户体验,让老人使用APP更加自如。方法 以数量化理论Ⅰ为基础的老年人APP用户体验设计方法,首先采用文献研究和焦点小组法得到老年人APP设计要素,并基于正交设计原则设计APP样本,接着建立用户体验评价体系对APP样本进行对比评估,最后应用数量化Ⅰ类进行老年人APP的用户体验与设计要素数学模型构建,对数学模型进行求解,得到两者之间的关系。结论 研究表明,所提出的设计方法,可以有效地对老年人APP进行设计指导。     

Affordance based design: a relational theory for design

After reviewing current approaches to design theory, which are based on the transformative concept of function, we argue that this basis in function limits the scope of design problems and explanatory power of current design theories. As an alternative with greater potential for explanatory power and a framework for solving a wider array of design problems, we propose that a relational theory of design is needed. Such a relational theory should mirror those currently developed in mathematics, physics, computer science, and even philosophy. We develop a relational theory for design based on the concept of affordances from perceptual psychology. Affordances help to explain the entanglement between designers, users, and artifacts—relationships that are not currently handled by function based approaches to design. Affordance based design, as developed in this paper, does not offer a radical new approach to doing design, but rather a shift in design thinking. Our focus in this paper is therefore on the explanatory power and potential innovation fostered by this change in design thinking, as illustrated through several examples, and not on specific methods.     

Decision monotonicity in incremental design: A case study of design for manufacture

Design has often been described as searching the space of solutions to a given problem for either a feasible or optimal solution. Usually, this search is conducted in an incremental, iterative manner. Unfortunately, there is a tendency for the feasible space in some domains to exhibit such poor structure that the incremental design process becomes both difficult and time consuming. This is especially true in the domain of design-for-manufacture by machining. In this paper we present the view that in such cases the sources of ill-structure must be aggressively eliminated by making strategic improvements and modifications to the target technology. To illustrate this point, we show that the domain of design-for-manufacture is ill-structured due to a class of interactions known as global interactions. We then show how global interactions can be virtually eliminated by a combination of a new workholding technology and a new interfacing technique. In the absence of global interactions, we show how the design structure exhibits a property of monotonicity. We describe the ramifications of this monotonicity on the design process, and show how design can then be considered to be deterministic. As a backdrop, we draw examples from other fields where similar strategies have resulted in greater designability.     

Design of marine structures with improved safety for environment

The paper describes a method for design of marine structures with increased safety for environment, considering also the required investment costs as well as the aspects of risk distribution onto the maritime stakeholders. Practically, the paper seeks to answer what is the optimal amount that should be invested into certain safety measure for any given vessel. Due to the uneven distribution of risk, as well as the differing impact of costs emerging from safety improvements, stakeholders experience conflicting ranking of alternatives. To solve this multi-stakeholder decision-making problem, in which each stakeholder is a decision-maker, the method applies concepts of group decision-making theory, namely the Game Theory. The method fosters axiomatic definition of the optimum solution, arguing that the solution, or the final selected design, should satisfy the non-dominance, efficiency, and fairness. These three are thoroughly discussed in terms of structural design, especially the latter. Considering the coupling of environmental risk and structural design, the method also builds on the preference structure of four maritime stakeholders: yards, owners, oil receivers and the public, who either share the risks or directly influence structural design. Method is presented on a practical study of structural design of a tanker with a crashworthy side structure that is capable of reducing the risk of collision. The outcome of this study outlines a number of possibilities for successful improvement of tanker safety that can benefit, concurrently, all maritime stakeholders.     

A topological model of limitations in design for manufacturing

Design for manufacturing (DFM) is a methodology that requires the use of specific manufacturing information at all stages of design. The method relies on a collection of informal and often controversial principles that seem to have eluded the benefits of formal analysis. The transition from design to manufacturing can be modeled as a mathematical mapping, and it has been previously shown how the discontinuity of this mapping formally captures the folklore that small design changes can lead to significantly increased manufacturing cost. We study the properties of the transition map in the presence of design and manufacturing variations, and show that its continuity is closely related to the structure of design and manufacturing topological spaces. The main result of this paper establishes conditions on these spaces under which design for manufacturing cannot be described by any continuous transition map. In practical terms, our study reveals the limitations of many DFM systems and approaches in their ability to relate design and manufacturing knowledge, and explains these limitations in terms of a basic incompatibility between the underlying design and manufacturing representations. We discuss how our model applies to DFM relative to traditional manufacturing methods (such as casting and stamping) and we speculate what changes might occur for alternative manufacturing technologies (such as electrical discharge machining (EDM), stereolithography, laser machining, and particle deposition).     

浅谈电子商务专业英语的课程建设及模块化教学

文章针对电子商务的应用在国际贸易中不断加强以及对电子商务专业人才的需求,指出了电子商务专业英语课程设置的必要性,并提出引入模块化教学改革的方法以强化电子商务专业英语的课程建设.     

Quantitative evaluation of product disassembly for recycling

This paper presents a method for evaluating the ease-of-disassembly of products. Its primary use is in designing products for recycling, but it also facilitates consideration of servicing and maintenance, and making environmentally-related decisions. The method is developed and discussed in the context of relatively small products that can be disassembled by a seated person using hand-held tools. The evaluation procedure is centered around a spreadsheet-like chart and uses a catalog of task difficulty scores. The scores were derived from work-measurement analyses of standard disassembly tasks, and provide a means of identifying weaknesses in the design and comparing alternatives quantitatively. The structure of the evaluation chart and the derivation of difficulty scores are explained, followed by a demonstration of analyzing a computer central processing unit. The limitations of the method and future extensions are outlined.     

The role of topology in engineering design research

Aspects of the mathematical specialty of topology appear within several seemingly distinct areas of engineering design and engineering design theory. Indeed, the expression topology of a design is often used informally. In this article a primary intent is to demonstrate the diversity of applications of topology within engineering design. A complementary goal is to introduce the engineering design community to topology as a rich, formal, well-established mathematical discipline that may be of value for wider study. Upon reviewing some of these topological applications, it appears that topology holds promise as a basis for formalizing engineering design theory. This article considers topology as a basis for unifying design abstractions. The potential benefit may be the realization of commonalities between design aspects previously considered separately, where each now has its own attendant specialized, expensive analyses.     

A critical review of General Design Theory

This study is a critical review of General Design Theory (GDT), a mathematical theory of design. It reviews the assumptions (axioms) and predictions (theorems) of GDT with respect to design and illustrates them with simple examples. The scope of GDT with respect to design, the guidelines it provides for building computer-aided design (CAD) systems, and the possibility of implementing these guidelines are examined. GDT assumptions are too restrictive to apply directly to design, and several potential avenues for modifying the theory to attempt to broaden its scope are discussed. Nevertheless, these modifications may not lead to proving strong predictions about design. Treating GDT as a model, rather than as an accurate reflection of design, allows treating the guidelines as hypotheses to be tested empirically. The article discusses these guidelines and some experimental implementations that embody some of them.     

A heuristic for optimizing stochastic activity networks with applications to statistical digital circuit sizing

A deterministic activity network (DAN) is a collection of activities, each with some duration, along with a set of precedence constraints, which specify that activities begin only when certain others have finished. One critical performance measure for an activity network is its makespan, which is the minimum time required to complete all activities. In a stochastic activity network (SAN), the durations of the activities and the makespan are random variables. The analysis of SANs is quite involved, but can be carried out numerically by Monte Carlo analysis. This paper concerns the optimization of a SAN, i.e., the choice of some design variables that affect the probability distributions of the activity durations. We concentrate on the problem of minimizing a quantile (e.g., 95%) of the makespan, subject to constraints on the variables. This problem has many applications, ranging from project management to digital integrated circuit (IC) sizing (the latter being our motivation). While there are effective methods for optimizing DANs, the SAN optimization problem is much more difficult; the few existing methods cannot handle large-scale problems. In this paper we introduce a heuristic method for approximately optimizing a SAN, by forming a related DAN optimization problem which includes extra margins in each of the activity durations to account for the variation. Since the method is based on optimizing a DAN, it readily handles large-scale problems. To assess the quality of the resulting suboptimal designs, we describe two widely applicable lower bounds on achievable performance in optimal SAN design. We demonstrate the method on a simplified statistical digital circuit sizing problem, in which the device widths affect both the mean and variance of the gate delays. Numerical experiments show that the resulting design is often substantially better than one in which the variation in delay is ignored, and is often quite close to the global optimum (as verified by the lower bounds).     

Structural synthesis under manufacturability constraints: A CAD system for the design of injection-molded product housings

We describe a computer-aided design system that automatically constructs the internal functional surface shapes of plastic injection molded product housings. Fundamental manufacturability constraints related to the geometry of injection mold parting and the solidification of molten plastic are identified. These constraints are embodied in structural synthesis operators that create the internal shapes given a set of functional requirements. An implementation, which is integrated with a system that automatically designs the external visible surface of the housing, is discussed. Algorithms for the structural synthesis operators are provided along with sample output demonstrating their operation.     

Why mechanical design cannot be like VLSI design

It is widely agreed that the design methods and computer support of VLSI design are generally more mature than those of mechanical items. Why is this so, and is there any hope of the gap being significantly closed? This paper argues that there are fundamental reasons, that is, reasons based on natural phenomena, that keep mechanical design from approaching the ideal of VLSI design methods. The argument is accompanied by examples and brief histories of the evolution of VLSI design methods and attempts to systemize mechanical design. Brief attention is also given to the paradoxical fact that VLSI design itself is currently receding from the ideal and taking on the flavor and problems of mechanical design. This paper is based on several reports and working papers with limited circulation. The one relied on primarily is Whitney et al. (C.S. Draper Lab Report R-2577, Dec., 1993). The author wishes to acknowledge the contributions of his co-authors of that report. He also acknowledges the many discussions he had with people mentioned in the footnotes who enriched his approach to this topic.