Design methodologies: Industrial and educational applications

The field of Design Theory and Methodology has a rich collection of research results that has been taught at educational institutions as well as applied to design practices. First, this keynote paper describes some methods to classify them. It then illustrates individual theories and methodologies focusing on industrial and educational use. Theories and methodologies that are found most practically useful are “math-based methods”, “methodologies to achieve concrete design goals,” and “process methodologies”, while at educational institutes in addition to these, traditional design methodologies are also taught. The paper discusses this gap between practical and educational usages.     

Theoretical analysis and experimental study to support the development of a more valuable roll-bending process

A new roll-bending model is proposed which improves upon traditional roll-bending processes. The new forming model not only resolves some inadequacies of traditional roll-bending processes, but also allows more flexibility in the formation of large bending parts. The upper-bound and lower-bound methods are used to research the bending mechanisms of roll-bending processes and to provide some rules for the development of a new roll-bending process. Finite element modeling is also implemented for comparison with the upper-bound and lower bound results. Finally, a roll-bending experiment was carried out to attempt a real application, with the design of the experimental device based on the new roll-bending concept. All these efforts demonstrate that the new roll-bending model has potential for future use in industry.     

基于现值质量损失的并行公差技术研究

在并行设计环境中,用多变量质量损失函数在连续复利条件下把产品质量特征的退化作为一个连续的现金流量函数进行建模,从而建立了多重质量特征产品的质量损失现值与其相关工序参数的函数关系。在此基础上,把质量损失的现值和产品随时间退化的影响集成到总的装配成本模型中,建立了并行公差设计的优化模型。产品的并行优化设计与工序公差,通过使总的装配成本最小化获得。一个圆锥齿轮装配的并行优化分配设计与工序公差实例验证了该模型在实践中的有效性。     

Generation of manufacturing tolerancing with ISO standards

Current developments in tolerancing with ISO standards for the purpose of defining parts now call for new methods to analyze these three-dimensional specifications and to generate manufacturing specifications with ISO standards. In this pursuit, the proposed method has been based on a graphical representation of part features, process plans and functional requirements defined with an ISO standard that includes datum reference frames. A simple iterative procedure determines the ISO specifications of each phase according to the workpiece set-up. This algorithm uses a vectorial representation of the tolerance zone that corresponds to degrees of freedom imposed by each set-up surface. The presentation is limited to the machining process alone. An application on a 3D milling machine will also be displayed.     

Integrated Tolerancing Process for conceptual design

For car and aircraft industries, the management of geometrical variations has become an important issue in product design process and concurrent engineering. Indeed, designers need to manage dimensional and geometrical tolerances and to know information that contributed to their determination. The goal here is to put tolerancing in a concurrent engineering context. There are important questions that would need to be looked upon: How to integrate the tolerance synthesis in the design process? How to ensure the transition from function to geometrical specifications on parts? How to keep traceability of tolerances during the design process? Few answers exist today in academic works and there are few supports in CAD systems. Therefore, to build a coherent data model taken into account tolerances, we describe in this paper a multi-level approach that enables a tolerancing process integrated with conceptual design. The first level integrates information relating to functional aspects of an assembly. The second describes the structure of the assembly, and concerns the integration of functional needs and technological solutions. The last level translates functional requirements into geometrical requirements between/or on parts of the products, and provides the geometrical specifications on each part satisfying the geometrical requirements. This multi-level architecture is represented as an object oriented data model based on UML (Unified Modelling Language) that enable data management for functional tolerancing in design and keeping traces when querying about data.     

A three-step approach to designing a metal-forming process

This paper presents a hierarchical design and analysis approach for the design of metal-forming processes. The methodology entails a three-step design process comprising conceptual design, preliminary design, and final design. The conceptual design stage is based on methodologies such as axiomatic design and is followed by a preliminary design that is accomplished through simplified forming models and design confirmation using more accurate finite-element methods. This methodology provides a scientific approach to design and analysis and considerably reduces the time and effort necessary to achieve a workable solution.     

Dimensional Micro and Nano Metrology

The need for dimensional micro and nano metrology is evident, and as critical dimensions are scaled down and geometrical complexity of objects is increased, the available technologies appear not sufficient. Major research and development efforts have to be undertaken in order to answer these challenges. The developments have to include new measuring principles and instrumentation, tolerancing rules and procedures as well as traceability and calibration. The current paper describes issues and challenges in dimensional micro and nano metrology by reviewing typical measurement tasks and available instrumentation. Traceability and calibration issues are discussed subsequently. Finally needs and gaps are identified based on these observations.     

FDM工艺中的支撑自动生成技术研究

在FDM工艺中,基于其成型特点,在加工过程中需要添加支撑。支撑结构的合理性对成型件的精度和加工效率都有很大的影响。提出的基于扫描线的支撑自动生成技术生成支撑的速度快且无遗漏,在此基础上还能快速完成路径优化,实际应用效果较好。     

A general approach for error modeling of machine tools

This paper presents a general and systematic approach for geometric error modeling of machine tools due to the geometric errors arising from manufacturing and assembly. The approach can be implemented in three steps: (1) development of a linear map between the pose error twist and source errors within machine tool kinematic chains using homogeneous transformation matrix method; (2) formulation of a linear map between the pose error twist and the error intensities of a machine tool; (3) combination of these two models for error separation. The merit of this approach lies in that it enables the source errors affecting the compensatable and uncompensatable pose accuracy of the machine tool to be explicitly separated, thereby providing designers and/or field engineers with an informative guideline for the accuracy improvement by suitable measures, i.e. component tolerancing in design, manufacturing and assembly processes, and error compensation. Two typical multi-axis machine tools are taken as examples to illustrate the generality and effectiveness of this approach.     

Agent Based Negotiation for Collaborative Design Decision Making

Complex design involves trade-offs and teamwork. To make collaborative design decisions, designers must negotiate with each other to resolve their discrepancies through exploring the design space, generating new ideas and compromising for agreement. Advances in negotiation research have been made in social psychology, distributed artificial intelligence, and decision theory. But few have been applied to design. Built on existing negotiation research, we are developing an agent based negotiation framework to support collaborative design decision-making. This paper presents the negotiation protocol, information models, and negotiation strategies of the framework followed by discussion of an application case example.     

Scalability in manufacturing systems design and operation: State-of-the-art and future developments roadmap

The paper covers the main design, management and operational aspects of scalability in manufacturing systems (MS). It promotes scalability as an area of research of MS theory and practice in order to enhance techniques and methodologies in existing MS paradigms using advanced and emerging design and management approaches and ICT, and meet challenges of emerging MS paradigms and support their promotion and effective and efficient deployment in practice. The paper presents an introduction to scalability, state-of-the art in manufacturing and computer science, and related applications including manufacturing and education and a roadmap for future research and developments.     

Comparison of arc stability and variability of geometry of welds obtained by MIG/MAG and FCAW processes

Despite their similarity, the MIG/MAG and Tubular Electrode processes display particular features with regard to arc stability and variability in the characteristics of the beads. Thus, selection of one of these processes for a specific application will have to consider how these particular features affect the quality of the welds. To support this choice, the present study aimed to investigate how changing the average current affects the stability and regularity of metal transfer in welds carried out with constant voltage and pulsed current and compare the variability in the geometry and dilution of these welds. To achieve these aims, automatic welding was carried out, with steel ABNT 1020 as base metal and wire AWS ER70S-6 and AWS E71T-1 as filler metals. Besides the welds with variation in the average current, the tests involved determination of the parameters for occurrence of stable short circuiting, drop and pulsed transfer. The results showed that the voltage that gives the highest stability in short circuiting transfer is independent of the welding speed and increases with the wire speed, and also showed that welds made with hollow wire displayed greater variability compared to solid wire.     

基于Windchill的产品配置管理研究

探索产品配置管理和产品知识重用的处理过程,首先讨论产品结构和产品配置的功能,并分析用模型类型定义和树结构表达产品配置的可行性方法.提出在Windchill系统下用树结构和模型类型定义相结合以实现产品配置管理的方法,给出产品配置和定义的数据库表结构基本描述和实现技术,叙述如何合理利用原有历史数据和单机版的产品数据和模型集成为网络化协同产品设计信息.并叙述Windchill 的用户化应用的基本开发过程和方法.     

Multiscale analyses and characterizations of surface topographies

This work studies multiscale analyses and characterizations of surface topographies from the engineering and scientific literature with an emphasis on production engineering research and design. It highlights methods that provide strong correlations between topographies and performance or topographies and processes, and methods that can confidently discriminate topographies that were processed or that perform differently. These methods have commonalities in geometric characterizations at certain scales, which are observable with statistics and measurements. It also develops a semantic and theoretical framework and proposes a new system for organizing and designating multiscale analyses. Finally, future possibilities for multiscale analyses are discussed.     

Statistical and Deterministic Tolerance Analysis and Synthesis Using a Unified Jacobian-Torsor Model

This paper presents a model for computer-aided tolerancing which enables to perform tolerance analysis and tolerance synthesis in both deterministic or statistical situations. The model combines the benefits of the Jacobian and torsor approaches developed for computer aided tolerancing. The proposed unified model is formulated using interval-based arithmetic. The paper describes how different solving engines of the same set of interval-based equations lead to different types of problems being solved, i.e. deterministic (worst case) or statistical problems. The paper also shows how the unified analysis model can be numerically inverted for performing synthesis calculations.     

Optimization method for stamping tools under reliability constraints using genetic algorithms and finite element simulations

Controlling variability and process optimization are major issues of manufacturing processes which should be tackled together since optimal processes must be robust. There is a lack of numerical tool combining optimization and robustness. In this paper, a complete approach starting from modelling and leading to the selection of robust optimal process parameters is proposed. A model of stamping part is developed through Finite Element simulation codes and validated by experimental methods. The search for optimal tool configurations is performed by optimizing a desirability function and by means of a genetic algorithm based optimization code. Several tool configurations are selected from the resulting solutions and are observed through robustness analysis. Noise parameters relating to friction and material mechanical properties are taken into consideration during this analysis. A quadratic response surface developed with design of experiments (DOE) links noise parameters to geometrical variations of parts. For every optimal configuration, the rate of non-conform parts which do not satisfy the design requirements is assessed and the more robust tool configuration is selected. Finally, a sensitivity analysis is performed on this ultimate configuration to observe the respective influence of noise parameters on the process scattering. The method has been applied on a U-shape part.     

板材塑性成形理论和技术在汽车工业中的应用及其发展趋势

依靠冲压工艺成形的汽车外蒙皮件及框架结构件在汽车工业生产中扮演着一个重要的角色 ,并在很大程度上决定着一种新车型能否最终赢得市场。所以 ,对其相关的技术必须给予高度的重视。只有依托高水平的技术支持 ,才能获得高质量的产品。涉及冲压工艺生产的相关技术包括 :板材塑性力学 ,冲压工艺过程的有限元分析(FEA) ,具体的成形工艺设计等。其中 ,塑性力学 ,包含其最基本的屈服准则 ,本构关系 ,大变形过程中其各向异性板材方向特性的再定义 ,以及适合于不同冲压工艺的成形极限图 (FLD)等。而对于有限元模拟 ,其关键的实用技术 ,是了解不同应用程序的使用特点及局限性 ,并找到相关的控制措施。涉及具体的成形工艺 ,则必须以可成形性及经济性为准则进行相关的压边工序及辅助部分的设计 ,并对成形道次进行综合分析 ,以获得经济、高效的成形工艺方案     

凝聚和离散——制备纳米材料的两大思路

纳米材料制备是当前材料领域研究的热点。本文从分析人：亡最早获得的纳米级TiO2的制备方法开始，进而综观迄今为止已经被证明属于成功的制备方法的特点，结合制备技术原理，讨论当前众多的纳米材料制备的思路，认为制备方法可以从不同大小粒子的相互运动和作用归结为凝聚和离散两类，即两大思路，两大思路不仅在过去为发明这一新型材料提供了设计思路，也将成为下一步纳米材料开发的主流设计途径。