An integrated expert operation planning system with a feature-based design model

A framework of a knowledge-based expert operation planning system, TURNPLAN, is described. The system incorporates a feature-based part representation scheme to smooth the essential information flow from design intent to manufacturing practice. Its main functions initially consist of the determination of machining sequence, cutting parameters and cutting tools. To make this system a complete working module for full integration of CAD/CAM, its knowledge base has been further upgraded so that determination of work-holding methods, and generation of tool paths and the associated NC part programs, are included in the system. This integrated system is developed on a PC-based computer using PROLOG, which is found suitable in a batch-type job shop environment for industrial applications. A practical example is included to highlight certain features of the system and the paper concludes with implications for further research.     

A new history-independent modeling approach for feature-based design

The majority of current feature-based modeling systems employ model history to store feature creation operations and re-execute them sequentially after each modification, which is called history-based modeling. Due to the static feature creation order, history-based modeling causes some problems during the reevaluation of the model, such as the evaluated model does not correspond to its specification, the operation can only refer to the boundary entities created by the previous operations, high computation cost, etc. In this research work, a new history-independent modeling approach is proposed. For the “remove feature” operation, only boundary faces originating from the feature being removed, and the intersecting features are modified for updating the resulting BRep model. For the “modify feature” operation, the feature being modified is first removed from the product model and then re-added with the new specifications, thus its creation step in the model history is changed. As a result, some of the problems caused by the static feature creation order are solved. During the reevaluation, the computation time is dependent solely on the execution of the feature and its intersecting features being edited. The computational complexity of the boundary evaluation using the proposed method for three representative models has been analyzed based on Open CASCADE. A case model was studied in a proof-of-concept prototype system to demonstrate the proposed modeling approach.     

基于特征的多分辨FEM模型快速生成

为了提高有限元分析效率,对零件进行不同精度的有限元分析应该使用不同分辨的零件有限元网格(FEM)模型。针对这一需要,提出了一种基于特征的多分辨FEM模型快速生成方法。首先确定出零件所有特征之间的接口;然后对零件所包含的每一个设计特征和分析特征进行了以相关接口为约束的网格划分;最后根据不同的特征层次结构选择相应的特征及其网格组合产生零件不同分辨的FEM模型。实验结果表明该方法快速而有效。     

支持产品形象识别的色彩智能设计模型研究

为了解决产品色彩设计过程中的形象识别问题,进而在CAD平台上实现支持产品形象识别的色彩智能设计,在明确色彩设计领域知识的基础上,结合产品家族色彩方案库,通过层级关系结构图建立了产品形态识别数据与色彩识别数据之间的映射,构建了基于产品家族色彩方案库的色彩智能设计模型,实现了支持产品形象识别的主色驱动配色和智能色彩衍生设计。同时,初步完成了原型系统的开发,实现了系统与三维设计平台SolidWorks2006的集成,并在产品的色彩设计中进行了应用验证。     

Developing an integrated framework for feature-based early manufacturing cost estimation

The major objective of concurrent engineering is to consider the related downstream manufacturing during the design stage. Estimating manufacturing cost during the early design stage is one area that has been given little attention by researchers. However, if the product manufacturing cost can be estimated during the design stage, designers can modify a design to achieve proper performance as well as a reasonable cost at an early stage of the product development process.Basically, manufacturing cost is determined by shape complexity, product precision and tooling process. That is, if these data can be obtained and considered during the design stage, estimating manufacturing cost during the early product development stage will become a feasible task.In this research, a framework for estimating the manufacturing cost in terms of a feature-based approach is proposed. This system tends to estimate the manufacturing cost of a design according to the shapes and precision of its features. The objective of this research is to provide a tool to assist a designer, who has little knowledge about the manufacturing process, to estimate the fabrication cost of a design during its conceptual stage, in order to reduce unnecessary costs in the downstream process.     

并行工程中产品、活动和组织的集成建模

新产品开发系统建模是应用并行工程的基础 ,模型的目的是建立一个环境 ,从而有利于产品开发信息在企业不同部门之间的流动和共享。然而 ,除了信息共享的障碍以外 ,系统如何适应活动和组织的变化 ,也是成功实现开发系统集成和应用并行工程的重要问题。文中将新产品开发系统分为产品层、活动层和组织层 3个层次。通过对各层建模方法及它们之间相互关系的分析 ,提出活动模型、产品模型与产品开发组织模型的集成 ,是并行工程应用模型的关键。并且在活动模型的基础上 ,对活动模型、产品模型和组织模型集成的方法进行了研究。     

本体在机械产品智能设计中的应用研究

对本体的概念及相关技术进行了概述,从知识表示、知识检索以及知识重用等方面介绍了本体在机械设计中的应用情况,并对本体在机械产品智能设计中的应用前景进行展望。     

产品装配协调顺序模糊综合评价方法研究

装配协调顺序受到多种因素的影响,为了在装配工艺规划中获得最佳的装配协调顺序,提出面向装配过程的装配协调顺序综合评价方法,从装配协调路线、装配成本、装配精度三个方面,分别给出相应的评价函数,并通过层次分析法获得各评价函数的权重因子,再采用模糊综合评价法,得出最佳的装配协调顺序.实践表明,该方法在某型飞机机翼装配中得到应用,验证了算法的有效性.     

An intelligent estimation method for product design time

The planning and control of product development is based on the pre-estimation of product design time (PDT). In order to optimize the product development process (PDP), it is necessary for managers and designers to evaluate design time/effort at the early stage of product development. However, in systemic analytical methods for PDT this is somewhat lacking. This paper explores an intelligent method to evaluate the PDT regarding this problem. At the early development stage, designers lack sufficient product information and have difficulty in determining PDT via subjective evaluation. Thus, a fuzzy measurable house of quality (FM-HOQ) model is proposed to provide measurable engineering information. Quality function deployment (QFD) is combined with a mapping pattern of “function→principle→structure” to extract product characteristics from customer demands. Then, a fuzzy neural network (FNN) model is built to fuse data and realize the estimation of PDT, which makes use of fuzzy comprehensive evaluation to simplify structure. In a word, the whole estimation method consists of four steps: time factors identification, product characteristics extraction by QFD and function mapping pattern, FNN learning, and PDT estimation. Finally, to illustrate the procedure of the estimation method, the case of injection mold design is studied. The results of experiments show that the intelligent estimation method is feasible and effective. This paper is developed to provide designers with PDT information to help them in optimizing PDP.     

榫卯结构的参数化智能装配设计方法研究

以榫卯结构设计为例,提出一种榫卯参数化智能装配设计的方法.抽象出榫卯的参数化设计特征、特征模块化构建以及智能装配设计技术,实现了基于SolidWorks的榫卯结构参数化智能装配设计系统,并以官帽椅的设计进行设计过程的验证.     

支持产品复用的集成产品开发研究

企业在长期的生产活动中积累了大量宝贵的产品资源。如何有效利用这些产品资源是缩短产品开发周期、提高产品质量以及实现对市场的快速响应的关键。将基于实例的推理技术引入产品数据管理,提出一种基于产品数据管理的支持产品复用的集成产品开发环境结构;针对产品属性的特点,提出一种新的实例检索模型,并给出相应算法;为了实现基于实例的设计系统与产品数据管理系统之间的数据交流,开发了两者之间的数据接口;以某钢厂典型产品开卷机为对象,开发了Smar Team环境下的开卷机集成设计系统。该系统能够有效地支持对现有产品资源的复用,缩短开发周期,提高设计质量。研究成果可以推广应用至其他典型产品。     

A structure-based approach to evaluation product adaptability in adaptable design

Adaptable design, as a new design paradigm, involves creating designs and products that can be easily changed to satisfy different requirements. In this paper, two types of product adaptability are proposed as essential adaptability and behavioral adaptability, and through measuring which respectively a model for product adaptability evaluation is developed. The essential adaptability evaluation proceeds with analyzing the independencies of function requirements and function modules firstly based on axiomatic design, and measuring the adaptability of interfaces secondly with three indices. The behavioral adaptability reflected by the performance of adaptable requirements after adaptation is measured based on Kano model. At last, the effectiveness of the proposed method is demonstrated by an illustrative example of the motherboard of a personal computer. The results show that the method can evaluate and reveal the adaptability of a product in essence, and is of directive significance to improving design and innovative design.     

A systematic approach for green design in modular product development

In response to the changing market trend of having large varieties within a small production, green design and modular design have assumed significant roles in the product development process. This research applied quality function deployment (QFD) to achieve the goal of analyzing customers' needs. It also applied design structure matrix (DSM) based on the modular concept to group different design parts together to obtain optimized module efficiency. A balance between product development and ecological (ECO) friendliness can be achieved in advance if green QFD (GQFD) and DSM were introduced during the early design and manufacturing stages. Furthermore, using the result of GQFD, we proposed the analysis of DSM to find the result of coupled tasks. A pairwise comparative algorithm and loop analysis algorithm in DSM were utilized to decrease the number of module groups and find the most suitable clustering approach for further green design consideration. In this research, an electronic translator was used as a case study for the integration of green design with modularity. The main goal of this paper is to sort the importance weight values for green consideration by QFD during product development. These results can then be applied to finish modular grouping by DSM for subsequent green assembly and disassembly considerations of the products.     

A view-based approach to modeling product semantics in design chains

To reduce “time-to-market”, semantics of a product must be synchronized in a design chain, because inconsistencies during collaborative product development cause an unnecessary waste of time. To guarantee semantic synchronization, all enterprises should co-operate and maintain semantics whenever they are updated. In this paper, a V2-model is proposed to share product semantics during collaborative product development through view-based semantic synchronization. The V2-model has two kinds of model layers for semantic synchronization: a view-independent model (VIM) layer and a view-specific model (VSM) layer. Semantics in the VIM is the well-structured semantics shared among all enterprises and thus are published across the collaborative design chain. On the other hand, semantics in the VSM is the inconsistent semantics for product information that occurs during the early design stage, when different enterprises may have differing views about product concepts that are constructs of semantics. The inconsistencies between the different views can be solved by a decision and sharing (DnS) process and V2-model. The DnS process transforms the concepts in the VSM to the concepts in the VIM by utilizing topic maps-based scoping and merging functions. The proposed V2-model has been successfully applied to the design process of a washing machine model.     

A rapid and intelligent approach to design forming shape model for precise manufacturing of flanged part

Adjusting the part shape with complex flanges to compensate springback deformation is key to forming shape design for manufacturing rapidly and precisely. Classical forming shape design by displacement adjustment (DA) method using finite element (FE) simulation is usually time-consuming and not accurate enough for complex surface part in industrial application. In this paper, the forming shape is modeled by changing the relations of geometric features of part model with the new flange control surfaces directly. Control surface processing (CSP) method is presented including control surface trimming, cross section division, springback compensation, and extending to design forming shape model of doubly curved flange part with joggles rapidly. The algorithms of cross section curves division of control surfaces and subsequent subdivision of each curve with circular arc and line segments are proposed. A case-based reasoning (CBR) technique and gray relation analysis (GRA) are used to support the intelligent springback prediction of each bending segment of the cross section curve. The geometric data of control surface is expressed in XML format to realize the integration of the CAD-based tools of control surface division and compensation with the Web-based springback prediction system. The approach is demonstrated on an industrial aircraft wing rib part. The forming shape model could be designed rapidly by comparison with DA method. The part shape deviations of flange angle (?0.465° ~ 0.528°) and surface position (?0.3 mm ~ 0.3 mm) were detected by comparing the desired geometry with the actual digital formed part shape, and the results indicate that the approach can achieve the industrial part manufacturing rapidly and precisely.     

产品方案的虚拟设计初探

介绍了产品设计的虚拟化,说明了虚拟设计在产品开发中的重要作用,探讨了虚拟设计在产品设计各个环节的实现。并且以设计一台扫描仪为例,应用3DMAX和VRML为工具,尝试了对产品的造型设计和产品展示虚拟化的实现。     

智能支持的LC-QDPDS集成模型关键技术应用研究

质量驱动产品设计(QDPD)是一种产品设计新思想，在分析QDPD国内外研究现状的基础上，建立了智能支持的基于全生命周期质量驱动产品设计系统(LC-QDPDS)的集成模型，详细论述了LC-QDPDS集成模型的五大重要组成模块及其实现的关键技术，并将其应用于仪表新产品开发决策支持系统中。