Research On Design Knowledge Management System For Mechanical Products

In order to provide products of best quality for market with the fastest speed and lowest cost, product design gradually shows the trend of high speed, modularization and knowledge coverage. It is required to know the detailed processes of product design and obtain useful knowledge of product design in the possible shortest time. Therefore, in this paper, from the development trend of product design, considering the diversity, dynamic and relativity characteristics of design knowledge, design knowledge management is researched focusing on the representation of design knowledge, modeling and planning of design process, thereby the purpose of giving the right knowledge to the right person at the right time is achieved. It can speed up product design, accumulate design knowledge, and encourage the development of modular design.From the view of multi-derived, personnel-related, process-related and heterogeneous properties of design knowledge, design knowledge is divided into six kinds, such as descriptive knowledge, judgment knowledge, structural knowledge, process knowledge, methodological knowledge and manual knowledge. Analyzing the keystones and difficulties of design Ontology, the establishment method of design Ontology is presented. On this basis, taking design processes, design organizations, design objects and knowledge objects as the hard core of Ontology, extracting the main concepts and properties from every parts, the corresponding Ontology models are formed. They can help to associate design processes, design organizations, design objects and knowledge objects together, realize the representation of six kinds of knowledge, and lay the foundation for the following knowledge embedding and reuse.Responding to the development trends of product design, with the characteristics of parametrization and repeatability for product design, the workflow method is selected as a reference technology for design process modeling, and a meta-model of design guide is presented based on the extended workflow model. In order to achieve the driving function of design knowledge in product design process, based on the design knowledge representation using Ontology, a knowledge flow engine which supports knowledge embedding is formed, and it is ensured that knowledge can be embedded in design processes. Using workflow model of IBM FlowMark for reference, a process model of design guide is proposed, and four kinds of task models like module task, part task, abstract task and behavior task are established. They can achieve the purpose of tracking how a designer accomplish tasks and how to design products and their parts, and provide process models and relationships of information dependence for the following design process planning.A hierarchical DSM based on BOM is proposed, and the approach of design process planning with the combination of BDSM and NDSM is researched to assure both the efficiency of the planning and the high planning accuracy. In the planning process, we put forward an improved dissevering approach of coupled tasks which contains task sequence norm and information sequence norm, and it can make the quantities of design interactions and loops to be small. With the study of three coupling forms like full coupling, partial coupling and closed-loop of multiple tasks, according to three dissevering approaches of combination, decomposition and integration of two ways above, a dissevering strategy based on the restriction of coupling degree and task scale is presented in virtue of information exchange and traversal between hierarchical DSMs, and the measurement of coupling degree and task scale is defined. This method can help to the reconfiguration and modularization of product structures, design teams and design processes, and then the purpose of strengthening the design knowledge management is achieved.Based on the research of key technologies above, an overall framework of design knowledge management system is established, which introduces a knowledge map, sets up knowledge classification map, knowledge distribution map, knowledge utilization map and knowledge transfer map, and decomposes their corresponding functions in detail. It can provide a visualization tool for knowledge search and retrieval. In order to apply related information from product lifecycle in design process, convert them into enterprise knowledge, and form different knowledge maps designers needed, an integration framework based on information of PLM system and an Ontology mapping model taking Ontology of design knowledge management system as mainstay are proposed, and an Ontology mapping algorithm which contains two main parts of glossary similarity and concept similarity is researched. Then, the accurate migration of information from PLM system to design knowledge management system is realized.Finally, the design methods and functions of design knowledge management system are presented, and the prototype system is developed. The feasibility is illustrated through an engineering instance.