Research On Engineering Change Impact Analysis Based On Knowledge

Engineering changes are considered inevitable for a manufacturing company. The causes of engineering changes are various, and come form different stages of the product lifecycle. Each engineering change will increases the cost and prolongs the periods of the product design. The impacts analysis is an important step in handling the engineering changes, and it is the pivotal problem for effective engineering changes management. But, there are insufficient attentions in science researches and practice. For this reason, this paper focuses on the impacts analysis in engineering changes.At first, taking products design knowledge as the basis of the engineering changes impacts analysis, this paper presents a representation method for design knowledge based on ontology. Taking design object, processes, functions, organizations and documents as the hard core of Ontology, extracting the main concepts and properties from every part, the corresponding Ontology models are formed. The design knowledge is described canonically and formally. They associate design object, processes, functions, organizations and documents together and lay the foundation for the engineering changes impacts analysis.Secondly, the method and the model of impacts analysis are presented. Impacts analysis is an important stage in engineering changes disposal process.This stage is separated to three main stages: ensuring the range of engineering changes propagation, confirming the scenarios of changes, and evaluation of the scenarios. Summarizing the causes of engineering changes propagation, which can be separated to propagation based on parameter, propagation based on function and propagation based on process, this paper presents the method to forecast the range of engineering changes propagation using design knowledge ontology. Then the engineering changes are tracked in the range using working flow technology, the impacts and the scenarios of changes can be obtained at last. The factors considered in changes decision are separated as incomes and costs, and we can make decision to ensuring the scenarios by scale the balance between incomes and costs.Then, because of the fact that one company may be confronted with the same engineering changes case in the practice, this paper introduces CBR (Case Based Reasoning) theory to the domain of engineering changes impact analysis. This section discusses the representation and the retrieve methods. Impact analysis case ontology models are formed. Presenting the method to retrieve the change cases, the emphases is the local similarity for attributes of change cases and the method for ensuring the weights for each attribute.Finally, ECIAS( Engineering Change Impact Analysis System) are design and developed.