Key Technologies Of Life Cycle Assessment For The Scheme Design Of Mechanical Products

As a quantized environmental management tool, LCA (Life Cycle Assessment) is a key supporting technology for green design & manufacturing and the theory foundation of the sustainable development for China’s manufacturing industry.Aimming at the problems that there is little reflection on the scenario characteristics in the most LCA methods which are difficult to support the scheme design so far, main efforts have been made on the methodologies and key technologies of LCA of mechanical product for scheme design in this dissertation.(1) Analyzing of the main contents and the basic characteristics of products in the whole life cycle processes, an input-output model of environment is built based on the materials and energy. Various life-cycle scenarios of product are summarized and the common attributes are extracted to generate the scenario model. The choice matrix of multi-scenarios is founded based on product statistic. And the probabilities of scenarios calculated from the choice matrix are used to gather together the environmental impacts of multi-scenarios in proportion. The life cycle scenario models of single product, product class and product design scheme are respectively built for the forecast of LCA of product design scheme.(2) The midpoint and endpoint categories and their characterization are discussed and are combined according to the environmental mechanism. The diversity of regional environment is pointed out and a method is presented to divide the environmental spatial scale. The characteristic factors of environmental spaces are proposed and the calculation methods are described in detail by analyzing the endurance capacity of regional environmental and environmental standards. The main environmental spaces of China are discussed and divided and the characteristic factors are calculated based on the methods above. An LCIA method based on the multi-environmental spatial scales division is proposed under the framework of ISO14044. (3) The concept of green feature is proposed which integrates the product informations of life cycle, environmental emissions and constraints. The choice functions are built based on the environmental constraints to extract the green informations in life cycle of products which are integrated into the green feature matrixes. A rapid LCA method is proposed based on the green features by analyzing the thoughts of simplied LCA. And the method processes are discussed that can be applied in the product scheme design. The multivariate regression analysis is used to study the uncertainty and sensibility of LCA which can identify the key parameters in the LCA.(4) The mapping relationship is constructed between functional structure and green feature by analyzing the design processes of them. Suiting China’s national conditions, the evaluation index system is built based on the factors of environment, technology and economy. For the qualitative indexes, a quantitative table and standardization process are presented based on the fuzzy assessment principle. For quantitative indexes, a model of standardization process is proposed based on the numerical analysis methods. The AHP-FCE comprehensive assessment model is built for green design scheme combining the analytic hierarchy process and the fuzzy evaluation method. And the calculation steps and process of the model are discussed in detail.(5) Software of LCA, named MLCAS that can be applied on the web, is built for electromechanical products based on the object oriented techniques under the framework of ISO14040. The design details of MLCAS are described including the framework, structure and model units. Those are introduced including the main structure, parameters and life cycle scenarios of Y80 electromotor. It is evaluated by the MLCAS software and the uncertainty and the sensibility of the assessment are analyzed based on the multivariate regression method. The LCA results are interpreted according to the life cycle of product.