| Abstract: | Life cycle assessment (LCA), as an assessment tool for environmental performance, is used widely in decision making of product design. However, apparently, it is not sufficient to make final decision only depending on environmental assessment results for profit-directed organizations. One of the main purposes of this paper is to propose a methodology for integration of LCA and economic analysis tool-life cycle costing (LCC) in order to get the integrated evaluation results. A framework of integration of LCA and LCC has been introduced, which is contained by four components: the definition of unity time and physical boundaries, integration of inventory analysis, integration of impact assessment, environmental and economic interpretation. However, the integrated evaluation results always indicate that the relationship between economic and environmental performance is not in balance. Optimization is as important as integration to eco-balance. An optimization method is proposed to improve the initial product design with maximizing the integrated environmental and economic benefit for mechanical product. In optimization step, product system is divided two parts with environmental subsystem and economic subsystem. The integrated evaluation results are adopted to support for the optimization. Some mathematic optimization models are set up for environmental and economic subsystems. Multidisciplinary design optimization is applied to optimize these models so that the initial mechanical product design can achieve the best environmental and economic performance result. A case study of type 4135G diesel engine is presented to validate the rationality and feasibility. |
