Study On Calculation Method Of Product Disassembly Probability Based On Topological Graph

With the rapid development of the number of the vehicle,the nubmber of the end-of-life vehicles is also rising fast. It is predicted that there will be more than 800 million vehicles scrapped during the"Eleventh Five-Year" period. There is no doubt that automobile has brought us a lot of the convenience and comfort, at the same time, we should also note that the increasing end-of-life vehicle bring our a lot of negative issues. On the one hand, end-of-life vehicles contain a variety of heavy metals, chemical liquid, plastic and other materials. If they are dealed with unproperly, they will cause serious pollution to the environment; on the other hand, end-of-life vehicles contain many renewable resources. If they can not effectively use, which would be a great waste of resources. Recycling of end-of-life vehicles not only can generate considerable economic benefits, but also can benefit the sustainable development of the entire auto industry.Disassemble is defined as "the prcocess of systematic removal of desriable cosnstiute parts from an assembly whlile ensuring that there is no impairment of the parts due to the process". Disassemble is the prerequisite for efficient recycling,only in this way, can we achieve high purity of material recycling, and realize the probably reuse of parts. Two methods are generally used to remove components or materials: destructive and non-destructive disassemble. The most common methods for destructive disassembly are shredding processes. shredding processes could be damege the potential re-use parts, meanwhile, shredding processes also result in hybrid materials which is not conducive to the recovery of high purity materials. Therefore, the current research of the question of dismantling mainly focuses on the study of non-destructive disassembly.Tradtionally, products are designed mainly to meet functional requriements, therefore, recycling and environmental issues are rarely considered during the design process. Most companies do not consider methods of retiring EOL products and their impact on the environment. Design for Disassembly (DFD) has become an important issue due to the growing concerns about the environment and the shortage of natural resources. Design for Disassembly is one of the main targets of the Green Design. It demands that disassembly is the one of the major goal during at the initial stage of product design, Therefore, it can make our designed product more good manufacturing processes and maintenance, and also be easy to dismantle to recover and resue EOL products, and as a result, can save natural resources and prevent environmental pollution.In this paper, based on the inland and outland research on DFD, introduce the systemic structure of Design for Disassembly and do some deep research on the foundation of disassembly model, disassembly sequence generation and planning, product disassembly probability calculation and evaluation of the dismantlbility and so on, the main contents of the study are summarized as follows:(1) The purpose and significance of DFD are introduced. To begin with, DFD can save natural resources and reduce environmental pollution, what is more, it is conducive to the development of the auto industry, even the entire manufacturing. In addition, the systemic structure of Design for Disassembly is presented and the study status of guideline of DFD, disassembly sequence generation and planning and evaluation of the dismantlbility also are introduced.(2) The necessary information of dismanting model is presentede, such as, product basic information, connect information and process information and so on. Then the necessary information of dismanting model are expressed by the application of graph theory. Summarize the disadvantage of the common methods of building the model, such as, the undirected graph, the directed graph, AND/OR graph and so on. The new disassembly network graph is constucted based on the adjacency matrix, constraint matrix and the hybrid method which is composed of undirected graph, the directed graph, AND/OR graph. Therefore, it has laid a foundation for disassembly analysis and evaluation.(3) Removal and dismantling/disassembly are differentiated which are confused by many researchers and theirs concepts and relevant definitions are given.The new disassembly study idea which must be on the basis of the study of removal is put forward. The hypothesis that the prerequisite of generation of product disassembly sequences is also given, and then complete disassembly sequence and target disassembly sequence are generated based on the constraint matrix and the new disassembly network graph.However,the target disassembly sequence have two kinds: one is the single target disassembly sequence; the other is multi-target disassembly sequence. In addional, the relationship between the single target disassembly sequence and multi-target disassembly sequence are described through the logic of math.(4) Dismantling planning, which carry out the optimization process or sequence put the most efficient, lowest cost, dismantling the shortest time, energy consumption and pollution at least as the target.Firstly, certaint planning method is carry out without the consideration of dismantling, and then based on the randomicity of removal time, the disassembly probability planning method is put forward on the disassembly sequence. As a result, compared with the former, it can more clearly and accurately describe the process of the actual dismantling products through the introduction of two parameters of removal time and dismantlbility degree.(5) Product disassembly uncertain factors are analysed and the existing problems of the current evaluation methods of dismantling are presented. A new dismantlbility evaluation method is put forward based on the probability theory. And then, the related concept of dismantlbility evaluation is presented, such as, removability degree, disassemability degree, disassembly degree and so on. The formulary of disassemability degree is given and its heoretical derivation and mathematical proof also is presented. So product can be quantitative evaluation through disassemability degree. At last, taken the typical final drive as an example, the calculation of disassemability degree is given.In short, this paper put forward the new method of disassemability evaluation based on the randomicity of removal time and bring forward disassembly study new idear that disassembly research must be on the basis of the further study of the removal. we hope it provide a guiding role to make the dismantling research developed in the microcosmic direction.