The Collaborative Design System Of Welding Processes Built On The Basis Of Agent Technology And Finite Element Analysis

As a key techonolgy in advanced manufacturing field, welding techonolgy has affected the facrication industry markedly. With the imporovement of advanced technologies, automatization, intelligence and flexibility have become the inevitable trend in welding techonogly. Furthermore, it is necessary to design welded processes before manufacturing, in which collaborative optimization by using computer technology, net technology, information technology and distributed artificial intelligence is very important for welding structure optimization.Based on welding processing characteristics, Welding processes collaborative design system (WPCDS) using agent technology and finite element analysis (FEA) was proposed to make welding processes optimized collaboratively. In the thesis, according to the collaborative strategy of multi-parameter in single process and multi-process in continuous manufacturing, WPCDS is built on basis of agent technology and some other critical agents were discussed and researched, furthermore, net simulation environment was also built correspondingly.A coupled method of genetic optimization and FEA is proposed for optimizing multi-parameter in single process considering characteristics of welding FEA, and its validity and rationality were proved by optimizing an oil tank welded structure by this coupled method.Optimization of parameters in multi-process is necessary to be studied for all engineering product must be produced by multi-pass processes. A three layers structure including designing layer, processing layer and parameters layer was proposed to describe these processes; function model of each layer and production model were defined respectively, in addition, those processes were classified and corresponding optimization strategy was discussed. The analysis shows: the complex and difficulty of traditional CO method can be overcame by using this new strategy; those designing parameters are no more dependent, static and experienced, but the internal relationship of variable process parameters and process stage can be discovered during collaborative optimization; technology research groups and experts can cooperate better. The strategy is used to optimize welding parameters of oil tank structure with the fittness function criterion of maximum deformation of all nodes being minimized, the results show that multi-FEA tasks are done collaboratively using a unified controlling mechanism and a group of better welding parameters are found.Based on collaborative strategy mentioned above, the framework including five modules and one machine database of WPCDS was built, and was interpreted by a typical design process. Furthermore, the multi-agent system (MAS) prototype for welding processes collaborative design was studied in detail based on agent technology and MAS was built using MaSE method, main steps are as follows: goal analysis, use case analysis and role definition. Because agent is autonomous, dynamic and heterogeneous, the designing process of welding product becomes flexible. Obviously, it is seen that FEA tasks can be finished collaboratively and welding product can be designed rapidly by WPCDS.Welding FEA module in WPCDS was studied emphatically and welding joint database agent, pre-welding assembly agent and welding filler simulation agent were proposed because they are important for WPCDS based on agent technology. The utility of those agents for oil tank welded structure shows that spending time in building model of welding FEA is discreaesed sharply and the computing efficiency is improved using welding joint database agent; the loadcase definition related with welding assembly is easy and vivid by using pre-welding assembly agent, welding VRML(virtual reality modeling language) model is operated according to user click mouse or keyboard, not tedious menu operations anymore; welding filling simulation agent discussed based on the theory of"node dynamic relaxation method"is a better method to simulate weld filling process comparing with "deactive element method"and"quiet element method". Thus, WPCDS is extended by three special agents mentioned above.Net environment for WPCDS was built because different disciplines and study groups need remote cooperation; even different local computer also need integration. On JADE platform, according to the different tasks of agents, an amount of physical computer resources are divided, collaborative simulation environment is set up, necessary ontologies are defined. So it is useful for the data sharing, information sharing and technology sharing from different analysis and design software, and it is also helpful for the loose integration of engineer softwares, the reality of open system for rapid designing and optimization.