| In product design procedure, assembly design is the phase of the largest workload and the most time-consuming. During airplane design and manufacture phases, the workload of assembly and installation is the 50~60 percent of the total because of the complexity of the airplane structure and the large quantity of components and connectors. It is obvious that assembly design and assembly performance is significant for assuring airplane quality and reliability, decreasing the cost and enhancing the market competitiveness. Virtual assembly technology becomes a powerful tool for solving airplane assembly problem. Virtual Assembly technology can be applied in many phases of airplane design and manufacture: using virtual assembly technology, general arrangement is carry out in conceptual and preliminary design phases, assembly scheme is obtained in detail design phase, and assembly process of according with actual manufacture is built as a guidance.The main solution for virtual assembly is that, the relevant CAD models are first created using traditional CAD software, such as ProE, UGâ…¡or CATIA, the constructed CAD models are then converted into polygonal models and are imported into a VR environment. Adopting this solution, CAD system and virtual assembly system are isolated with each other, informations transfer uni-directionally, the design result can be transfered from CAD to virtual assembly, but not be feed back in time, virtual assembly becomes information silo. Currently, Integration for virtual assembly is the developing trend. A solution is that, designers are able to create both the solid model of a part and the assembly model of a product in 3D space by direct 3D manipulations and voice commands intuitively and easily, to perform assembly planning interactively in 3D space, and to simulate and check assembly process. Adopting this solution, virtual assembly system does not need transer information with other CAD, but also becomes isolated with other CAD. Another solution is that virtual assembly is built in CAD system, many algorithms of CAD can be directly used by this solution, but extensibility is not good, and relative theory, method is not mature.To tackle the information silo in virtual assembly system, based on the strategy of Integrate VR into CAD, an integrated virtual assembly solution was proposed in this paper:1. A virtual environment integrated into CAD was built, including stereo display, integrating data glove with CAD, interaction technolody in virtual environment, and collision detection algorithm so on. 2. To overcome the limitation of information exchange between traditional virtual assembly system and CAD, a VA-CADPIM model of bi-directional information transfer was presented, can effectively improve efficiency of product assembly design and analysis.3. A virtual assembly process information model based on assembly task was established. A hierarchical assembly process was employed to express the virtual assembly process. The crossing procedure and installation adjustment were realized through the strategy of crossing assembly of task target body and an adjustment approach given herein. The method to cut down the redundant assembly task was proposed.4. An assembly constraint recognization method was given, and the exact placement technology of component in virtual assembly environment based freedom analysis was introduced.5. To satisfy integrated virtual assembly system function, and to make targets of high integration, good expansibility and portability, a virtual assembly architecture integrated with CAD was built.6. Based on CATIA V5R14, its 3rd part development environment and Immersion Virtual Hand SDK, a prototype system instance IVADS was developed, which can finish many functions, such as virtual scene navigation, virtual assembly planning, assemblability evaluation, and a general arrangement application for electron cabin of some airplane forward fuselage was given, accuracy and validity of theory and methods were tested.
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