The System Design Of Pose Adjustment Tooling For Aircraft Digital Assembly

Nowadays, the technology of aircraft assembly is developed to digital assembly step by step in China. The fuselage pose can be achieved by the cooperative motion of positioners which constitute pose adjustment tooling system during digital aircraft assembly. The capacity of pose adjustment tooling system is the key point to good aircraft assembly quality. Several crucial techniques on parameter optimization of fuselage joint and positioner such as the loading status of joint, the connection way between fuselage and joint, the supporting technique of fuselage and the stiffness distribution of Cartesian positioner components are studied deeply.The present state of aircraft assembly technique and the key techniques of aircraft digital assembly are introduced. The application of FEA (finite element analysis) to aircraft assembly and the modeling methods of pose adjustment tooling system are introduced. The principle of fuselage pose adjustment is expounded. The key subsystems:the pose adjustment tooling, the control system, the measurement system, the software system and their integration are summarized. The characteristic of pose adjustment tooling system are summarized. Then the contents regarding the optimum design of pose adjustment tooling system are presented.The fuselage joint is designed for connection between fuselage and positioners. Then the distributing principle of fuselage joint is proposed. The finite element model is constructed to investigate the fuselage joint supporting capacity and the fuselage loading status. The load distribution on fuselage and bolts is analyzed with beam bolt mode. The effect of fuselage joint parameter on bolt load distribution is investigated. The distribution of the connection area between fuselage and joint is obtained. The variation of axial load and radial load of bolts is obtained by different connection way between fuselage and joint. Some conclusions about load distribution on fuselage and status are drawn to optimize the connection way between fuselage and joint.In order to avoid misjudging of fuselage manufacturing errors and assembly errors, the number and arrangement of positioners should be designed reasonably. According to the fuselage structure, the finite element model of the fuselage is established, which consists of skins, stringers, frames, reinforced frames and preserving frames. Under different supporting conditions, the deformation of fuselage is analyzed. Then the factors which influence the fuselage deformation are identified and analyzed, such as the number and arrangement of positioners, the location of joint. At last, the design method of supporting technique for the fuselage is obtained.The structure and the operating principle of a positioner are expounded. Based on the principle of multi-body system dynamics, the kinematic model of the positioner is established. The deformation of each component is analyzed during the fuselage pose alignment by FEA. At last the positioning error model is established.By analyzing the characteristics of deformation of fuselage and positioner, the relationship between locating error of positioner and pose error and deformation of fuselage is established based on the positioning error model of the Cartesian positioner. The parameters which describe the pose error and deformation of fuselage are defined. The calculation method of fuselage pose error and deformation, which combines positioning error model of positioner and FEA model of fuselage pose adjustment tooling is proposed. The stiffness parameter of spring element in FEA model is calculated according to the flexibility matrix of positioner. The pose error and deformation of fuselage are calculated by iteration for the coupling relationship between deformation of positioner and deformation of fuselage.To guarantee the aircraft assembly quality the method for stiffness parameter configuration of positioner components is proposed which will meet the needs of fuselage pose precision with lower cost. Then the evaluation criterion and procedure of components stiffness parameters configuration is proposed. Under different stiffness parameters configuration of positioner components, the pose error and deformation of fuselage are calculated by orthogonal test according to quintic polynomial trajectory. Consequently the constraint condition of components stiffness parameters configuration is obtained. At last the stiffness parameter configuration of the components is obtained for minimum weight.Finally, the whole work in this dissertation is summarized, and the future work is discussed.