Panel is an important component of keeping aerodynamic shape in the aircraft. To ensure the flight performance of aircraft, it is essential to improve the assembly accuracy of the panel’s boundary dimensions. However, the traditional study mainly focused on the deformation analysis of the rivets and rivet holes, and the effect of riveting process on the global deformation was seldom considered. In this paper, the panel’s automatic drilling and riveting was taken as the object of study,and a solution of acquiring deformation, namely “local-global” method, was proposed based on the single-rivet FE model. The solid elements are used in the adjacent regions of rivet hole, and the shell elements are used in the remaining regions of the panel. By means of the linking method of solid element and shell element, the “local-global” mapping model was established. Using this model, the complex stress-strain appearance around the rivet hole was transferred to the shell element in a relatively simple state by the solid element, which improved the computational efficiency. The numerical simulation of large panel riveting deformation was also realized. Finally, in order to minimize the maximum riveting deformation, the genetic algorithm was used to optimize the riveting sequence. And the result showed that the deformation has been effectively controlled.

Based on the analysis of the defects induced in the process of forming and drilling of composite components,the main factors influencing the distribution of assembly-induced-stress and the influence law are investigated from three aspects, including the forming quality of components, the machining quality and fitting quality of connection hole. It indicates that the assembly-induced-stress of connection zone can reach 537MPa as assembly gap is 1.0mm while it is over 300MPa with 1° perpendicularity error. Moreover, when the coaxiality error of connecting holes is 0.03mm, the assembly-induced-stress exceeds 443MPa. Large assembly-induced-stress results in the propagation of the defects induced in forming and drilling and secondary damage, thus severely diminishing the assembly quality. Therefore, ef-fective inhibition strategies for the initiation and propagation of secondary damage are put forward from the two aspects of reducing initial damage with reasonable design of structure and layers, optimization of forming process and drilling parameters; and simultaneously declining assembly-induced-stress by automated assembly technology, fixture device optimization, reasonable arrangement of assembly process and application of shimming compensation process, which provide theoretical approaches and technical support for high-quality and precise assembling of large-scale composite bearing components.

A testing of tensile property of countersunk composite single-hole and single-lap joint based on the ASTM standard was designed and completed. During the test, the experimental data such as load-displacement curve, surface strain field and displacement outside of upper surface were collected by non-contact field strain measurement system (VIC-3D). The unilateral stretching static implicit and dynamic explicit 3D finite element models of the composite joint are established based on the Abaqus/Standard and Abaqus/Explicit respectively. The test results are verified by the deformation of the lap region. Compared to the test results, when using dynamic explicit algorithm, the error of squeezing stiffness of the joint and the out-ofplane displacement of upper surface are 13.1% and 11.9% separately. While using static implicit algorithm, the error are 14.4% and 20.5% respectively. Therefore, the dynamic explicit algorithm is more accurate, and there is strong reliability on contact modeling, which can be applied to multi-hole joint and some large complex structures modeling for example the integral panel
modeling subsequently.

An experimental investigation was conducted to determine the effect of several influencing factors on the fatigue behavior of interference-fit bolted composite joints. The types of bolts, the sizes of interference fit, different materials of laps, and stacking sequences of main laminates were separately considered. Tension-compression reversed force/stress ratio, R=-1, was selected to evaluate the fatigue tests. The appropriate levels of fatigue stress were determined by the ultimate bearing strength of the fastener structure obtained from the static tensile tests. The bearing stress and the fatigue life (S-N) data of all specimens were presented and the relationship between influencing factors and fatigue life were obtained. The experimental results show that the appropriate size of interference fit, the right type of fasteners, and the matched laps could improve the fatigue life of composite joints; however four stacking sequences of main laminates are not sensitive to the fatigue life of composite joints.

Riveting is the main way of mechanical connection for aircraft structures, and the riveting force is an important factor affecting the quality of riveting. Traditional computation methods of riveting force are usually based on the constant-volume assumption, without considering the volume of the rivet material being pressed into the rivet hole, which caused the big error of the model. To this end, according to the simulation results and the flow trend of rivet material, the volume reduction coefficient is introduced to take into account the volume of the nail bar being pressed into the rivet hole,establishing a prediction model of riveting force and comparing with the available experimental data. The results show that the calculated values are in good agreement with the experimental ones, so this model can be used to predict the magnitude of riveting force in riveting process.

The limitations of conventional riveting methods were discussed, and electromagnetic riveting technology was proposed for the riveting of aerospace conical structures. The method of semi-automatic electromagnetic riveting system of aerospace conical structure assembly was developed to avoid the disadvantages of manual and automatic electromagnetic riveting, and the details of the structure design and work-flow for the bracket of semi-automatic electromagnetic riveting system were also presented. The key technologies of the bracket include: automatic alignment of the rivet gun and top iron, the automatic angle adjustment of the workpiece, and the damping system design of the riveting gun. Finally, relevant problems which should be beyond controlled in manual riveting but solved by using semi-automatic electromagnetic riveting bracket are summarized.

In order to quantitatively evaluate the balance of aviation fastener production line and improve it, a typical aviation fasteners production line is analyzed. Combining with the concept of streamline balance and the characteristics of aviation fasteners production line, a set of quantitative evaluation index system is established by means of formula derivation, through which the streamline balance can be measured from different angles, the method and feasibility of its application are also expounded. By comparing several methods of current research on streamline balance, a conclusion is drawn that the streamline balance of aviation fastener is more suitable for the method of industrial engineering in analysis; the solution of streamline balancing is studied, which points out that the bottleneck process has important influence on streamline balance. By shortening the processing time of a bottleneck process, the balance of the entire production line can be improved, and also a significant increase in efficiency is obtained for each process on the production line. Finally, the above theories and methods are applied and verified by calculation in an example.

According to the development trend and application characteristics of turbofan engine assembly technology, the three advanced processes of overall assembly, intelligent tightening and assembly detection are analyzed and summarized. turbofan engine applies pulsating assembly line and multi-degree of freedom assembly platform for overall assembly to highly increase production efficiency; Intelligent tightening equipment can precisely control and monitor the fixed torque and angle of engine connecting parts to improve the connected uniformity, stability and reliability of critical rotor parts; Rotor stack optimization technology can optimize assembly position prediction and concentricity, electronic stopper can eliminate measurement error caused by different operators. The engine digital assembly is constantly introducing a variety of efficient and advanced automated intelligent equipments, and automation, intelligence, digitizing will be the future development direction of turbofan engine assembly process and equipment.

The tensile creep rupture and creep damage mechanism of 2D-Cf/SiC composite were investigated in present work in air. The applied temperatures are 700℃ and 900℃ , and the stresses are 50MPa, 75MPa and 100MPa, respectively. The creep rupture time of the material was fitted by Larson-Miller equation. The microstructures and fracture morphology were analyzed by a scanning electron microscopy. The results show that the rupture time of the 2D-Cf/SiC composite was influenced by the applied stress and temperature. Higher stress or temperature causes the shorter creep rupture time. During the creep, the oxidation plays critical role in determining the creep rupture time. The creep damage of 2D-Cf/SiC resulted from stress and the oxidation. Compared with the former, the damage caused by the latter made a more significant effect on the creep rupture time of the composites.

The Microstructure, tensile strength, impact property and low-cycle fatigue testing properties were studied for TC4-DT liner friction welded (LFW) joint of the aircraft. Test results show that an excellent properties of weld joint can be obtained after post-weld heat treatment (temperature: 700℃ , longtime: 3h). The room and high tensile strengths of TC4-DT LFW joint can reach more than 97% of TC4-DT base metals, and the impact property of the weld joint is slightly higher than the base metal, the low-cycle fatigue property is close to the TC4-DT base metals.

The lightning impulse test is carried out on carbon fiber composite laminated board for simulating thunderstroke damage. The transient thermography test method is implemented for detecting the damage defect of different sample, which is a new test method for using the long pulse as a thermal excitation resource. The results of different time is analysed, compared, the outline of the defect is draw, and the size is measured. The research achievement shows that the transient thermography method can detect the delamination defect inside the composite exactly. The transient thermography can differentiate the severity of damage and failure. The measurement result of size and area is correct.

In order to solve the problems that modeling was complex and a large computation was costed for calibration and compensation of aviation drilling robot, a calibration and compensation method based on extreme learning machine was proposed. The aviation drilling robot was regarded as a black-box system in this method which ignored the influence of geometric factors and non-geometric factors of robot. Then, according to robot positional errors measured by a high-accuracy laser tracker, a robot error prediction model based on extreme learning machine was trained and established. Next, the positional error in desired position could be predicted by robot error prediction model and the robot position was compensated to achieve the robot calibration. Final, experimental studies were carried on an aviation drilling robot. The experimental results showed that the mean and maximum positional error of robot was reduced by 75.69% and 78.16%, respectively.

Large deformation appears after turning of ultra-thin parts. To realize the prediction and analysis of the deformation, a finite element simulation system was established to simulate the finishing process. The accuracy of the finite element system was verified by the machining experiment. Deformation of ultra-thin parts after unloading was explained based on the system, which could guide the improvement of processing and reduce deformation.

In recent years, the enormous progress of aeronautical manufacturing has promoted the superalloy industry little by little, especially the rapid development of nickel-based superalloy industry. The hard processing problem of superalloy material is one of the difficulties of manufacturing. And in the process of cutting, there are some phenomenons, such as large cutting force, high cutting temperature which directly affect the surface quality of workpiece and tool life, and so on. Therefore, the research on measurement and analysis of the cutting force is the effective approach of superalloy cutting processing. This article explores the change rule of cutting force in superalloy cutting by the PCBN cutting tool. Firstly, the material properties and processing characteristics of the superalloy are expounded; Secondly, the single factor and orthogonal tests are designed and conducted, which aim to explore the effect and influence rule of the negative chamfer on the cutting force, then the cutting force prediction model of turning superalloy GH4169 by PCBN cutting tool is established and investigated; Finally, the model optimization is finished and compared with experimental data. The above efforts provide certain reference for superalloy technological parameter optimization.

The article mainly introduces the non-destructive measuring technologies of mechanics, leakage, damage and contact deformation for aviation rubber seals and their applications. The measuring technologies contain pressure difference method for leakage measurement; ultrasonic testing technology for contact stress; infrared thermal imaging technology for damage and leakage detection; digital image correlation method for measuring contact deformation. Meanwhile, the non-contact measurement technologies of aviation rubber seals in the future are prospected.