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The friction stir joining experiment was performed on a 6061-T6 aluminum alloy sheet 1 mm thick by optimization of different process parameters, and the microstructure and performance analysis of the joint area using a metallographic microscope, friction and wear testing machine, and scanning electron microscope were evaluated. The results show that the crystalline grains in the joint area of the specimen were refined under a given parameter, and the precipitation of the reinforcing phase improved the performance of the joint area. The best parameters for grain refinement were found to be a rotation speed of 8000 rpm and a traverse speed of 300 mm/min. The specimen obtained at 15,000 rpm and 200 mm/min exhibited the smallest milling weight loss. The smallest average friction coefficient of the specimen was observed at 8000 rpm and 300 mm/min. The friction weight loss trend of the specimens obtained under each parameter was basically the same as the friction coefficient. The wear form of each specimen was found to be mainly the adhesive wear, accompanied by the abrasive one.

During high-speed machining of aeronautical monolithic components, the initial residual stresses will cause the workpiece deformations with the removal of material. Therefore, it is crucial to investigate the prediction and control of workpiece deformations for the achievement of a machining process with high efficiency and precision. Above all, the mechanical model is established for the deformation analysis of 7075 aluminum alloy aeronautical monolithic components. Based on the formulated theoretical model, the finite element model is also suggested for the solution of the workpiece deformation. The comparison between the calculated values and the simulated results shows that they are in good agreement with each other. Subsequently, the presented method is adopted to reveal the fact that the different machining positions will cause different workpiece deformations. The deformation experiments are carried out at two machining positions of the workpiece. The measurement results show that whether for the amplitude or the deformation curve, the simulated results are in accordance with the measured data. The relative errors of two groups of data are 9.26% at position 16.5 mm and 19.66% at position 9 mm. Finally, an optimal model is created for the minimum deformation as well as the corresponding step decrease iterative solution method so that the proper machining position is achieved when the step is within the given threshold value. In comparison with the middle position method which is usually adopted by the enterprises, the optimal machining position, obtained by the presented step decrease iterative method, can decrease machining deformations by 99.79%.

Research on pre-deformation influences on material properties in multistep hot forming is of important scientific interest. In this paper, hot tensile tests at 850 °C and a strain rate of 0.001 s−1 were performed to study the microstructural evolution and mechanical properties of Ti-6Al-4V with pre-strains at 0.05, 0.1 and 0.15. The tensile test results showed that the specimen with 0.05 pre-strain exhibited higher flow stress and larger elongation. Additionally, increasing the pre-strain resulted in a decrease in ultimate tensile strength (UTS) and elongation (EL). The EBSD results showed that the main deformation mechanism of Ti-6Al-4V was high-angle grain boundary sliding. Pre-strain promoted dynamic recrystallization (DRX) by increasing the deformation substructure. The refinement of grains and the eradication of dislocations enhanced the deformability, resulting in an increase in flow stress.

The routing of multi-branch cable harness in aircraft relies heavily on manual work and experience, which is highly time-consuming. In order to realize the automatic 3D layout of multi-branch cable harness, this paper presents a novel approach by solving the layout as a multi-objective optimization problem that is NP-hard. The optimization objectives are to minimize the weight of multi-branch cables, to maximize the proportion of main roads, and to maximize the openness of the wiring path. Various regulatory and functional design rules are considered to be constraints. And the number and spatial position of branch points are taken as decision variables. As a result, a multi-objective layout optimization problem model of multi-branch cable based on Steiner tree is established. Then an improved multi-objective particle swarm optimization based on decomposition (MOPSO/D) is proposed to obtain the Pareto solution set of multi-branch cable layout. Finally, the feasibility of the proposed method is verified by the cable layout of the aircraft cabin.

A CVD diamond coating tool with prismatic crystal structure was prepared by hot filament chemical vapor deposition (HFCVD) method to improve sapphire’s lapping efficiency. The full plastic removal ...

CVD diamond films were prepared on the cemented carbide substrate by hot filament chemical vapor deposition method. The diamond coatings were observed with SEM and Raman spectroscopy. The results s...

An effective pretreatment method of carbon fiber reinforced plastic (CFRP) aircraft skin was proposed. In this article, the function of the amino thermosetting abrasives entrained by the airflow on the CFRP aircraft skin is introduced and discussed to achieve the purpose of enhancing the coating adhesion and prolonging the service life. An orthogonal experiment with five factors and four levels was designed and carried out, including jet pressure, target distance and impact angle, moving speed and particle size. The best pretreatment process was obtained by analyzing surface morphology, wettability and adhesion. The erosion mechanism of CFRP coating pretreatment with abrasive impact was studied emphatically. The results show that the critical pressure for fiber damage is 0.4 MPa, and the better surface energy is 38.0 mN/m. Semi-ductile erosion has been identified as the main erosion mechanism of amino thermosetting abrasives eroding CFRP. Effective assurance was provided for the improved surface of the aircraft CFRP skin and enhanced coating adhesion in this study.

The surface and subsurface damage of monocrystalline germanium wafer directly affect the performance and life of the product, so it is necessary to reduce the occurrence of damage during the lapping and polishing process. The changes in ambient temperature and temperature in the process will affect the shape precision of the workpiece, and also influence the surface of the material and the quality of subsurface. In this paper, the angle polishing method was used to measure the subsurface damage of germanium wafer. The effects of different processing ambient temperature on the surface and subsurface damage of germanium wafer after lapping were compared and analyzed. The results show that compared with normal processing, the surface topography of germanium after low temperature lapping is flatter, less surface pits, more and more narrow shallow cracks, and less cracks on both sides of the cracks. The subsurface damage depth can be reduced effectively by low temperature processing. The shapes of subsurface crack are mainly line, herringbone, and dendrimer.