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In this study, milling large wheels for spiral bevel gears by the profile method, the effect of cutting speed, depth of cutting and feed rate on the residual stress on the machined surface is studied. According to the characteristics of spiral bevel gears machined by the forming method, a three-dimensional simulation model of bevel cutting is established to simulate the cutting process of gears, and the effects of cutting speed, feed rate, depth of cutting and coolant on the residual stresses on the surface of the workpiece are simulated using the single factor method. The simulation results show that the residual stresses on the machined surface of the spiral bevel gear are distributed in a "spoon" pattern along the depth of cut, the residual tensile stresses are on the surface, and the residual compressive stresses are on the sub-surface. The surface residual tensile stress increases with the increasing feed rate and cutting speed, the layer depth of residual stress deepens with the increasing feed, and the depth of cut has no significant effect on the residual stress. The addition of coolant reduces the residual tensile stress on the surface. Through this research, a theoretical reference is provided for the analysis of residual stresses in the cutting of spiral bevel gears.

The cone-beam oral CT requires high transmission accuracy, and harmonic reducers with smooth operation, high precision efficiency and safety factor are mostly used. Its flexspline is prone to failure due to periodic deformation under alternating load when rotating. The tooth profile of the flexspline is designed, modeled by SolidWorks, and imported into the Ansys Workbench for the static analysis, modal analysis, and transient dynamic analysis. The results show that the flexural strain is mainly located at the long and short axes of the wave generator, and the axial strain decreases gradually along the cylinder. The maximum stress is located at the contact between the wave generator and the flexspline, and the maximum stress is located at the connection between the tooth root and the cylinder during the transient dynamic analysis. At the same time, the stress and strain of the flexspline are also affected by tooth width, barrel length and barrel thickness.

In order to predict the peak value of residual compressive stress and the depth of residual compressive stress layer on the surface of hot rolling gear profiles, the machining process of face gears during hot rolling is simulated by DEFORM-3D finite element simulation software, and the peak value of residual compressive stress and the depth of residual compressive stress layer on the surface of gear profile under different combinations of process parameters are obtained. Taking the simulation results as data samples, the response surface method is used to establish the prediction model of residual compressive stress and compressive stress layer depth on the surface of hot rolling gear profiles, and the optimal process combination is obtained by taking the maximum peak value of residual compressive stress and the minimum depth of residual compressive stress layer as the optimization objective. Taking the optimal process combination as the actual processing parameters, the measured value of residual stress on the surface of tooth profile is compared with the predicted value. It is found that the measured value is less than the predicted value, and the maximum error is no more than 17%. The results show that the prediction model can measure and control the surface residual stress of hot rolling gears.

Energy loss during interactions between high-energy particles and target materials mainly consists of nuclear and electronic energy losses. Electronic stopping and electron-phonon coupling effects are two different mechanisms that reflect electronic energy loss effects. To accurately simulate the irradiation damage process of high-energy particles, it is necessary to solve the key scientific problem of the influence of electronic energy loss on irradiation damage. This paper reviews the most recent progress on the irradiation damage behavior study of several key structural materials under the influence of electronic energy loss effects, elaborates the effects of electronic stopping, electron-phonon coupling, and electronic thermal conductivity on irradiation defects. The influence laws of electronic energy loss effects on the irradiation damage of target materialsare summarized and the existing problems in the research of high-energy particle irradiation of target materials are highlighted. Finally, the prospectives are outlined for future research directions.

In this article, the welding technology of large diameter thick wall 08Cr9W3Co3VNbCuBN (G115) heat-resistant steel pipes for the main steam pipe of a 650°C ultra-supercritical power station boiler has been investigated, and the mechanical properties and microstructure of welded joints at different wall thickness positions have also been analyzed. The results show that the mechanical properties of narrow gap welded joint of 115 mm thick large diameter 08Cr9W3Co3VNbCuBN heat-resistant steel pipe obtained by Gas tungsten arc welding (GTAW) + shielded metal arc welding (SMAW) + automatic submerged arc welding (SAW) can meet the requirements of relevant standards after tempering at 780°C. The tensile failure of the welded joint occurs in the base metal zone far away from the weld, an obvious necking phenomenon appears at the fracture position, and the welded joint has good tensile properties. No δ ferrite phase was found in the weld and heat-affected zone (HAZ). The microstructures of each zone are tempered martensite.

With experimental facilities being developed globally, producing superheavy nuclei using heavy-ion collision has become feasible, which is essential for exploring charge and mass limits of nuclei and understanding the r-process in nuclear astrophysics. Fusion reactions are crucial for the synthesis of superheavy nuclei, yet only neutron-deficient superheavy nuclei get produced due to the limited neutron number of stable beams. Recent experiments suggest that multinucleon transfer reactions are promising for producing new neutron-rich superheavy nuclei. As a result, transport models are required for extracting physics information from these experiments and making predictions about incident energies and projectile-target combinations, to synthesize new super-heavy nuclei. In this article, we introduce the development of transport models such as the dinuclear system (DNS) model, quantum molecular dynamics (QMD) type model, Boltzmann type model, and Time-dependent Hatree-Fock (TDHF) type model, and conclude with their latest applications in the synthesis of superheavy nuclei, especially in fusion reactions and multinucleon transfer reactions. In addition, various international large-scale scientific facilities, as well as their scientific objectives, and future plans, are also summarized.

A kind of eccentricity combined modification method of cycloid gear profile is proposed for solving the problem of the common combination modification method could not simultaneously satisfy the requirements of high bearing capacity and low rotation error. Firstly,based on the precision measurement of the cycloid gear of the RV-40 E reducer with the three-coordinate measuring instrument,the equation of cycloid gear profile is derived by using the method of least square to fit the parameters of the measured cycloid gear tooth profile. And then,by using the optimization function in Matlab,taking the obtained equation curve as the target tooth profile to optimize the cycloid gear profile formed by the three kinds of modification methods that are the combination methods of "eccentricity + isometric + shift","isometric + shift"and "isometric + shift + rotation". Through the comparative analysis,the results indicate that the deviation between the curve obtained by the combined modification of "isometric + shift + eccentricity"and the fitting curve is smaller,compared to the combined modification method of "rotation + isometric + shift"and "isometric + shift",which illustrates the feasibility of the combined modification method of "eccentricity + isometric + shift".

By taking rotate vector (RV) reducer as the research object, the factors affecting the transmission accuracy are studied, including the machining errors of the main parts, assembly errors, clearance, micro-displacement, gear mesh stiffness and damping, bearing stiffness. Based on Newton second law, the transmission error mathematical model of RV reducer is set up. Then, the RV reducer transmission error curve is achieved by solving the mathematical model using the Runge-Kutta methods under the combined action of various error factors. Through the analysis of RV reducer transmission test, it can be found that there are similar variation trend and frequency components compared the theoretical research and experimental result. The presented method is useful to the research on dynamic transmission accuracy of RV reducer, and also applies to research the transmission accuracy of other cycloid drive systems.