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Copyright of Science Technology & Engineering is the property of Chinese Society of Technology Economics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the existing finite element models of ultrasonic shot peening, most of them ignore the influence of elastic and plastic deformation of the projectile on the numerical simulation results. There are few reports on the influence of the friction coefficient between the surface of the projectile and the surface of the sprayed material on the numerical prediction results of ultrasonic shot peening. Therefore, taking pure copper as the research object, the influence of friction coefficient and projectile deformation on pure copper by ultrasonic shot peening was studied by combining the ultrasonic shot peening experiment and numerical simulation process. Firstly, a three-dimensional finite element model of single ultrasonic shot peening was established based on ABAQUS platform. Then, the single ultrasonic shot peening experiment was designed, and the influence of shot peening distance on velocity was analyzed according to the experimental conditions. The experimental conditions were input into the simulation model, and the experimental and simulation results were compared from the aspects of shot velocity and indentation morphology. Finally, under the condition of friction coefficient of 0.1,0.2,0.3,0.4 and 0.5, the ultrasonic shot peening numerical simulation of pure copper specimens was carried out by respectively using rigid shot, elastic shot and elastic-plastic shot. The surface morphology and residual stress of the treated surface were analyzed. The obtained results show that when the friction coefficient between the shot and the pure copper is larger than 0.2, the influence of the friction coefficient on the morphology of indentations and residual stress formed by ultrasonic peening of pure copper is no longer significant. With the increase of the contact stiffness between the shot and the pure copper, the indentation size, the depth of the compressive residual stress field, the maximum compressive residual stress and the surface tensile residual stress induced by ultrasonic shot peening of pure copper increase accordingly. The research results have important guiding significance for the numerical modeling of ultrasonic shot peening. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, Standard ke, RNG ke and Realizable ke are three turbulence models of high Reynolds number are used to simulate the CAARC model under different meshing, different wind fields environment, and different wind directions. The numerical simulation results were compared with wind tunnel test data at home and abroad, the conclusions are as follows: (1) The precision of the building boundary layer grid model has an important influence on the simulation results. When the best grid model is selected for simulation, the RMSE of RNG ke model is equal to that of wind tunnel test data, and the root mean square error of RNG model is 50% - 70% less than that of sparse grid model, and the error of other two models is about 40% - 50%. (2) In the case of B-type and D-type wind farms, the variation area and trend of the average wind pressure coefficient obtained by RNG ke model are basically the same, and there is no obvious difference, while the variation trend of the other two models is in different wind farms. The change range of environment is also very different, the difference is mainly reflected in the crosswind side and leeward side of the building. (3) On the leeward side, the average error of the model is about 90% smaller than that on the leeward side, and about 5% lower than that of the other two models. Generally speaking, under different simulation conditions, the accuracy, stability and regularity of the results obtained by RNG ke model are higher than those of the other models. [ABSTRACT FROM AUTHOR]

In order to study the effects of preload on the residual stresses induced by surface mechanical rolling treatment（SMRT）, the three-dimensional finite element models in conjunction with a novel computation framework coupling the explicit dynamics and implicit statics were developed to simulate the process of surface mechanical rolling of AISI 4340 steel under preload. At first, the elastic deformation was produced in the finite element model to be surface mechanical rolled by applying the displacement load. Secondly, the displacement-preloaded side was completely constrained for freezing the displacement-induced elastic deformation. On this basis, the surface mechanical rolling of the finite element model with the freezing elastic deformation was then carried out. Lastly, the residual stresses induced by surface mechanical rolling treatment were comparatively studied after the freezing elastic deformation was released. The obtained results show that the surface mechanical rolled materials can produce the unfavorable tensile residual stresses in the treated surface, and the maximum compressive residual stresses can be reduced if the preloading direction is opposite to the direction of rolling pressure. The compressive residual stresses in the subsurface of surface mechanical rolled materials can be further reduced when the preload is released. It is therefore necessary to avoid the preload in the surface mechanical rolling process. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A theoretical calculation method for the formation of hyper shaped charge jet is proposed. The theoretical relations among material density and thickness of additional body, and cone angle, material density and thickness of truncated liner and the velocity and effective mass of hyper-accumulation shaped charge jet are given. The simulated results of the formation process of hyper shaped charge jet based on AUTODYN software are basically the same as the theoretically calculated results. The numerical results of hyper shaped charge jet penetration are in good agreement with the experimental results. The results show that, within a certain range, the velocity of hyper shaped charge jet decreases and its mass increases with the increase in cone angle the velocity, effective mass and penetration ability of hyper shaped charge jets are much larger than those of classical shaped charge jets. [ABSTRACT FROM AUTHOR]

Because wind turbine blades are exposed to complex natural environment for a long time, as time goes on, rain, snow, dust and other particles will gradually erode the surface of blade, then causing the erosion on the blade surface, especially at the leading edge of the blades, which is the area with the most serious wear. With wind turbine running time increasing, under the impact of various complex particles, the erosion process on wind turbine blades typically starts with the formation of small pits at the leading edge, which quickly develop into gouges with larger size and deeper depth, and then the increasing pits and gouges eventually lead to the fact that material of the leading edge falls off largely, forming delamination. In order to simulate the leading edge erosion of wind turbine as accurately as possible, a geometric model which is close to the actual wear profile was established and a mathematical model which is suitable for airfoil calculation was selected. According to the erosion features on leading edge of wind turbine blade operating in actual wind farm, the leading edge of DU96-W-180 airfoil profile was modified to study the effects of aerodynamic characteristics caused by leading edge erosion on wind turbine blades. At the same time, a geometric model was built and numerical simulations were performed to solve the RANS equation based on SST k-ω turbulence model. Lift force, drag force and flow field characteristics of the erosion airfoil were analyzed. And then the conclusions were drawn. In the situation that leading edge erosion is characterized by pits and gouges, the coefficients of lift and drag have a small change, and as the attack angle increases, the lift coefficient and lift-drag ratio decrease slightly, and the drag coefficient increases slightly. The influence of leading edge delamination is notable, especially under the situation of high attack angle, and the lift coefficient and lift-drag ratio are significantly reduced and the drag coefficient is sharply enlarged with the increase of the attack angle, and this change becomes more notable with the increase of erosion. The leading edge erosion intensifies the flow separation near the trailing edge of the airfoil suction surface, and makes the separation point move forward. The phenomenon of separation is more and more obvious as the degree of wear and tearing is gradually deepening, and the eddy forms after separation gradually becomes larger, resulting in the fact that lift reduces and resistance increases. Pits and gouges have small influence on the flow near the airfoil leading edge. On the contrary, delamination leads to the step-flow around the airfoil surface, and air bypasses the step with separating flow, and then adheres to the airfoil surface again, so the delamination has a significant impact on the flow near the leading edge, which leads to the deterioration of airfoil aerodynamic performance. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)