Search

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press 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 Chinese Journal of Andrology is the property of Chinese Journal of Andrology 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 Journal of Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department 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 order to explore the transient impact effect of high-temperature and high-pressure propellant gas on the response to barrel strength, the finite element method is utilized to establish a three-dimensional numerical model for a large-caliber gun barrel. The variation of loading boundary of propellant gas with the projectile motion is defined. The evolution process of non-uniform distribution of temperature field in barrel at different moments under the first firing condition was obtained through numeric computation. The influences of thermal load, pressure and the heat-pressure joint effect on the dynamic stress response of barrel are further investigated, respectively. The calculated results show that the difference of thermal shock loads at different axial positions leads to an axial non-uniform temperature distribution, which makes the axial temperature gradient large and causes a significant axial thermal stress. In the area with intense temperature response, the compressive stress induced by thermal load and the tensile stress induced by pressure incircumferential direction make the stress component act as the interaction between the tensile stress and the compressive stress. Compared with the gas pressure effect, the stress amplitude in the high stress region on the inner wall is weakened, and presents a trend of falling first and then rising with the temperature. [ABSTRACT FROM AUTHOR]

Recoil resistance and muzzle disturbance are the key factors influencing the firing accuracy. In order to reduce maximum value of recoil resistance and muzzle disturbance, a rigid-flexible coupling system dynamics model is established for a large caliber gun. In the case of recoil mechanism and overall structure, the basic development module of ADAMS is used in conjunction with niche genetic algorithm to solve the multi-objective optimization function for gun recoil mechanism. Maximum value of recoil resistance and muzzle disturbance can be effectively reduced through optimization. The result shows that the proposed optimization method is reasonable and feasible, and can provide reference for optimization design of overall structure and recoil mechanism. [ABSTRACT FROM AUTHOR]

A structure optimization strategy using adaptive radial basis function artificial neural network (RBF ANN) is proposed for the large computational cost, slow convergence and easy to fall into local optimum in the multidisciplinary optimization design of gun. The high and low temperature-pressure curves of gun barrel are calculated based on the interior ballistic theory, as the load of numerical calculation of the finite element analysis model, by the secondary development of ABAQUS, which is used to obtain the optimization objectives. Then a RBF ANN is built to approximate the surrogate model for understanding the nonlinear relationships among the design variables and the optimization objectives. Penalty function method is used to solve the constraint problem, and the genetic algorithm is used to obtain current optimal solution. In the process of optimization, new sampling points are added, and the surrogate model is updated according to all the samples and their responses to improve the approximation accuracy around the local and global optimal solution. The multi-objective optimization strategy is validated by numerical test and the problem of optimization of the gun barrel structure performance to prove the efficiency of this optimization strategy. The results show that , compared to the initial design, the mass of optimized gun barrel is decreased by 6.63%, the structural stiffness is increased by 5.60%, and the maximum Von Mises stress is decreased by 6.34%. Furthermore, compared to GA without surrogate model, the number of function evaluation is decreased by 86.5%, and the total runtime is decreased by 83.3%. [ABSTRACT FROM AUTHOR]

To study the effective ways to improve the firing dispersion and solve its optimal design problem considering random factors,a calculation method of parameters interval oriented by the predefined indicators is proposed by using robust design theory based on random model and random optimization. A large caliber howitzer data is used to calculate firing dispersion based on Monte Carlo simulation and six degrees of freedom exterior ballistics model,and the statistical properties of firing dispersion are analyzed. A random model of robust design is built by calculating the objective criteria of robust design including unqualified probability and sensitivity index. Based on multi-objective genetic algorithm（ NSGAII） and BP neural network,the random model is optimized to determine the parameters interval of random factors which meet the requirements. The analysis results show that the proposed method can ensure the optimality and robustness of firing dispersion,and is feasible for the prediction of firing dispersion. [ABSTRACT FROM AUTHOR]