带三维落角约束的寻的导弹制导与姿控系统设计

针对带三维落角约束的寻的导弹制导与姿态控制系统设计问题,提出一种基于终端滑模控制和扩张状态观测器的六自由度制导控制系统设计方法。建立包含模型不确定项的寻的导弹六自由度质心与绕质心模型,设计内外双层环路六自由度制导控制系统框架;基于弹-目三维相对运动模型和坐标系转移矩阵建立以攻角和侧滑角为输入的三维全耦合导引方程,利用终端滑模控制方法和扩展状态观测器得到期望的攻角和侧滑角并将其转化为对应的俯仰、偏航和滚转角指令;根据线性形式的寻的导弹绕质心动力学方程,设计与俯仰、偏航和滚转角相关的滑模面向量,并利用终端滑模控制方法和扩张状态观测器得到寻的导弹的副翼偏角、方向舵偏角和俯仰舵偏角指令。六自由度数值仿真结果验证了该方法的有效性和鲁棒性,并证明了该制导控制系统设计方法能以较少的控制设计参数完成预设的制导控制任务。     

舰船结构塑性动力响应研究进展

从舰船结构塑性动力响应的工程背景出发,简要介绍了该问题当前的研究进展．主要评述了国内外学者所关注的一些基本问题和研究方法,主要包括解析法、近似法、数值法等,以及冲击载荷作用下梁、板、板架、壳体等结构塑性动力响应的研究进展．     

Multi-objectives nonlinear structure optimization for actuator in trajectory correction fuze subject to high impact loadings

This paper presents an actuator used for the trajectory correction fuze, which is subject to high impact loadings during launch. A simulation method is carried out to obtain the peak-peak stress value of each component, from which the ball bearings are possible failures according to the results. Subsequently, three schemes against impact loadings, full-element deep groove ball bearing and integrated raceway, needle roller thrust bearing assembly, and gaskets are utilized for redesigning the actuator to effectively reduce the bearings' stress. However, multi-objectives optimization still needs to be conducted for the gaskets to decrease the stress value further to the yield stress. Four gasket's structure parameters and three bearings' peak-peak stress are served as the four optimization variables and three objectives, respectively. Optimized Latin hypercube design is used for generating sample points, and Kriging model selected according to estimation result can establish the relationship between the variables and objec-tives, representing the simulation which is time-consuming. Accordingly, two optimization algorithms work out the Pareto solutions, from which the best solutions are selected, and verified by the simulation to determine the gaskets optimized structure parameters. It can be concluded that the simulation and optimization method based on these components is effective and efficient.     

Damage modeling of ballistic penetration and impact behavior of concrete panel under low and high velocities

This work presents a numerical simulation of ballistic penetration and high velocity impact behavior of plain and reinforced concrete panels. This paper is divided into two parts. The first part consists of numerical modeling of reinforced concrete panel penetrated with a spherical projectile using concrete damage plasticity (CDP) model, while the second part focuses on the comparison of CDP model and Johnson-Holmquist-2 (JH-2) damage model and their ability to describe the behavior of concrete panel under impact loads. The first and second concrete panels have dimensions of 1500 mm × 1500 mm × 150 mm and 675 mm × 675 mm × 200 mm, respectively, and are meshed using 8-node hexahedron solid elements. The impact object used in the first part is a spherical projectile of 150 mm diameter, while in the second part steel projectile of a length of 152 mm is modeled as rigid element. Failure and scabbing characteristics are studied in the first part. In the second part, the com-parison results are presented as damage contours, kinetic energy of projectile and internal energy of the concrete. The results revealed a severe fracture of the panel and high kinetic energy of the projectile using CDP model comparing to the JH-2 model. In addition, the internal energy of concrete using CDP model was found to be less comparing to the JH-2 model.     

Real-time prediction of projectile penetration to laminates by training machine learning models withfinite element solver as the trainer

Studies on ballistic penetration to laminates is complicated, but important for design effective protection of structures. Experimental means of study is expensive and can often be dangerous. Numerical simu-lation has been an excellent supplement, but the computation is time-consuming. Main aim of this thesis was to develop and test an effective tool for real-time prediction of projectile penetrations to laminates by training a neural network and a decision tree regression model. A large number of finite element models were developed;the residual velocities of projectiles fromfinite element simulations were used as the target data and processed to produce sufficient number of training samples. Study focused on steel 4340tpolyurea laminates with various configurations. Four different 3D shapes of the projectiles were modeled and used in the training. The trained neural network and decision tree model was tested using independently generated test samples using finite element models. The predicted projectile velocity values using the trained machine learning models are then compared with thefinite element simulation to verify the effectiveness of the models. Additionally, both models were trained using a published experimental data of projectile impacts to predict residual velocity of projectiles for the unseen samples. Performance of both the models was evaluated and compared. Models trained with Finite element simulation data samples were found capable to give more accurate predication, compared to the models trained with experimental data, becausefinite element modeling can generate much larger training set, and thus finite element solvers can serve as an excellent teacher. This study also showed that neural network model performs better with small experimental dataset compared to decision tree regression model.     

基于CREAM的后方仓库叉车装卸运输弹药HRA评估

针对我军后方仓库弹药装卸运输环节对人员叉车操作的安全性需求,设计出了叉车操作测试场地路线,归纳总结了人员操作叉车进行弹药装卸运输环节中的安全失效形式及失效原因,构建了HRA评估数学模型．选取我军某后方仓库搬运机械建制班人员为对象,进行了实地测试,得到了弹药装卸运输环节的人为失误概率．测试结果表明,基于CREAM方法能够较好地解决后方仓库弹药装卸运输环节人为失误概率的量化问题．     

Damage visualization and deformation measurement in glass laminates during projectile penetration

Transparent armor consists of glass-polymer laminates in most cases. The formation and propagation of damage in the different glass layers has a strong influence on the ballistic resistance of such laminates. In order to clarify the course of events during projectile penetration, an experimental technique was developed, which allows visualizing the onset and propagation of damage in each single layer of the laminate. A telecentric objective lens was used together with a microsecond video camera that allows recording 100 frames at a maximum rate of 1 MHz in a backlit photography set-up. With this technique, the damage evolution could be visualized in glass laminates consisting of four glass layers with lateral dimensions 500 mm × 500 mm. Damage evolution was recorded during penetration of 7.62 mm AP projectiles with tungsten carbide core and a total mass of 11.1 g in the impact velocity range from 800 to 880 m/s. In order to measure the deformation of single glass plates within the laminates, a piece of reflecting tape was attached to the corresponding glass plate, and photonic Doppler velocimetry (PDV) was applied. With the photonic Doppler velocimeter, an infrared laser is used to illuminate an object to be measured and the Doppler-shifted light is superimposed to a reference light beam at the detector. The simultaneous visualization and PDV measurement of the glass deformation allow determining the deformation at the time of the onset of fracture. The analysis of the experimental data was supported by numerical simulations, using the AUTODYN commercial hydro-code.     

Analysis on the resistive force in penetration of a rigid projectile

According to the dimensionless formulae of DOP (depth of penetration) of a rigid projectile into different targets, the resistive force which a target exerts on the projectile during the penetration of rigid projectile is theoretically analyzed. In particular, the threshold V_c of impact velocity applicable for the assumption of constant resistive force is formulated through impulse analysis. The various values of V_c corresponding to different pairs of projectile-target are calculated, and the consistency of the relative test data and numerical results is observed.     

基于ADAMS的某重机枪复杂载荷施加方法研究

以某重机枪虚拟样机动力学模型的枪膛合力与气室压力的施加为例,设置一个与位移相关的传感器(Sensor)来实现通过位移控制外力施加的时机,并通过一个附加因子成功解决了以复进开始时为初始状态的自动机运动过程中的载荷施加。同时对该机枪三连发和四连发情况进行了仿真与分析,证明该方法可行有效。     

局部火灾场钢框架结构等效楼面活荷载分析

通过对火灾场钢结构框架梁极限抗弯、抗剪承载力的分析,提出采用等效楼面活荷载来描述火灾场对结构极限承载力的削弱,建立了火灾场等效楼面活荷载的计算公式,通过具体算例分析了厚涂型不同保护层厚度的框架钢梁极限抗弯、抗剪承载力及等效楼面活荷载的变化规律。分析结果表明,采用等效楼面活荷载可以直观地描述火灾场对结构构件极限承载能力的削弱,使火灾场钢结构受力分析变得简单、清晰。