基于杂波模型的天基目标红外探测波段选择

对美国国防支援计划（DSP）系统对导弹目标的探测波段及其选择方法进行了探索性研究。提出了一种基于背景杂波模型的波段选择方法。首先推导了简化的场景辐射参数表达形式,建立了场景空间杂波模型,给出了综合信噪比解析式;然后通过遍历目标辐射特性空间、背景杂波水平空间与谱段空间选择了最佳工作波段,使得探测系统在不同背景杂波水平下对辐射特性相似的一类目标的综合探测性能达到最佳;最后通过算例说明了该方法的有效性。经计算分析发现,系统最佳探测波段与场景的空间杂波水平以及目标的辐射特征密切相关;在不同的杂波水平下,选用两个目标辐射模板,DSP的最佳探测波段为2.73~2.85μm与4.2~4.43μm。     

空间激光终端二维转台U型架结构优化设计

空间激光终端二维转台是建立星地/星间高精度激光通信链的关键部件,其U型架结构的性能直接影响转台的稳定性和测量精度。为了适应发射阶段载荷过载及满足空间环境的严苛要求,文中提出了一种基于铝基碳化硅材料的U型架结构优化设计方案。该方案综合考虑材料特性和结构布局,对U型架的11种典型尺寸参数进行了分析和优化,实现了结构的轻量化和高刚度。研究发现,U型架支撑端厚度和侧肋斜率是影响其一阶基频和重量的关键因素。仿真结果表明,优化后的U型架质量减轻了25.03%,一阶基频提高了85.48 Hz。实物U型架随二维转台的力学试验验证表明,二维转台的整体性能和可靠性得到了有效提升。     

门座起重机转台结构拓扑优化设计

根据门座起重机转台结构的力学模型对转台进行Ansys拓扑优化设计,在满足使用要求的前提下,使转台结构合理,受力明确,减轻转台结构自重并有效地减少回转支承的载荷,降低整机自重,减少设备投资和码头投资。     

门座起重机转台结构拓扑优化设计

根据门座起重机转台结构的力学模型对转台进行Ansys拓扑优化设计,在满足使用要求的前提下,使转台结构合理,受力明确,减轻转台结构自重并有效地减少回转支承的载荷,降低整机自重,减少设备投资和码头投资。     

基于牛顿反射式红外系统的二维转台的结构设计与有限元分析

针对轻武器红外光学瞄具稳定性检测的需求,设计了一种基于牛顿反射式红外系统进行工作的电动二维精密转台。利用CATIA建立了电动二维精密转台的三维模型,该二维精密转台采用小型二维U形转台结构形式,采用直流力矩伺服电机直接驱动和24位绝对式轴角编码器进行角度测量。通过有限元分析软件PATRAN对转台的关键部件进行热力学分析与模态分析,获取转台的应力分布云图。云图结果表明,其设计方案可行,结构合理。     

海洋背景下运动目标的天基红外探测场景生成系统

围绕海洋背景下飞机和海面舰船等运动目标的探测需求,本文研究了目标和载荷在多个坐标系下的空间位置与运动特性,建立了天基探测场景的几何模型;通过Pierson-Moskowitz海洋谱模型计算海面起伏,实现大气层外海面辐射亮度的建模仿真;利用多种目标的三维几何模型,实现目标辐射特性的建模仿真。在上述研究的基础上,利用MATLAB平台,开发了一套海洋背景下多种运动目标的天基红外探测场景生成系统。结果表明:该系统生成的海洋辐射亮度均值在中波红外谱段优于Modtran的生成结果,在长波红外谱段与Modtran的生成结果之差小于3%。该系统可生成连续的海面背景下运动目标的辐射亮度图像,为开发天基红外探测系统提供技术支撑。     

仿真转台框架的结构优化设计

从优化的角度来评估倒角形状对某转台外框的影响程度,首先根据静动态特性,用优化准则法实施拓扑优化,得到满足要求的最少材料分布,为倒角优化提供可行性;接着在参数化建模的基础上对圆倒角半径进行了尺寸优化,先采用随机搜索法获得可行解,再用函数逼近法进行寻优,以得到倒角大小对结构的影响规律,对同类结构的设计具有指导和借鉴意义。     

高空作业车转台有限元结构分析

以某型高空作业车转台为研究对象,运用有限元分析方法,借助ANSYS软件对转台进行了有限元分析,确定了转台在危险工况时的应力分布和变形,并提出结构改进方案,为作业车转台的结构设计和改造提供理论依据。     

轮胎式起重机转台结构的数值分析

在分析DLQ25轮胎式起重机起升机构工作时转台结构受力情况的基础上,对转台结构在载荷作用下的工作应力分布情况进行数值分析.根据转台结构在起吊工况下的动力学特性,结合实际情况建立有限元动力学模拟的载荷模型.运用有限元法分别模拟承受静载和动载的转台结构的应力分布情况,重点研究旋转支承法兰与盖板焊缝处环形区域(30°＜θ＜150°)的应力分布.有限元分析结果表明, 结构的应力分布主要集中于旋转支承法兰与盖板焊缝处,呈现出典型的双峰特征;而随着循环次数的增加,最大变形有明显累积.     

折臂式随车起重机转台的拓扑优化设计

为了使折臂式随车起重机转台在最大应力不超过材料许用应力的前提下实现轻量化设计的目的,通过ADAMS软件仿真确定其极限工况,对转台进行静力学分析及拓扑优化。通过拓扑优化得到了理想的材料分布。基于优化结果调整转台结构,并对改进后的转台进行静力学分析。结果表明,优化后的转台能够满足实际的使用需求。同时,转台质量降低了12%,证明了优化设计的有效性和可行性,并为折臂式随车起重机的相关设计提供了一定的借鉴。     

空间相机碳纤维框架的设计与优化

设计了一个应用于轻小型空间相机的碳纤维框架。根据光学系统中各光学元件的空间分布特点,通过比较选择结构性能和工艺性能优异的M40J碳纤维复合材料完成了相机框架的结构设计,并使用TC4预埋镶嵌的方法解决了碳纤维框架接口精度低的问题。对碳纤维框架进行区域划分,采用集成仿真与优化设计方法、遗传算法全局寻优与单纯型下山法局部寻优的组合优化策略对碳纤维框架各区域结构参数进行优化设计。经过优化,碳纤维框架包含TC4预埋件的总质量为15.6kg,仅占相机整机质量的18.4%,相机的一阶频率达104.8Hz。最后通过力学环境试验得到相机整机一阶频率为102Hz,与仿真结果相符,进一步验证了设计的合理性和正确性。文中提出的碳纤维框架方案对轻小型空间相机设计有一定的借鉴意义。文中所采用的优化方法可广泛应用于空间相机光机结构设计中,能大幅度提高设计效率,缩短研制周期。     

Structural scheme optimization design for the stationary platen of a precision plastic injection molding machine

The current development of precision plastic injection molding machines mainly focuses on how to save material and improve precision, but the two aims contradict each other. For a clamp unit, clamping precision improving depends on the design quality of the stationary platen. Compared with the parametric design of stationary platen, structural scheme design could obtain the optimization model with double objectives and multi-constraints. In this paper, a SE-160 precision plastic injection molding machine with 1600 kN clamping force is selected as the subject in the case study. During the motion of mold closing and opening, the stationary platen of SE-160 is subjected to a cyclic loading, which would cause the fatigue rupture of the tie bars in periodically long term operations. In order to reduce the deflection of the stationary platen, the FEA method is introduced to optimize the structure of the stationary platen. Firstly, an optimal topology model is established by variable density method. Then, structural topology optimizations of the stationary platen are done with the removable material from 50%, 60% to 70%. Secondly, the other two recommended optimization schemes are given and compared with the original structure. The result of performances comparison shows that the scheme II of the platen is the best one. By choosing the best alternative, the volume and the local maximal stress of the platen could be decreased, corresponding to cost-saving material and better mechanical properties. This paper proposes a structural optimization design scheme, which can save the material as well as improve the clamping precision of the precision plastic injection molding machine.     

解耦型三维动力平台的机构分析与结构优化

基于运动解耦的三维动力平台,可用于加工设备上进行复杂曲面的加工。为了使三维动力平台工作满足一定的刚度、精度的要求,对该平台进行了受力分析,并对其主要连接件进行了有限元分析与结构优化。     

Massively efficient filter for topology optimization based on the splitting of tensor product structure

In this work, we put forward a massively efficient filter for topology optimization (TO) utilizing the splitting of tensor product structure. With the aid of splitting technique, the traditional weight matrices of B-splines and non-uniform rational B-spline implicit filters are decomposed equivalently into two or three submatrices, by which the sensitivity analysis is reformulated for the nodal design variables without altering the optimization process. Afterwards, an explicit sensitivity filter, which is decomposed by the splitting pipeline as that applied to implicit filter, is established in terms of the tensor product of the axial distances between adjacent element centroids, and the corresponding sensitivity analysis is derived for elemental design variables. According to the numerical results, the average updating time for the design variables is accelerated by two-order-of-magnitude for the decomposed filter compared with the traditional filter. In addition, the memory burden and computing time of the weight matrix are decreased by six- and three-order-of-magnitude for the decomposed filter. Therefore, the proposed filter is massively improved by the splitting of tensor product structure and delivers a much more efficient way of solving TO problems in the frameworks of isogeometric analysis and finite element analysis.     

Fault detection observer design for 2-D continuous nonlinear systems with finite frequency specifications

This research studies the problem of fault detection observer design for two-dimensional (2-D) continuous-time nonlinear systems in Takagi–Sugeno (T–S) form. Finite frequency (FF) specifications are used to design the observers, which makes observer designing different from previously proposed 2-D detection observers. Faults and disturbances are considered to be dominated in two different FF domain intervals. Fault sensitivity and disturbance robustness are measured by two FF performance indices, respectively. The aim of this paper is to design fault detection observers such that the residual error system has the sensitivity to faults and the desired robustness to disturbances. Sufficient conditions for the existence of a desired fault detection fuzzy observer are established in terms of linear matrix inequalities (LMIs). Simulation results indicate that faults can be detected effectively using the proposed method.     

无人机小翼隐身结构的质量和刚度优化

为了降低无人机的侧向雷达散射截面,提出了一种无人机翼梢小翼的隐身结构布局方案:隐身结构的翼面蒙皮由玻璃钢制成,主承力件为碳纤维复合材料层板结构,蒙皮与主承力件之间填充吸波材料。为获得力学特性最佳的主承力结构件的形状,在建立隐身结构参数化模型的基础上,应用有限单元法对隐身结构的强度和刚度进行了分析,并应用多目标遗传算法对主承力结构件的形状进行了优化,计算后获得了一组结构质量和翼尖位移最小的解集。优化结果为隐身结构方案的确定提供了定量依据。