某型飞行器的运动模型建立及仿真

为解决大型联合作战仿真系统中飞行器建模需求,从军事概念模型和软件模型两个角度梳理了飞行器建模要素,建立了飞行器的飞行轨迹仿真模型.为建立落点精度估计模型,提出了利用试验数据改进飞行轨迹仿真计算模型的优化方法,并进行了仿真打靶计算.计算结果表明,飞行器仿真模型在程序优化和计算效率方面都取得了明显的效果,能够满足联合作战仿真系统设计需要,并且保证较好的计算精度.     

复合材料与金属接头胶接建模精度研究

为了准确预测复合材料与金属接头胶接承受不同载荷的强度,对区域的胶层建模方法及建模精度进行了研究.提出建立了胶层的三种模型,即忽略胶层共节点方法、将胶层划分简化有限元模型以及精细有限元模型,并对以上模型施加相同载荷进行仿真.结果表明,忽略胶层的建模方法与基准模型误差达到9.7％,而有胶层的模型与基准模型的误差仅为0.6％;简化模型和精细模型与理论值在整体应力水平及整体应力分布上相差较小,精细模型与理论值的误差只有0.3％,简化模型与理论值的误差达到了1.3％.说明,对于有胶层结构来说,胶层不可忽略,若不关注胶层附近受力状态,在误差允许范围内,可将胶层建立为简化模型,否则应使用精细模型来仿真胶层.     

900 t 移梁机结构有限元仿真分析

为保证900 t 移梁机的作业安全,利用ANSYS 有限元软件建立移梁机整体空间模 型,基于作业工况进行有限元分析。介绍了900 t 移梁机的结构组成、功能特点和作业工况,提 出了移梁机有限元模型的建模原则与方法。结合各种作业工况进行移梁机有限元仿真分析,得到 不同工况下等效应力和结构变形云图,并将仿真计算结果与试验数据进行了对比分析。结果表明, 利用上述建模原则得到的有限元仿真分析结果与试验数据较为吻合。最后分析了个别有限元结果 与试验数据存在偏差的原因。研究结果可为移梁机的设计制造提供借鉴指导。     

某地铁车体静强度分析及试验验证

为优化某地铁中间车结构,缩短设计周期,建立车体有限元分析模型;依据EN 12663 2010标准,计算车体有限元模型在主要工况下的应力分布,并将仿真结果与试验数据进行对比分析.大多数点的仿真结果与试验数据很接近,误差大多数在10%以内,表明计算建模可靠;同时发现个别误差较大点所在位置,分析误差产生的原因.     

卫星结构板优化设计

利用MSC Patran对某板式卫星结构进行有限元建模,采用MSC Nastran对卫星进行模态分析,获取整星结构的模态参数,并与试验结果进行比对,验证有限元模型的正确性和准确度。在满足结构强度和刚度的约束条件下,对安装有效载荷单机的关键底板进行刚度和强度优化设计。优化前后结构的有限元仿真分析表明：优化设计可有效抑制载荷单机处的振动位移响应。     

基于有限试验数据与流场仿真的套筒阀流量特性获取方法

为提高大口径套筒阀流量特性的获取效率以及准确性,提出一种基于有限试验数据与流场仿真分析相结合的套筒阀的流量特性获取方法。通过对套筒阀进行三维建模并以此建立流场仿真模型,以有限试验数据为参考对该模型进行优化使得仿真结果满足精度要求,进而通过流场仿真计算获取套筒阀的完整流量特性插值表。与目前常用的试验数据处理方法相比,该方法有效减少了对试验数据的需求量并保证了仿真精度。通过验证对比,以该方法获取的流量特性来计算的仿真流量与实际测量流量相比,最大误差不超过8%。     

轨道动力车车架结构强度与刚度分析

为了计算轨道动力车车车架的静强度,保证动力车正常的工作和运行,提出了一种在三维软件中建模方法与边界条件的施加方法。运用ANSYSWORKBENCH软件对车架进行结构静强度和刚度的有限元分析并与试验结果对比。结果表明:车架的静强度和刚度均满足设计要求,对于同一测试点其仿真分析的应力值与试验得到的应力值误差基本在15%以内,结果一致性较好,所提出的方法也可以为其他类型的车架建模及仿真分析提供参考。     

车辆悬架用电磁执行器的建模与试验研究

应用电磁感应的基本原理,设计了一种新型的车辆主动悬架用电磁直线执行器,该执行器具有响应快,出力大和动行程大的特点。通过两种不同的建模手段,即有限元建模和集总元件动力学建模的电磁力仿真对比分析,两者基本吻合,表明了执行器模型的准确性。利用所建立的有限元模型,研究了执行器结构参数如气隙厚度和次级铜层厚度对电磁力的影响规律,并选取合理的参数进行执行器的样件试制。通过对加工后的样机模型进行电磁力响应的试验测试,并分别与有限元模型和集总元件动力学数学模型进行相应的比较,试验数据与仿真结果基本一致,进一步验证了模型的准确性。     

航空相机的模态分析及轴承模型的修改

为了研究航空相机的动态结构刚度,运用有限元分析和试验相结合的模态分析法获得系统的固有频率和模态振型.应用大型通用有限元软件MSC.Nastran/Patran建立了航空相机的有限元模型,分析得出该相机的固有频率和模态.利用有限元分析结果中的模态振型指导试验模态分析中测点位置的选择,通过试验测得相机系统固有频率的实际值,并与有限元分析结果进行比较,验证了有限元分析的合理性,确定相机结构达到了设计性能指标.在有限元建模中采用改进的线性轴承模型后,降低了系统的计算难度,使有限元分析结果与试验值更加接近.     

座椅骨架静强度分析方法

汽车座椅骨架的结构静强度是影响座椅安全和舒适性的重要因素,必须进行静强度试验,但是物理试验存在复杂和不确定性,一旦出现试验失效,重复试验会增加大笔额外开支和研发周期.在分析座椅骨架载荷基础上,根据国家法规要求,通过有限元技术进行了座椅骨架静强度仿真.用Hypermesh对物理模型进行前处理,Abaqus软件进行有限元分析计算,Hperview进行计算结果的后处理,并按国家法规对座椅静强度要求对设计模型进行子检验.基于多种有限元软件,可以在座椅骨架设计阶段就能快速有效地对设计结构进行验证,以检验其合理性.     

Concepts and implementation of parallel finite element analysis

The design of complex engineering systems such as advanced aircraft structures and offshore platforms requires continually increasing levels of detail in supporting analysis. The finite element method is widely used as a computational method with which to model physical systems in various engineering problems. For detailed analyses of complex designs, structural models composed of several thousands of degrees of freedom are no longer uncommon. Such design activities require large order finite element and/or finite difference models and excessive computation demands in both calculation speed and information management. The computer simulation of the nonlinear dynamic response of structures and the implementation of parallel FEM systems on a high speed multiprocessor have received considerable attention in recent years. The driving forces of these activities included the reliable simulation of automotive and aircraft crash phenomena, and the increased performance of computers. Most existing major structural analysis software systems were designed 10–20 years ago and have been optimized for current sequential computers. Such systems often are not well structured to take maximum advantage of the recent and continuing revolution in parallel vector computing capabilities. These parallel vector computer architectures not only occur in the form of large supercomputers, but are now also occurring for minicomputers and even engineering workstations. To benefit from advances in parallel computers, software must be developed which takes maximum advantage of the parallel processing feature.     

Development of a multibody system for crashworthiness certification of aircraft seat

This work proposes a multibody approach in the simulation of 16-g aircraft seats, referred to the front-row of seats located behind bulkheads compliance with the Head Injury Criteria (HIC) requirement. The multibody model of the seat structure has been developed and analysed by using a home-made algorithm implemented in Matlab^® code, as a 2D system of rigid bodies interconnected by springs and joints. The research has been oriented to assess the capability of simulating a 16g frontal impact of a sled equipped with the seat of a regional aircraft on which an anthropomorphic dummy is arranged. This sled test, for which experimental data were available, has been used as test case; inertial and structural properties of the system have also been experimentally and numerically evaluated in order to make the numerical model compliant with the real one.One of the primary goals of the paper is to provide an intuitive, easily extendable numerical tool to support designers in multibody simulation and to define a tool able to obtain global sled-test results in very short time, especially if compared to the computational time of a detailed finite element simulation. This tool will allow running sensitivity analysis and first level optimisation of key design parameters, integrating itself in the design cycle, not in place of, but as a support to the main simulation tools.     

某直升机平尾有限元仿真与试验验证

为在满足静强度、刚度和疲劳寿命的条件下使直升机平尾质量最小,选取最大的设计载荷进行静强度和刚度计算,利用有限元仿真技术对平尾结构进行载荷传递的计算,确定结构的基本布局,对部件进行初步尺寸定义;利用有限元仿真技术对平尾进行详细尺寸定义.按照尺寸定义制造实物平尾,并进行静力和疲劳试验,结果表明该平尾结构的强度和疲劳性能满足设计要求.     

Blended wing body structures in multidisciplinary pre-design

The structural analysis of blended wing body (BWB) aircraft configurations is presented in the context of a preliminary, multidisciplinary aircraft design process by means of the aircraft design and optimization program (PrADO) of the Institut of Aircraft Design and Lightweight Structures of the TU Braunschweig. A multidisciplinary process is described that enables parametric creation of detailed finite element models and its loads. Iteratively different flight conditions are trimmed and corresponding pressure distributions calculated by the higher-order subsonic and supersonic panel code HISSS. Each defined loading condition is used for the iterative structural sizing of the primary structure. Based on finite element idealization, a mass estimation of all structural masses is performed. The primary and secondary masses are fed back into the closed overall aircraft optimization loop of PrADO until this iterative procedure shows convergence on calculated aircraft variables (e.g., aircraft masses and static engine thrust). This automated process enables further configuration improvements using manual parametric variations or optimization features of PrADO with an objective function being defined by fuel consumption, aircraft mass, or direct operating costs. Different structural solutions and their integration in the global model are presented for passenger versions of a 700 passenger BWB with special consideration of a pressurized cabin. As an example, structural masses and parametric studies on the influence of the center body rib spacing are presented and compared by weight breakdowns.     

固体燃料冲压增程炮弹瞬态结构完整性分析

研究固体燃料冲压增程炮弹发射瞬态高过载下的结构完整性,结构强度优化是保证完整性的前提.为获取炮弹在发射过程中的瞬态结构强度,应用有限元软件对冲压增程炮弹发射瞬态的结构动力学特性进行了研究.建立了冲压增程炮弹的三维模型,采用有限元软件和瞬态动力学模型对冲压增程炮弹发射瞬态结构强度进行数值计算,计算结果验证了数值计算方法的有效性,冲压增程炮弹在发射高过载下的结构完整性良好,但在应力集中较大的部位仍然需要强化设计,结果对固体燃料冲压增程炮弹的设计具有重要的参考价值.     

太阳能无人机机翼颤振动力学建模与分析

太阳能无人机作为一种大展弦比轻质飞行器,其机翼的气动弹性效应显著,其中颤振问题尤为关键。此类飞机具有大尺寸和低刚度特点,通过风洞试验研究机翼颤振问题,成本高而且难度大,难以实现,因此仿真计算是分析此类飞机颤振问题的主要手段。针对国内某翼展为40米的太阳能无人机大展弦比机翼,首先对机翼有限元模型进行工程化处理,在此基础上开展结构动力学分析和颤振计算,重点计算了机翼上不同吊舱布置下的颤振速度。经过仿真计算,得到该太阳能无人机机翼颤振速度为26m/s, 满足设计要求,进一步分析表明,可以通过增加发动机连杆的长度、在发动机上增加配重以及改变吊舱在机翼上的展向站位等手段来提高此无人机的颤振速度。     

‘Integral’ finite elements for designing the strong frames of highly maneuverable airplanes

The experience of using classical finite element programs in the computer-aided design of airframes is discussed. A set of features in the classical finite element method is mentioned which hinder the implementation of programs for automated structural optimization with respect to strength requirements. Principles simplifying implementation of such programs are proposed, including the principle of two-dimensional elements being identical to natural structural elements. The approximating functions are introduced on the basis of exact solutions for a beam and an anisotropic plate subjected to concentrated and distributed loads, these solutions being subsequently used to describe displacements of these elements. This approach is exemplified by test problems and is demonstrated in application to the highly maneuverable aircraft strong frame design.     

Optimal design of aircraft structures with damage tolerance requirements

Damage tolerance analysis (DTA) was considered in the global design optimization of an aircraft wing structure. Residual strength and fatigue life requirements, based on the damage tolerance philosophy, were investigated as new design constraints. The global/local finite element approach allowed local fatigue requirements to be considered in the global design optimization. AFGROW fatigue crack growth analysis provided a new strength criterion for satisfying damage tolerance requirements within a global optimization environment. Initial research with the ASTROS program used this damage tolerance constraint to optimize cracked skin panels on the lower wing of a fighter/attack aircraft. For an aerodynamic and structural model of this type of aircraft, ASTROS simulated symmetric and asymmetric maneuvers during the optimization. Symmetric maneuvers, without underwing stores, produced the highest stresses and drove the optimization of the inboard lower wing skin. Asymmetric maneuvers, with underwing stores, affected the optimum thickness of the outboard hard points. Subsequent design optimizations included DTA and von Mises stress constraints simultaneously. In the configuration with no stores, the optimization was driven by the DTA constraint and, therefore, DTA requirements can have an active role to play in preliminary aircraft design.     

基于有限元法的高压直流输电线路电场强度值模拟研究

为了解决现有的高压直流输电线路电场强度值模拟方法存在模拟完整度较低、误差较大的弊端,提出一种基于有限元法的高压直流输电线路电场强度值模拟方法。该方法引入有限元法并优化,以此为理论基础,根据高压直流输电线路电场强度值模拟的需求对有限元软件ANSYS进行设计,以实际高压直流输电线路为基础构建高压直流输电线路模型,基于此,采用有限元软件ANSYS实现高压直流输电线路电场强度值的模拟计算。实验结果表明,与现有的高压直流输电线路电场强度值模拟方法相比,所提方法能够提高模拟完整度、降低模拟误差,充分说明所提出的高压直流输电线路电场强度值模拟方法具备更好的模拟性能。