基于移动最小二乘法,提出了一种应变测量数据场重构的方法.该方法将受轴压铝制圆筒的应变测量数据与相应的理论结果进行比较,筛选出了有效的应变测量数据.通过计算有效测点之间距离和采用冒泡排序法确定这些距离顺序的方式,高效简便地计算了各个有效测点的支撑域半径.根据获得的有效应变测量数据和计算得到的移动最小二乘形函数,重构出了重构区域三维表面各个节点的应变值,并且绘制出了相应的应变云图.数值计算结果验证了本文方法的合理性、精确性和高效性.

跨介质飞行器水下发射或高速入水过程中,空泡在壁面溃灭会产生较大压力脉冲,使舱体由于局部外压发生变形,由此引起的局部应变会成为载荷测量中截面应变的干扰应变,对截面载荷测量产生较大影响.为了从应变桥路中消去壳体局部弯曲应变的影响,基于壳体受力模式分析,本文提出在舱段表面打孔将应变片直接贴在中面的方法,以期消除局部弯曲应变的影响.并通过有限元仿真方法确定打孔及虚拟电桥应变片位置,消除了局部高强度外压对弯矩桥路应变的影响;提出了基于均匀外压标定得到环向非均布外压影响的耦合灵敏度标定方法并通过有限元验证了该方法的合理性.地面验证试验表明,考虑外压耦合灵敏度,在保证弯矩识别精度的前提下,轴力识别误差明显降低.

针对弹体外表面平方米级区域的高峰值、短脉宽压力加载难题,依据一维可压缩流设计了高压腔、膜片腔、试验腔的气腔加载系统,附加了与试验件随形、扩展加压面积、均化压力分布的水腔,实现了平方米级区域1 MPa峰值、10 ms上升沿的脉冲压力加载要求,建立了弹性水腔的两自由度压力分析模型,获得了水腔系统的动特性参数,计算拟合曲线与试验曲线有良好的一致性.

为了获取六种边界等直梁振动响应的解析解,采用特征变换方法,得到了广义质量的解析解,并由此获得了不同边界和载荷作用下位移、速度、加速度和截面弯矩的动态响应放大系数的解析解和曲线,指出了速度与截面弯矩动态响应放大系数的相似特征和载荷响应分析的阶次要求.进一步推导出了有效质量的解析表达式,为基础激励方式的适用性分析提供了理论依据.

采用C~1自然单元法研究了不同工况下圆形、菱形、等边多边形薄板的极限承载力。根据薄板极限上限分析的迭代求解格式,构造出了满足平衡方程和边界条件的广义应力场,并由极限下限定理和得到的广义应力场,建立了求解薄板结构极限下限载荷乘子的迭代格式。提出的数值方法克服了极限下限定理中约束条件的强非线性,降低了下限分析的计算规模,具有易于程序实现的优点。该数值方法与极限上限分析方法相结合可以有效估算出薄板结构极限载荷的范围。数值算例表明,提出的求解薄板结构上、下限载荷的方法是有效的,具有较高的计算精度和较快的收敛性。

针对编织复合材料计算模型横向力学性能误差大和强度试验数据缺乏的研究现状,补充了纵横方向的刚度和强度试验数据,基于简单的刚度体积加权模型,考虑面元转弯交叉纤维的横向刚度约束效应,本文引入刚度调整因子——编织致密度,提出了面元刚度横向约束修正模型,纵横刚度和泊松比的计算误差在10％以内;结合层合板Tsai-Hill强度准则的修正模型,其纵横强度的计算误差在20％以内,获得了方法简单、较高精度的理论分析成果.

基于有限体积VOF方法以及势流体有限单元优势,提出了一种火箭贮箱液体晃动等效模型参数快速而精确的数值计算方法,并用具有解析解的圆柱贮箱模型对该方法的准确性进行了全面的验证.由于该方法不受贮箱外形和内部装置的限制,可用于任意贮箱液体晃动的研究.

This paper proposes a numerical solution method for upper bound shakedown analysis of perfectly elasto-plastic thin plates by employing the C $$^{1}$$ natural element method. Based on the Koiter’s theorem and von Mises yield criterion, the nonlinear mathematical programming formulation for upper bound shakedown analysis of thin plates is established. In this formulation, the trail function of residual displacement increment is approximated by using the C $$^{1}$$ shape functions, the plastic incompressibility condition is satisfied by introducing a constant matrix in the objective function, and the time integration is resolved by using the König’s technique. Meanwhile, the objective function is linearized by distinguishing the non-plastic integral points from the plastic integral points and revising the objective function and associated equality constraints at each iteration. Finally, the upper bound shakedown load multipliers of thin plates are obtained by direct iterative and monotone convergence processes. Several benchmark examples verify the good precision and fast convergence of this proposed method.

为获取运载火箭结构在飞行过程中准确的截面动态载荷,基于应变测量原理设计了一套飞行载荷测量系统,通过多向载荷标定试验获得结构的灵敏度矩阵,采用非线性载荷模型将飞行过程测量的应变响应转换为截面的动态飞行载荷.在某型号中首次开展了运载火箭飞行载荷测量工作,获得了二级箱间段和有效载荷支架在整个飞行过程中的轴向力、弯矩载荷,并与飞行时序、地面模态试验结果进行了详细对比,结果表明:2个部段的飞行载荷数据质量良好,飞行载荷有变化的时段均与飞行时序对应,并与过载的遥测结果趋势一致,同时也发现了多项飞行动态载荷的特点,为载荷设计提供了数据支撑,有助于后续型号的优化与改进设计.

针对冷发射火箭尾部密封环密封性能考核需求,提出一种新的动态压力加载试验方法.该方法解决了准静态试验加压缓慢导致过考核的问题.通过计算预示给出了系统控制参数和加载结果的规律关系,能够指导系统加载控制参数的确定,并降低试验调试难度.研究表明,该试验系统对外径1m以上的密封环,在建压峰值1.5～5.6MPa,建压时间100～10000ms的区间内,营造的动态压力环境精确可控.

为了获取舱段载荷和应变之间的关系,进而获得运载火箭在飞行过程中的截面动态载荷,基于应变测量原理设计了一种基于振动载荷的灵敏度标定方法.给出了载荷测量的原理,推导了动态轴向力的频响特性,建立了载荷计算模型,给出了振动标定试验和验证试验的设计方法.设计了一个典型的光筒薄壁舱段,开展了振动载荷灵敏度标定试验,获得了舱段的轴向力、弯矩载荷灵敏度系数.随后开展了验证试验,结果表明,计算与实测载荷之间的均方根误差不超过5％,该方法具有可行性和较高的测量精度,可为后续的运载火箭飞行载荷测量提供一种新的方案.

根据端部带质量和弹簧约束悬臂梁的特征值条件,提出了一种特征变换方法,获得了带约束悬臂梁广义质量和振动响应的解析解.通过分析根部弯矩、端部位移、速度和加速度放大系数的变化特征可知,端部弹簧的刚度对静态和一阶载荷响应有明显的影响,减载设计时可以放宽对端部质量的限制,载荷响应分析阶次介于速度和加速度的分析阶次之间.提出的特征变换方法可应用于求解其他载荷分布、边界条件和端部约束悬臂梁的振动响应解析解.

通常情况下,压电材料应用于结构中可实现对外界能量的俘获,但是在能量收集过程中,热弹性耗散将对其能量俘获效率产生影响.因此,本文提出了压电俘能结构热弹性耗散特性的研究方法;首先,基于Euler-Bemoulli梁理论,并结合压电结构变形影响时的热传导方程以及压电结构电场方程,推导出在压电热弹性耦合下不同振动形式时结构的控制方程;然后,通过数值计算和仿真分析的方法得出结构的频率漂移及热弹性阻尼的变化,得到了不同振动形式下温度场对压电结构的影响;同时,针对结构几何尺寸对结构热弹性耗散的影响进行了讨论,得到了压电热弹性耦合对压电装置能量俘获的影响.

In the process of exiting from water, submarine launched missile will suffer fluctuating pressure due to bubble collapse, which may cause great dynamic response and load in the structure. The underwater modal characteristic and damping characteristic of the missile have a direct influence on the dynamic load and response in the water-exit process. Based on dynamic similitude model, modal tests of cylindrical structure in air and in water are carried out using relief method. Damped vibrating signals are processed in the time domain using Hilbert transformation, and the velocity-weighted average frequency and damping ratio are given. Through comparison between the parameters of dry modal and wet modal, the effecting parameters of water on the motion of the structure are obtained. The damping ratio of the first-order bending vibration mode is approximately 3%, and the added mass coefficient is approximately 0.5, or 1 in the case of rigid body. The results can be used in analysis and calculation of structure response.

航天贮箱结构特点是充内压结构,在分析整个箭体或弹体动特性时,贮箱是否充内压对整体结构模态有何影响,一直是航天工程领域关注的问题.为了解内压对圆筒结构模态的影响,本文针对相关理论公式进行了推导,并基于Abaqus软件对某型号局部实例模型自由-自由状态圆筒壳结构建立有限元模型,将有内压和无内压时的模态进行了分析比较,对理论公式进行了验证.分析结果表明,同一个结构,有内压和无内压相比较,充内压只是提高了壳体呼吸模态频率,而整体弯曲模态频率并不受影响.

为研究复合材料开口加筋壁板承载能力和失效模式,设计实施了壁板压缩试验,并基于复合材料层合板剪切理论和金属塑性硬化理论建立了复合材料开口加筋壁板有限元模型,研究了边界条件对壁板承载能力的影响,提出在加载边施加简支及铰弹簧约束,较好地模拟了壁板压缩失效过程.通过对比发现,压缩试验与仿真计算的失效模式均为壁板中部弯曲,对于开口附近位移结果光测试验和仿真计算误差小于 6.3%.采用二维 Hashin 准则和最大应力准则分别评估了各铺层纤维损伤趋势和桁条塑性特征,并结合承力构件损伤程度分析了开口加筋壁板的压缩破坏机制.

For honeycomb structure,a analysis method based on equivalent theory combine with sub-model technology was proposed.The equivalent method based on sandwich plate theory is deduced and equivalent model of full height honeycombs structure is obtained.The global equivalent model of full height honeycombs structure is analyzed by finite element simulation,and sub-model analysis technology is applied to extract the region of interest from global equivalent model of full height honeycombs structure for detail analysis,the comparison of simulation and experimentation indicated the analysis method have better accuracy.Appling the analysis method for full height airfoil honeycombs structure,through simulation results investigated the relation between geometry parameters of full height airfoil honeycombs structure and per unit mass of instability failure load through simulations,moreover the result shows that per unit mass buckling load increases along with thickness of wing skin ‘ s and airfoil honeycombs structure cell’ s wall grow,reduces along with thickness of airfoil honeycombs structure cell's grows,besides in a bound which changes on the small side.Appling multi-objective optimization for full height airfoil honeycombs structure,the results show that per unit mass buckling load stay in great bound when the three geometry parameters of honeycombs structure'cell stay in a specifically bound.

针对3米直径机铣正置等边三角形网格和斜置正交网格加筋圆柱壳的轴压承载能力,从工程算法、有限元分析计算及纯轴压载荷试验三方面进行了分析.获得了两种网格加筋圆柱壳轴压承载能力和失稳模式,计算的试验修正系数均在1.0附近.另外,同种加工工艺、同直径且等重量的情况下,正置等边三角形网格的轴压承载能力要较斜置正交网格的提高了17％以上,为网格加筋壳设计和在贮箱上的应用提供参考.

The state of art of techniques for measurement of in-flight loads is present in this paper. Load measurement for launch vehicle has been doing for the first time in China. A new test was done, namely accuracy verify test through compound loads. The result of this verifying test shows that larger load have strong influence on the smaller load measurement. In order to solve the problem, a linear and a nonlinear fit model is developed based on all test cases. The nonlinear fit model made the load measurement error cut down to 13% from 70%, about five multiple linearity of main load channel. At the same time, correlation coefficient improved to 0.996, and the requirement for load measurement was satisfied. The linear fit model is recommended when coupling effect between different channels is non-significant. And load measurement error is about two multiple linearity of main load channel.

Orthogonal measure points are not available, sometimes, when measuring dynamic load in flight for launch vehicle. In order to obtain sectional load of a launch vehicle, a new kind of strain measure point placing method is proposed. Non-orthogonal measure points are taken to obtain sectional load. Three sensitivity scaling means are presented and the methods of how to calculate the sectional load are given also. Static experiment is done, and linear relationship is clear between load and strain. That is to say that the method is good enough to be used in structural load measurement. The proposed method is applied in load measurement during flight. The difference between the three load calculating methods is analyzed approximately.