基于静力与稳定性分析的小卫星主接头选型优化

基于对预埋主接头蜂窝板的静力与稳定性分析,对小卫星主接头进行选型优化。采用三明治夹心板理论建立预埋分叉式和面板式小卫星主结构连接接头的蜂窝板试件有限元模型,分析得到了蜂窝板最大应力值与失稳载荷,通过与试验结果的对比分析确定了蜂窝板试件破坏原因。在此基础上讨论结构参数对蜂窝板承载性能的影响,确定出最优的接头设计形式。     

921A钢在海水中腐蚀的力学化学效应

为了研究弹性应力和弹塑性应变对921A船体钢在模拟海水中腐蚀行为的影响,采用自制的载荷-电化学实验装置对921A钢在载荷与腐蚀介质协同作用时的开路电位、动电位极化曲线和电化学阻抗谱等电化学性能进行了测试,并由电化学阻抗谱拟合得到的电荷传递电阻定义载荷下的腐蚀速率修正因子,将实验得到的腐蚀速率修正因子与理论值进行了对比。结果表明:弹性拉应力与弹性压应力对力学化学效应的影响具有对称性。力学化学效应随着弹性应力的增大而增大,随着弹塑性应变的增大先增大后减小。弹塑性应变对力学化学效应的影响远远大于弹性应力的影响。在研究范围内,弹塑性应变引起的腐蚀电位负移量最大为62.6 mV,相应的腐蚀速率修正因子高达4.113,而弹性应力引起的腐蚀电位负移量最大为24.5 mV,相应的腐蚀速率修正因子为1.746。由此可见,应力应变对921A钢在海水中腐蚀行为的影响不容忽视。     

考虑入口和出口容积效应的涡轮动力学模型

建立了考虑涡轮入口和出口容积效应的涡轮动力学模型 ,利用该模型计算了燃气涡轮气瓶启动的动态响应过程 ,分析了影响涡轮动态特性的主要因素。计算结果表明 :涡轮前容积对涡轮入口压力和出口背压的过渡过程均有显著的影响 ,涡轮后容积对涡轮入口压力的过渡过程影响不大 ,对涡轮出口背压的影响显著。     

应力-强度模型的Bayes可靠性分析

当应力、强度分别服从于正态分布、指数分布和Weibull分布时 ,分析了应力 -强度模型的可靠性评估 ,着重讨论了无信息验前下的Bayes可靠性评估。仿真结果表明 ,无信息验前下的评估结论可以很好地用频率学派的观点来解释。     

伞盘结构对大长径比发动机药柱结构完整性的影响

为了提高大长径比发动机药柱结构完整性水平,基于三维黏弹性有限元法,计算某大长径比固体发动机在温度和内压荷载联合作用下的结构响应;研究伞盘结构及其位置对药柱最大Von Mises应变的影响规律;讨论当伞盘位于药柱中部时,伞盘最大Von Mises应变随伞盘宽度、深度以及顶部圆弧半径比的变化规律。结果表明,伞盘位于药柱中部时可以有效地降低大长径比药柱的最大Von Mises应变,增加伞盘宽度、深度或选取合适的半径比均可降低伞盘结构的最大Von Mises应变。所得结论可为固体发动机设计提供参考。     

电磁轨道炮轨道温度场与热应力数值仿真

在电磁轨道炮发射过程中,因热量累积而引起的急速温升与热应力对轨道性能和寿命有着重要的影响。为获得发射过程中轨道温度场及热应力分布情况,在分析轨道热载荷的基础上,建立了热载荷计算模型,并在给定的参数下,利用有限元仿真软件ANSYS Workbench对3种典型截面轨道的温度场与热应力进行了数值仿真。仿真结果表明:轨道温度场与热应力轴向上呈梯度分布,纵向上只扩散到内表面很薄的区域,温度与热应力最大值在电枢初始位置处;相较于矩形与凹形截面轨道,凸形截面轨道温升与热应力较低,性能较好。     

初始先验分布未知条件下的DLMR及其Bayes预测

讨论了具有无信息初始先验分布的矩阵变量动态线性模型 (简记为DLMR)及其Bayes预测 ,利用MDIP方法 ,就尺度方差阵∑已知和未知两种情况 ,分别给出模拟初始状态参数(θ1 |D0 )和 (θ1 ,∑ |D0 )的无信息先验分布 ,进而给出其Bayes预测。     

钢筋混凝土外粘钢板结构裂缝的有限元数值模拟

随着高技术武器的不断发展,防护工程正面临着前所未有的威胁和挑战,新型防护结构及材料已经成为研究的热点。针对这一实际背景,运用ANSYS大型有限元软件,采用数值模拟的方法对普通钢筋混凝土结构和外粘钢板混凝土结构在相同均布面荷载作用下的变形、钢筋应力以及结构裂缝的开展情况进行了比较。结果表明外粘钢板的钢筋混凝土结构能够大大增强结构的抗力,并且有效的抑制了裂缝的开展。     

Study on dynamic response of multi-degree-of-freedom explosion vessel system under impact load

In order to study the dynamic response and calculate the axial dynamic coefficient of the monolayer cylindrical explosion vessel, the wall of vessel is simplified as a multi-degree-of-freedom (MDoF) undamped elastic foundation beam. Decoupling the coupled motion equation and using Duhamel's integrals, the solutions in generalized coordinates of the equations under exponentially decaying loads, square wave loads and triangular wave loads are calculated. These solutions are consistent in form with the solutions of single-degree-of-freedom (SDoF) undamped forced vibration simplified model. Based on the model, equivalent MDoF design method (also called MDoF dynamic coefficient method) of cylindrical explosion vessel is proposed. The traditional method can only predict the dynamic coefficient of torus portion around the explosion center, but this method can predict that of the vessel wall at any axial n dividing point position. It is verified that the prediction accuracy of this model is greatly improved compared with the SDoF model by comparing the results of this model with SDoF model and numerical simulation in different working conditions. However, the prediction accuracy decreases as the scaled distance decreases and approaches the end of the vessel, which is related to the accuracy of the empirical formula of the implosion load, the simplification of the explosion load direction, the boundary conditions, and the loading time difference.     

Dynamic modeling and parameter identification of a gun saddle ring

In this study, a theoretical nonlinear dynamic model was established for a saddle ring based on a dynamic force analysis of the launching process and the structure according to contact-impact theory. The ADAMS software was used to build a parameterized dynamic model of the saddle ring. A parameter identification method for the ring was proposed based on the particle swarm optimization algorithm. A loading test was designed and performed several times at different elevation angles. The response histories of the saddle ring with different loads were then obtained. The parameters of the saddle ring dynamic model were identified from statistics generated at a 50° elevation angle to verify the feasibility and accuracy of the proposed method. The actual loading history of the ring at a 70° elevation angle was taken as the model input. The response histories of the ring under these working conditions were obtained through a simulation. The simulation results agreed with the actual response. Thus, the effectiveness and applicability of the proposed dynamic model were verified, and it provides an effective method for modeling saddle rings.