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本文以多片平行悬壁板为模型,对平行结构流固耦合振动特性问题从理论上进行了探讨,导出了便于分析计算的理论表达式,并进行了计算与实验验证。结果说明,分析方法正确,对于分析实际水工结构的完全流固耦合问题具有实现意义。 相似文献
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本文根据实验拟事出流固耦联系统的非一函数和模态参数。建立了此系统的非线性振地系统的数值和解析分析,论证了充液旋转壳的流固耦联自激振动特性,求出了流固耦联系统的霍普分叉解,阐明了只结文物鱼洗的振动机理。本文结论对同类自激振动的研究具有重要的参考价值 相似文献
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针对某煤矿井下救生舱,利用ANSYS和LS-DYNA软件建立救生舱、瓦斯/瓦斯煤尘和巷道三维有限元模型。分别进行了真实内瓦斯/瓦斯煤尘爆炸作用下救生舱流固耦合数值分析,等效三角波爆炸冲击荷载作用下救生舱动态模拟和静水压力荷载作用下救生舱的极限承载力和极限变形的数值计算,确定救生舱动/静态承载能力变化规律和变形模式,给出瓦斯/瓦斯煤尘爆炸超压与救生舱承载能力和变形模式的变化规律。研究结果表明,等效三角波爆炸冲击荷载作用下该救生舱整体结构的极限超压明显比流固耦合计算分析结果大,流固耦合计算分析结果更接近于实验结果。该救生舱满足爆炸冲击波荷载下的变形要求时,其在静水压荷载作用下的变形也能满足。 相似文献
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爆炸引起的颅脑损伤已经成为现代战场单兵的主要致伤形式,而相关的致伤机理尚未完全阐明。本文中,针对头部在爆炸冲击波作用下的动态响应及相关致伤机理进行了数值模拟研究。首先,基于颅脑的核磁共振切片建立了人体头部三维数值模型,该模型真实地反映了颅脑的生理特征与细节构造;利用该模型对人体头部碰撞实验进行数值模拟,模拟结果与实验结果吻合良好,验证了头部模型的有效性。在此基础上,基于欧拉-拉格朗日耦合(Euler-Lagrangian coupling method,CEL)方法发展了爆炸冲击波-头部流固耦合模型,对头部受到爆炸冲击波正面冲击工况进行了数值模拟,分别从流场压力分布、脑组织压力、颅骨变形与加速度等方面对头部动态响应过程进行了分析。爆炸冲击波峰值压力在流固耦合作用下增大为入射波的3.5倍,致使受到直接冲击处的颅骨与脑组织发生高频振动,相应的振动频率高达8 kHz,这与碰撞载荷下的脑组织动态响应是完全不同的。同时,该处颅骨的局部弯曲变形会沿着颅骨进行“传播”,影响着整个颅骨的变化构型,从而决定了脑组织压力与损伤的演化过程。
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水下爆炸导致舰船结构毁伤是一个复杂的非线性大变形流固耦合过程,高精度的流固耦合计算是获得高置信模拟结果的关键。基于浸没边界思想,本文提出一种面向大变形壳理论的流固耦合数值方法,可精确刻画流固耦合界面并高效求解流固界面约束方程。基于该方法,本文提出了完整的适用于水下爆炸舰船结构毁伤的大变形流固耦合数值计算方案,并基于大规模并行编程框架,研发形成适用于舰船结构毁伤的流固耦合大规模并行计算软件。与泰勒平板理论解和水下爆炸结构冲击响应实验数据等进行对比表明,本文方法可有效模拟大变形流固耦合工程问题,具备较高数值求解精度。在此基础上,完成了水下爆炸整船结构毁伤过程大规模数值模拟。该方法可有效应用于舰船毁伤等级评估,应用前景广阔。 相似文献
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冲击温度的近似计算方法 总被引:5,自引:0,他引:5
将冲击温度的计算归纳为三种近似方法,并对这三种方法进行了概述,同时还给出了一些材料参数的估算方法.在利用等熵线计算冲击温度时,从冲击绝热线出发推导了一个半解析的等熵方程.计算了铁的冲击温度,并与实验测量值作了比较.结果表明,利用三项式物态方程并考虑熔化相变潜能的影响后算得的冲击温度与测量值符合得比较好,另外,本文还对影响冲击温度计算值的若干因素进行了分析. 相似文献
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轴向冲击圆柱壳非弹性响应 总被引:1,自引:0,他引:1
简要论述承受轴向冲击载荷圆柱壳非弹性动屈曲响应的研究进展。采用Karman-Donnell运动方程研究轴向流固冲击载荷作用下的圆柱壳轴对称弹塑性动屈曲问题。本构关系采用增量理论,借助增量数值方法求解动力方程组。研究不同边界条件对屈曲的影响,以及径向外压力在不同边界条件下对屈曲的影响。 相似文献
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DYNAMIC BUCKLING OF STATICALLY PRELOADED RING-STIFFENED CYLINDRICAL SHELLS UNDER AXIAL FLUID-SOLID IMPACT LOADING 总被引:1,自引:0,他引:1
The Initial Imperfection Amplified Criterion is applied to investigate the geometric nonlinear dynamic buckling of statically
preloaded ring-stiffened cylindrical shells under axial fluid-solid impact. Taking account of the effects of large deformation
and initial geometric imperfection, the governing equations are obtained by the Galerkin method and solved by the Runge-Kutta
method. The effects of static preloading (uniform external radial pressure) on the buckling features and the load-carrying
ability of ring-stiffened cylindrical shells against axial impact are discussed.
The project is supported by the National Natural Sciences Foundation of China (No. 19802017). 相似文献
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《European Journal of Mechanics - A/Solids》2008,27(6):1075-1087
This paper reports the results of an investigation into the vibration of functionally graded cylindrical shells with flowing fluid, embedded in an elastic medium, under mechanical and thermal loads. By considering rotary inertia, the first-order shear deformation theory (FSDT) and the fluid velocity potential, the dynamic equation of functionally graded cylindrical shells with flowing fluid is derived. Here, heat conduction equation along the thickness of the shell is applied to determine the temperature distribution and material properties are assumed to be graded distribution along the thickness direction according to a power-law in terms of the volume fractions of the constituents. The equations of eigenvalue problem are obtained by using a modal expansion method. In numerical examples, effects of material composition, thermal loading, static axial loading, flow velocity, medium stiffness and shell geometry parameters on the free vibration characteristics are described. The new features in this paper are helpful for the application and the design of functionally graded cylindrical shells containing fluid flow. 相似文献
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主要研究受轴向冲击圆柱壳非对称屈曲耗能,从轴向屈曲变形、环向屈曲变形和轴向压缩变形3个角度进行理论推导. 结果表明: 环向屈曲变形能随屈曲折叠边数增加有减小趋势, 且占总耗能比例很小,可知圆柱壳受轴向冲击屈曲过程中外力做功主要转变为轴向变形能,环向屈曲变形消耗外力功很少. 相似文献
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Experimental studies on dynamic plastic buckling of circular cylindrical shells under axial impact 总被引:1,自引:0,他引:1
In the present paper, experimental studies on dynamic plasticbuckling of circular cylindrical shells under axial impact are
carried out. Hopkinson bar and drop hammer apparatus are used for dynamic loading. Three groups of circular cylindrical shells
made of copper are tested under axial impact. From the experiments, the first critical velocity corresponding to the axi-symmetric
buckling mode and the second critical velocity corresponding to the non-axisymmetric buckling mode are determined. The present
results come close to those of second critical velocity given by Wang Ren[4–6]. Two different kinds of non-axisymmetric buckling modes oval-shaped and triangle shaped are founded. The buckling modes under
two loading cases, viz. with small mass but high velocity and with large mass and low velocity using Hopkinson bar and drop
hammer, are different. Their critical energies are also discussed.
The project is supported by the National Natural Science Foundation of China (19672039) and the Foundation for Returned Scholar
from Abroad of Shanxi Province 相似文献
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S. A. Bochkarev V. P. Matveenko 《Journal of Applied Mechanics and Technical Physics》2012,53(5):768-776
The stability of an elastic circular cylindrical shell of revolution interacting with a compressible liquid (gas) flow having both axial and tangential components is analyzed. The behavior of the fluid is studied within the framework of potential theory. The elastic shell is described in terms of the classical theory of shells. Numerical solution of the problem is performed using a semianalytical finite element method. Results of numerical experiments for shells with different boundary conditions and geometric dimensions are presented. The effects of fluid rotation on the critical flow velocity and the effect of axial fluid flow on the critical angular velocity of fluid rotation were estimated. 相似文献