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1.
压剪复合冲击下氧化铝陶瓷的剪切响应实验研究   总被引:4,自引:0,他引:4  
通过对92.93%氧化铝陶瓷进行倾斜板碰撞实验,研究了多晶陶瓷材料在压剪复合冲击下的非弹性变形响应和剪切波传播规律。压剪复合冲击实验由57 mm开槽气体炮驱动铜飞片对陶瓷靶板加载,通过试件内埋植的电磁速度计来测量内部质点速度历程。将纵向粒子速度从感应电动势曲线中分离后得到横向粒子速度历程,发现在压剪复合冲击下由于材料剪切刚度的降低而引起的剪切波衰减。冲击软回收试件的扫描电子显微镜(SEM)观察表明,冲击载荷低于屈服强度时,多晶氧化铝陶瓷中存在沿晶界、气孔的微裂纹成核与扩展,在高于屈服强度的冲击加载下进一步产生了穿晶微裂纹,微裂纹系统导致了材料在卸载后的显著的体积膨胀。  相似文献   

2.
本文在考虑大变形、忽略阻尼影响的情况下,基于高散加筋板模型,对具有弹性约束边界的加筋板在流固冲击载荷下的非线性瞬态响应进行了理论研究.取样条函数作为挠度试函数,运用加权残值法求得加筋板动力响应的控制方程,采用四阶Runge-Kutta法求解该方程,并用Fortran语言编制了相应的计算程序.构造的B样条函数能适应板侧边上的任意弹性转动约束.文中不仅分析了不同的冲击载荷形式对加筋板动力特性的影响,还讨论了载荷峰值、冲击栽荷持续时问、加强筋和弹性转动约束的影响.  相似文献   

3.
用GM(几何中线)屈服准则,对受线性荷载作用下的简支圆板进行塑性极限分析,求得极限载荷的解析解.该解为圆板半径a、切向应力最大点半径r0以及极限弯矩的函数.与Tresca、Mises和TSS(双剪应力)屈服准则预测的极限载荷比较表明,Tresca屈服准则预测极限载荷的下限,TSS屈服准则预测极限载荷的上限,GM准则预测的极限载荷恰居二者中间,并靠近Mises解.圆板半径a与切向应力最大点半径r0的变化关系为r0随着a的增加而增加,满足线性关系,r0分别出现在r0=0.7710a和r0=0.5472a的位置上.  相似文献   

4.
多孔金属夹层板在冲击载荷作用下的动态响应   总被引:14,自引:4,他引:10  
赵桂平  卢天健 《力学学报》2008,40(2):194-206
借助两种有限元软件ABAQUS和 LS_DYNA, 模拟和分析了两种厚度不同的泡沫铝合金夹层板(三明治板)、方孔蜂窝形夹层 板和波纹形夹层板在冲击载荷下的动态响应. 4种夹层板的单位面积密度相同,冲击载荷分 别用泡沫铝子弹与不锈钢子弹模拟. 讨论了泡沫金属夹层板和格构式夹层板在不同冲击 载荷作用下的变形机制,重点在于对夹层板的吸能特性及板内各部分吸能变化规律的探讨. 研究结果表明: 在泡沫子弹冲击下,夹层板主要是通过自身变形来消耗子弹动能,并转化为 自身内能. 厚度为22\,mm的泡沫金属夹层板吸收能量最多,底面变形最小,是结构性能最优的 夹层板;在刚性子弹高速冲击穿透过程中,格构式夹层板的吸能性能比单位面积密度相同的 泡沫金属夹层板的吸能性能更好. 波纹形夹层板的能量吸收能力在4种板中最高.  相似文献   

5.
舱内爆炸载荷及舱室板架结构的失效模式分析   总被引:15,自引:0,他引:15  
通过对典型半穿甲导弹打靶实验中舰艇结构破坏模式的观察,结合数值模拟,分析了舱内爆炸载荷的特征以及舱内爆炸下舱室板架结构的失效模式。结果表明,舱内爆炸下,舱室板架结构承受的冲击载荷及失效模式与敞开环境爆炸下加筋板结构承受的冲击载荷及失效模式有较大区别,其动态响应难以用敞开环境爆炸下加筋板结构的动态响应描述;舱内爆炸载荷主要有壁面反射冲击波、角隅汇聚冲击波以及准静态气体压力,其中两壁面和三壁面角隅汇聚冲击波的强度分别为相同部位壁面反射冲击波强度的5倍和12倍以上;舱室板架结构主要有4种失效模式,其中模式Ⅲ、Ⅳ较常发生;舱室板架结构加强筋布置在迎爆面将使板架中部的局部破坏程度增加,但有利于削弱角隅汇聚冲击波强度,减小板架沿角隅部位的撕裂破坏。  相似文献   

6.
鸟与叶片的撞击过程是一个复杂的加载过程。为了将其简化,以建立一个简单且合理的鸟撞击载荷模型,需要分析鸟撞击载荷的各种因素对叶片响应的影响。本文通过计算机数值模拟进行上述工作。以矩形悬臂板模拟实际叶片,以冲击载荷模拟鸟撞击载荷,采用有限元法计算悬臂板在冲击载荷下的非线性瞬态响应。从鸟撞击载荷的冲量、时间因索、空间因素三个方面分析了冲量、加载持续时间、力-时间函数、初始冲击压力、加载位置、载荷的空间分布以及载荷类型等七种因素对叶片响应的影响。本文得出的结论为合理简化鸟撞击加载过程及建立鸟撞击载荷模型提供了参考与依据。  相似文献   

7.
基于相场理论,论文构建了热力耦合作用下热-弹性材料的复杂断裂控制方程,采用光滑有限元法对该模型进行了数值离散;设计编写了相应的Matlab计算程序;开展了热-力载荷下的二维拉伸断裂模拟,将结果和有限元计算结果对比,吻合一致.同时采用该模型开展热冲击下陶瓷板的多裂纹扩展过程模拟,计算结果和实验结果吻合良好,验证了论文方法的有效性.  相似文献   

8.
结构受冲击载荷作用可能会变形甚至失效.合理的结构形式有助于增强结构的抗冲击性能.本文对冲击载荷作用下板杆组合结构的动力学行为进行了分析,采用有限元方法模拟冲击载荷下结构的大挠度变形模式和能量吸收特性,并研究了杆件长度对抗冲击性能的影响.  相似文献   

9.
本文从轴对称板壳理论的基本方程出发,通过建立Green函数,导出了轴对称线载荷下解的一般表述式,由此可以求出任意轴对称载荷下的解,然后本文分别讨论了圆板和扁球壳受线载问题的解,文中的结果适用于各种边界条件。  相似文献   

10.
为了研究冲击载荷作用下考虑应力波效应弹性矩形薄板的动力屈曲,根据动力屈曲发生瞬间的能量转换和守恒准则,导出板的屈曲控制方程和波阵面上的补充约束条件,真实的屈曲位移应同时满足控制方程和波阵面上的附加约束条件。满足上述条件,建立了该问题的完整数值解法,对屈曲过程中冲击载荷、屈曲模态和临界屈曲长度之间的关系进行研究,定量计算了横向惯性效应对提高薄板动力屈曲临界应力的贡献。研究表明:板的厚宽比一定时,临界屈曲长度随冲击载荷的增大而减小;由于屈曲时的横向惯性效应,应力波作用下薄板一阶临界力参数是相应边界板的静力失稳临界力参数的1.5倍;随着边界约束逐渐减弱,板临界力参数逐渐减小,动力特征参数逐渐增大。  相似文献   

11.
12.
功能梯度压电圆板自由振动问题的三维精确分析   总被引:2,自引:0,他引:2  
张晓日  仲政 《力学季刊》2005,26(1):81-86
本文对周边为广义刚性滑动和广义简支两种边界条件下的功能梯度压电材料圆板自由振动问题进行分析。根据轴对称横观各向同性压电材料基本方程,并利用有限Hankel变换得到了功能梯度压电材料圆板的状态空间方程。假设材料的机械和电学性质均沿板厚方向按统一的指数函数形式梯度分布,从而获得了周边为广义刚性滑动和广义弹性简支两种边界条件下功能梯度压电圆板自由振动问题的三维精确频率方程,该方程是一个关于自由振动频率的超越方程,通过求解该超越方程可得到在不同板厚以及不同的材料性质梯度变化情况下的圆板自由振动频率值,结果表明在相同的材料性质梯度变化情况下频率均随着板厚增加而增大,而在相同的板厚情况下频率则随材料性质梯度变化指数的增大而减小的结论。  相似文献   

13.
功能梯度矩形厚板的三维热弹性分析   总被引:7,自引:1,他引:6  
直接从三维热弹性力学基本方程出发,通过引入两个位移函数和两个应力函数,导出了一个二阶的齐次状态方程和一个四阶的非齐次状态方程。分析中采用了层合近似模型,即将板划分成厚度足够小的若干薄层,从面可将每一层内的材料常数近似为常数。给出了任意厚度的四边简支横观各向同性功能梯度矩形板的热弹性分析,特别当板较薄时,与薄板理论进行了数值对比,发现两者结果吻合很好。最后研究了材料梯度指标对热弹性场的影响,结果显示梯度指标对热应力和位移都有着显著的作用:在不同的区间,梯度指标对它们有不同的影响;并且在同一区间,梯度指标对两者的影响程度也有所不同。  相似文献   

14.
In the framework of the linear theory of elasticity, an exact bending equation is obtained for the median plane of a plate whose material is a monoclinic system with the axis of symmetry perpendicular to the plate plane. As an example, the equation of the median plane of an isotropic plate is considered; the operator of this equation coincides with the operator of Sophie Germain’s approximate equation. As the plate thickness tends to zero, the right-hand side of the equation is asymptotically equivalent to the right-hand side of the approximate equation. In addition, equations relating the median plane transverse stresses and the total stresses in the plate boundary planes to the median plane deflexions are obtained.  相似文献   

15.
In this research work, an exact analytical solution for buckling of functionally graded rectangular plates subjected to non-uniformly distributed in-plane loading acting on two opposite simply supported edges is developed. It is assumed that the plate rests on two-parameter elastic foundation and its material properties vary through the thickness of the plate as a power function. The neutral surface position for such plate is determined, and the classical plate theory based on exact neutral surface position is employed to derive the governing stability equations. Considering Levy-type solution, the buckling equation reduces to an ordinary differential equation with variable coefficients. An exact analytical solution is obtained for this equation in the form of power series using the method of Frobenius. By considering sufficient terms in power series, the critical buckling load of functionally graded plate with different boundary conditions is determined. The accuracy of presented results is verified by appropriate convergence study, and the results are checked with those available in related literature. Furthermore, the effects of power of functionally graded material, aspect ratio, foundation stiffness coefficients and in-plane loading configuration together with different combinations of boundary conditions on the critical buckling load of functionally graded rectangular thin plate are studied.  相似文献   

16.
An exact expression is derived for a path independent integral surrounding an elliptical hole in an infinite plate with tensile tractions at infinity for plane stress loading conditions. The plate is composed of a non-work-hardening material satisfying the Tresca yield condition under proportional loading and small strain assumptions. This problem may serve as a simple classroom example for the derivation of a relationship between crack opening displacement and path independent integral for a nonlinear elastic material satisfying the Tresca yield condition.   相似文献   

17.
Based on the von Karman plate theory of large deflection, we have derived a non-linear partial differential equation for the vibration of a thin orthotropic plate under the combined action of a transverse magnetic field and a transverse harmonic mechanical load. The influence of the magnetic field is due to the magnetic Lorentz force induced by the eddy current. By employing the Bubnov-Galerkin method, the non-linear partial differential equation is transformed into a third-order non-linear ordinary differential equation. The amplitude-frequency equations are further derived by means of the multiple-scale method. As numerical examples for an orthotropic plate made of silver, the influence of the magnetic field, orthotropic material property, plate thickness, and the mechanical load on the principal resonance behavior is investigated. The higher-order effect and stability of the solution are also discussed.  相似文献   

18.
The stability of the harmonic solution of the forced Duffing equation governing the relative motion of a load on an inclined plate rotating at a constant angular speed about an arbitrary axis is studied. The load is supported by two identical simple shear springs made of a quadratic rubber-like material. It is found that the stability of motion about the center points is governed by the solutions of Hill's equation with three parameter. For certain values of the design parameters, Hill's equation reduces to the Mathieu equation and stability of the motion is studied following the standard procedure. In the general case, an intermediate bifurcation of the response amplitude occurs for motions about the negative center points. It is shown that the position of the center of mass of the load with respect to the plate center in the undisturbed state affects the nature of the response to a great extent. Without extensive analysis, the stability of motion in the general case is predicted for a specific range of the values of the angular speed of the plate.  相似文献   

19.
In a typical pin-loaded joint used to assemble glass plates, the hole in a glass plate is reinforced by a steel ring glued to the glass plate via a soft resin layer. Thus, the ring is in direct contact with the steel bolt and prevents the glass plate from high stress concentration. This paper proposes an analytical approach to solving the resulting conforming contact problem. The strain and stress fields inside the resin layer are first determined by exploiting the fact that the stiffness of the material constituting it is much smaller than the stiffness of steel and glass. After finding the relevant Green functions for the ring and pin, the frictionless contact between them is then formulated in terms of an integral equation with a Fourier series as the kernel. This integral equation is solved by neglecting the terms of high orders and transforming it into the Cauchy singular integral equation. The derived analytical results for the contact pressure and angle are finally compared to and validated by those obtained by the finite element method.  相似文献   

20.
李世荣 《力学学报》2022,54(6):1601-1612
功能梯度材料微板谐振器热弹性阻尼的建模和预测是此类新型谐振器热?弹耦合振动响应的新课题. 本文采用数学分析方法研究了四边简支功能梯度材料中厚度矩形微板的热弹性阻尼. 基于明德林中厚板理论和单向耦合热传导理论建立了材料性质沿着厚度连续变化的功能梯度微板热弹性自由振动控制微分方程. 在上下表面绝热边界条件下采用分层均匀化方法求解变系数热传导方程, 获得了用变形几何量表示的变温场的解析解. 从而将包含热弯曲内力的结构振动方程转化为只包含挠度振幅的偏微分方程. 然后,利用特征值问题在数学上的相似性,求得了四边简支条件下功能梯度材料明德林矩形微板的复频率解析解, 进而利用复频率法获得了反映谐振器热弹性阻尼水平的逆品质因子. 最后, 给出了材料性质沿板厚按幂函数变化的陶瓷?金属组分功能梯度矩形微板的热弹性阻尼数值结果. 定量地分析了横向剪切变形、材料梯度变化以及几何参数对热弹性阻尼的影响规律. 结果表明, 采用明德林板理论预测的热弹性阻尼值小于基尔霍夫板理论的预测结果, 而且两者的差别随着相对厚度的增大而变得显著.   相似文献   

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