板自由振动分析的混合型条元法

本文基于广义变分原理,以条元节线处的位移和弯矩为基本未知参数,构造了一种分析中厚板自由振动的混合型有限条元。这种混合型条元计算精度较高,能适应比较复杂的板边界条件,它是板自由振动分析的一种有效方法。     

环加肋圆柱壳振动分析的复合有限条法

提出一种分析环加肋圆柱壳自由振动问题的高效半解析方法──复合有限条法。该方法可在一个有限条元内计入若干个横向加肋的影响，包含横向加肋的有限条元称为复合有限条元，环加肋圆柱天采用一系列复合有限条元进行离散。复合有限条法可按加强肋骨的实际分布情况进行计算，而不必采用将加肋的影响平均到整个壳体的方法，且可考虑肋骨偏心的影响，它是一种子结构求解技术。算例表明，复合有限条法具有良好的求解精度和很高的求解效率，与常规有限元法相比，复合有限条法大大减少了系统自由度和计算工作量，且易于程序实现，是一种分析加肋板壳结构振动问题的较理想方法。     

夹层板与复合材料板振动分析的有限厚板条

本文用有限厚条法进行夹层板、复合材料板的振动分析,与一般有限元、有限条相比具有自由度少、精度高的特点。文中推导了适用于各种形状、边界及构造的夹层与复合材料板的有限厚条法计算格式,并给出了许多算例,和相应现有的数值与解析方法结果进行比较。     

圆板振动分析的有限条-传递矩阵法

本文提出一种圆板及环板振动特性分析的新方法,其做法是把结构振动特性分析的传递矩阵法与有限条法相结合,使得联立方程阶数大大降低。此方法不仅可以节省计算机内存,而且简便、实用。     

基于结线解析函数的半解析有限元方法

本文提出一种适用于具有复杂边界条件的矩形板的半解析有限元方法,它是对有限条方法的改进。本方法从结线位移出发构造半解析函数,推导动力平衡方程。给出了几种板的自由振动和静力问题的数值算例,表明本方法具有很好的精度。     

三维退化壳条分析钢筋混凝土板壳

将三维退化壳条应用到板壳结构的非线性分析,几何非线性是通过VonKármán假定考虑的。将钢筋混凝土结构的材料非线性特性应用于壳条,该壳条可以用来分析变厚度、任意配筋的钢筋混凝土板壳几何和材料非线性。利用“拟刚度矩阵法”,消除了有限条法在非线性分析时刚度矩阵与级数项的耦合,大大简化了有限条在处理非线性问题时的数值计算。两个算例的结果验证这种理论方法的有效性和精度。     

先进复合材料格栅加筋板的总体稳定性分析

通过建立复合材料格栅结构单元的基本力学假设和分析模型, 推导了一种新的等效刚度计算方法, 用于分析复合材料格栅加筋板的总体稳定性。该方法充分考虑了筋条和面板的相互作用和中面偏移效应, 并具有通用性。结合Rayleigh-Ritz能量近似法, 推导出了求解加筋板总体屈曲载荷的通用特征方程; 分析了多种算例, 并与修正平铺法进行了比较, 结果吻合得很好。      

正交异性板钢桥面的设计计算

本文对正交异性板钢桥面的合理设计计算进行探讨。（１）研究分析国内外桥梁中正交异性板钢桥面设计的计算；（２）结合我国桥梁荷载轴重及其加载原则，应用有限条方法，建立适当的位移函数，把荷载用Ｆｏｕｒｉｅｒ级数表示，求解其恒载和活载效应；（３）将有限条方法对悬索桥正交异性板钢桥面进行计算分析的结果与Ｐｅｌｉｋａｎ－Ｅｓｓｌｉｎｇｅｒ方法计算结果进行了比较。     

材料和几何线性的有限条分析

本文建立了大挠度弹塑性有限条法,用以计算初曲板在面内荷载作用下的极限荷载。分析中采用了伴随修正的Ilyushin屈服准则或修正的Ivanov屈服准则和Prandtl—Reuss塑性流动法则的面积法。通过与前人对板屈曲后弹塑性分析算例的比较,证明该方法对于板的大挠度弹塑性分析具有相当高的精度。     

复合有限条法研究水压作用下加肋柱壳的后屈曲

为了研究水压作用下的加肋柱壳的后屈曲状况,并且能考虑到肋骨的实际截面形状和分布情况,本文将复合有限条方法应用于环加肋圆柱壳的后屈曲分析。在对后屈曲路径的跟踪过程中,使用了正交弧长法。算例表明,复合有限条方法同纯粹的有限元方法相比在速度上能提高10倍以上,并且方程阶数与壳体尺寸无关,是一种分析加肋板壳结构的理想方法;实际应用的加肋圆柱壳在水压下的后屈曲路径一般来说不存在分叉点,在后屈曲阶段,随着变形的增加常常要求压力有所增加。     

Higher-order B-spline finite strip model for laminated adaptive structures

This paper presents the development of a higher-order isoparametric B-spline finite strip model, applied to the static and free vibration analysis of composite laminated plate/shell structures, which can have arbitrary lay-ups, loading and boundary conditions. The model considers the possibility of existing embedded and/or surface bonded piezoelectric actuators and sensors, enabling passive control of parameters, such as displacements and natural frequencies. The structure is discritized in a finite number of strips and the geometry and the displacement components of each strip are represented by interpolating functions written as products of cubic B-spline functions and Lagrange and Hermite functions along the y and x strip directions, respectively. The whole structure is modeled through the assembly of a finite number of flat section strips. Several examples are presented and discussed to illustrate the accuracy and capability of the model.     

不同板条形状对艉轴承的力学性能影响研究及其结构优化

 为了提高板条式艉轴承的润滑性能，应用有限元法研究不同板条形状对艉轴承力学性能的影响及其结构优化．具体探讨不同曲率半径凹弧型和凸弧型板条以及不同楔形空间承载面积板条的力学特性，将结构优化前后力学性能进行对比．结果表明：就3种不同形状板条而言，平板型板条的力学性能相对较好；不同曲率半径的凹弧型、凸弧型板条对艉轴承力学性能的影响规律有着较大差异；在不同楔形空间与单个板条承载面积之间存在应力最大、应变最小，力学性能相对最优的临界点；对平板型板条进行优化后，其力学特性有了明显的改善．     

Hybrid finite element/volume method for shallow water equations

A hybrid numerical scheme based on finite element and finite volume methods is developed to solve shallow water equations. In the recent past, we introduced a series of hybrid methods to solve incompressible low and high Reynolds number flows for single and two‐fluid flow problems. The present work extends the application of hybrid method to shallow water equations. In our hybrid shallow water flow solver, we write the governing equations in non‐conservation form and solve the non‐linear wave equation using finite element method with linear interpolation functions in space. On the other hand, the momentum equation is solved with highly accurate cell‐center finite volume method. Our hybrid numerical scheme is truly a segregated method with primitive variables stored and solved at both node and element centers. To enhance the stability of the hybrid method around discontinuities, we introduce a new shock capturing which will act only around sharp interfaces without sacrificing the accuracy elsewhere. Matrix‐free GMRES iterative solvers are used to solve both the wave and momentum equations in finite element and finite volume schemes. Several test problems are presented to demonstrate the robustness and applicability of the numerical method. Copyright © 2010 John Wiley & Sons, Ltd.     

高层结构计算的有限元-有限条杂交法

本文提出用插值法改进传统有限条法的横向局部位移。这种改进过的方法用于高层结构计算中,很好地解决了传统方法遇到的剪力失真问题。该方法较传统有限条法计算精度高,结果可靠,未知量却增加很少。     

The use of bubble functions for the post-local buckling of plate assemblies by the finite strip method

The finite strip displacement functions for post-local buckling are augmented with so-called bubble functions, which are extra modes associated with internal or nodeless degrees of freedom. A non-linear finite strip method of analysis including bubble functions is described for the post-local buckling of geometrically imperfect plate assemblies. It is shown that the use of bubble functions improves significantly the convergence of the method. The non-linear finite strip method is then used to study channel and I-section members in compression and bending.     

An assessment of buffer strips for reduction of stress concentration at cutouts in composite laminates

A shear lag solution for a hybrid unidirectional buffer strip laminate containing a rectangular cutout is presented. Fiber stresses and displacements in the main panel and buffer strips are given as explicit functions of fiber and matrix properties, and laminate and cutout configurations. Stress concentration factors and laminate ultimate strengths for both soft and stiff buffer strips are presented. A substantial improvement in the notched strength is shown to be possible by using low modulus and high strength fibers for buffer strips. The stress concentration factors for a rectangular cutout are compared with those of a rectilinear crack in a buffer strip laminate.     

Post‐buckling analysis of imperfect laminates using finite strips based on a higher‐order plate theory

A finite strip procedure has been developed for the post‐buckling analysis of composite laminates when subjected to progressive end shortening. The finite strips are developed based on a higher‐order shear deformation plate theory and there are nine variables at each nodal line. Initial imperfection expressed in the form of suitable trigonometric function is allowed. Examples including isotropic plates and laminates with arbitrary lay‐up arrangement are presented. Numerical results for laminates with and without initial imperfection are used to illustrate the effect of imperfection. Copyright © 2003 John Wiley & Sons, Ltd.     

环加肋圆柱壳屈曲分析的有限条法

导出了有限条法分析环加肋圆柱壳在静水压力作用下总体屈曲的计算格式，将环加肋圆柱壳作为一个构造上的正交各向异性壳处理，推导了考虑环向加肋影响后有限条元的正交各向异性弹性矩阵。对两端简支环加助圆柱壳总体屈曲临界载荷的计算表明，本文方法计算结果与解析解符合良好。有限条法是分析密加肋圆柱壳屈曲问题的有效数值方法。     

Transverse Distributions of Front and Back Tension Stresses in Cold Strip Rolling

In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con-tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third powerB-spline finite strip method—is put forward to simulate strip rolling process.Front and back tension stressesare formulated.The computed results of the transverse distributions of the front and back tension stresses areclose to the experimental results.The paper lays a foundation for further analysing the three-dimensionalstresses and deformations of strip rolling.