螺栓角钢钢节点的三维非线性有限元分析

对螺栓角钢钢节点半刚性连接采用非线性有限元分析方法 ,对连接中的主要构件的顶部、底部、腹板角钢、高强螺栓、梁翼缘、柱翼缘和柱翼缘加劲肋进行三维非线性有限元精细模拟 ,针对有无柱加劲肋、有无腹板角钢等几种连接的情况进行比较分析 ,探讨了螺栓角钢半刚性连接的受力性能。     

恒定水深拖拉铺管管线的三维大挠度静态应力分析

海洋管线具有复杂的工程结构,在恶劣的海洋环境中,承受着比陆地管线更为复杂的载荷。为了保证管线安全工作,需对其进行准确的应力分析。本文应用有限元法对恒定水深拖拉铺管的管线内力、应力及位移进行了计算,并将结果与已有的计算结果进行对比,进一步分析了各种海洋环境因素对管线弯曲效应的影响,取得了有一定实用性的成果,可供海洋拖拉铺管施工时参考。     

潜油电机碟形弹簧的动力学分析

为了降低潜油电泵机组的振动对止推轴承性能的影响,在潜油电机中节和下节的止推轴承静块底部安装了蝶形弹簧。用有限元方法进行模态分析,确定了蝶形弹簧的主振型和固有频率,然后进行瞬态动力学分析,求解蝶形弹簧在一定载荷下的应力和位移。依此设计的蝶形弹簧将进一步延长止推轴承的使用寿命。     

裂缝各向异性介质中P-SV转换波正演模拟

裂缝介质正演是研究裂缝性油藏的各向异性、裂缝检测方法、裂缝AVO反演等的前提。在裂缝方位各向异性(EDA)介质模型的基础上，重点研究了纵波震源激发的地震波所产生P-SV波的有限差分正演模拟方法。从各向异性单斜对称系统的刚性矩阵推导出的波动方程，可以满足EDA介质模型不同方位角入射的二维差分模拟要求。在有限差分模拟中，采用了普通的Kelly差分格式、二阶各向异性吸收边界条件和一般的纵波震源的解析形式，并应用修正的通量传输校(FCT)方法来消除频散。同时，对纵波震源的解析式进行了技术处理，取得了较好的效果。     

基于遗传算法的土钉支护结构优化设计研究

通过建立三维有限元模型,对土钉支护的变形和受力性能进行分析,得出土钉力的合理分布。在此基础上,考虑土钉支护的水平位移,采用遗传算法,对土钉支护的结构优化设计进行研究,建立了土钉支护结构的优化设计数学模型,并编制了相应的计算程序。通过算例分析,并与基于极限平衡分析的优化结果相比较,得出合理的土钉支护结构设计的参考结论。     

高压射流冲击破碎岩石的有限元计算

高压射流冲击破岩是一个复杂的非线性问题。通过MSC．Marc建立模型，分别使用动态接触作为非线性冲击载荷模拟高压水射流冲击岩石。通过动力计算分析，根据岩石内部应力的变化使用Hoffman失效准则研究了岩石的破碎过程。分析表明，增加射流冲击速度可以提高射流破碎岩石的效率，当射流速度迭到某一临界值时，射流水锤作用使得岩石发生大块破碎。     

Bifurcation points and bifurcated branches by an asymptotic numerical method and Padé approximants

The aim of this work is to develop a reliable and fast algorithm to compute bifurcation points and bifurcated branches. It is based upon the asymptotic numerical method (ANM) and Padé approximants. The bifurcation point is detected by analysing the poles of Padé approximants or by evaluating, along the computed solution branch, a bifurcation indicator well adapted to ANM. Several examples are presented to assess the effectiveness of the proposed method, that emanate from buckling problems of thin elastic shells. Especially problems involving large rotations are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

A p‐version,first order shear deformation,finite element for geometrically non‐linear vibration of curved beams

A p‐version, hierarchical finite element for curved, moderately thick, elastic and isotropic beams is introduced. The convergence properties of the element are analysed and some results are compared with results published elsewhere or calculated using a commercial finite element package. It is verified that, with the proposed element, shear locking does not affect the computation of the natural frequencies and that low dimensional, accurate models are obtainable. Geometrically non‐linear vibrations due to finite deformations, which occur for harmonic excitations with frequencies close to the first three natural frequencies of vibration, are investigated using Newmark's method. The influence of the thickness, longitudinal inertia and curvature radius on the dynamic behaviour of curved beams are studied. Copyright © 2004 John Wiley & Sons, Ltd.     

Second-order accurate constraint formulation for subdivision finite element simulation of thin shells

We present a new method for enforcing boundary conditions within subdivision finite element simulations of thin shells. The proposed framework is demonstrated to be second-order accurate with respect to increasing refinement in the displacement and energy norm for simply supported, clamped, free and symmetric boundary conditions. Second-order accuracy on the boundary is consistent with the accuracy of subdivision-based approaches for the interior of a body. Our proposed framework is applicable to both triangular and quadrilateral refinement schemes, and does not impose any topological requirements upon the underlying subdivision control mesh. Several examples from an obstacle course of benchmark problems are used to demonstrate the convergence of the scheme. Copyright © 2004 John Wiley & Sons, Ltd.     

A direct stiffness analysis of a composite beam with partial interaction

The use of the conventional semi-analytical stiffness method in finite element analysis, in which interpolation polynomials are used to develop the stiffness relationships, leads to problems of curvature locking when beam-type elements are developed for composite members with partial interaction between the materials of which it is comprised. The curvature locking phenomenon that occurs for composite steel–concrete members is quite well reported, and the general approach to minimizing the undesirable ramifications of curvature locking has been to use higher-order polynomials with increasing numbers of internal nodes. This paper presents an alternate formulation based on a direct stiffness approach rather than starting from pre-defined interpolation polynomials, and which does not possess the undesirable locking characteristics. The formulation is based on a more general approach for a bi-material composite flexural member, whose constituent materials are joined by elastic shear connection so as to provide partial interaction. The stiffness relationships are derived, and these are applied to a simply supported and a continuous steel–concrete composite beam to demonstrate the efficacy of the method, and in particular its ability to model accurately both very flexible and very stiff shear connection that causes difficulties when implemented in competitive semi-analytical algorithms. Copyright © 2004 John Wiley & Sons, Ltd.