四边简支加劲板的几何非线性自由振动及内共振

研究了加劲板非线性振动的求解方法与振动特性。将加劲板分为母板与加劲肋两个部分考虑,其中母板视为大挠度板,加劲肋视为Euler梁。分别建立板与加劲肋的应变能与动能的表达式,并用张量的形式表示。将应变能与动能代入Lagrange方程,得到一系列关于面内与面外广义坐标的非线性振动微分方程组,多模态解可以通过增量迭代法求出,而单模态解可以用椭圆函数表示。最后,对一个四边简支且不可移动的加劲板前4阶模态进行分析,分别讨论了两个方向设置不同数量加劲肋的情况下非线性自振频率与振幅的关系,并分析了系统的内共振,得到了加劲板非线性振动一些特性,对工程设计有一定的参考意义。     

具有初始几何缺陷加劲板的动态屈曲

针对工程中常用的加劲板,研究了动态屈曲的求解方法。将加劲板分为母板与加劲肋两个部分考虑,其中母板按经典薄板理论计算,加劲肋视为Euler梁。假定加劲板的位移,利用Hamilton原理结合系统能量和振型叠加法建立了加劲板的动态屈曲特征方程。最后,选择四边简支加劲板进行数值分析,分析中考虑初始几何缺陷的影响,并讨论了初始几何缺陷、加劲肋的数量及其刚度的变化对动态屈曲临界荷载的影响。结果表明：一阶模态的初始几何缺陷对加劲板的临界荷载影响很大,而增加加劲肋的数量及其刚度可以提高加劲板的抗动态屈曲能力。研究结果也为加劲板的结构设计方法提供一定的参考。     

U肋加劲板焊接残余应力的一种简化计算方法

基于焊接残余应力数值模拟方法, 分析了U 肋加劲板各组成板件的板宽、板厚对焊接残余应力分布的影响, 揭示了U 肋与母板残余应力合力的分配规律, 提出了针对不同构造尺寸的U 肋加劲板焊接残余应力分布简化计算方法。研究结果表明:各组成板件的板宽变化对焊接残余拉应力的分布影响较小, 但对焊接残余压应力的大小影响较大;U 肋与母板的板厚比对U 肋与母板残余应力的分配比例影响较大。U 肋加劲板受压承载力计算时, 焊接残余应力分布可以采用简化方法计算, 其结果与根据数值模拟得到的焊接残余应力分布计算的结果基本一致。     

高强度钢加劲板焊接残余应力测试及分析

为研究高强度钢的板肋加劲板焊接残余应力分布特点,该文利用切割法对板肋加劲板试件进行了应力测试研究,建立了三维实体热弹塑性有限元模型,采用单元生死和动态约束技术模拟焊缝填充和焊接热输入过程,对比分析了高强度钢和普通钢的应力分布特点,比较研究了母板厚度、肋板厚度、肋板间距和高度对焊接残余应力的影响。研究结果表明:板肋加劲板T型接头角焊缝的焊接顺序与残余应力的分布不相关;高强度钢非焊接区域残余压应力小于普通钢;板件厚度和肋板高度是影响高强度钢的板肋加劲板焊接残余应力的主要因素。     

U肋加劲板焊接残余应力数值模拟分析

通过数值模拟和实验方法对U 肋加劲板焊接残余应力进行了估算和分析,建立了三维热弹塑性有限元模型,采用生死单元法模拟焊缝填充和焊接热输入过程,实现了整个焊接过程中的动态应力和变形变化,得到了U肋加劲板的焊接温度场和应力场,分析了U 肋加劲板的焊接残余应力分布,并与残余应力测试试验结果比较.结果显示:U 肋加劲板近焊缝区残余拉应力达到材料屈服强度,母板远离焊缝区残余压应力平均值约为材料屈服强度的0.2 倍,其分布趋势与实验测试得到的残余应力分布比较接近,证明了所采用的焊接数值模拟方法的正确性.     

火灾下加劲肋对梁柱外伸端板连接性能的影响

为深入了解柱腹板加劲肋对外伸端板连接节点耐火性能及破坏模式的影响,采用非线性有限元法研究了加劲肋对外伸端板连接节点耐火性能及破坏模式的影响。结果表明:柱腹板加劲肋对节点的耐火极限及破坏模式影响很大。柱腹板不设加劲肋,柱腹板承拉及承压域内的塑性应变随温度升高不断增加,最终形成塑性铰,柱失稳;只设承压加劲肋时,柱腹板承拉区屈服,导致柱失稳,节点失效;设置承拉及承压加劲肋时,节点域内的塑性应变较小,破坏模式为端板承拉区形成塑性效线并与柱翼缘脱开,引发梁的大转动,导致梁承压下翼缘局部屈曲失稳及梁轴向温度内力减小。梁轴向温度内力的减小有助于柱及整体框架结构火灾下的稳定。     

铁路正交异性桥面加劲肋-横隔板局部疲劳受力特性研究

正交异性钢桥面因整体性好、承载力强等优势在铁路大跨度桁梁及箱梁斜拉桥、拱桥等桥型中应用越来越广泛,其疲劳特性与公路桥面具有显著的差异。针对铁路正交异性钢桥面加劲肋与横隔板连接处的疲劳敏感区,通过弹性支撑梁理论及闭口薄壁杆件理论分析其局部受力特征,提出了加劲肋疲劳敏感部位面内疲劳应力的解析公式,分析了解析公式中各疲劳影响因素的影响程度及作用机理。基于甬江特大桥——大跨度铁路斜拉桥的钢箱梁正交异性桥面设计了包含2个U肋及2个V肋的正交异性桥面疲劳试验模型,并进行了560万次疲劳加载。研究结果表明:解析公式与有限元分析、试验测试结果相符良好;试验模型测试结果能准确反映疲劳敏感点的应力情况,解析理论则能够反映疲劳敏感点应力的影响因素与规律;在铁路荷载下,加劲肋与横隔板的焊缝长度和加劲肋腹板倾角的增大能够有效降低加劲肋的疲劳应力幅;在铁路正交异性钢桥面板中面积相近、抗弯刚度相等的V肋比U肋具有更好的抗疲劳工作性能。     

聚氨酯-钢板夹层正交异性桥面板试验研究

通过2个不同纵向加劲肋间距的聚氨酯-钢板夹层结构正交异性三跨连续桥面板的钢箱梁模型试验,结合有限元计算分析方法建立多种加劲肋间距桥面板的钢箱梁计算模型进行计算对比,研究该种桥面板的受力性能,试验模型按实桥同种材料的箱梁缩小1/4制作,按汽车荷载在跨中及支点截面产生最大弯矩时测试截面各关键点的纵向、横向应变和挠度。结果表明:桥面板各点应变试验值与计算值基本吻合;采用聚氨酯-钢板夹层结构正交异性桥面板可大幅削减局部应力集中峰值,从而可大幅减少加劲肋数量,减少程度主要取决于夹层板厚度;板面有些部位要同时承受两个正交方向的反号应力;相应截面中间加劲肋底部纵向应力最大;夹层桥面板的应力和挠度随着芯层厚度减小,增幅加大。     

梁柱端板连接节点的初始刚度计算

将节点分为受弯端板、受弯柱翼缘和受剪节点域三类组件,分别计算各组件的初始刚度并将其进行组装,提出了端板连接节点初始刚度的理论计算方法。该方法考虑了端板有加劲肋、无加劲肋两种构造形式,考虑了螺栓预拉力对节点刚度的影响,考虑了柱翼缘对节点域刚度的贡献,通过与试验和有限元结果对比表明该方法具有足够的精度,可用于节点刚性的判断。最后利用理论方法对按照现行规范设计的端板连接节点刚性进行了初步评价,并讨论了端板加劲肋的影响。     

竖向槽钢加劲钢板剪力墙剪切屈曲

对设置多道竖向闭口加劲肋的钢板剪力墙的剪切屈曲进行了有限元弹性屈曲分析,得到了剪切应力随加劲肋抗弯和加劲肋抗扭刚度变化曲线,以加劲板临界应力等于小区格按简支计算的剪切屈曲应力为条件,得到了双面加劲肋的门槛刚度。刚度小于门槛刚度时给出了剪切屈曲临界应力与加劲肋刚度的关系;将双面加劲同单面加劲、交错单面加劲两种情况进行比较,得出了后两者的门槛刚度放大系数。与数值结果比较表明:公式具有良好精度且偏安全。     

Boundary element analysis of shear deformable stiffened plates

In this paper a boundary element formulation for analysis of shear deformable stiffened plates is presented. The formulation is derived by coupling boundary element formulation of shear deformable plate and two-dimensional plane stress elasticity. Both concentric and eccentric stiffeners have been considered. The interaction forces between stiffeners and the plate are treated as either line distribution or area distribution of body forces along the attachment. A rectangular stiffened plate and a circular stiffened plate under uniform load are analysed by the proposed method. Good agreement has been achieved compared with other published results.     

Stiffened cracked plates analysis by dual boundary element method

In this paper a boundary element formulation for analysis of shear deformable stiffened cracked plates is presented. By coupling boundary element formulation of shear deformable plate and two dimensional plane stress elasticity, dual boundary integral equations are presented. The interaction forces between stiffeners and the plate are treated as line distributed body forces along the attachment. Both concentric and eccentric stiffeners have been considered. Rectangular stiffened plate containing a single crack and double cracks subjected to uniform distributed moment on the crack surface and uniform shear load on the plate are analysed by the proposed method. Good agreement has been achieved compared with analytical solutions.     

Nonlinear dynamical analysis of eccentrically stiffened functionally graded cylindrical panels

Based on the classical shell theory with the geometrical nonlinearity in von Karman–Donnell sense and the smeared stiffeners technique, the governing equations of motion of eccentrically stiffened functionally graded cylindrical panels with geometrically imperfections are derived in this paper. The characteristics of free vibration and nonlinear responses are investigated. The nonlinear dynamic buckling of cylindrical panel acted on by axial loading is considered. The nonlinear dynamic critical buckling loads are found according to the criterion suggested by Budiansky–Roth. Some numerical results are given and compared with the ones of other authors.     

Buckling of folded plate structures subjected to partial in‐plane edge loads by the FSDT meshfree Galerkin method

This paper presents a meshfree Galerkin method that is based on the first‐order shear deformation theory (FSDT) to study the elastic buckling behaviour of stiffened and un‐stiffened folded plates under partial in‐plane edge loads. The un‐stiffened folded plates are modelled as assemblies of flat plates. The stiffness and initial stress matrices of the flat plates are derived by the meshfree Galerkin method. A treatment is implemented to modify the stiffness and initial stress matrices, and the matrices are then superposed to obtain the stiffness and initial stress matrix of the entire folded plate. The analytical process for stiffened folded plates is similar, except that the effects of the stiffeners must be taken into account. Because no mesh is required, the proposed method is superior for studying problems that would involve remeshing in the finite element method. Several examples are employed to show the convergence and accuracy of the proposed method. The results obtained show good agreement with the results computed from the finite element analysis software ANSYS. Copyright © 2005 John Wiley & Sons, Ltd.     

Vibration of stiffened skew Mindlin plates

Summary This paper presents a formulation for the free vibration analysis of skew Mindlin plates with intermediate parallel stiffeners attached in two directions. The Mindlin theory is used to account for the effects of transverse shear deformations and rotary inertia of the plate while the Engesser theory associated with the consideration of torsion is employed for stiffeners. Based on these two theories, the energy functionals for the plate system have been derived. To obtain the vibration frequencies, these energy functionals are minimized with the shape functions assumed in a set of two-dimensional mathematically complete polynomials. This procedure has been implemented numerically to compute the vibration solutions. Convergence studies have been performed to verify the accuracy of this method. Sets of first known results have been presented for several stiffened plate structures.     

爆炸载荷作用下双向加筋方板的大挠度塑性动力响应

从分别列出加筋板面板以及加强筋的运动方程出发,分析了爆炸载荷作用下双向加筋固支方板的大挠度塑性动力响应。分析表明:取决于加强筋的相对刚度以及爆炸载荷峰值的大小,加筋板的运动将呈现3种不同的模式。该文限于讨论加筋板的总体变形模式,具体讨论了十字加筋以及双十字加筋固支方板在忽略弯矩影响下的薄膜解法。理论结果与已有的试验结果在多数情况下符合良好,表明该文提出的简化理论分析方法能对爆炸载荷下双向加筋方板的永久变形做出较为合理的预报。     

带有加强筋的Mindlin板动态刚度阵法

以加筋中厚矩形板为研究对象，推导了加筋板的动态刚度阵，为动态刚度阵法提供一种新单元。板的运动微分方程由Mindlin厚板理论给出，同时还考虑了板平面内的振动。对于板上加强筋的处理，则通过Hamilton原理对板的运动方程作相应的修正，最终得到加筋板的运动微分方程。而方程的解析解直接用于单元刚度阵的推导，所得加筋板单元的动态刚度阵结合传统有限元方法的单元组装和求解方法即可用于计算整个结构的动力响应。此外，还给出了加筋板单元的均方响应计算公式，可用来计算结构的平均振动能量。最后通过数值算例验证本文方法，计算结果与传统有限元方法进行分析比较。