爆炸载荷作用下单向加筋方板的大挠度塑性动力响应分析

从分别列出加筋板面板以及加强筋的运动方程出发,详细分析了爆炸载荷作用下单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载荷峰值的大小,加筋板的运动将呈现三种不同的模式.限于讨论加筋板的总体变形模式.首先讨论了同时计及弯矩和面力(轴力)作用的解析解,在此基础上进一步讨论了忽略弯矩影响的薄膜解以及能量解.理论结果与已有的试验结果在多数情况下符合良好,表明提出的简化理论分析方法能对爆炸载荷下单向加筋固支方板的永久变形做出较为合理的预报.     

基于LS-DGF-DG方法的船体板架结构近场水下爆炸毁伤特性研究

基于可压缩流体力学基本理论,采用间断迦辽金(DG)方法结合直接虚拟流(DGF)方法和水平集(LS)方法(LS-DGF-DG方法),首先建立水下爆炸爆轰模型,对不同装药形式的水下爆炸冲击波载荷进行对比研究,分析讨论装药形状对冲击波载荷特性和爆轰产物初始形态的影响,随后将数值结果与经验公式进行对比,验证LS-DGF-DG计算程序的有效性,最后通过非线性有限元软件ABAQUS建立船体加筋板架模型,将LS-DGF-DG计算得到的近场水下爆炸载荷传输给ABAQUS,模拟加筋板架结构在近场水下爆炸载荷作用下的毁伤过程,并将计算结果与实验进行对比分析,总结相关规律。结果表明:起爆初期,柱形装药逐渐形成椭球形的爆轰产物,最终膨胀为球形;装药径向的冲击波压力峰值高于轴向,柱形装药的冲击波压力峰值高于球形装药的压力峰值;在近场水下爆炸载荷的作用下,加筋板架结构出现塑性大变形和剪切破坏的现象,数值结果与试验值吻合良好;加强筋的强弱对板架结构的破坏模式和塑性变形程度有较大影响,加强筋较强,破坏首先从加强筋位置出现,加强筋较弱,破坏主要出现在固支边界处。     

基于抗振动疲劳的薄板加筋设计分析

振动是航空薄板常见的载荷形式,通常采用加强筋来减小振动幅度,从而提高薄板寿命.研究薄板的抗振动疲劳加筋方法,探讨加强筋与板的连接方式以及加强筋的布置方向对薄板振动与疲劳的影响机制.首先,基于振动理论和板筋变形协调条件,建立加筋薄板的运动方程.然后,建立铆接、点焊和滚焊连接形式的加筋薄板有限元模型,探讨连接单元的动力学建模方法;在此基础上,研究连接形式和加筋安装方向对薄板结构动力学特性的影响;最后,结合动力响应分析探讨板筋连接方式和加筋安装方向对疲劳寿命的影响.研究结果表明,双向加筋薄板在低频振动时刚度高于单向加筋薄板,双向加筋有利于提高结构抗疲劳强度,铆接单向加筋薄板的振动疲劳寿命最短.     

爆炸冲击作用下加筋板结构变形研究

为了预报加筋板结构在爆炸冲击载荷作用下的变形程度，将加筋板的变形分为整体变形和局部变形，借助数值计算拟合了两者能量分配关系，进而提出了爆炸冲击作用下加筋板结构变形的理论计算方法，并与实验结果进行比较，结果吻合较好。     

固支方板在水下爆炸气泡射流作用下动态响应

为研究水下爆炸气泡溃灭发生射流时对水中结构的影响,借助于商用瞬态动力学有限元软件MSC. Dytran,对固支方板在水下爆炸载荷作用下的动态响应进行研究。对底部爆炸和侧面爆炸两种典型情况进行计算,将气泡运动过程与试验结果进行对比分析,两者吻合较好,验证所建立方法的可行性。在此基础上,对射流发生时流场情况以及固支方板的响应特点进行分析,认为射流载荷是局部载荷,可以引起严重的局部破坏,在近场水下爆炸研究中必须予以重视。     

水下爆炸载荷作用下加筋板变形及开裂试验研究

为了解加筋板结构在水下爆炸载荷作用下的变形模式,以及为数值仿真计算提供材料的开裂判据,通过试验研究,给出了加筋板的两种不同塑性变形模式.通过测量试验后加筋板裂纹的减薄率,利用体积等效原理确定了Q235钢在加筋板边界拉伸撕裂破坏模式中的开裂极限应变值,为结构在爆炸冲击作用下破损的数值仿真奠定了基础.     

金属薄板与加筋板爆炸冲击响应研究进展

综述了爆炸冲击载荷作用下金属薄板与加筋板塑性动力响应研究新进展。评述了近距离/接触爆炸实验加载方法及确定冲击波载荷的近似理论和数值方法,介绍了爆炸冲击载荷作用下金属薄板与加筋板失效模式、塑性变形和起裂与破口的研究进展,指出了需要进一步研究的问题。     

冲击载荷下(纤维/聚合物)-金属层合板的大挠度动力响应

对冲击载荷下固支（纤维/聚合物）-金属层合方板和圆板的大挠度动力响应进行了理论研究。基于理想刚塑性假定和塑性极限屈服条件,建立了质量块体和爆炸冲击载荷下（纤维/聚合物）-金属层合板大挠度动力响应的理论模型,给出了固支（纤维/聚合物）-金属层合方板和圆板考虑弯曲和拉伸相互作用的大挠度响应解析解,进一步忽略弯曲的影响,得到了其动力响应的膜力解。研究结果表明,理论预测与已有实验结果吻合较好,该理论模型可以有效地预测质量块体和爆炸冲击载荷下（纤维/聚合物）-金属层合板的最大挠度。      

动载荷激励下板壳结构加筋自适应成长方法

自适应成长法是基于自然界分支系统形态形成机理的一种高效结构拓扑优化设计方法。通过引入等效静态载荷法理论,运用自适应成长法解决板壳加筋结构在承受动载荷激励下的动态响应拓扑优化设计问题。根据板壳结构所受的动载荷边界条件,构建以动柔度为目标的优化数学模型,推导迭代公式,使板壳结构的加强筋从"种子"开始,沿着使结构最佳力学性能方向成长,从而形成最优加强筋分布形态。研究在简谐载荷和冲击载荷作用下的板壳结构加强筋设计例,并与静态载荷作用下的设计结果进行比较。研究结果表明,板壳结构在动态载荷作用下,其主加强筋布局形态和在静态载荷作用下相同,但在靠近载荷作用点附近出现与主加强筋平行的截面积较小的加强筋,以增加抵抗动态载荷的作用;而冲击载荷作用下的加强筋与一般简谐载荷作用下的加强筋相比,多出一层较复杂的框型筋板抵抗瞬时冲击力。     

小当量柱型装药水下近场爆炸固支单层方形钢板毁伤特性研究

为研究小当量柱形装药水下近场爆炸固支单层方形钢板毁伤特性,采用高精度龙格库塔间断迦辽金(Runge-Kutta discontinuous Galerkin,RKDG)方法求解柱形装药水下近场爆炸载荷,并与水下爆炸经验公式进行对比,吻合良好。将计算得到的爆炸载荷加载到LS-DYNA非线性有限元求解器中,得到固支单层方形钢板的毁伤特性,与试验结果进行对比,证明模型的精确性,表明龙格库塔间断迦辽金-有限元法(Runge-Kutta discontinuous Galerkin-finite element method,RKDG-FEM)耦合计算模型能够精确模拟柱形装药在近场爆炸条件下固支单层方形钢板的响应特性。随后研究了固支单层方形钢板在板厚4 mm、药量5~30 g和板厚3~8 mm、药量20 g的毁伤模式。研究发现,固支单层方形钢板的毁伤模式主要为塑性大变形、花瓣型破口和冲塞型圆形破口等。并拟合了考虑药量、板厚因素的破口尺寸估算公式,可为小当量柱形装药水下近场爆炸单层板的毁伤研究提供参考。     

联肢加劲钢板剪力墙滞回性能试验研究与数值分析

完成了3个1/3比例的3层联肢钢板剪力墙试件的低周反复加载试验。3个试件的钢板剪力墙分别采用非加劲、槽钢竖向加劲和井字加劲的形式,钢板剪力墙的竖向边缘构件采用方钢管混凝土。得到了联肢钢板剪力墙试件的荷载-位移滞回曲线和破坏形态,对试件的骨架曲线、应力发展、延性及耗能能力等进行了分析。采用有限元软件ABAQUS对试件进行了数值模拟。结果表明:非加劲和槽钢竖向加劲墙板先屈曲后屈服,井字加劲墙板先屈服后屈曲,墙板屈服后连梁与钢板剪力墙边框梁相继屈服。方钢管混凝土柱脚屈服较早,屈服后仍具有良好的承载力和弹塑性变形能力。采用非加劲墙板的试件承载力最低,滞回环捏缩效应最严重,其次是采用槽钢竖向加劲墙板的试件。采用井字加劲墙板的试件滞回环较饱满。井字加劲和槽钢竖向加劲试件的峰值荷载分别比非加劲试件的峰值荷载提高了11.7%和6.9%,井字加劲和槽钢竖向加劲试件的等效黏滞阻尼系数分别比非加劲试件的等效黏滞阻尼系数提高了65.9%和19.9%。各试件的延性系数均大于4.5,表明不同加劲形式的联肢钢板剪力墙均具有良好的延性。数值分析与试验结果吻合较好,可充分地反映试件的滞回性能和破坏过程。加劲肋对连梁和边缘构件的内力影响较小,但可显著提高剪力墙板的抗剪承载力。相较于两片单肢钢板剪力墙,联肢钢板剪力墙的承载力和耗能能力均有大于20%的提高。     

Asymptotic bounds on the globally optimal positions of orthogonal stiffeners for rectangular plates in elastostatic bending

The present paper treats the problem of finding the asymptotic bounds for the globally optimal locations of orthogonal stiffeners minimizing the compliance of a rectangular plate in elastostatic bending. The essence of the paper is the utilization of a method of analysis of orthogonally stiffened rectangular plates first presented by Mazurkiewicz in 1962, and obtained herein in a closed form for several special cases. Asymptotic expansions of the expressions for the deflection field of a stiffened plate are used to derive limit-case globally optimal stiffening layouts for highly flexible and highly rigid stiffeners. A central result obtained in this work is an analytical proof of the fact that an array of flexible enough orthogonal stiffeners of any number, stiffening a simply-supported rectangular plate subjected to any lateral loading, is best to be put in the form of exactly two orthogonal stiffeners, one in each direction.     

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。     

An extended layerwise/solid-element method of stiffened composite plates with delaminations and transverse crack

The stiffened composite plates with the transverse crack and delamination were studied in this paper, and an extended layerwise/solid-element (XLW/SE) method was developed. In the proposed method, the governing equations of composite plates and stiffeners were established based on the extended layerwise method and 3D solid elements, respectively. The final governing equation of stiffened composite plates is assembled by using the compatibility conditions and internal force equilibrium conditions at the joint interface between the plates and stiffeners. For the stiffened composite plates with damages, the XLW/SE method can obtain the local stress and displacement fields accurately and simulate the in-plane transverse cracks and delaminations simultaneously, considering complicated stiffeners without any assumptions. In the numerical examples, the results obtained by the proposed method are compared with those obtained by the 3D elastic models developed in the general finite element code, and the good agreements were achieved for the stiffened composite plates with/without delaminations and/or transverse crack.     

Buckling analysis of corrugated plates using a mesh-free Galerkin method based on the first-order shear deformation theory

This paper deals with elastic buckling analysis of stiffened and un-stiffened corrugated plates via a mesh-free Galerkin method based on the first-order shear deformation theory (FSDT). The corrugated plates are approximated by orthotropic plates of uniform thickness that have different elastic properties along the two perpendicular directions of the plates. The key to the approximation is that the equivalaent elastic properties of the orthotropic plates are derived by applying constant curvature conditions to the corrugated sheet. The stiffened corrugated plates are analyzed as stiffened orthotropic plates. The stiffeners are modelled as beams. The stiffness matrix of the stiffened corrugated plate is obtained by superimposing the strain energy of the equivalent orthotropic plate and the beams after implementing the displacement compatibility conditions between the plate and the beams. The mesh free characteristic of the proposed method guarantee that the stiffeners can be placed anywhere on the plate, and that remeshing is avoided when the stiffener positions change. A few selected examples are studied to demonstrate the accuracy and convergence of the proposed method. The results obtained for these examples, when possible, are compared with the ANSYS solutions or other available solutions in literature. Good agreement is evident for all cases. Some new results for both trapezoidally and sinusoidally corrugated plates are then reported.     

Stiffened plate bending analysis in terms of refined triangular laminated plate element

Based on the higher-order global–local theories, a finite element model is proposed to study the bending behavior of stiffened laminated plates. The proposed model treats the embedded stiffeners as the part of laminated plate, so that the compatibility of displacements and stresses between the plate and the stiffeners can be automatically satisfied. Distributions of the displacements and stresses through the thickness of laminates were also given for the first time, which can serve as references for future investigations as such information is lacking in the published literature. In addition, the impact of the stiffeners on the bending response of the stiffened laminated plates is also studied in terms of the quantity, the collocation and the geometry of stiffeners. Numerical results showed that the higher-order global–local theories are more suitable for predicting the bending response of thick and moderately thick stiffened laminated plates compared to the first order theory commonly used in engineering. By varying the quantity, the collocation and the geometry of stiffeners, the stiffness and the strength of stiffened laminated plates can be remarkably improved.     

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。     

轴向冲击下环向加筋复合材料圆柱壳的非线性动力响应

采用半解析的方法，建立离散加筋圆柱壳模型，基于复合材料多层扁壳大挠度的剪切变形理论，利用Hamilton原理导出环向加筋复合材料圆柱壳的非线性运动控制方程；用Galerkin方法对空间变量进行离散，将位移和载荷展开为双级数，得到有关时间的常微分方程组，最后采用R-Kutta方法数值求解．通过算例，讨论了加筋肋骨几何参数、铺层角度、辅层方式、铺层层数等因素对动力响应的影响。     

用耦合有限元／边界元方法研究加筋板的声传输

采用耦合的有限元／边界元方法,建立了考虑流体结构耦合的加筋板结构声传输计算模型,并利用该模型计算研究了加筋板的声传输特性。数值计算表明：结构的传声损失与结构的固有频率和激励频率密切相关,避免共振仍是产要的;改变板厚或肋骨惯性矩后,由于结构固有频率发生了变化会使得结构传声损失曲线上极小值的位置发生改变;当声波从空气经结构向空气中传递时,增大板厚或肋骨惯性矩可明显增大结构的传声损失;而当声波从空气经结构向水中传递时,增大板厚或肋骨惯性矩也增大了结构的传声损失,但效果明显不如当声波从空气经结构向空气中传递时显著。