轴向压缩作用下管的建模过程

对铝管截面在轴向压缩作用下的有限元分析中的单元类型和公式的影响进行了分析。结果显示:基于固体单元的有限元模拟,在板耗能和折叠方式的预测上与试验有更好的吻合度,而基于应力壳单元的模拟则明显低估了板的耗能能力。研究同时发现:具有厚度的壳单元对耗能的计算相比没有厚度的壳单元模型,其结果与采用固体单元的有限元计算结果更为贴近。     

Modelling of tubes subjected to axial crushing

In the present study, the influence of element type and formulation is investigated in finite element analyses of aluminium profiles subjected to axial crushing. It is shown that solid element-based simulations give predictions in better agreement with experiments both with respect to energy dissipation and folding pattern, while plane stress shell elements markedly underestimate the energy dissipation. It is further found that shell elements with thickness stretch give dissipated energies in better agreement with those obtained in simulations with solid elements.     

TX型和TT型圆管节点轴向承载力的影响因素分析

空间管节点几何构形多样,受力复杂,影响其承载性能的因素较多．本文采用有限元软件ANSYS,选用SHELL181壳体单元建模计算,并考虑了焊缝的影响,分析了荷载路径、弦管轴向应力对TX型圆管节点轴向承载力的影响,以及弦管长度和边界条件对TT型圆管节点轴向承载力的影响．     

Energy absorption capability of fibreglass composite square frusta subjected to static and dynamic axial collapse

The crashworthy behaviour of square frusta of fibreglass composite material subjected to axial compression at various strain rates is reported. The effect of specimen geometry and the loading rate on the energy absorbing capability was experimentally studied. The mechanics of the axial crumbling process from macroscopic and microscopic points of view were also investigated theoretically and experimentally. The collapse modes at macroscopic and microscopic scale during the failure process were observed and analysed. A theoretical analysis of the observed stable collapse mechanism of the components crushed under axial compression, for calculating crushing loads and energy absorbed during collapse, is proposed. A good agreement between theoretical and experimental results was obtained indicating the efficiency of the theoretical model in predicting the energy absorbing capacity of the collapsed shell.     

Energy absorption of aluminium alloy circular and square tubes under an axial explosive load

The energy absorption of circular and square aluminium alloy tubes subjected to an axial explosive load, which is transmitted to a tube by a small attached mass, is discussed. Particular attention is paid to the interaction between the inertia of the attached mass and a tube when the importance of the initial compression phase is revealed. The effect of this phase on the mean load, which is characteristic of the energy absorption capacity of structural elements, is demonstrated. The influence of the material models on the prediction of the response of aluminium alloy circular and square tubes is also discussed in relation with the temperature effects caused by the high strain rates. The analysis shows that the material properties play an important role for the formation of the buckling pattern due to the finite duration of the initial compression phase when plastic stress waves at different speeds propagate along a shell.     

部分预制装配型钢混凝土柱抗震性能试验研究

为充分发挥型钢混凝土结构受力性能及预制装配结构施工性能方面的优势，提出了部分预制装配型钢混凝土实心柱(PPSRC柱)和空心柱(HPSRC柱)，结合2个系列10个柱试件的拟静力试验，对两种柱的抗震性能进行了研究。通过对试件的破坏形态、滞回曲线、骨架曲线、耗能能力及变形能力、承载力及刚度退化的研究，并结合各试件的实测应变结果，对柱截面形式、轴压力、配箍率和现浇混凝土强度对PPSRC柱和HPSRC柱抗震性能的影响进行了分析。研究结果表明：PPSRC柱试件的最终破坏形态分为弯曲破坏与弯剪破坏，HPSRC柱试件均发生弯剪破坏，所提出的高强高性能预制混凝土外壳能够很好地与型钢及现浇混凝土协同工作，主要受力方向型钢与外部混凝土之间未发现明显的黏结裂缝；由于内部混凝土的存在，PPSRC柱相比于HPSRC柱拥有更好的耗能及变形能力；轴压力较低、配箍率较大的试件表现出更好的耗能能力及变形能力。通过对两种柱试件的受弯承载力分析可知，中低轴压比的PPSRC柱与HPSRC柱拥有相近的受弯承载力，在同一结构中HPSRC柱可与PPSRC柱沿竖向混合使用，以有效避免柱变截面处的刚度及承载力突变带来的影响。     

Analysis of failure mechanisms observed in axial collapse of thin-walled circular fibreglass composite tubes

Theoretical analysis of the failure mechanism of the stable mode of collapse of thin-walled fibreglass composite tubes under static axial compression, based on experimental observations and taking into account all possible energy absorbing mechanisms developed during the process, is reported. Crushing loads and the energy absorbed are theoretically predicted. The proposed theoretical model was experimentally verified for various composite materials and tube geometries and proved to be very efficient for theoretically predicting the energy absorbing capacity of the shell.     

Buckling of cylindrical shells containing granular solids

Thin-walled shell structures are likely to buckle under axial loading way below the classical value. In the presence of granular solids (e.g. sand) in cylindrical shells the stiffness of the contents has a positive influence on the buckling load, similar to internal pressure. In practical silo design this effect is not considered. This is because not much is known about the interaction between the shell and the flexible granular contents and about how to handle this in a computational model. The present study will focus on some simple interaction models. It will be seen that the presence of a granular solid can increase the buckling load remarkably, and also that small modifications in the interaction assumptions have a major influence on the buckling loads.     

泡沫填充的薄壁圆柱壳体轴向压碎的分析模型

由于填充轻型泡沫的薄壁钢管有良好的耗能能力而被广泛地应用于工程中。当结构轴心受压时,钢管与泡沫芯之间的作用对吸收能量起到关键作用。已有理论研究的大部分对象为完全填充的钢管。本文提出了一个理论模型,用于分析部分填充的钢管的轴向对称压碎性能。采用改进的模型分析壳体,并考虑了泡沫芯的作用。由能量平衡原理得到极限压力的平均值。建议公式得到的结果与先前文献中的结果吻合。参数分析用于研究泡沫芯稳定时期的压力值(σf),以及填充的比例和壳体的径厚比对结构轴向受压性能的影响。为薄壁结构的吸能性能方面的设计提供指导。     

Multiobjective optimization of orthogonally stiffened cylindrical shells for minimum weight and maximum axial buckling load

In the present research, the weight and axial buckling optimization of orthogonally stiffened cylindrical shells is carried out by the Genetic Algorithm. Constraints include two nondimensional functions of weight and buckling load in such a way that the stiffened shell has no increase in the weight and no decrease in the buckling load with respect to the initial unstiffened shell. In analytical solution, the Rayleigh–Ritz energy procedure is applied and the stiffeners are treated as discrete members. The optimization is implemented for shells with simply supported end conditions stiffened by four shapes of stiffeners including rectangular-, cee-, I-, and hat-shaped ones. The results show that the I-section and rectangular-section stiffeners are, respectively, the most and the least efficient in designing stiffened cylindrical shells for minimum weight and maximum critical axial buckling load.     

金属薄壁圆柱壳轴压试验研究

对在轴压作用下充液的金属薄壁圆柱壳屈曲前沿柱壳不同高度的轴向和径向应变以及上端液体的内压变化进行了研究,找出了轴向和径向应变的变化规律,试验发现：轴压和内压基本呈线性规律;径向应变变化以中点上下基本对称,轴向应变变化大致呈均匀分布。     

Effects of modal coupling on the dynamics of parametrically and directly excited cylindrical shells

Cylindrical shells exhibit a dense frequency spectrum, especially in the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to multiple internal resonances. The aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under lateral and axial forcing with equal natural frequencies. The shell is modeled using the Donnell nonlinear shallow shell theory. A consistent modal solution for this problem is deduced and used to discretize the equations of motion by applying the Galerkin method. A parametric analysis is conducted to clarify the influence of the modal interaction among these nonlinear vibration modes on coexisting solutions, bifurcations, resonances curves and stability boundaries of the shell.     

Experimental research on seismic behavior of reinforcedconcrete shear wall with construction joint

施工缝的存在会在一定程度上影响剪力墙的性能,为研究施工缝对钢筋混凝土剪力墙抗震性能的影响,对整浇和带施工缝两种剪力墙试件进行拟静力试验。通过对比分析施工缝对剪力墙破坏过程的影响,并从滞回曲线、承载能力、变形能力、耗能、刚度退化和破坏过程等方面分析施工缝对剪力墙抗震性能的影响。研究结果表明,同等条件下带缝剪力墙与整浇剪力墙的最后破坏形态基本一致,但是裂缝发展过程明显不同,带缝试件初始裂缝及贯通裂缝出现在施工缝处,而整浇试件的初始裂缝及贯通裂缝出现位置比较随机。轴压比较小时,整浇试件的承载力和耗能比带缝试件高;轴压比较大时,轴向力抵消了施工缝的不利影响,带缝试件的承载力和耗能比整浇试件的高;整浇试件的延性和刚度退化均比带缝试件的小;配筋率提高使带缝试件的承载力提高、耗能增大,但对刚度的影响较小;轴压比增大使带缝试件的延性降低、刚度退化变快。     

Schalenbeulen von Sandwichzylindern mit einem neuen Elastomer als Verbundwerkstoff

Shell buckling of cylindrical sandwich shells with a new elastomer as composite material. Alternatively to cylindrical steel shells a sandwich shell with a new elastomer as composite material is investigated with regard to the stability. The sandwich shell has an inner and an outer steel face, which are bonded adhesively to an elastomer core between them. In cooperation with Krupp Stahlbau Hannover GmbH the institute for steel construction of University of Hannover checked, if the application of this sandwich technology is possible for towers of wind energy converters. Especially the combination with high strength steel is a point of interest. In comparison with numerical buckling analyses the validity of a laminate composites shell theory is proven. Finally the stability of the sandwich construction is investigated against shell buckling due to axial compression and torsion. The results are compared to the stability of cylindrical steel shells.     

节点刚度对方管空间三角形桁架动力性能的影响

为研究节点刚度对方管空间三角形桁架动力性能的影响,以精细壳元模型为标准,采用可考虑节点轴向刚度的简化模型和不能考虑节点轴向刚度的刚接模型,对方管空间三角形桁架进行了模态分析和地震时程分析.结果表明:节点刚度对方管桁架的动力性能有不可忽视的影响,不宜采用刚接模型分析方管桁架的动力反应;本文中采用的简化模型可以较好地模拟方管桁架的动力性能,体现了节点刚度对结构动力性能的影响,更适用于实际工程分析.     

直锚式涨壳锚杆抗拔特性现场试验研究

普通锚杆在承受拉拔荷载时受力不均匀易发生杆体拔出破坏,因此涨壳式锚杆等新型锚杆逐渐得到了研发应用.本研究在强—中风化和中风化两种场地下,对36mm和52mm直径的普通锚杆和自制涨壳锚杆进行了现场拉拔试验,研究了场地类型、锚杆直径及是否涨壳等因素对锚杆拉拔承载力的影响.并进一步通过构造小波函数对粘结应力随深度变化曲线进行...     

Transient dynamic response of composite circular cylindrical shells under radial impulse load and axial compressive loads

Free and forced vibration of composite circular cylindrical shells are investigated based on the first love's approximation theory using the first-order shear deformation shell theory. The boundary conditions (BCs) are considered as clamped-free edges. The dynamic response of the composite shells is studied under transverse impulse and axial compressive loads. The axial compressive load was less than critical buckling loads. The modal technique is used to develop the analytical solution of the composite cylindrical shell. The solution for the shell under the given loading conditions can be found using the convolution integrals. The effect of fiber orientation, axial load, and some of the geometric parameters on the time response of the shells has been shown. The results show that dynamic responses are governed primarily by natural period of the structure. The accuracy of the analysis has been examined by comparing results with those available in the literature and experiments.     

Buckling of thin and moderately thick anisotropic cylinders under combined torsion and axial compression

The effects of anisotropy, transverse shear stiffness, length, and their interactions on buckling under pure torsion and under combined axial compression and torsion were investigated using a previously derived analytical model based on deep shell theory including anisotropy and transverse shear stiffness. The model was verified only for buckling under pure axial compression, hence results for buckling under torsion have now been compared with the results of previous analyses, and the comparison showed that the model has good accuracy for buckling under torsion. Investigation showed that the buckling loads of a cylindrical shell are affected not only by anisotropy and transverse shear stiffness but also by shell length. This means that the shallow shell theory (Donnell-type theory) is not appropriate and deep shell theory including anisotropy and transverse shear stiffness must be used.     

Schweißverzug,Schweißeigenspannungen und Schalenstabilität

Weld distortion, residual stress and stability of shells. Imperfections have an influence on the stability behaviour of cylindrical shells and arise, among others, from the assembling process. This article deals with numerical analyses on the welding distortion and residual stresses in the weld of cylindrical shells with single‐pass circumferential weld and their influence on the stability behaviour under axial load. Cylinders and cylinder segments made of the steel grades S235 and S355 with plate thicknesses of 1 mm to 4 mm and radii of 200 mm to 1600 mm are considered. The developmental process of the weld distortion is explained by means of a cylinder and the qualitative process of radial deformation after welding is shown. Special features for developing residual stresses are explained. The influence of the transient welding process of single‐ply radial welds on the axial limited stress of the cylindrical shell is considered using a parameter study. Regularities for welding distortion with different cylinder slenderness ratios are determined from this parameter study.     

摩擦摆隔震支座在网壳结构中多尺度模型分析

为研究摩擦摆隔震支座在网壳中的隔震特性和局部受力特性,利用ABAQUS有限元软件建立摩擦摆支座的实体模型,并将其应用于网壳结构,建立网壳结构的多尺度模型,并对该多尺度模型进行动力分析。分析表明摩擦摆隔震支座的加入可以有效的延长结构低阶振型的自振周期,而对结构的高阶振型的自振周期影响很小。通过对网壳结构输入单向地震波,探讨不同地震动输入强度下摩擦摆支座水平刚度变化对网壳节点加速度峰值、节点位移峰值及杆件轴力的影响。研究表明随着地震强度增加,摩擦摆隔震支座的水平刚度变化对网壳隔震响应影响越显著。在强震作用下摩擦摆隔震支座发生局部破坏,但不影响整体模型的多尺度分析。