任意变壁厚及开孔对圆柱壳轴压屈曲临界载荷影响研究

发布时间：2018-06-04 07:55

本文选题：任意变壁厚圆柱壳 + 轴压屈曲　；参考：《浙江大学》2016年博士论文

【摘要】：变壁厚和开孔圆柱壳结构被广泛应用在石油、化工和航空航天等领域。变壁厚和开孔会破坏圆柱壳结构的连续性,探索其对圆柱壳轴压屈曲临界载荷的影响规律依然是国内外研究的热点。本文综合采用理论推导、实验测试和非线性有限元数值模拟等手段,进行了任意变壁厚和开孔这两种因素对圆柱壳轴压屈曲临界载荷影响的研究,开展的主要工作如下。(1)建立了一种可用于计算任意(非轴对称)变壁厚圆柱壳轴压屈曲临界载荷的理论分析方法。获得了屈曲临界载荷、应力函数和径向位移这三者关于厚度表征参数的渐进表达式;针对壁厚沿轴向以指数形式变化的圆柱壳,讨论了屈曲载荷削减因子λ与变壁厚参数ε、屈曲载荷削减因子λ与壁厚衰减波长参数a之间的关系。(2)从增大工作台面尺寸、降低压头与工作台面的距离、加大液压缸行程、在工作台面增加对中用的同心圆环和实现轴向载荷与应变数据的同步采集等方面升级改造了轴压屈曲试验专用平台,提升了平台的测量范围以及测量数据的准确性和可靠性。(3)利用有限元特征值法初步研究了开孔高度、开孔率以及贯穿件壁厚等因素对仅开孔圆柱壳和含贯穿件圆柱壳轴压屈曲临界载荷的影响规律,制订了仅开孔和含贯穿件圆柱壳轴压屈曲实验方案,设计并制作了多个具有代表性和较高加工精度的圆柱壳试件;同时开展了试件材料的拉伸试验,完成了试件几何参数的复测工作。(4)综合开展了仅开孔圆柱壳轴压屈曲实验和非线性有限元数值模拟研究,提出了一种全新的基于圆柱壳实测几何形貌数据的几何模型创建方法,探讨了开孔率、初始几何缺陷、径厚比和高径比等因素对仅开孔圆柱壳轴压屈曲临界载荷的影响并给出相关规律。(5)进行了含贯穿件圆柱壳轴压屈曲实验研究,比较了含贯穿件前后开孔圆柱壳试件的实验现象和实验数据,结合经过实验验证的非线性有限元数值模拟方法,研究了初始几何缺陷和贯穿件壁厚等因素对含贯穿件圆柱壳轴压屈曲临界载荷的影响,提出了贯穿件壁厚参数的概念,并得到了该参数对含贯穿件圆柱壳轴压屈曲临界载荷的影响规律。
[Abstract]:Variable wall thickness and perforated cylindrical shell structures are widely used in petroleum, chemical, aerospace and other fields. Variable wall thickness and open hole will destroy the continuity of cylindrical shell structure. It is still a hot topic to study the influence of variable wall thickness and opening hole on the critical load of axial buckling of cylindrical shells. In this paper, the influence of arbitrary variable wall thickness and open hole on the critical load of cylindrical shells under axial compression is studied by means of theoretical derivation, experimental test and nonlinear finite element numerical simulation. The main work of this paper is as follows: (1) A theoretical analysis method for the axial buckling of cylindrical shells with arbitrary (non-axisymmetric) thickness under axial compression is developed. The asymptotic expressions of critical buckling load, stress function and radial displacement on the parameters of thickness characterization are obtained, and for cylindrical shells whose wall thickness changes exponentially along the axis, the critical buckling load, the stress function and the radial displacement are obtained. The relationship between buckling load reduction factor 位 and variable wall thickness parameter 蔚, buckling load reduction factor 位 and attenuation wavelength parameter a of wall thickness is discussed. The special platform for axial compression buckling test has been upgraded in the aspects of adding concentric ring to the working table and synchronously collecting axial load and strain data. The measurement range of the platform and the accuracy and reliability of the measurement data are improved. (3) using the finite element eigenvalue method, the open hole height is preliminarily studied. The influence of perforation ratio and perforated wall thickness on the axial buckling critical load of cylindrical shells with only perforated and perforated cylindrical shells is studied. The experimental scheme of axial compression buckling of cylindrical shells with only perforated and perforated cylindrical shells is established. Several typical cylindrical shell specimens with high machining accuracy were designed and fabricated, and tensile tests of the specimens were carried out. In this paper, the experimental results of axial compression buckling and nonlinear finite element numerical simulation of cylindrical shells with only holes have been carried out. A new method for creating geometric models based on the measured geometric topography data of cylindrical shells has been proposed. In this paper, the effects of porosity, initial geometric defects, ratio of diameter to thickness and ratio of height to diameter on the critical load of axial compression buckling of cylindrical shells with only open holes are discussed, and the relevant law is given. The experimental study of axial buckling of cylindrical shells with perforated elements is carried out. The experimental phenomena and experimental data of cylindrical shells with perforations before and after opening are compared, and the nonlinear finite element numerical simulation method is used to verify the experimental results. The effects of initial geometric defects and wall thickness on the critical load of axial compression buckling of cylindrical shells with perforated elements are studied, and the concept of wall thickness parameters of perforated cylindrical shells is proposed. The influence of this parameter on the critical load of axial compression buckling of cylindrical shells with perforated elements is obtained.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TH114

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