应变强化压力容器外压屈曲研究

发布时间：2018-04-03 20:35

本文选题：应变强化　切入点：外压屈曲　出处：《浙江大学》2015年硕士论文

【摘要】：深冷容器作为低温液化气体的常用储运装备,在化工、机械、航空航天等领域已得到了广泛应用,需求量也不断增长。应变强化技术能够减薄壁厚、降低重容比,实现节能省材、降耗减排的目标,符合安全与经济并重、安全与资源节约并重的发展理念,已广泛应用于奥氏体不锈钢应变强化深冷容器的制造。然而,应变强化对容器外压稳定性的影响尚不明确。应变强化技术在提高材料强度实现轻量化的同时,对外压稳定性的影响也可能会成为制约其轻量化效果的关键因素。因此,研究应变强化对容器外压稳定性的影响就显得非常必要。本文在浙江省重点科技创新团队项目(项目编号2010R50001)、中央高校基本科研业务费专项资金(项目编号2014FZA4024)、中国博士后科学基金(项目编号2014M551731)等的支持下,开展应变强化压力容器的外压屈曲研究,主要完成工作如下：(1)介绍了外压容器的设计方法,阐述了屈曲问题的通用求解策略、有限元中屈曲问题求解的基本理论以及ANSYS中常用的屈曲分析方法,建立了应变强化深冷容器的非线性分析模型并模拟应变强化过程,通过比较数值模拟值和产品实测值,验证了模型的准确性与方法的合理性,基于此模型分析了强化带来的影响,确立了适用于分析应变强化压力容器外压稳定性的非线性屈曲分析方法。使用本文建立的模型和方法进行了理想容器强化后的屈曲分析,认为强化前后容器均呈现不稳定的分支屈曲,有必要考虑缺陷的影响。(2)对比了在无法精确获得实际结构真实完整的缺陷数据时考虑初始几何缺陷的两种常用方法,选择不圆度作为容器的初始几何缺陷形式,并建立了含初始不圆度容器模型,应用本文确立的应变强化压力容器外压屈曲分析方法求解强化后容器的屈曲载荷,探究了应变强化过程对于含初始不圆度容器不圆度以及屈曲载荷的影响规律,发现了强化后容器外压稳定性增强,屈曲载荷有稳定化趋势,并从强化对容器屈曲类型的影响方面分析了原因。(3)基于应变强化对含初始不圆度容器外压屈曲的综合影响规律,分别分析了应变强化过程的加载历史、应变强化过程中容器的变形以及强化-卸载后的残余应力三方面因素对容器屈曲载荷的影响,明确了应变强化过程中容器的变形是应变强化对于容器外压屈曲最主要的影响因素,进一步阐明了应变强化对容器外压屈曲的影响规律。提出在分析容器强化后的性能时,可考虑只提取应变强化过程中产生的变形,以简化对于应变强化过程影响的考虑。
[Abstract]:Cryogenic vessels, as common storage and transportation equipment for cryogenic liquefied gases, have been widely used in chemical, mechanical, aerospace and other fields, and the demand is increasing.Strain strengthening technology can reduce the thickness of the wall, reduce the ratio of weight to capacity, achieve the goal of saving energy and materials, reduce consumption and reduce emissions, and accord with the development concept of equal emphasis on safety and economy, safety and resource saving.It has been widely used in the manufacture of austenitic stainless steel strain-strengthened cryogenic vessels.However, the effect of strain strengthening on the external pressure stability of the vessel is unclear.Strain strengthening technology can improve the strength of materials to achieve lightweight, at the same time, the influence of external pressure stability may also be a key factor restricting the lightweight effect.Therefore, it is necessary to study the effect of strain strengthening on the external pressure stability of the vessel.This paper is supported by the key scientific and technological innovation team project of Zhejiang Province (project number 2010R50001), the special fund for basic scientific research operating expenses of central colleges and universities (project number 2014FZA4024), the China Post-doctoral Science Foundation (project number 2014M551731), etc.The research on external pressure buckling of strain-strengthened pressure vessel is carried out. The main work is as follows: 1) the design method of external pressure vessel is introduced, and the general solution strategy of buckling problem is expounded.The basic theory of solving buckling problem in finite element method and the buckling analysis method commonly used in ANSYS are established. The nonlinear analysis model of strain-strengthened cryogenic vessel is established and the strain strengthening process is simulated. The numerical simulation value and the product measured value are compared.The accuracy of the model and the reasonableness of the method are verified. Based on the model, the influence of strengthening is analyzed, and a nonlinear buckling analysis method is established to analyze the external pressure stability of pressure vessels strengthened by strain.By using the model and method established in this paper, the buckling analysis of the ideal vessel after strengthening is carried out, and it is concluded that the vessel presents unstable branch buckling before and after reinforcement.It is necessary to consider the effect of defects. (2) comparing the two common methods of considering initial geometric defects when the true and complete defect data of the actual structure can not be obtained accurately, the non-circular degree is chosen as the initial geometric defect form of the vessel.The model of vessel with initial non-roundness is established. The buckling analysis method of strain-strengthened pressure vessel is used to calculate the buckling load of the vessel after strengthening.The influence of strain strengthening process on the unroundness and buckling load of vessel with initial non-roundness is investigated. It is found that the external pressure stability of the vessel is enhanced and the buckling load is stabilized after strengthening.Based on the comprehensive effect of strain strengthening on the buckling of vessels with initial non-roundness, the loading history of the strain strengthening process is analyzed respectively from the point of view of the effect of strengthening on the buckling types of containers.The effect of the deformation of the vessel and the residual stress after strengthening and unloading on the buckling load of the vessel during strain strengthening.It is clear that the deformation of the vessel is the most important factor affecting the external pressure buckling of the vessel during strain strengthening, and the effect of strain strengthening on the buckling of the vessel under external pressure is further clarified.In order to simplify the consideration of the effect of strain strengthening, it is suggested that only the deformation produced in the process of strain strengthening can be taken into account in the analysis of the performance of the vessel after strengthening.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH49

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