【作者】 刘康；

【导师】 顾安忠； 汪荣顺；

【作者基本信息】 上海交通大学 ， 制冷与低温工程， 2007， 博士

【摘要】 低温液体的有效安全储运,不仅具有重要的经济价值,也事关人民群众生命和国家财产安全,尤其在航天工业、国防工业等高科技研究应用领域,以低温液体作为能量供应源(如液氢、液氧、液化天然气等)或冷量供应源(如液氮、液氦等),直接关系国家尖端科技发展、国土安全防卫等根本性战略保障问题,具有重要的研究价值和意义。本论文针对抗强冲击特种低温液体储运容器内支撑结构在设计、选材、性能测试、热-结构耦合场分析、抗强冲击性能分析等方面做了深入的研究工作,确认采用玻璃纤维增强环氧树脂基复合材料作为抗强冲击特种低温液体储运容器径向内支撑在低温强冲击工况下的适用性,该研究工作同样适用于一般低温液体储运容器内支撑结构方面的设计评价。首先,本文对各类常用纤维增强聚合物基复合材料的性能,特别是低温下的热性能和力学性能进行了总结性对比,重点在热力品质因数如比强度、比模量、强度-导热系数比、模量-导热系数比方面突出了纤维复合材料在常、低温下的性能优势,分析结果表明,玻璃纤维增强复合材料在77K以上常-低温温区具有最佳热力性能优势,因此被广泛应用于航天器结构支撑、低温杜瓦结构支撑、压力容器和低温储罐制材等方面。其次,考虑到20m3特种液氧储罐内外筒体径向最大间距70mm、两侧轴向间距不超过450mm的实际结构设计尺寸,确定采用布置于两侧的厚壁纤维增强复合材料支撑管和连接内外筒体的不锈钢管以组合套管形式作为径向内支撑,同时结合两侧抗冲击辅助支撑、轴向支撑形成液氧储罐内支撑整体结构。在此基础上,成功研制壁厚300mm以上、轴宽范围60mm~136mm的玻璃纤维布增强环氧树脂基复合材料支撑管,并完成113K~293K温区范围管材常、低温热性能、机械性能测试,结果表明环氧玻璃钢管适合作为承受径向压缩载荷作用支撑件,但同时应避免出现过大径向拉伸应力和层间剪切应力作用。第三,专门搭建低温液体储运容器径向支撑结构大温差热力试验平台,用以检验环氧玻璃钢管在真实试验工况下的性能表现和应用安全性。试验平台径向支撑结构尺寸与特种液氧储罐相同,测试对象包括试验平台从内筒体充注液氮起至最终实现稳态热力平衡过程中环氧玻璃钢管90?径向测点位置上的温度、应变分布变化情况,以及环氧玻璃钢管径向支撑与内、外筒体不锈钢支撑管之间270?间隙变化情况。试验结果反映: a)环氧玻璃钢管测点温度范围为122.22K~230.88K ,环氧玻璃钢管与不锈钢管低温端界面温差范围为20.9K~109.6K,常温端界面温差范围为53.5K~70.86K;b)径向支撑结构漏热量为56.23W;c)平衡状态下各测点位置径向均为压应力,最大为10.58MPa;层向随半径增大由拉应力过渡为压应力,其中最大拉应力为45.30MPa,最大压应力为16.58MPa;d)各测点位置最大应力均小于各自极限强度,根据修正Tsai-Hill强度理论和Hoffman强度理论分析环氧玻璃钢管未发生结构破坏但常温端内圈相对具有更大的强度校验结果;e)平衡状态下试验平台径向支撑界面间隙变化及总体位移量很小。第四,根据热弹性耦合理论分别建立径向支撑传热分析模型和结构分析模型,利用ANSYS建立试验平台径向支撑有限元热-结构耦合分析模型,在理论分析和假设前提下参照已有试验结果完成静载热分析和结构分析计算工作,得到径向支撑结构初始边界条件。模型计算结果反映:a)环氧玻璃钢管各测点位置温度计算结果与试验结果误差范围为±6%,整体温度场范围为110.72K~233.39K,环氧玻璃钢管与不锈钢管低温端界面温差范围为26.3K~119.9K,常温端界面温差范围为56K~82.2K;b)环氧玻璃钢管径向支撑漏热量为46.62W;c)平衡状态下各测点位置径向均为压应力,最大为43.55MPa;层向随半径增大由拉应力过渡为压应力,其中最大拉应力为35.44MPa,最大压应力为14.93MPa;d)环氧玻璃钢管各方向最大应力均小于材料相应极限强度,根据修正Tsai-Hill强度理论和Hoffman强度理论分析环氧玻璃钢管未发生结构破坏,最大强度校验值位于常温端内圈受最大拉应力作用位置;e)试验平台径向支撑结构热力平衡状态时,冷热两端界面在周向0o~180o范围均处于过盈接触状态且过盈量小。对比计算结果和试验结果可以看出,有限元分析模型中选取界面边界条件能够有效反映环氧玻璃钢管与不锈钢管径向支撑结构真实工况,计算结果在合理误差范围内具备较高的可信度,能够作为对试验结果的补充扩展和进一步关于20m3液氧储罐内支撑结构热力耦合理论分析计算的参考依据。第五,沿用大温差热力试验平台热-结构耦合理论分析模型中径向支撑结构界面边界条件,建立20m3液氧储罐有限元分析模型,以顺序耦合场分析方法完成模型热分析计算和静载、垂向10g冲击载荷下的结构分析计算。最终的模型计算结果反映:a)环氧玻璃钢管径向支撑的温度场范围为96.0K~277.2K,径向温差范围为57.6K~173.6K;b)液氧储罐内支撑结构整体漏热量为99.86W,占设计许可最大漏热量的49.31%,其中径向支撑结构漏热量为57.21W,占内支撑结构整体的57.3%;c)静载工况下径向支撑结构中环氧玻璃钢管与不锈钢管之间界面间隙在周向0o~180o范围均有减小,去除初始间隙影响,低温端接触界面在0o~168o发生过盈,常温端接触界面在30o~144o发生过盈;d)垂向强冲击作用下模型左侧环氧玻璃钢管常温端内圈90°靠外筒体边角位置XY剪切正应力将高出对应剪切极限强度4.6%,达到34.3MPa,右侧环氧玻璃钢管低温端外圈表面90°靠内筒体边角位置XZ剪切正应力将高出对应剪切极限强度2.5%,达到43.3MPa;e)冲击作用造成径向支撑结构冷热两端界面在周向0o~180o范围均处于过盈接触,其中低温端接触界面过盈量范围为0.003~0.611mm,常温端接触界面过盈量范围为0.013~0.459mm;f)虽然垂向10g冲击作用将造成环氧玻璃钢管局部发生剪切破坏,但位置均处于边缘且破坏区域径向、轴向上均受压应力作用,在树脂基体中所出现的局部裂纹无进一步扩展的空间,不会造成更大破坏,环氧玻璃钢管径向支撑在20m3液氧储罐设计强冲击载荷作用下仍然具有良好的支撑隔热能力。采用纤维复合材料作为抗强冲击特种低温容器内支撑结构部件具备相当高的应用安全性。第六,对套管形式径向支撑结构界面间隙在热-结构耦合作用下随不同初始边界条件的变化规律以及对漏热的影响进行分析研究,证实该支撑结构界面间隙在适合边界条件下的自适应特性:a)静载热力平衡状态下径向支撑冷热端界面间隙在过盈接触区域变化小,初始间隙变化对于过盈区域影响小;b)界面间隙变化过程中形成虚拟接触区域,对结构漏热进行动态阻隔,同时使环氧玻璃钢管所分布应力处于较低水平,径向支撑结构具备良好的低温应用稳定性。以环氧玻璃钢管和不锈钢管在组合结构设计作为抗强冲击特种低温容器径向支撑结构,能够承受来自径向360°范围的强冲击载荷作用,应用于20m3液氧储罐径向内支撑结构被证实在设计强冲击载荷作用下能够有效保障支撑能力。经由理论分析和试验结果确认建立的特种低温容器内支撑结构热力耦合有限元分析模型,能够有效反应内支撑结构在真实工况下的性能表现及反应,为进一步的材料性能与结构设计优化工作提供可靠的理论分析手段。更多还原

【Abstract】 The efficient and safe storage of cryogenic liquid not only has high economic value, but also concerns the safety of people’s life and nation’s property. Except that, cryogenic liquid is widely used in high-tech research and application fields including space flight and national defense industries in the way of energy resource (including LH2、LO2、LNG etc) and quantity of cold resource (including LN2、LHe ect). All above these directly relate with the problem of fundamental strategic supply and guarantee for the development of national advanced science and technology, as well as country security and defense. So the efficient and safe storage of cryogenic liquid owns great research value and meaning.The article focus on the inner support structure of special drastic shock-resistant cryogenic liequid tanks, do lots research works in-depth about the support structure design、suitable material selection、material performance testing、thermal structure coupled field analysis on the support structure、anti-drastic shock material performance analysis etc. Finally on the basis of above works the applicability of glass fiber reinforced epoxy resin matrix composite tube as the radial inner support structure of special drastic shock-resistant cryogenic liequid tanks is confirmed. These works are also suitable for the design, choice and evaluation for the inner support structure of gengeral cryogenic liquid storage and transportation vessels.At first the performance of some usual kinds of fiber reinforced polymer matrix composite especially that of thermal and mechanical at cryogenic temperature are summarized and contrasted. The advantages of fiber reinforced polymer matrix composites in performance at normal and cryogenic temperatures are emphasized by the thermal-mechanical quality factors as specific strength、specific modulus、the ration of strength to conductivity and modulus to conductivity. The results indicate glass fiber reinforced polymer matrix composites has the best thermal-mechanical performance respectively above 77K. Then this fiber reinforced polymer matrix composites is widely used as structure supports in aerospace vehicle and cryogenic Dewar、materials for pressure vessel and cryogenic tank ect.Secondly, considering the actual design dimension of 20m3 special LO2 storage tank that the maximum radial spacing between inner and outer tank is 70mm and the axial spacing between them is less than 450mm,the radial inner support structure of 20m3 LO2 storage tank in this article is designed as tubing composed with thick-wall fiber reinforced polymer matrix composite tube and 0Cr18Ni9 pipes connected with inner and outer shells respectively, and placed at both sides of the tank. Furthermore, the whole support structures include assistant shock resistance supports and axial supports for fixing the inner shell. The glass fiber cloth reinforced epoxy resin matrix composite tube has been made, whose thickness is over 300mm and the axial width is between 60mm and 136mm. The thermal and mechanical performances between 113K and 293K are also been tested, and the results indicate the glass fiber reinforced composite tube is adapt well to be support part to sustain radial compression load, but also need to avoid overlarge radial tension and interlaminar shear stresses which should be less than 26MPa and 41.4MPa respectively at 113K.Thirdly, to investigate the amount of heat loss through the radius inner support structure, confirm the thermal mechanical performance of radial support structure and evaluate the application security of glass fiber reinforced composite tube in working conditions including interspace vacuum environment and a large radius temperature difference acted from room to cryogenic operating temperature, one experimental setup has been build and the same-size glass fiber reinforced composite tube is taken as the test object.From the LN2 been filled into the inner tank of the setup till the setup is at thermal-mechanical equilibrium state, the temperature, strain at the test points on the 90? radial surface of the glass fiber reinforced composite tube, as well as the clearance change situation at the 270? radial direction between the glass fiber reinforced composite tube and 0Cr18Ni9 pipes are been tested. The results showed: a) the temperature results range at test points is 122.22K~230.88K, the interface temperature differences range on the radial support structure near cryogenic temperature and normal temperature are 20.9K~109.6K and 53.5K~70.86K respectively; b) the amount of heat loss throught the radial support structure is 49.75W; c) at the equilibrium state the radial stress at each test poins is compression stress ant the maxim value is 10.58MPa, the circumferential stress is changed from tension to compression with the increase of radius, and the maxium tension stress is 45.30MPa while the maxium compression stress is 16.58MPa; d) the maxium stress values at each test points are all less than the corresponding material ultimate strength, according to the failure theory of modified Tsai-Hill and Hoffman the glass fiber reinforced composite tube doesn’t occur structural damage while the failure index is higher at the inner race of the glass fiber reinforced composite tube; e) at the equilibrium state the amount of clearance change between interfaces and the total radial displacmet of the support structure is small。Fourthly, the heat transfer model and structure analysis model about the radius supports in special cryogenic vessels have been build according to the thermoelasticity coupled theory. The finite element analysis model for the radius supports in experimental setup has also been build through the program ANSYS. At the basis of therical analysis and assumption, further contrasted with the test results, the thermal and structure analysis and compution works on the inner support structure under static load have been finished. The initial boundary conditions of the radius supports are confirmed. The results indicate: a) the error range of the computational temperature results with the tested results is±6%, the whole temperature range on the glass fiber reinforced composite tube is 110.72K~233.39K, the interface temperature differences range on the radial support structure near cryogenic temperature and normal temperature are 26.3K~119.9K and 56K~82.2K respectively; b) the amount of heat loss throught the radial support structure is 46.62W; c) finally the radial stress at each test poins is compression stress ant the maxim value is 43.55MPa, the circumferential stress is changed from tension stress to compression stress with the increase of radius, and the maxium tension stress is 35.44MPa while the maxium compression stress is 14.93MPa; d) the maxium stress values on the glass fiber reinforced composite tube are all less than the corresponding material ultimate strength, according to the failure theory of modified Tsai-Hill and Hoffman the glass fiber reinforced composite tube doesn’t occur structural damage while the failure index is highest at the inner race of the glass fiber reinforced composite tube where is acted by the maximum radial tension stress; e) at the equilibrium state the interfaces of both sides are at the state of interference and the amount is small. It can be concluded by contrasting the computational and test results that the interface boundary conditions applied in the finite element model efficiently simulate the true working conditions for the radial support structures. The computational results can be regard as supplement to test results and reference for the next work on the thermal-mechanical coupled therical analysis and computation about the inner support structures in 20m3 LO2 storage tank.Fifthly, the thermal and structure analysis and compution works on the inner support structure under static and vertical 10g impact load have been finished with the sequencial coupled field method through the ANSYS finite element analysis model for 20m3 LO2 storage tank, in which the interface boundary conditions in the coupled thermal structure theoretical model for the experimental setup are applied directedly. The final results indicate: a) the temperature range on the glass fiber reinforced composite tube is 96.0K~277.2K, the radial temperature difference range is 57.6K~173.6K; b) the amount of whole heat loss through the inner support structures in LO2 storage tank is 99.29W, in which the amount through the radial support structures in 56.64W; c) the interface clearances are all reduced in the range of circumferential 0o~180o. Eliminating the initial clearance, the contact interface at the side near cryogenic temperature becomes to be shirnk fit in the range of circumferential 0o~180o while at the side near normal temperature the range is 30o~150o; d) under the impact load, the positive XY shear stress at the corner of 90°inner race of the left-side glass fiber reinforced composite tube near outer tank is 34.3MPa and over 4.6% than the corresponding ultimate strength, while the positive XZ shear stress at the corner of 90°outer race of the right-side glass fiber reinforced composite tube near inner tank is 43.3MPa and higher2.5% than the corresponding ultimate strength; e) under the impact load, the contact interface at both sides near cryogenic and normal temperature becomes to be shirnk fit in the range of circumferential 0o~180o, both shirnk range is 0.003~0.611mm and 0.013~0.459mm; f) although there have local structure shear damages under vertical 10g impact load, the positions are at corner and with the radial and axial compresson stress action, the microcracking caused in the matrix have no more space to expand, so the damage won’t be serious. The computation and experimental results are all proved that the glass fiber reinforced composite tube owns reliable support and heat-insulatioo ability under the designed drastic shock load for the 20m3 LO2 storage tank. Fiber reinforce polymer matrix composites as the material for parts of inner support structure in special cryogenic vessels are confirmed with high security during applications.Sixthly, the change laws about the interface clearance in the radius tubing support structure along with differential initial boundary conditions under the coupling effect from heat exchange and structure deforming have been studied. The adaptive property of the support structure with the proper initial boundary condition is proved: a) the amount of clearance change and interference for interference interfaces at both cryogenic and normal temperature sides is small, the corresponding effect of the initial clearances to the structure stress and the range of interference interfaces is small too; b) the part of suppositional contact on the interfaces is from the dynamic change process of the interfaces clearance, and can minish the heat loss dynamically while the stresses on the glass fiber reinforced polymer matrix composite tube is at low level, the radius support structure has good stability for cryogenic applications.The composed structure with thick-wall fiber reinforced polymer matrix composite tube and 0Cr18Ni9 pipes is designed as the radial support structure in special cryogenic vessels and needs to sustain the radia drastic shock from circumferential 360°extent. After therical analysis and experiment tests, this structure as radial support structure in 20m3 LO2 storage tank has been sured to own enough supporting ability under designed drastic shock. The thermal-mechanical finite element analysis model for the inner support structure in special cryogenic vessels confirmed by the computation and experimental results can efficiently reflect the performance and behave about the inner support structures, and can be takn as therical analysis tool for further optimization for material performance and structure design.更多还原