Research On The Applicability Of Fiber Reinforced Polymer Matrix Composites At The Condition Of Cryogenic Temperature And Drastic Shock

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.