軸壓復合材料柱形殼屈曲特性及工程應用
發(fā)布時間：2019-01-10 11:27
【摘要】：復合材料具有比強度高、比模量大、可設(shè)計性強、耐腐蝕性好等特點,柱形殼具有很好的承載能力與空間利用率,常被用于海洋平臺樁腿、潛水器耐壓殼等結(jié)構(gòu)的制造。本文研究了軸壓復合材料柱形殼的屈曲特性與優(yōu)化設(shè)計方法,以提高其軸向承載能力。從生產(chǎn)制造與工程實際出發(fā),系統(tǒng)地建立復合材料柱形殼設(shè)計計算流程、失穩(wěn)分析方法,對于復合材料柱形殼的設(shè)計、校核、優(yōu)化具有指導性作用。(1)由碳纖維復合材料單軸拉伸試驗得到試驗材料的力學屬性,用于柱形殼的計算與分析。對軸壓復合材料柱形殼進行線彈性屈曲分析,得出前50階屈曲失穩(wěn)模式,即模態(tài)缺陷。基于復合材料薄殼理論、NASA SP-8007規(guī)范,分別得到軸壓復合材料柱形殼屈曲臨界載荷解析解、經(jīng)驗值,驗證線彈性數(shù)值模型正確性。基于弧長法研究不同模態(tài)缺陷條件下軸壓復合材料柱形殼的非線性屈曲特性。由復合材料柱形殼三維掃描試驗得到其初始幾何缺陷,由軸向壓縮試驗得到其軸壓屈曲特性。(2)將數(shù)值分析結(jié)果、理論計算結(jié)果與軸壓試驗結(jié)果作對比分析,結(jié)果表明:對于軸壓復合材料柱形殼屈曲問題,第1階模態(tài)缺陷不一定是最差缺陷,高階模態(tài)缺陷條件下的非線性屈曲臨界載荷與試驗值較為吻合;屈曲載荷下降受缺陷形狀、幅值雙重影響,復合材料柱形殼屈曲計算需考慮多模態(tài)問題;NASA規(guī)范求出的復合材料柱形殼屈曲載荷低于試驗值較多,往往會造成結(jié)構(gòu)笨重、材料浪費、性能降低。(3)綜合運用線彈性屈曲與非線性屈曲分析方法,研究材料鋪層、殼體尺寸對軸壓復合材料柱形殼屈曲特性的影響,得到較為合理的鋪層方式與殼體尺寸。結(jié)合仿生學原理對柱形殼進行形狀優(yōu)化,運用等質(zhì)量、等容積兩種方法,設(shè)計與柱形殼開口直徑相同的蛋形殼,并進行線彈性與非線性屈曲分析。結(jié)果表明:相對復合材料柱形殼,蛋形殼具有更好的軸向承載能力與更低的缺陷敏感度。(4)從工程實例出發(fā),以單立柱固定式海洋平臺的柱形殼樁腿為背景,采用分段式模塊化設(shè)計的方法,在5%多模態(tài)缺陷條件下,研究一般鋼結(jié)構(gòu)柱形殼樁腿、碳纖維復合材料柱形殼樁腿、碳纖維復合材料多蛋交接形樁腿的軸壓屈曲特性。由DH-300電子比重計測量復合材料密度。結(jié)果表明:在相同的承載能力下,復合材料多蛋交接形樁腿具有更小的質(zhì)量、更低的缺陷敏感度與更好的穩(wěn)定性。
[Abstract]:The composite material has the characteristics of high specific strength, high specific modulus, strong designability, good corrosion resistance and so on. The cylindrical shell has good bearing capacity and space utilization ratio. It is often used in the manufacture of offshore platform pile leg and pressure shell of submersible. In this paper, the buckling characteristics and optimum design method of composite cylindrical shells under axial compression are studied in order to improve their axial bearing capacity. Based on the production and engineering practice, the design and calculation flow of composite cylindrical shell, the method of instability analysis, and the design and verification of composite cylindrical shell are systematically established. The optimization is instructive. (1) the mechanical properties of the tested materials are obtained from uniaxial tensile tests of carbon fiber composites and used in the calculation and analysis of cylindrical shells. Based on the linear elastic buckling analysis of axially compressed composite cylindrical shells, the first 50 order buckling modes, i.e. modal defects, are obtained. Based on the theory of thin composite shell and NASA SP-8007 code, the analytical solution of buckling critical load of composite cylindrical shell under axial compression is obtained, and the empirical values are obtained to verify the correctness of the linear elastic numerical model. The nonlinear buckling behavior of composite cylindrical shells subjected to axial compression under different modal defects is studied based on arc length method. The initial geometric defects of composite cylindrical shell were obtained by three-dimensional scanning test, and the axial compression buckling characteristics were obtained by axial compression test. (2) the results of numerical analysis, theoretical calculation and axial compression test were compared with those of axial compression test. The results show that the first order modal defect is not necessarily the worst for the buckling of composite cylindrical shells under axial compression, and the nonlinear buckling critical load under the condition of high order modal defects is in good agreement with the experimental values. The reduction of buckling load is affected by the shape and amplitude of the defect, so the multimodal problem should be considered in the buckling calculation of composite cylindrical shells. The buckling loads of composite cylindrical shells calculated by NASA Code are much lower than the experimental values, which often result in bulky structure, material waste and poor performance. (3) the linear elastic buckling and nonlinear buckling analysis methods are comprehensively used to study the material layering. The effect of shell size on the buckling characteristics of composite cylindrical shells under axial compression was investigated, and a more reasonable lamination method and shell size were obtained. Based on the bionic principle, the shape of cylindrical shell is optimized. Using equal mass and equal volume, the eggshell with the same opening diameter as cylindrical shell is designed, and the linear elasticity and nonlinear buckling analysis are carried out. The results show that the eggshell has better axial bearing capacity and lower defect sensitivity than the composite cylindrical shell. (4) based on the engineering example, the pile leg of the single column fixed offshore platform is taken as the background. In this paper, the axial buckling characteristics of the common steel structure pile-leg with cylindrical shell and carbon fiber composite with multi-egg junction are studied under the condition of 5% multi-mode defect by using the segmented modular design method. The density of composites was measured by DH-300 electronic hydrometer. The results show that under the same bearing capacity, the composite multi-egg joint pile leg has lower mass, lower defect sensitivity and better stability.
【學位授予單位】：江蘇科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33
本文編號：2406252
[Abstract]:The composite material has the characteristics of high specific strength, high specific modulus, strong designability, good corrosion resistance and so on. The cylindrical shell has good bearing capacity and space utilization ratio. It is often used in the manufacture of offshore platform pile leg and pressure shell of submersible. In this paper, the buckling characteristics and optimum design method of composite cylindrical shells under axial compression are studied in order to improve their axial bearing capacity. Based on the production and engineering practice, the design and calculation flow of composite cylindrical shell, the method of instability analysis, and the design and verification of composite cylindrical shell are systematically established. The optimization is instructive. (1) the mechanical properties of the tested materials are obtained from uniaxial tensile tests of carbon fiber composites and used in the calculation and analysis of cylindrical shells. Based on the linear elastic buckling analysis of axially compressed composite cylindrical shells, the first 50 order buckling modes, i.e. modal defects, are obtained. Based on the theory of thin composite shell and NASA SP-8007 code, the analytical solution of buckling critical load of composite cylindrical shell under axial compression is obtained, and the empirical values are obtained to verify the correctness of the linear elastic numerical model. The nonlinear buckling behavior of composite cylindrical shells subjected to axial compression under different modal defects is studied based on arc length method. The initial geometric defects of composite cylindrical shell were obtained by three-dimensional scanning test, and the axial compression buckling characteristics were obtained by axial compression test. (2) the results of numerical analysis, theoretical calculation and axial compression test were compared with those of axial compression test. The results show that the first order modal defect is not necessarily the worst for the buckling of composite cylindrical shells under axial compression, and the nonlinear buckling critical load under the condition of high order modal defects is in good agreement with the experimental values. The reduction of buckling load is affected by the shape and amplitude of the defect, so the multimodal problem should be considered in the buckling calculation of composite cylindrical shells. The buckling loads of composite cylindrical shells calculated by NASA Code are much lower than the experimental values, which often result in bulky structure, material waste and poor performance. (3) the linear elastic buckling and nonlinear buckling analysis methods are comprehensively used to study the material layering. The effect of shell size on the buckling characteristics of composite cylindrical shells under axial compression was investigated, and a more reasonable lamination method and shell size were obtained. Based on the bionic principle, the shape of cylindrical shell is optimized. Using equal mass and equal volume, the eggshell with the same opening diameter as cylindrical shell is designed, and the linear elasticity and nonlinear buckling analysis are carried out. The results show that the eggshell has better axial bearing capacity and lower defect sensitivity than the composite cylindrical shell. (4) based on the engineering example, the pile leg of the single column fixed offshore platform is taken as the background. In this paper, the axial buckling characteristics of the common steel structure pile-leg with cylindrical shell and carbon fiber composite with multi-egg junction are studied under the condition of 5% multi-mode defect by using the segmented modular design method. The density of composites was measured by DH-300 electronic hydrometer. The results show that under the same bearing capacity, the composite multi-egg joint pile leg has lower mass, lower defect sensitivity and better stability.
【學位授予單位】：江蘇科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33
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