本文關(guān)鍵詞：功能梯度材料軟夾芯夾層板殼自由振動解析分析方法研究　出處：《華中科技大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 功能梯度材料 軟夾芯 夾層板殼 自由振動 高階夾層板理論 多層理論 流固耦合 格柵增強

【摘要】：功能梯度材料通常由金屬和陶瓷混合而成,其在組成和微結(jié)構(gòu)上隨空間逐漸變化,在微觀上是非均質(zhì),在宏觀上卻是均質(zhì)的復(fù)合材料。這些優(yōu)點可以有效地減小由于材料屬性的不匹配導(dǎo)致的應(yīng)力突變,并且提高粘合強度。因此,功能梯度材料常用于夾層板殼上,以提高夾層板殼芯層與面板之問的粘合強度及減小由于芯層與面板材料屬性不匹配導(dǎo)致的應(yīng)力突變。結(jié)構(gòu)的振動特性是表征結(jié)構(gòu)性能的重要指標之一,因此對功能梯度材料夾層板殼的振動研究具有重要的理論意義與實用價值。 本文采用高階夾層板理論研究了多種新型功能梯度材料軟夾芯夾層板殼的自由振動,包括：面板和芯層同為功能梯度材料的軟夾芯夾層板,雙線性功能梯度材料軟夾芯夾層板,軟質(zhì)功能梯度材料填充格柵增強夾層板,浸水功能梯度材料軟夾芯復(fù)合材料夾層圓柱殼和軟質(zhì)功能梯度材料填充格柵增強夾層圓柱殼。主要研究工作包括： (1)對面板和芯層同為功能梯度材料的軟夾芯夾層板的自由振動進行了解析分析方法研究。采用改進的高階夾層板理論研究了其自由振動,功能梯度材料屬性按照指數(shù)函數(shù)變化,面板采用一階剪切理論而對于軟芯層采用三維彈性解,僅考慮橫向正應(yīng)力和橫向剪切應(yīng)力,基于面板和芯層交界面處的位移和應(yīng)力連續(xù),利用哈密頓原理推導(dǎo)了運動方程。通過與參考文獻中的退化模型-面板為功能梯度材料,芯層為均質(zhì)軟夾芯夾層板模型的理論結(jié)果進行對比,驗證了方法的準確性。同時,對理論結(jié)果與有限元數(shù)值結(jié)果進行了對比,結(jié)果吻合很好。最后,進行了參數(shù)研究包括功能梯度材料屬性的分布,厚度邊長比對振動頻率的影響。 (2)對雙線性功能梯度材料軟夾芯夾層板的自由振動特性進行了解析分析方法研究。由于其芯層是雙線性的,因此認為其芯層是由兩層單調(diào)梯度變化的軟芯層組成。對層合的雙芯層采用多層理論進行分析,對于整個夾層板的分析采用改進的高階夾層板理論和多層理論相結(jié)合的方法,這樣保證了面板與芯層界面,芯層與芯層界面的位移和應(yīng)力的連續(xù)性,而且相對于三維理論和整體多層理論有效地降低了計算量。 (3)對于軟質(zhì)功能梯度材料填充格柵增強夾層板的自由振動進行了解析分析方法研究。由于柵格材料與填充材料的不一致,以往的文獻通常采用平攤或者均質(zhì)的理論方法來處理柵格,本文采用離散法對格柵加筋進行處理。另外,由于柵格采用的是鋼質(zhì)或者硬質(zhì)材料,不能采用軟芯層的處理方式,因此不能忽略芯層的面內(nèi)應(yīng)力,在采用高階夾層板理論時芯層同時考慮面內(nèi)應(yīng)力和橫向應(yīng)力,面板采用薄板理論,基于面板和芯層界面處的位移連續(xù),采用Hamilton原理建立了拉格朗日方程,而后假定Chebyshev多項式的形函數(shù),采用李茲法進行求解。 (4)對浸水功能梯度材料軟夾芯復(fù)合材料夾層圓柱殼的自由振動進行了解析分析方法研究。對于夾層圓柱殼采用改進的高階夾層板理論,對于流體,采用波傳播法,假定波在殼的軸向方向的傳播近似于波沿梁軸向傳播,通過波動方程,求得流體載荷,基于流體和圓柱殼外表面位移的連續(xù)性,采用哈密頓原理推導(dǎo)了運動方程。 (5)對軟質(zhì)功能梯度材料填充格柵增強夾層圓柱殼的自由振動進行了解析分析方法研究。圓柱殼采用與軟質(zhì)功能梯度材料填充格柵增強夾層板相同的方法,建立了拉格朗日運動控制方程。通過假定納維葉解形式的形函數(shù),求得軟質(zhì)功能梯度材料填充格柵增強夾層圓柱殼自由振動頻率 論文對多種功能梯度材料軟夾芯夾層板殼的自由振動進行了理論分析,為功能梯度材料軟夾芯夾層板殼的自由振動研究提供了新的研究思路和途徑,對今后的理論研究和工程設(shè)計具有一定的參考價值。
[Abstract]:Functionally graded materials usually made of metal and ceramic mixture, its composition and microstructure gradually changes with space, in the micro is heterogeneous, composite material is homogeneous in the macro. These advantages can effectively reduce the material property mismatch stress due to the mutation, and therefore improve the bonding strength., functionally graded materials commonly used in sandwich shell, in order to improve the sandwich shell core layer and the panel asked the bonding strength of the core layer and the panel and reduce the material property mismatch stress due to the mutation. The vibration characteristics of structure is one of the important indexes characterizing the structure and properties, so the research on vibration of functionally graded materials with sandwich shell the theoretical significance and practical value.
This paper uses high order sandwich plate theory, the free vibration of a variety of new functional gradient material soft sandwich shell of the study includes: the panel and core layer with FGM soft sandwich plate, bilinear functional gradient material soft sandwich plate, soft FGM filled geogrid reinforced sandwich plate, soaking FGM soft sandwich composite sandwich cylindrical shell and soft FGM filled geogrid reinforced sandwich cylindrical shell. The main research work includes:
(1) of the panel and core layer with FGM sandwich soft sandwich plate free vibration was studied. By analysis of improved high order sandwich plate theory the free vibration study of functionally graded materials properties of the exponential function change, using the first-order shear panel theory for soft core by the three-dimensional elastic solution, only considering transverse normal stress and transverse shear stress, displacement of panel and core layer at the interface and stress continuity based on the equation of motion is derived by using the Hamilton principle. With the degradation model - panel in the reference for functional gradient materials, the core layer is compared with homogeneous soft sandwich laminate model theoretical results, verify the accuracy of the method. At the same time, the theoretical results and numerical results were compared. The results are in good agreement. Finally, a parametric study was conducted including functionally graded material properties Distribution, the influence of the thickness of the thickness to the vibration frequency.
(2) on the free vibration characteristics of bilinear FGM sandwich plate of soft sandwich method of analysis. The core layer is bilinear, so that the core layer is composed of soft core layer two layer monotone gradient. Changes of dual core laminated layer by layer theory to analyze, for the sandwich plate were analyzed with the improved method of higher order sandwich plate theory and multi-layer combination of theory, so as to ensure the panel and core layer interface, the continuity of displacement of core layer and core layer interface and stress, but also relative to the three-dimensional theory and integrated multilayer theory can effectively reduce the amount of computation.
(3) for soft FGM filled geogrid reinforced sandwich plate for the free vibration analysis method of analysis. As the grid material and filling material is not the same, to deal with the previous literature usually grid method is used in flat or homogeneous, the dispersion method of geogrid reinforced processing. In addition, because the grid is used in steel or hard materials, can not be treated by the soft core layer, it can not ignore the in-plane stress of the core layer, the higher order sandwich plate theory core layer considering the in-plane stress and transverse stress, displacement of panel panel using thin plate theory, and the core layer at the interface is based on the continuous. The Lagrange equation is built using the Hamilton principle, and then assumed shape function of Chebyshev polynomials, the Ritz method is used to solve the problem.
(4) the free vibration of functionally graded materials immersed soft sandwich composite sandwich cylindrical shell was studied. Analytical analysis for sandwich cylindrical shell with improved high order sandwich plate theory for fluids, using the wave propagation method, assuming the propagation wave in the axial direction of the shell along the axial propagation approximation of Yu Bo beam, the fluctuation the equation of fluid loading, continuous fluid and outer surface of shells based on displacement, using the Hamiltonian principle deduced the equation of motion.
(5) of soft FGM filled geogrid reinforced free vibration of sandwich cylindrical shell was studied. Analysis of cylindrical shells with soft FGM filled geogrid reinforced sandwich plate in the same way, control equations are established by assuming that the solution of Navier Lagrange motion. The shape function form, obtained soft function gradient filling material of geogrid reinforced sandwich cylindrical shell vibration frequency
The free vibration of functionally graded materials of soft sandwich plate was analyzed, the research provides new ideas and approaches for the study of free vibration of functionally graded materials of soft sandwich plate, which has a certain reference value for further research and engineering design.

【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TB34

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本文編號：1389782