發(fā)布時間：2018-04-23 18:20

  本文選題：夾層板 + 有限元��； 參考：《燕山大學》2015年博士論文

【摘要】：本文針對夾層板結構組成單元的材料搭配設計,通過有限元三維實體建模,采用有限元非線性屈曲分析與動態(tài)應變試驗相結合的方法,研究蜂窩夾層板組元材料幾何與物理參數(shù)改變對屈曲載荷與動態(tài)響應的影響。首先由彈性力學板殼理論,結合邊界條件、幾何變形與協(xié)調(diào)方程,推導出夾層板靜力廣義平衡方程;再通過臨界平衡條件得到板的屈曲平衡方程,并以單向受壓兩端簡支狹長矩形板為例,得出屈曲應力表達式。然后改變表板厚度、夾芯網(wǎng)格高度、夾芯網(wǎng)格疏密程度、夾芯胞壁厚度以及表板和夾芯材料進行有限元建模,通過有限元非線性屈曲分析,分別研究在單向壓縮載荷與彎曲載荷作用條件下,各參數(shù)對夾層板臨界屈曲載荷的影響規(guī)律與敏感度。發(fā)現(xiàn)夾芯高度、表板厚度和夾芯密度是影響壓縮臨界載荷的敏感因素;胞壁間距與夾芯高度是影響彎曲臨界載荷的敏感因素;厚夾芯夾層板各參數(shù)的敏感性受夾芯網(wǎng)格疏密影響較大,呈非線性變化。通過動態(tài)應變實驗分析,驗證了有限元計算得到的大部分規(guī)律,通過各測點應變變化與加載曲線結合實驗現(xiàn)象分析了蜂窩夾層板受壓局部與整體屈曲的破壞形式。利用微力試驗機以分階段加載的方式,對六邊形蜂窩夾層板進行壓縮屈曲實驗,研究了夾芯的壓屈破壞過程。等效理論對優(yōu)化復雜夾層結構的建模分析至關重要,文中結合微小試樣的動態(tài)熱性能試驗(DMA)與夾層板結構的實驗模態(tài)分析和有限元調(diào)參方法,討論了夾層結構的實驗等效模量的測試與研究方法。研究了夾層板表板對軟硬夾心復合材料的儲能模量與損耗因子等本構參數(shù)隨著環(huán)境溫度與工作振動頻率的影響趨勢。發(fā)現(xiàn)表板對軟夾芯提高整體復合材料的動態(tài)模量效果顯著,對于硬夾芯材料基本沒有顯著的改善作用。金屬表板對提高粘彈性材料彎曲模量具有顯著地效果;表板對抑制樹脂夾芯隨溫度升高過程中發(fā)生較大變形有顯著效果。本文以模態(tài)分析方法,通過改變表板厚度、夾芯網(wǎng)格高度、夾芯網(wǎng)格疏密程度、夾芯胞壁厚度以及表板和夾芯材料屬性,研究各參數(shù)對夾層板固有頻率的影響規(guī)律;研究發(fā)現(xiàn)夾層板固有頻率對夾芯高度變化敏感,對夾芯疏密不敏感,表板厚度的影響隨不同夾芯高度變化。通過不同表板厚度與夾芯高度的矩形夾層板與大尺寸夾層圓板的實驗模態(tài)分析驗證了上述研究規(guī)律,為夾層板的優(yōu)化設計提供了有價值的參考數(shù)據(jù)。
[Abstract]:In this paper, according to the material collocation design of sandwich plate structure elements, the finite element three-dimensional solid model is established, and the nonlinear buckling analysis of finite element method and dynamic strain test are adopted. The effects of geometric and physical parameters on the buckling load and dynamic response of honeycomb sandwich plates are studied. Based on the theory of plate and shell in elastic mechanics, combined with boundary condition, geometric deformation and coordination equation, the static generalized equilibrium equation of sandwich plate is derived, and then the buckling equilibrium equation of sandwich plate is obtained by critical equilibrium condition. The buckling stress expression is obtained by taking the simple supported rectangular plate with simple support at both ends of unidirectional compression as an example. Then the thickness of the plate, the height of the sandwich mesh, the density degree of the sandwich mesh, the thickness of the sandwich cell wall, the surface plate and the sandwich material are modeled by finite element method, and the nonlinear buckling analysis is carried out by the finite element method. The effects of different parameters on the critical buckling load of laminated plates under uniaxial compression and bending loads are studied. It is found that the height of the core, the thickness of the surface plate and the density of the core are the sensitive factors affecting the critical load of compression, and the cell wall spacing and the height of the sandwich are the sensitive factors affecting the critical load of bending. The sensitivity of each parameter of thick sandwich plate is greatly influenced by the mesh density of sandwich core, which shows nonlinear variation. Most of the laws obtained by finite element method are verified by dynamic strain experimental analysis. The failure modes of local and global buckling of honeycomb sandwich plates under compression are analyzed by means of the strain variation and loading curves of various measuring points combined with experimental phenomena. The compression buckling experiments of hexagonal honeycomb sandwich plates were carried out by means of a micro-force testing machine, and the buckling failure process of the sandwich cores was studied. The equivalent theory is very important to optimize the modeling and analysis of complex sandwich structures. In this paper, the dynamic thermal performance test of small specimens is combined with the experimental modal analysis of sandwich plate structures and the finite element parameter adjustment method. The test and research method of the experimental equivalent modulus of sandwich structure is discussed. The influence trend of constitutive parameters such as storage modulus and loss factor of sandwich panels on soft and hard sandwich composites with ambient temperature and working vibration frequency was studied. It is found that the table plate can improve the dynamic modulus of the whole composite material significantly, but it has no significant effect on the hard core material. The metal sheet has a significant effect on increasing the flexural modulus of viscoelastic materials, and it has a remarkable effect on restraining the larger deformation of the resin sandwich core with the increase of temperature. In this paper, by changing the thickness of the plate, the height of the sandwich mesh, the density of the sandwich mesh, the thickness of the sandwich cell wall and the properties of the plate and the sandwich material, the influence of various parameters on the natural frequency of the sandwich plate is studied by modal analysis method. It is found that the natural frequency of sandwich plate is sensitive to the height of sandwich core, but not sensitive to the density of sandwich core, and the influence of plate thickness varies with the height of sandwich core. The experimental modal analysis of rectangular sandwich plate and large scale sandwich circular plate with different thickness and height of sandwich plate verifies the above research rule and provides valuable reference data for the optimization design of sandwich plate.
【學位授予單位】：燕山大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：O344.1

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