本文選題：功能梯度材料　切入點：夾芯結(jié)構(gòu)　出處：《太原理工大學》2015年博士論文

【摘要】：多孔夾芯結(jié)構(gòu)由于其綜合了芯層的可壓縮性與面板的延展性等特點，具有優(yōu)異的力學性能和物理特性被廣泛地應用于航空航天、交通運輸、軍事工業(yè)以及建筑等領域。關于多孔金屬夾芯結(jié)構(gòu)在準靜態(tài)載荷和動載荷下的力學行為研究已成為國內(nèi)外學者研究的熱點問題。通�？梢杂米鲓A芯結(jié)構(gòu)芯層的材料和結(jié)構(gòu)包括點陣、格柵材料，金屬泡沫材料，聚酯泡沫材料，圓環(huán)、圓管等薄壁類結(jié)構(gòu)。隨著研究的不斷深入，功能梯度夾芯結(jié)構(gòu)由于其能夠有效地發(fā)揮各類芯層的優(yōu)點，減輕結(jié)構(gòu)重量，，提高結(jié)構(gòu)的力學性能，逐漸成為夾芯結(jié)構(gòu)研究領域的重要課題。但是，目前對爆炸與沖擊等強動載荷下梯度夾芯結(jié)構(gòu)的動力學行為的研究還比較少。 本文采用數(shù)值模擬計算、實驗和理論分析相結(jié)合的方法系統(tǒng)地研究了爆炸荷載作用下梯度夾芯結(jié)構(gòu)（球殼、柱殼、方板）的變形失效模式和塑性動力響應，并與傳統(tǒng)非梯度夾芯結(jié)構(gòu)的抗沖擊性能做了對比。主要討論了芯層不同的密度分布對夾芯結(jié)構(gòu)變形失效模式、能量吸收及抗沖擊性能的影響。梯度夾芯結(jié)構(gòu)在爆炸荷載作用下芯層從迎爆面開始逐層壓縮，各芯層的壓縮過程相互耦合，芯層壓縮結(jié)束后伴隨有小幅的回彈和振蕩。通過對比背爆面中點的撓度發(fā)現(xiàn)：芯層相對密度單調(diào)遞減的梯度夾芯結(jié)構(gòu)抗沖擊性能最佳，后面板動能和殘余撓度最小。 采用自行研制的彈道沖擊擺系統(tǒng)對梯度蜂窩夾芯板結(jié)構(gòu)在爆炸荷載下的動力響應做了實驗研究，并與數(shù)值模擬結(jié)果進行對比。分析了結(jié)構(gòu)的變形失效模式以及芯層排列組合方式對結(jié)構(gòu)動力響應的影響，對比了不同芯層排列方式下結(jié)構(gòu)抗爆性能差異。實驗發(fā)現(xiàn)結(jié)構(gòu)獲得的沖量不僅與裝藥情況緊密相關，而且與結(jié)構(gòu)的幾何構(gòu)型有關；結(jié)構(gòu)主要呈現(xiàn)出三種變形模式，分別為：局部變形；整體彎曲大變形和貫穿失效；梯度結(jié)構(gòu)的抗爆炸沖擊能力優(yōu)于非梯度夾芯結(jié)構(gòu)，當夾芯板較厚時，這種優(yōu)勢更為明顯。改變芯層的組合順序時，夾芯板后面板撓度和各芯層的壓縮情況有明顯變化；通過數(shù)值模擬發(fā)現(xiàn)，當沖擊載荷較小時，梯度試件并沒有表現(xiàn)出較好的抗沖擊能力。隨著沖擊載荷的增加，梯度試件呈現(xiàn)出更好的抗沖擊性能，并且相對密度遞減的芯層排列方式具有最佳的抗爆炸沖擊性能。 基于一維應力波傳播控制方程，分析了一維梯度泡沫圓桿受剛性塊撞擊時應力波的傳播規(guī)律和剛性塊速度的衰減規(guī)律，并與有限元模擬結(jié)果做了比較，理論與模擬結(jié)果吻合較好。為研究梯度材料中應力波傳播規(guī)律和芯層優(yōu)化設計提供了理論和技術支持。
[Abstract]:Porous sandwich structures have been widely used in aerospace, transportation, military industry and architecture because of their excellent mechanical and physical properties because of their compressibility of core layer and ductility of panel.The study on the mechanical behavior of porous metal sandwich structures under quasi-static and dynamic loads has become a hot topic for scholars at home and abroad.The materials and structures that can be used as core layer of sandwich structure include lattice, grid material, metal foam material, polyester foam material, ring, tube and other thin-walled structures.With the development of research, functionally gradient sandwich structure has become an important subject in the field of sandwich structure research because it can effectively play the advantages of all kinds of core layer, reduce the weight of structure, improve the mechanical properties of structure.However, there are few studies on the dynamic behavior of gradient sandwich structures under strong dynamic loads such as explosion and impact.In this paper, the deformation failure mode and plastic dynamic response of gradient sandwich structure (spherical shell, cylindrical shell, square plate) under explosion load are studied systematically by means of numerical simulation, experiment and theoretical analysis.Compared with the traditional non-gradient sandwich structure, the impact resistance of the structure is compared.The effects of different density distribution of core layer on deformation failure mode, energy absorption and impact resistance of sandwich structure are discussed.Under the action of explosion load, the core layer of the gradient sandwich structure begins to compress layer by layer from the face of the explosion, and the compression process of each core layer is coupled with each other. After the compression of the core layer is finished, there is a small rebound and oscillation.By comparing the deflection of the middle point of the back blasting surface, it is found that the gradient sandwich structure with decreasing relative density of the core layer has the best impact resistance, and the kinetic energy and residual deflection of the rear panel are the least.The dynamic response of gradient honeycomb sandwich plate structure under explosion load is studied experimentally by using the ballistic impact pendulum system developed by ourselves and compared with the numerical simulation results.The influence of deformation failure mode and core layer arrangement and combination mode on the dynamic response of the structure is analyzed, and the difference of structure anti-explosion performance under different core layer arrangement mode is compared.The experimental results show that the impulse obtained by the structure is not only closely related to the charge condition but also to the geometric configuration of the structure. There are three main deformation modes of the structure: local deformation, large global bending deformation and penetrating failure.The impact resistance of gradient structure is better than that of non-gradient sandwich structure, which is more obvious when the sandwich panel is thicker.When the combination order of the core layer is changed, the deflection of the back panel and the compression of each core layer are obviously changed, and the numerical simulation shows that the gradient specimen does not exhibit better impact resistance when the impact load is small.With the increase of impact load, the gradient specimen exhibits better impact resistance, and the core layer arrangement with decreasing relative density has the best anti-explosion impact performance.Based on the governing equation of one-dimensional stress wave propagation, the propagation law of the stress wave and the attenuation law of the velocity of the rigid block are analyzed when the one-dimensional gradient foam rod is impacted by a rigid block, and the results are compared with the results of finite element simulation.The theoretical results are in good agreement with the simulation results.It provides theoretical and technical support for the study of stress wave propagation law and core layer optimization design in gradient materials.
【學位授予單位】：太原理工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.4

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