本文選題：輕質(zhì)結(jié)構(gòu) + 點(diǎn)陣結(jié)構(gòu)�。� 參考：《哈爾濱工業(yè)大學(xué)》2013年博士論文

【摘要】：為了實(shí)現(xiàn)飛行器減輕重量、增加有效載荷的目的,發(fā)展先進(jìn)輕質(zhì)復(fù)合材料結(jié)構(gòu),實(shí)現(xiàn)結(jié)構(gòu)輕量化和多功能化是迫切需要解決的科學(xué)問題。碳纖維復(fù)合材料格柵結(jié)構(gòu)和點(diǎn)陣結(jié)構(gòu)兼?zhèn)漭p量化和多功能化特點(diǎn),是當(dāng)前國(guó)際學(xué)術(shù)界公認(rèn)的最有前景的新一代超輕質(zhì)高強(qiáng)結(jié)構(gòu)之一。在本論文中,我們開展了碳纖維復(fù)合材料三維格柵結(jié)構(gòu)、碳纖維復(fù)合材料金字塔點(diǎn)陣結(jié)構(gòu)、碳纖維復(fù)合材料增強(qiáng)型點(diǎn)陣結(jié)構(gòu)、輕質(zhì)金字塔點(diǎn)陣曲面殼與圓柱殼的設(shè)計(jì)、制備及力學(xué)性能的研究工作。在緒論中回顧和評(píng)述了輕質(zhì)復(fù)合材料格柵結(jié)構(gòu)、復(fù)合材料點(diǎn)陣結(jié)構(gòu)、輕質(zhì)夾層曲面殼及圓柱殼力學(xué)行為的國(guó)內(nèi)外研究現(xiàn)狀,從中提煉出本課題需要解決的關(guān)鍵問題。設(shè)計(jì)并制備出芯子空間貫通的碳纖維復(fù)合材料三維格柵結(jié)構(gòu),推導(dǎo)了蛋殼型和金字塔型格柵結(jié)構(gòu)在平壓、側(cè)壓及三點(diǎn)彎曲載荷下的力學(xué)性能理論預(yù)報(bào)公式�？紤]到復(fù)合材料鋪層和芯子拓?fù)錁?gòu)型可變的特點(diǎn),繪制出蛋殼型和金字塔型格柵結(jié)構(gòu)在側(cè)壓和三點(diǎn)彎曲載荷下的失效機(jī)制圖。開展了三種不同相對(duì)密度試驗(yàn)件的平壓試驗(yàn),得到蛋殼型和金字塔型格柵結(jié)構(gòu)平壓模量、平壓強(qiáng)度及準(zhǔn)靜態(tài)吸能特性。依據(jù)側(cè)壓失效機(jī)制圖,設(shè)計(jì)了六組典型的側(cè)壓試件,觀察到了面板起皺、格柵間局部屈曲、面板壓潰、剪切型歐拉屈曲、芯子壓潰等失效模式。針對(duì)三點(diǎn)彎曲失效機(jī)制圖,設(shè)計(jì)了四組典型的三點(diǎn)彎曲試驗(yàn)件,觀察到面板起皺和面芯脫膠失效模式。面板起皺不能導(dǎo)致彎曲承載能力的急劇下降,但是會(huì)誘使面芯脫膠模式提前出現(xiàn),面芯脫膠是結(jié)構(gòu)主導(dǎo)的彎曲失效模式。設(shè)計(jì)了具有自主知識(shí)產(chǎn)權(quán)的組裝模具,采用模具熱壓工藝制備出碳纖維復(fù)合材料金字塔點(diǎn)陣結(jié)構(gòu),使得所有纖維均沿著桿件受載方向,充分發(fā)揮桿件中纖維增強(qiáng)的潛力。用掃描電鏡觀察了桿件典型截面的微觀組織結(jié)構(gòu)。開展了三組不同相對(duì)密度的平壓試驗(yàn),觀察到桿件歐拉屈曲、桿件斷裂、桿件分層及面芯脫膠失效模式,并與平壓理論預(yù)報(bào)結(jié)果進(jìn)行比較,發(fā)現(xiàn)本文制備的金字塔點(diǎn)陣結(jié)構(gòu)在低密度條件下具有優(yōu)越的平壓比強(qiáng)度。開展了四組不同相對(duì)密度的剪切試驗(yàn),觀察到桿件歐拉屈曲、桿件分層及面芯脫膠現(xiàn)象。推導(dǎo)出金字塔點(diǎn)陣結(jié)構(gòu)在側(cè)壓載荷下極值的理論預(yù)報(bào)公式,考慮到面板鋪層及芯子密度可變性設(shè)計(jì)三組典型的側(cè)壓試驗(yàn)件,觀察到面板起皺、面板壓潰及剪切型歐拉屈曲失效模式。推導(dǎo)出金字塔點(diǎn)陣結(jié)構(gòu)在三點(diǎn)彎曲載荷下中心點(diǎn)撓度和極值的理論預(yù)報(bào)公式,考慮了面板壓潰、面板起皺、芯子屈曲、芯子壓潰及面芯脫膠可能的失效模式。針對(duì)不同鋪層的面板及不同相對(duì)密度的芯子,繪制了三點(diǎn)彎曲載荷下金字塔點(diǎn)陣結(jié)構(gòu)的失效機(jī)制圖,并設(shè)計(jì)了八組典型的試驗(yàn)件驗(yàn)證理論模型及失效機(jī)制圖的準(zhǔn)確性。研究了雙層碳纖維復(fù)合材料金字塔點(diǎn)陣結(jié)構(gòu)在準(zhǔn)靜態(tài)平壓載荷下的力學(xué)性能及吸能特性,通過對(duì)不同相對(duì)密度雙層金字塔點(diǎn)陣結(jié)構(gòu)的低速?zèng)_擊試驗(yàn)揭示其能量吸收機(jī)理。針對(duì)碳纖維復(fù)合材料點(diǎn)陣結(jié)構(gòu)面芯界面性能較弱的瓶頸問題,采用電火花和激光切割工藝制備出碳纖維復(fù)合材料增強(qiáng)型點(diǎn)陣結(jié)構(gòu)。研究了激光切割工藝所制備的復(fù)合材料直柱和斜柱增強(qiáng)型點(diǎn)陣結(jié)構(gòu)在平壓及剪切載荷下的力學(xué)性能和失效機(jī)理,推導(dǎo)出預(yù)報(bào)直柱和斜柱增強(qiáng)型點(diǎn)陣結(jié)構(gòu)平壓模量、平壓強(qiáng)度、剪切模量及剪切強(qiáng)度的理論公式,并對(duì)結(jié)構(gòu)尺寸與比強(qiáng)度和比模量之間的內(nèi)在聯(lián)系進(jìn)行深入分析。試驗(yàn)及理論結(jié)果發(fā)現(xiàn)增強(qiáng)型點(diǎn)陣結(jié)構(gòu)可以明顯提高點(diǎn)陣結(jié)構(gòu)剪切性能的瓶頸值。設(shè)計(jì)并制備出輕質(zhì)復(fù)合材料金字塔點(diǎn)陣曲面殼及圓柱殼。其縱環(huán)筋采用7075鋁合金線切割批量成型,金字塔芯子通過環(huán)筋和縱筋嵌鎖而成,而曲面殼和圓柱殼的面板均為碳纖維復(fù)合材料。對(duì)兩種不同厚度面板的金字塔點(diǎn)陣曲面殼,觀察結(jié)構(gòu)的失效模式,發(fā)現(xiàn)了曲面殼獨(dú)特的M型失效模式。給出了預(yù)報(bào)曲面殼彎曲性能的理論公式,并用有限元方法對(duì)不同面板厚度的曲面殼進(jìn)行數(shù)值模擬�？紤]到圓柱殼可能的軸壓失效模式,推導(dǎo)出相應(yīng)的理論預(yù)報(bào)公式,并繪制了不同角度鋪層面板的金字塔點(diǎn)陣圓柱殼在軸壓載荷下失效機(jī)制圖。設(shè)計(jì)了三組典型的圓柱殼軸壓試驗(yàn)并得到點(diǎn)陣圓柱殼的極限承載能力及應(yīng)變值,同時(shí)觀察到筋格間面板局部屈曲和面板壓潰失效模式。
[Abstract]:In order to reduce the weight of the aircraft and increase the payload, the development of the structure of advanced lightweight composite materials and the realization of the lightweight and multi-function structure are the urgent needs to be solved. The structure of the grid and the lattice structure of carbon fiber composite materials is the most widely recognized in the current international academic circle. In this paper, we have carried out the three-dimensional grid structure of carbon fiber composites, the Pyramid lattice structure of carbon fiber composites, the reinforced lattice structure of carbon fiber composite materials, the design, preparation and mechanical properties of the light matrix camber shell and cylindrical shell in Pyramid, and the introduction of the mechanical properties. This paper reviews and reviews the domestic and foreign research status of light composite grid structure, composite lattice structure, light sandwich surface shell and cylindrical shell, and extracts the key problems to be solved in this topic. The theoretical prediction formula for the mechanical properties of the Pyramid type grid structure under flat pressure, lateral pressure and three point bending load. Taking into account the variable structure of the composite layer and core topology, the failure mechanism diagram of the shell and Pyramid grid structures under side pressure and three point bending load is drawn. Three different relative density tests have been carried out. The flat pressure modulus, flat pressure strength and quasi static energy absorption characteristics of the shell type and Pyramid type grid structure are obtained. According to the failure mechanism diagram of the side pressure, six groups of typical side pressure specimens are designed. The failure modes, such as panel wrinkling, local buckling between grille, panel crushing, shear type Euler buckling and core crushing, are observed. Three points are also observed. Four typical three point bending tests are designed for the bending failure mechanism diagram. The failure mode of the panel wrinkling and the surface core degumming is observed. The panel wrinkling can not lead to a sharp decline in the bending bearing capacity, but it will induce the appearance of the surface core degumming mode in advance, and the surface core degumming is the bending failure mode of the main guide of the structure. The independent knowledge is designed. The structure of the carbon fiber composite material Pyramid lattice structure was prepared by hot pressing of the mould. All the fibers were loaded along the load direction of the rod, and the potential of fiber reinforced in the rod was fully played. The microstructure of the typical section of the rod was observed by scanning electron microscope. Three groups of different relative density tests were carried out. The failure modes of Euler buckling, rod fracture, member delamination and surface core degumming are observed, and compared with the prediction results of flat pressure theory, it is found that the Pyramid lattice structure has superior compressive strength under low density. The shear test of four groups of different phase density is carried out, and the rod Euler buckling is observed and the rod is observed. A theoretical prediction formula for the extreme value of Pyramid lattice structure under lateral pressure is derived. Considering the three typical side pressure test parts of the panel and core density variability, the failure modes of panel wrinkling, panel crushing and shear type Euler buckling are observed. The structure of Pyramid lattice is deduced at three points. The theoretical prediction formula for the deflection and the extreme value of the center point under the bending load, considering the failure mode of panel crushing, panel wrinkling, core buckling, core crushing and core degumming. The failure mechanism diagram of the Pyramid lattice structure under three point bending loads is drawn for different layers and different relative density cores, and the design of the failure mechanism of the lattice structure is drawn. The accuracy of the theoretical model and failure mechanism diagram of the eight groups of typical test parts. The mechanical properties and energy absorption characteristics of the double carbon fiber composite Pyramid lattice structure under quasi static flat pressure are studied. The energy absorption mechanism is revealed by the low velocity impact test on the double layer lattice structure with different relative density in Pyramid. An enhanced lattice structure of carbon fiber composites was fabricated by electric spark and laser cutting. The mechanical properties and failure of the composite direct and oblique column reinforced lattice structures prepared by laser cutting were studied under the flat and shear loads. The theoretical formulas for predicting the modulus of pressure, the compressive strength, the shear modulus and the shear strength of the reinforced lattice structure of the straight column and the inclined column are deduced, and the internal relation between the structure size and the specific strength and the specific modulus is deeply analyzed. The experimental and theoretical results show that the reinforced lattice structure can obviously improve the shear property of the lattice structure. A lightweight composite Pyramid lattice shell and cylindrical shell is designed and prepared. The longitudinal ring is made by 7075 aluminum alloy wire cutting, and the core of Pyramid is locked through the ring and longitudinal bars. The surface of the curved shell and the cylindrical shell are both carbon fiber composites. The Pyramid dot matrix of two different thickness panels is made. The failure mode of the structure is observed and the unique M type failure mode of the curved shell is found. The theoretical formula for predicting the bending property of the curved shell is given. The finite element method is used to simulate the curved shell of different panel thickness. The corresponding theoretical prediction formula is derived considering the possible axial pressure failure mode of the cylindrical shell, and the corresponding theoretical prediction formula is derived, and the drawing is drawn. The failure mechanism diagram of the Pyramid lattice cylindrical shell with different angles is subjected to axial compression. Three typical cylindrical shell axial compression tests are designed and the ultimate bearing capacity and strain values of the lattice cylindrical shells are obtained. At the same time, the local buckling and the failure mode of the panel collapse are observed.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：V214.8
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本文編號(hào)：1967946