本文選題：復(fù)合材料折疊夾芯層 + DSC分析��； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：作為新型的夾芯結(jié)構(gòu),復(fù)合材料折疊夾層結(jié)構(gòu)具有比強(qiáng)度高,比剛度大和良好的吸能性等特點(diǎn),有望取代傳統(tǒng)蜂窩夾層結(jié)構(gòu)作為航空航天器的主承力結(jié)構(gòu)材料。本文的目的是通過(guò)實(shí)驗(yàn)手段探索一種簡(jiǎn)單可行的復(fù)合材料折疊夾芯結(jié)構(gòu)芯材制備方法,從而實(shí)現(xiàn)芯材制備批量化、標(biāo)準(zhǔn)化和高效率生產(chǎn),使得該結(jié)構(gòu)在工程應(yīng)用中占有一席之地。并找到不同材質(zhì)以及結(jié)構(gòu)、尺寸對(duì)其壓縮性能的影響規(guī)律,為該類(lèi)結(jié)構(gòu)材料的理論研究與實(shí)際應(yīng)用提供可靠的依據(jù)。針對(duì)這一目標(biāo),選取熱壓工藝作為制備手段。本次研究從復(fù)合材料的固化動(dòng)力學(xué)出發(fā),選擇C-03P-200碳纖維和Kevlar-49兩種不同性質(zhì)的平紋編織預(yù)浸料作為研究對(duì)象�；跓釅哼^(guò)程溫度、時(shí)間、壓力三要素,本文對(duì)工藝參數(shù)進(jìn)行了優(yōu)化選取。首先通過(guò)對(duì)兩種預(yù)浸料進(jìn)行5℃、10℃、15℃.20℃的非等溫DSC掃描熱分析,然后通過(guò)外推法確定預(yù)浸料最佳的凝膠溫度、熱壓固化溫度和后處理溫度。在此基礎(chǔ)上,對(duì)材料進(jìn)行了DSC等溫(凝膠溫度、固化溫度)掃描熱分析,然后以固化動(dòng)力學(xué)的基本原理為依據(jù),確定了預(yù)浸料固化度隨時(shí)間的變化曲線,并結(jié)合凝膠試驗(yàn)結(jié)果,初步確定了固化各階段所需要的時(shí)間。設(shè)計(jì)并制造了一套熱壓模具,對(duì)折疊芯子進(jìn)行了制備,并以芯材的抗壓強(qiáng)度、質(zhì)量、生產(chǎn)效率為目標(biāo),利用正交試驗(yàn)、極差分析法,分別對(duì)固化工藝各階段的保溫時(shí)間和工藝壓力進(jìn)行了優(yōu)化選取。在壓縮性能試驗(yàn)中,分別對(duì)不同厚度的芯子、不同約束條件下的夾芯結(jié)構(gòu)、不同材料組合形式多層折疊夾芯結(jié)構(gòu)進(jìn)行了靜態(tài)的壓縮試驗(yàn)。首先,通過(guò)改變芯壁的厚度,研究了芯子隨相對(duì)密度變化的壓縮力-位移變化規(guī)律及變形失效形式。最后對(duì)折疊夾芯結(jié)構(gòu)、多層結(jié)構(gòu)的折疊夾芯結(jié)構(gòu)進(jìn)行靜態(tài)壓縮試驗(yàn),得到了折疊夾芯結(jié)構(gòu)在靜態(tài)壓縮載荷作用下的力-位移變化曲線、破壞模式,進(jìn)而對(duì)其力學(xué)特性及吸能特性進(jìn)行了評(píng)估研究。為了探究不同幾何尺寸的折疊夾芯結(jié)構(gòu)在壓縮載荷下的力學(xué)性能和吸能特性變化規(guī)律,利用ANSYS/ADPL進(jìn)行數(shù)值化建模,使用LS/dyna有限元軟件,采用Chang-Chang和Tsai-Wu失效準(zhǔn)則分別對(duì)碳纖維和凱夫拉復(fù)合材料折疊夾芯結(jié)構(gòu)進(jìn)行準(zhǔn)靜態(tài)數(shù)值模擬研究,經(jīng)過(guò)與試驗(yàn)對(duì)比分析其可靠性。最后對(duì)芯材長(zhǎng)度折疊半角、寬度折疊半角,芯子高度、折疊邊長(zhǎng)和厚度對(duì)整個(gè)結(jié)構(gòu)承受峰值壓力、吸能特性的影響規(guī)律進(jìn)行了討論。
[Abstract]:As a new type of sandwich structure, the folded sandwich structure has the characteristics of high specific strength, large specific stiffness and good energy absorption. It is expected to replace the traditional honeycomb sandwich structure as the main bearing structural material of the aerospace vehicle. The purpose of this paper is to explore a simple and feasible composite sandwich core structure core through experimental methods. The preparation method of material has made the preparation of the core material batch, standardization and high efficiency production, which makes the structure occupy a place in the engineering application, and finds the influence law of different material and structure and size on its compression performance. It provides a reliable basis for the theoretical research and practical application of this kind of structure material. The hot pressing process is used as a preparation method. From the curing kinetics of the composite material, two kinds of plain weave prepreg with different properties of C-03P-200 carbon fiber and Kevlar-49 are selected as the research object. Based on the temperature, time, and pressure three factors of the hot pressing process, the process parameters are optimized. First of all, two kinds of preconditioning are adopted. The dipping was analyzed by non isothermal DSC scanning thermal analysis at 5, 10 and 15.20 C. Then the optimum gel temperature, hot pressing temperature and post treatment temperature were determined by extrapolation. On this basis, the DSC isothermal (gel temperature, curing temperature) scanning thermal analysis was carried out on the basis of the basic principle of curing kinetics. The change curve of the curing degree of prepreg with time is determined, and the time required for each stage is preliminarily determined with the result of gel test. A set of hot pressing die is designed and manufactured, the folding core is prepared, and the compression strength, quality and production efficiency of the core material are taken as the target, and the orthogonal test and the difference analysis method are used to separate the solid. In the compression performance test, the static compression test is carried out on the core of different thickness, the sandwich structure under the different constraint conditions and the multi-layer folding sandwich structure with different material combinations. First, the core is studied by changing the thickness of the core wall. In the end, the static compression test is carried out on the folded sandwich structure and the folded sandwich structure of multilayer structure. The force displacement curve and the failure mode of the folded sandwich structure under the static compression load are obtained, and then the mechanical properties and energy absorption characteristics of the folded sandwich structure are also carried out. In order to investigate the mechanical properties of the folded sandwich structures with different geometric sizes under the compression load and the change of the energy absorption characteristics, the numerical modeling was carried out by ANSYS/ADPL. The LS/dyna finite element software was used to use the Chang-Chang and Tsai-Wu failure criteria to carry out the folding sandwich structure of carbon fiber and Kevlar composite materials respectively. The reliability of the quasi-static numerical simulation is compared with the test. Finally, the influence law of the peak pressure on the whole structure and the energy absorption characteristic of the whole structure is discussed by the length folded half angle of the core, the width of the folded half angle, the height of the core, the fold length and the thickness.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TB33

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本文編號(hào)：2083175