本文選題：鋁合金 + 圓筒結(jié)構(gòu)��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：目前深潛結(jié)構(gòu)無論從結(jié)構(gòu)形式還是材料均已達到技術(shù)極限,表現(xiàn)為無法實現(xiàn)深潛結(jié)構(gòu)在進一步提高極限潛深的同時具備長航時、高容重比的技術(shù)指標(biāo),是制約海洋工程規(guī)模探測和深海開發(fā)的關(guān)鍵技術(shù)瓶頸�！皟�(nèi)拉外壓的環(huán)向殘余應(yīng)力”在提高極限承載能力的同時有利于拓寬容重比,協(xié)調(diào)探測深度與作業(yè)能力之間的矛盾,有望實現(xiàn)現(xiàn)有技術(shù)條件下耐壓殼技術(shù)的突破。基于這一現(xiàn)狀,本文以鋁合金圓筒結(jié)構(gòu)為研究對象,提出一種利用淬火處理所形成的殘余應(yīng)力來提高圓筒結(jié)構(gòu)綜合性能的方法。淬火是溫度、相變、應(yīng)力相互影響的復(fù)雜非線性過程,傳統(tǒng)方法對于測量淬火殘余應(yīng)力的分布有一定局限和不足,也難以精確跟蹤應(yīng)力場演變規(guī)律。針對目前鋁合金淬火模擬大多從固溶溫度開始的情況,本文利用有限元分析軟件ABAQUS,建立了能揭示加熱過程對鋁合金圓筒淬火模擬影響的有限元模型,采用有限元模擬的方法對淬火過程進行了熱固耦合分析。通過模擬計算,研究了圓筒在淬火過程中溫度場、應(yīng)力場的分布變化規(guī)律,淬火殘余應(yīng)力的形成歷程與機制,關(guān)鍵參數(shù)對淬火殘余應(yīng)力的影響規(guī)律,以及淬火殘余應(yīng)力對圓筒幾何形狀的影響�；跉堄鄳�(yīng)力釋放引起加工變形的特征,對淬火殘余應(yīng)力的分布特點進行了測試,并對其導(dǎo)致的圓筒淬火變形進行了試驗驗證。研究結(jié)果表明:(1)加熱過程對鋁合金圓筒淬火模擬的溫度場及殘余應(yīng)力影響很小,而對變形影響較大。(2)淬火初期,圓筒外層溫度急劇下降,內(nèi)外溫差迅速增大;隨著冷卻進行,圓筒降溫速度明顯減慢,內(nèi)外溫差越來越小,筒體溫度逐漸接近淬火介質(zhì)溫度。(3)淬火初期,圓筒外層快速收縮,受到內(nèi)層牽制而產(chǎn)生拉應(yīng)力,內(nèi)層受外層收縮影響而產(chǎn)生壓應(yīng)力,淬火后期應(yīng)力反向變化,最終形成了內(nèi)拉外壓的環(huán)向殘余應(yīng)力。(4)圓筒的徑厚比越小,材料的屈服強度越小、彈性模量越大、塑性模量越小,淬火工藝的固溶溫度越大、淬火水溫越小、冷卻速度越大,最終形成的環(huán)向殘余應(yīng)力就越大,長度對淬火環(huán)向殘余應(yīng)力的影響非常小。(5)試驗結(jié)果與模擬結(jié)果有較好的一致性,圓筒經(jīng)外表面噴淋淬火可形成內(nèi)拉外壓的環(huán)向殘余應(yīng)力,同時整體呈現(xiàn)雙頭喇叭形的微量變形趨勢,對圓筒結(jié)構(gòu)的承載性能影響很小。
[Abstract]:At present, the deep submersible structure has reached the technical limit in terms of structure form and material, which shows that it is impossible to realize the technical index of high bulk density ratio when the deep submarine structure can further improve the limit depth and have a high bulk weight ratio at the same time. It is the key technical bottleneck that restricts the scale exploration and deep-sea exploitation of ocean engineering. The "circumferential residual stress of internal and external pressure" can increase the ultimate bearing capacity and at the same time widen the volume-weight ratio and coordinate the contradiction between the detecting depth and the working ability, which is expected to achieve the breakthrough of the pressure-resistant shell technology under the existing technical conditions. Based on this situation, this paper takes the aluminum alloy cylinder structure as the research object, and puts forward a method to improve the comprehensive properties of the cylinder structure by using the residual stress formed by quenching treatment. Quenching is a complex nonlinear process in which temperature, phase transformation and stress affect each other. The traditional method has some limitations and shortcomings in measuring the distribution of quenching residual stress, and it is difficult to track the evolution of stress field accurately. In view of the fact that the quenching simulation of aluminum alloy mostly starts from the solution temperature, a finite element model which can reveal the effect of heating process on the quenching simulation of aluminum alloy cylinder is established by using the finite element analysis software Abaqus. The finite element method is used to analyze the heat-solid coupling of quenching process. Through simulation and calculation, the distribution and variation of temperature field and stress field, the formation history and mechanism of quenching residual stress, and the influence of key parameters on quenching residual stress are studied. And the effect of quenching residual stress on the geometry of cylinder. Based on the characteristics of machining deformation caused by residual stress release, the distribution characteristics of quenching residual stress are tested, and the quenching deformation caused by quenching deformation is verified. The results show that: (1) the effect of heating process on the temperature field and residual stress of aluminum alloy cylinder quenching is very small, but it has a great effect on deformation. (2) at the beginning of quenching, the temperature of the outer layer of the cylinder decreases sharply, and the temperature difference between inside and outside increases rapidly. The cooling rate of the cylinder obviously slows down, the temperature difference between inside and outside becomes smaller and smaller, and the temperature of the cylinder gradually approaches the quenching medium temperature. (3) at the beginning of quenching, the outer layer of the cylinder shrinks rapidly, resulting in tensile stress from the inner layer. Under the influence of outer layer shrinkage, the inner layer produces compressive stress, and the stress changes in reverse direction after quenching. (4) the smaller the diameter to thickness ratio of the cylinder, the smaller the yield strength of the material, the greater the elastic modulus and the smaller the plastic modulus. The larger the solution temperature of quenching process is, the smaller the quenching water temperature is, and the larger the cooling rate is, the greater the final circumferential residual stress is, and the effect of length on the annular residual stress of quenching is very small. (5) the experimental results are in good agreement with the simulation results. The circumferential residual stress of internal tension and external pressure can be formed by spray quenching on the outer surface of the cylinder, and the micro deformation trend of double head horn shape is presented as a whole, which has little effect on the bearing capacity of the cylinder structure.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U661.4;U663.91

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