發(fā)布時間：2018-04-20 05:09

  本文選題：7050鋁合金 + 線膨脹系數　； 參考：《青島理工大學》2015年碩士論文

【摘要】：隨著鋁合金材料的研發(fā)與使用,鋁合金的優(yōu)異性能逐漸顯現了出來,使得各種鋁合金被越來越廣泛地使用于眾多領域。近幾年隨著高鐵行業(yè)的快速發(fā)展,節(jié)能降耗意識在全球制造業(yè)的提高,對高速動車性能要求的不斷提高,大量采用高強度鋁合金結構件成為一種趨勢,鋁合金結構件可以大大減輕高速動車的重量,減少燃料的使用提高動車的機動性,同時,使得攜帶負載的能力大大提高,有效的緩解了安全、環(huán)保、能源[29]這三大課題,高速動車中零部件材質逐漸采用高強度鋁合金替換原來的各種鋼材。然而由于鋁合金材料具有較大的熱膨脹系數,導致其在加工與使用過程中的尺寸穩(wěn)定性受溫度變化的影響較大,進而導致了鋁合金零部件經濟性的降低。本研究主要從理論分析與實驗分析兩個角度出發(fā)對鋁合金的尺寸熱穩(wěn)定性進行較為深入的研究,希望研究結論可為正確制定鋁合金的加工工藝,特別是鋁合金零部件熱變形的補償,提供基礎的理論性指導,同時可為建立精密工程中常用材料的精確熱膨脹系數參考標準提供一定的參考依據[30]。通過對材料熱膨脹物理性以及材料熱膨脹現象與其比熱容(特別是晶格振動比熱容)的關系等的研究分析,發(fā)現了7050-T74鋁合金的線膨脹系數與溫度變化之間的相關性[31]。通過鋁合金軸箱體熱變形實驗,初步得到了7050-T74鋁合金在18℃-34℃溫度范圍內孔徑尺寸變化量與溫度之間的關系及其在該溫度范圍內的平均線膨脹系數[32]。通過利用DSC實驗儀器及相關軟件進行鋁合金比熱容隨溫度變化測量實驗,探究了7050鋁合金尺寸熱穩(wěn)定性與其比熱容變化的相關性,并根據實驗得出的7050-T74鋁合金熱容隨溫度變化的變化規(guī)律,通過格留乃申公式得出了線膨脹系數隨溫度變化的近似數學表達式以及7050-T74鋁合金在20℃~100℃(293K~373K)溫度范圍內材料線膨脹系數的平均值。通過鋁合金金相組織隨溫度變化觀察實驗,探究了溫度變化時7050-T74鋁合金組織變化對鋁合金尺寸熱穩(wěn)定性的影響。通過ABAQUS對750鋁合金軸箱體建立有限元模型,并劃定網格類型;對有限元模型施加相應的邊界條件和約束,包括參數化載荷;分析軟件將根據零件幾何模型對相應的有限元模型進行解算,并對解算結果作相應的后處理[33]。
[Abstract]:With the development and application of aluminum alloy materials, the excellent properties of aluminum alloy gradually appear, making various aluminum alloys are more and more widely used in many fields. In recent years, with the rapid development of high-speed rail industry, the awareness of energy saving and consumption reduction has been improved in the global manufacturing industry, and the performance requirements of high-speed motor cars have been continuously improved. It has become a trend to adopt a large number of aluminum alloy structures with high strength. Aluminum alloy structure can greatly reduce the weight of high-speed motor cars, reduce the use of fuel to improve the mobility of motor vehicles, at the same time, make the carrying capacity of load greatly improved, effectively alleviate the safety, environmental protection, energy [29] three major topics, High-strength aluminum alloy is gradually used to replace all kinds of steel in high-speed motor car. However, due to the large thermal expansion coefficient of aluminum alloy materials, the dimensional stability of aluminum alloy materials in the process of processing and use is greatly affected by the temperature change, which leads to the reduction of the economy of aluminum alloy parts. In this study, the dimension thermal stability of aluminum alloy was studied from two aspects of theoretical analysis and experimental analysis, and the conclusion of the study could be used to correctly formulate the processing technology of aluminum alloy. In particular, the compensation of thermal deformation of aluminum alloy parts provides basic theoretical guidance, and can also provide a certain reference basis for the establishment of reference standard for accurate thermal expansion coefficient of materials commonly used in precision engineering [30]. By analyzing the physical properties of material thermal expansion and the relationship between material thermal expansion phenomenon and its specific heat capacity (especially lattice vibration specific heat capacity), the correlation between linear expansion coefficient and temperature change of 7050-T74 aluminum alloy has been found [31]. The relationship between the change of pore size and temperature and the average linear expansion coefficient of 7050-T74 aluminum alloy in the temperature range of 18 鈩，

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