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  本文選題：ANSYS + 瞬態(tài)荷載　； 參考：《昆明理工大學(xué)》2014年碩士論文

【摘要】：在拱壩中,其溫度荷載是這種超靜定結(jié)構(gòu)的基本荷載之一,由溫度變化從而引起相應(yīng)的溫度應(yīng)力對拱壩的影響很值得研究。拱壩的體型是比較單薄的,對外界空氣及水的溫度的變化都是比較敏感。 本文應(yīng)用熱傳導(dǎo)理論和熱結(jié)構(gòu)耦合理論以及三維有限元法。以空心球為小例子,推導(dǎo)其在定解條件下受到外力以及瞬態(tài)變化的溫度作用下,溫度應(yīng)力耦合場的計算公式。用數(shù)學(xué)軟件Matlab對推導(dǎo)出來的理論解進行計算,再用有限元通用軟件ANSYS對同樣條件下的模型進行計算,通過兩者結(jié)果的對比,驗證了用ANSYS軟件對瞬態(tài)的熱結(jié)構(gòu)耦合問題進行計算的可行性。并對空心球模型進行不同網(wǎng)格尺寸的劃分,把得到的數(shù)值解與推導(dǎo)計算出的解析解進行對比分析,當(dāng)劃分網(wǎng)格的尺寸為空心球厚度的五分之一的時候,溫度和應(yīng)力的相對誤差控制在5%左右。由于空心球和拱壩的結(jié)構(gòu)具有相似的特點,要計算的拱壩的壩底厚度也是和空心球的厚度是一樣的尺寸,可以認為其網(wǎng)格劃分為更復(fù)雜的拱壩提供依據(jù)。 從空心球中網(wǎng)格劃分的方式推廣到拱壩上,在ANSYS軟件中采用和空心球同樣的單元進行熱結(jié)構(gòu)的直接耦合分析,引入—參數(shù)——壩體結(jié)構(gòu)總的應(yīng)變能,通過對十二個月拱壩在瞬態(tài)溫度荷載作用下的受力分析,得到在溫降時期,拱壩最不利荷載滯后最低溫度為15～20天,而在溫升時期,拱壩最不利荷載滯后最高溫度5-10天,即本文研究的某高拱壩最不利情況的時間就是在二月初到二月零五天間和七月零二十天到七月二十五天間。壩體最大徑向位移和氣溫的關(guān)系是呈反相關(guān)的,溫度升高,最大徑向位移減小,溫度降低,壩體最大徑向位移增大。最后通過用有限元分析數(shù)值解的精度分析,估計出應(yīng)變能的準(zhǔn)確解,通過比較十二個月中,用空心球推廣到拱壩上的網(wǎng)格劃分得到的應(yīng)變能與估計的應(yīng)變能的準(zhǔn)確解的相對誤差,驗證空心球小例子中的劃分網(wǎng)格的尺寸的在拱壩中的可行性。
[Abstract]:In the arch dam, the temperature load is one of the basic loads of the statically indeterminate structure. The influence of the corresponding temperature stress on the arch dam caused by the temperature change is worth studying. The arch dam is thin and sensitive to changes in air and water temperatures. In this paper, the heat conduction theory, thermal structure coupling theory and three-dimensional finite element method are applied. Taking the hollow sphere as a small example, the formula for calculating the thermal-stress coupling field is derived under the condition of the fixed solution and the transient change of temperature. The mathematical software Matlab is used to calculate the derived theoretical solution, and the finite element general software ANSYS is used to calculate the model under the same conditions. The feasibility of using ANSYS software to calculate the transient thermal structure coupling problem is verified. The hollow sphere model is divided into different mesh sizes, and the numerical solution is compared with the calculated analytical solution. When the mesh size is 1/5 of the thickness of the hollow sphere, The relative error of temperature and stress is about 5%. Because the structure of hollow sphere and arch dam have similar characteristics, the thickness of the bottom of arch dam to be calculated is the same size as the thickness of hollow sphere, so it can be considered that the mesh of the arch dam can be divided into more complex arch dams to provide the basis. The method of grid division in hollow sphere is extended to the arch dam. The thermal structure is directly coupled with the same element as the hollow sphere in ANSYS software, and the total strain energy of the dam structure is introduced. Through the stress analysis of the 12 month arch dam under the action of transient temperature load, it is obtained that the lowest temperature of the most unfavorable load lag is 1520 days in the temperature drop period, while in the temperature rise period, the maximum temperature lag of the most unfavorable load in the arch dam is 5-10 days. That is to say, the worst time of a high arch dam studied in this paper is from the beginning of February to February and from February to February and from 20 days to 25 days in July. The relationship between the maximum radial displacement of the dam body and the temperature is inversely correlated, the temperature increases, the maximum radial displacement decreases, the temperature decreases, and the maximum radial displacement of the dam body increases. Finally, by using the accuracy analysis of the numerical solution of finite element analysis, the accurate solution of strain energy is estimated. The relative error between the exact solution of the strain energy and the estimated strain energy obtained by the mesh division of the hollow sphere on the arch dam is extended to verify the feasibility of the mesh size of the hollow sphere in the arch dam.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV642.4;TV315

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