【摘要】：自由曲面結(jié)構(gòu)作為一種新穎又美觀的結(jié)構(gòu)形式逐漸地成為了結(jié)構(gòu)形態(tài)學(xué)研究的主要對(duì)象。自由曲面網(wǎng)殼結(jié)構(gòu)作為當(dāng)代空間結(jié)構(gòu)發(fā)展的一種新趨勢(shì),對(duì)其進(jìn)行更深入的創(chuàng)構(gòu)研究是不可或缺的。本文基于遺傳算法對(duì)自由曲面網(wǎng)殼結(jié)構(gòu)進(jìn)行了形態(tài)創(chuàng)構(gòu)方法的研究。闡述了遺傳算法的基本原理和一些遺傳算法的高級(jí)實(shí)現(xiàn)方法,建立了基于遺傳算法的自由曲面網(wǎng)殼結(jié)構(gòu)的形態(tài)創(chuàng)構(gòu)思路:首先,根據(jù)Loop網(wǎng)格細(xì)分法建立合理的自由曲面并通過完善生成自由曲面網(wǎng)殼結(jié)構(gòu)的基結(jié)構(gòu),然后,采用遺傳算法對(duì)基結(jié)構(gòu)進(jìn)行拓?fù)浜统叽鐑?yōu)化,對(duì)得到的優(yōu)化結(jié)果采用類模擬退火算法進(jìn)行改進(jìn)和完善。最后,采用敏感度解析法對(duì)最終優(yōu)化結(jié)構(gòu)進(jìn)行節(jié)點(diǎn)移動(dòng),完成結(jié)構(gòu)的形狀優(yōu)化。拓?fù)鋬?yōu)化時(shí),對(duì)穩(wěn)定的三角單元進(jìn)行編碼,采用二進(jìn)制0-1編碼的方式表示存在或者不存在;尺寸優(yōu)化時(shí),建立包含不同截面尺寸的截面表,結(jié)構(gòu)中的每根桿件的截面編碼值對(duì)應(yīng)于截面表中相應(yīng)的截面編號(hào),采用整數(shù)編碼的方式;形狀優(yōu)化時(shí),采用敏感度解析法對(duì)節(jié)點(diǎn)進(jìn)行移動(dòng),可以只移動(dòng)z坐標(biāo),也可以同時(shí)移動(dòng)x、y和z坐標(biāo)。本文基于遺傳算法并結(jié)合多種優(yōu)化方法對(duì)自由曲面網(wǎng)殼結(jié)構(gòu)進(jìn)行優(yōu)化,既彌補(bǔ)了遺傳算法局部搜索能力較差的弱點(diǎn),又提高了求解效率。優(yōu)化過程中提出了解碼之后的結(jié)構(gòu)中存在問題的處理方法和桿件自重荷載與均布荷載的等效轉(zhuǎn)換措施。包括:必須存在的支座節(jié)點(diǎn)和加載點(diǎn)都存在的處理方法;結(jié)構(gòu)中沒有獨(dú)立桿件團(tuán)的處理方法,確保不會(huì)生成剛度矩陣奇異的機(jī)構(gòu)。結(jié)構(gòu)受均布荷載作用時(shí),將結(jié)構(gòu)的平面投影分成許多細(xì)小的正方形,均布荷載乘以小正方形的面積轉(zhuǎn)換成集中荷載作用于小正方形的幾何形心上,最后分配到距離其最近的節(jié)點(diǎn)上。當(dāng)結(jié)構(gòu)不滿足材料強(qiáng)度、桿件長細(xì)比、構(gòu)件穩(wěn)定性和節(jié)點(diǎn)最大位移等約束條件時(shí),采用罰函數(shù)法進(jìn)行處理。在優(yōu)化目標(biāo)選取上,本文選取的兩個(gè)優(yōu)化目標(biāo)分別是結(jié)構(gòu)的質(zhì)量最小和結(jié)構(gòu)的質(zhì)量與外力功乘積最小,通過算例分析和比較說明各自的優(yōu)劣。并通過多個(gè)算例得到了受力性能良好而且新穎美觀的結(jié)構(gòu),說明本文提出的形態(tài)創(chuàng)構(gòu)方法的可行性和實(shí)用性。
[Abstract]:As a novel and beautiful structural form, free-form surface structure has gradually become the main object of structural morphology research. As a new trend of the development of the contemporary space structure, it is indispensable to study the free surface latticed shell structure more deeply. In this paper, the morphological method of free-form surface reticulated shell is studied based on genetic algorithm. The basic principles of genetic algorithm and some advanced implementation methods of genetic algorithm are described. The shape creation of free-form surface reticulated shell structure based on genetic algorithm is established. According to the Loop mesh subdivision method, a reasonable free form surface is established and the base structure of the free surface latticed shell structure is generated by perfecting it. Then, the topology and size of the base structure are optimized by genetic algorithm. The optimization results are improved and improved by using simulated annealing algorithm. Finally, the sensitivity analysis method is used to realize the shape optimization of the structure by moving the nodes to the final optimization structure. In topology optimization, the stable triangular units are encoded and binary 0-1 coding is used to indicate the existence or non-existence. When the size is optimized, a cross-section table containing different cross-section sizes is established. The cross-section coding value of each member in the structure corresponds to the corresponding section number in the cross-section table, and the method of integer coding is adopted. When the shape is optimized, the sensitivity analysis method is used to move the node, which can only move z coordinate, but also move xy and z coordinate simultaneously. In this paper, based on genetic algorithm and combined with various optimization methods, the free-form surface reticulated shell structure is optimized, which not only makes up for the weakness of the local search ability of genetic algorithm, but also improves the efficiency of solving the problem. In the process of optimization, the methods to deal with the problems existing in the decoded structure and the equivalent conversion measures between the deadweight load and the uniform load of the members are proposed. It includes: the processing method of supporting node and loading point that must exist, and the processing method of independent member cluster in the structure to ensure that the mechanism with singular stiffness matrix will not be generated. When the structure is subjected to uniform load, the plane projection of the structure is divided into many small squares. The uniform load multiplied by the area of the small square is converted into a concentrated load acting on the geometric center of the small square. Finally, it is assigned to the nearest node. The penalty function method is used when the structure does not satisfy the constraint conditions such as material strength, the aspect ratio of the members, the stability of the members and the maximum displacement of the joints. In the selection of optimization objectives, the two optimization objectives selected in this paper are the minimum quality of the structure and the minimum product of the mass of the structure and the product of the external force. The advantages and disadvantages of the two optimization objectives are illustrated through the analysis and comparison of the numerical examples. A novel and beautiful structure with good mechanical performance is obtained through several examples, which shows the feasibility and practicability of the proposed method.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU399

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本文編號(hào)：2353805