本文選題：改進遺傳算法　切入點：FRP梁板結(jié)構(gòu)　出處：《武漢理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：本課題來源于中央高�；究蒲袠I(yè)務費專項資金資助“基于自適應混合遺傳算法的復合材料及結(jié)構(gòu)損傷反演研究”(項目號2014-Ia-036)。本學位論文基于應變模態(tài)對復合材料層合梁板進行剛度識別:正問題計算借助于ANSYS有限元計算軟件、反問題計算利用MATLAB軟件編寫的改進遺傳算法,對FRP梁板結(jié)構(gòu)進行單元剛度識別。利用單純型搜索結(jié)合自編自適應遺傳算法的方式來加快收斂的速度和改善易陷入局部最優(yōu)解的缺點。具體的研究內(nèi)容如下:1、對有損懸臂梁結(jié)構(gòu)進行應變模態(tài)理論公式推導,并且對懸臂樹脂基玻璃纖維增強復合材料(FRP)層合梁結(jié)構(gòu)進行應變模態(tài)實驗,懸臂梁某處粘貼質(zhì)量塊以模擬剛度變化(損傷程度用剛度變化來表征);對有損和無損兩種工況進行單元剛度識別研究,并檢驗識別結(jié)果的準確性。實驗結(jié)果表明應變模態(tài)對單元損傷靈敏度高,能準確反映損傷位置。利用改進遺傳算法對單元剛度的識別結(jié)果與有限元模擬實驗吻合度高。2、對懸臂樹脂基玻璃纖維增強復合材料層合板結(jié)構(gòu)進行應變模態(tài)試驗,獲取其縱向方向的應變模態(tài),并以實驗數(shù)據(jù)為基礎進行縱向剛度識別。對比研究改進自適應遺傳算法和普通自適應遺傳算法的識別性能,并研究單元尺寸對識別結(jié)果的影響。研究表明以實驗模態(tài)為基礎進行的識別,改進遺傳算法識別的準確度更高,需要迭代的次數(shù)也較普通遺傳算法少。減小識別單元的尺寸,能有效的提高識別的準確度,但是在工程中需要花費更多的工程量,才能獲取全局的剛度信息。3、對懸臂樹脂基玻璃纖維增強復合材料層合板結(jié)構(gòu)進行有限元數(shù)值模擬實驗,計算應變模態(tài);在此基礎上對板的縱橫剛度進行識別。選取其中某些單元進行橫向和縱向的剛度折減,以縱向和45°方向的應變模態(tài)為基礎進行剛度識別研究。對識別結(jié)果進行對比研究,并討論靈敏度對識別效果的影響。并通過對不同位置,不同程度的損傷識別,檢驗識別方法的實用性和可行性。研究發(fā)現(xiàn)以45°一階應變模態(tài)為基礎,識別的效果最佳,而且采用的應變模態(tài)對單元剛度的改變越敏感,識別效果越好。以45°方向一階應變模態(tài)為基礎對不同位置不同程度的損傷識別可以得到理想的識別結(jié)果。且損傷位置的多少對識別迭代速度和結(jié)果的精度無絕對關系。
[Abstract]:This topic comes from the central university basic scientific research business expense special fund to fund "the composite material and the structure damage inversion research based on the adaptive hybrid genetic algorithm" (project number 2014-Ia-036A). This dissertation is based on the strain mode to the composite material. Stiffness identification of laminated beams and plates: the forward problem is calculated with the help of ANSYS finite element software. Inverse problem calculation is based on the improved genetic algorithm written by MATLAB software. The element stiffness of FRP beam-plate structure is identified. The simplex search method combined with self-made adaptive genetic algorithm is used to accelerate the convergence speed and improve the disadvantage of falling into the local optimal solution easily. The specific research contents are as follows: 1. The theoretical formula of strain mode is derived for the structure of lossy cantilever beam. And the strain mode experiment of the cantilever resin matrix glass fiber reinforced composite (FRP) laminated beam structure was carried out. A mass block attached to a cantilever beam is used to simulate the change of stiffness (the degree of damage is characterized by the change of stiffness). The experimental results show that the strain mode is sensitive to the damage of the element. The result of identification of element stiffness by improved genetic algorithm is in good agreement with finite element simulation experiment. Strain mode test of cantilever resin matrix glass fiber reinforced composite laminated plate structure is carried out. The longitudinal strain modes are obtained, and the longitudinal stiffness is identified based on the experimental data. The performance of improved adaptive genetic algorithm (AGA) and conventional adaptive genetic algorithm (AGA) is compared. The effect of unit size on the recognition results is also studied. It is shown that the improved genetic algorithm has higher accuracy and less iterations than the common genetic algorithm, and reduces the size of the recognition unit. It can effectively improve the accuracy of identification, but it needs more engineering cost in engineering to obtain global stiffness information. The finite element numerical simulation experiment of cantilever resin matrix glass fiber reinforced composite laminated plate structure is carried out. The strain mode is calculated. On this basis, the longitudinal and horizontal stiffness of the plate is identified. Some of the elements are selected to reduce the transverse and longitudinal stiffness. Stiffness identification is carried out on the basis of longitudinal and 45 擄strain modes. The results of identification are compared, and the influence of sensitivity on the recognition effect is discussed. The practicability and feasibility of the identification method are tested. It is found that based on the 45 擄first-order strain mode, the best result is obtained, and the more sensitive the strain mode is to the change of element stiffness, The better the recognition effect is, the better the result is. Based on the first-order strain mode of 45 擄direction, we can obtain the ideal identification results for different positions and different degrees of damage, and there is no absolute relation between the number of the damage location and the accuracy of the identification iterative speed and the result.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB33;TP18

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