本文選題：復合材料層合板 + 黏彈性阻尼材料　； 參考：《南昌航空大學》2015年碩士論文

【摘要】：復合材料的一些突出優(yōu)點,如比剛度、比強度高,自由設計性好,這種“輕而強、輕而堅”的材料在先進飛行器結構中應用廣泛。復合材料結構在復雜的工作環(huán)境下會引發(fā)振動和噪聲,其結構的一些力學性能會嚴重受到影響。然而,復合材料在航空航天中的使用已然不可阻擋。為了改善結構產生的振動、噪聲,以阻尼耗能成為復合材料夾層結構減振降噪的有效措施。由于阻尼材料的加入,原有結構的強度、剛度會有所變化。充分利用復合材料性能的方向性、結構性能的自由設計性是復合材料結構設計的關鍵。論文對黏彈性復合材料結構進行優(yōu)化設計,以權衡該結構在實際應用中的力學性能和阻尼特性。遺傳算法,模仿生物遺傳和進化開發(fā)出的一種計算機模擬的概率搜索算法。相比其他優(yōu)化算法,有其獨特的優(yōu)勢,能較好地應用于復合材料結構的優(yōu)化設計。針對遺傳算法早熟、局部搜索效率低和尋優(yōu)時間較長等缺陷,論文第2章結合采樣選擇和保優(yōu)策略,對基本遺傳算法的適應度函數(shù)進行改進,提出了一種改進的乘冪適應度函數(shù)自適應遺傳算法。性能測試表明,改進的自適應遺傳算法在優(yōu)化速度、優(yōu)化穩(wěn)定性和優(yōu)化精度都有顯著的提高。分別利用經典板殼理論、剪切變形理論,論文第3章對復合材料層合板做動態(tài)非線性分析及優(yōu)化設計�；谔撐灰圃砑扒笞兎滞茖С鱿鄳恼駝涌刂品匠�,建立復合材料板的固有頻率計算模型。討論分析跨厚比、彈性模量比、纖維鋪設角等因素的影響。以纖維鋪設角為設計參數(shù),基頻最大為優(yōu)化目標,以改進的自適應遺傳算法對復合材料板進行優(yōu)化設計。優(yōu)化后,復合材料板的基頻增大,可以有效地降低其共振的概率�；陴椥詮秃喜牧辖Y構的層與層之間沒有相互錯動的假設,且是小撓度形變,可用復合材料層位移表示黏彈性阻尼層位移。論文第4章利用Hamilton原理及求變分推導出結構的振動控制方程,建立固有頻率和結構損耗因子的計算模型。將結構損耗因子最大作為優(yōu)化目標,以改進的自適應遺傳算法進行優(yōu)化設計。優(yōu)化結果表明,通過對纖維鋪設角、黏彈性阻尼材料與復合材料的剪切模量比以及黏彈性阻尼層與復合材料層的厚度比的設計,增大了黏彈性復合材料結構的損耗因子,從而提高了結構阻尼減振降噪的性能。論文第5章簡要介紹了多目標優(yōu)化問題,利用Tsai-Hill強度理論建立黏彈性復合材料結構的強度計算模型。顯然,合理地權衡黏彈性復合材料結構的力學性能與阻尼特性才符合實際應用的需求。該章通過遺傳算法中的權重系數(shù)變換法建立黏彈性復合材料結構的阻尼與強度雙目標優(yōu)化模型,以改進的自適應遺傳算法對結構的阻尼-強度進行雙目標優(yōu)化設計,優(yōu)化結果令人滿意。
[Abstract]:Some outstanding advantages of composite materials, such as specific stiffness, high specific strength, good free design, this kind of "light and strong, light and solid" materials are widely used in advanced aircraft structures. Composite structures can cause vibration and noise in complex working environment, and some mechanical properties of composite structures will be seriously affected. However, the use of composite materials in aerospace is unstoppable. In order to improve the vibration and noise caused by the structure, damping energy dissipation has become an effective measure to reduce vibration and noise of composite sandwich structure. With the addition of damping material, the strength and stiffness of the original structure will change. Making full use of the directionality of composite properties and the free design of structural properties is the key to the structural design of composite materials. In order to balance the mechanical properties and damping characteristics of viscoelastic composite structure in practical application, the optimization design of viscoelastic composite structure is carried out in this paper. Genetic algorithm, a computer simulated probabilistic search algorithm developed to mimic biological genetics and evolution. Compared with other optimization algorithms, it has its unique advantages and can be applied to the optimization design of composite structures. Aiming at the defects of genetic algorithm, such as precocity, low local search efficiency and long searching time, chapter 2 improves the fitness function of basic genetic algorithm by combining sampling selection and optimal preservation strategy. An improved adaptive genetic algorithm for power fitness function is proposed. The performance tests show that the improved adaptive genetic algorithm can improve the speed, stability and precision of optimization. Using classical plate and shell theory and shear deformation theory, the dynamic nonlinear analysis and optimization design of composite laminated plates are made in chapter 3. Based on the principle of virtual displacement and variation, the corresponding vibration control equation is derived, and the natural frequency calculation model of composite plate is established. The effects of span thickness ratio, elastic modulus ratio and fiber laying angle are discussed. With the fiber laying angle as the design parameter and the maximum fundamental frequency as the optimization objective, the improved adaptive genetic algorithm is used to optimize the design of composite plate. After optimization, the fundamental frequency of composite plate increases, which can effectively reduce the probability of resonance. Based on the assumption that there is no interaction between layers and layers of viscoelastic composite structures, and the deformation is small deflection, the displacement of viscoelastic damping layer can be expressed by the displacement of composite layer. In chapter 4, the vibration control equation of the structure is derived by using the Hamilton principle and the variational method, and the calculation model of the natural frequency and the loss factor of the structure is established. The maximum loss factor of the structure is taken as the optimization objective, and the improved adaptive genetic algorithm is used to optimize the design. The optimized results show that the loss factor of viscoelastic composite structure is increased by the design of fiber laying angle, shear modulus ratio of viscoelastic damping material to composite material and thickness ratio of viscoelastic damping layer to composite layer. Thus, the performance of damping vibration and noise reduction is improved. In chapter 5, the multi-objective optimization problem is briefly introduced, and the strength calculation model of viscoelastic composite structures is established by using Tsai-Hill strength theory. It is obvious that the mechanical properties and damping properties of viscoelastic composite structures can meet the requirements of practical application. In this chapter, the double objective optimization model of damping and strength of viscoelastic composite structures is established by the weight coefficient transformation method of genetic algorithm, and the modified adaptive genetic algorithm is used to optimize the damping strength of structures. The optimization results are satisfactory.
【學位授予單位】：南昌航空大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：V214.8

【參考文獻】

相關期刊論文 前1條

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本文編號：1900324