發(fā)布時(shí)間：2018-04-07 19:11

  本文選題：阻尼結(jié)構(gòu)　切入點(diǎn)：減振特性　出處：《南昌航空大學(xué)》2016年碩士論文

【摘要】：阻尼結(jié)構(gòu)減振是一種實(shí)用的、有效的被動(dòng)控制減振技術(shù),而黏附粘彈性阻尼材料是一種常用的方式。在一些對(duì)產(chǎn)品性能要求較高或近乎苛刻的行業(yè)領(lǐng)域,如航空航天、武器裝備等,對(duì)附加減振阻尼材料勢(shì)必提出更高的動(dòng)力學(xué)特性要求。研究阻尼結(jié)構(gòu)的振動(dòng)特性和減振最優(yōu),必然顯得尤為重要。本文重點(diǎn)研究了在動(dòng)力學(xué)方面阻尼結(jié)構(gòu)減振特性和阻尼材料的拓?fù)鋬?yōu)化方法。構(gòu)建阻尼結(jié)構(gòu)的動(dòng)力學(xué)有限元模型是研究工作展開的基礎(chǔ)�？紤]到阻尼材料的粘貼厚度與長(zhǎng)寬相差較多的數(shù)量級(jí),一般地呈現(xiàn)薄板殼結(jié)構(gòu)的特性,進(jìn)而引入了阻尼結(jié)構(gòu)層與層之間位移場(chǎng)的連續(xù)性。在此基礎(chǔ)上,給出了位移場(chǎng)方程并據(jù)此建立了結(jié)構(gòu)的動(dòng)力學(xué)分析有限元模型理論。基于ANSYS二次開發(fā)編程語(yǔ)言對(duì)模型進(jìn)行求解并利用實(shí)驗(yàn)數(shù)據(jù)和解析數(shù)據(jù)驗(yàn)證了該模型的有效性,為后續(xù)研究拓?fù)鋭?dòng)力學(xué)迭代優(yōu)化提供了計(jì)算基礎(chǔ)。從微分角度,研究不同體積、不同位置的阻尼材料作用于結(jié)構(gòu)減振時(shí)帶來的利弊,形成對(duì)阻尼材料應(yīng)用拓?fù)鋬?yōu)化的構(gòu)想。將靜力學(xué)中研究應(yīng)用成熟的變密度法拓展至動(dòng)力學(xué)領(lǐng)域。以阻尼材料用量、振動(dòng)特征方程、模態(tài)頻率為約束,以多模態(tài)損耗因子倒數(shù)加權(quán)和最小為目標(biāo),建立阻尼結(jié)構(gòu)拓?fù)鋬?yōu)化模型,并引入MAC因子控制結(jié)構(gòu)的振型以避免躍階。在引入質(zhì)量陣懲罰因子基礎(chǔ)上,推導(dǎo)出優(yōu)化目標(biāo)靈敏度。在接下來的仿真中,發(fā)現(xiàn)了靈敏度數(shù)值的正負(fù)性不統(tǒng)一影響優(yōu)化迭代格未更新每一個(gè)設(shè)計(jì)變量,分析了產(chǎn)生不連續(xù)尋優(yōu)的根本原因。鑒于考慮目標(biāo)函數(shù)的非凸性,而采用常規(guī)優(yōu)化準(zhǔn)則法(OC)則尋優(yōu)可能會(huì)使拓?fù)渥兞砍霈F(xiàn)負(fù)值或陷入局部?jī)?yōu)化解,故引入數(shù)學(xué)規(guī)劃移動(dòng)漸近技術(shù)對(duì)OC法進(jìn)行改進(jìn),從而將全體拓?fù)渥兞考{入改進(jìn)算法的優(yōu)化迭代過程,演算了其數(shù)學(xué)推導(dǎo)過程,提出∞-范數(shù)的概念。編程實(shí)現(xiàn)了阻尼結(jié)構(gòu)改進(jìn)OC法拓?fù)鋭?dòng)力學(xué)優(yōu)化并對(duì)改進(jìn)算法性能進(jìn)行了仿真。應(yīng)用本文研究的減振有限元模型和改進(jìn)算法理論,仿真常見的阻尼結(jié)構(gòu),并從單模態(tài)和多模態(tài)以及諧響應(yīng)特性分析方面給予了優(yōu)化結(jié)果數(shù)據(jù)分析展示。研究結(jié)果表明,引入層層位移場(chǎng)連續(xù)的有限元模型具有較高的精度,阻尼材料使用量50%-80%時(shí)減振效果較好以及粘貼在應(yīng)變最大處減振最佳,優(yōu)化中自由結(jié)構(gòu)的模態(tài)損耗因子均有所下降而約束阻尼結(jié)構(gòu)有一定的增加。在對(duì)OC法優(yōu)化的對(duì)比分析中,改進(jìn)算法迭代穩(wěn)定性更好、尋優(yōu)效率更高、更具全域最優(yōu)性。諧響應(yīng)分析進(jìn)一步說明了多模態(tài)優(yōu)化的改進(jìn)算法更能較好地抑制共峰幅值。
[Abstract]:Damping structure is a practical and effective passive damping technique, and adhesion to viscoelastic damping material is a common method.In some industries, such as aeronautics and astronautics, weaponry and so on, it is necessary to require higher dynamic characteristics of additional damping materials.It is necessary to study the vibration characteristics and optimal damping of damped structures.In this paper, the damping characteristics of damped structures and the topology optimization method of damping materials are studied.The dynamic finite element model of damping structure is the foundation of the research work.Considering the order of magnitude between the thickness and width of damping material, the characteristics of thin shell structure are generally presented, and the continuity of displacement field between layers of damping structure is introduced.On this basis, the displacement field equation is given and the finite element model theory of the dynamic analysis of the structure is established.The model is solved based on ANSYS secondary programming language, and the validity of the model is verified by experimental data and analytical data, which provides a computational basis for further research on topology dynamics iterative optimization.In this paper, the advantages and disadvantages of damping materials with different volume and position are studied from the differential point of view, and the idea of topology optimization of damping materials is formed.The application of the mature variable density method in statics is extended to the field of dynamics.Taking damping material dosage, vibration characteristic equation and modal frequency as constraints, and taking the inverse weighted sum of multi-mode loss factor as the objective, the topology optimization model of damping structure is established, and the mode shape of the structure controlled by MAC factor is introduced to avoid the jump step.On the basis of introducing the penalty factor of mass matrix, the sensitivity of optimization target is deduced.In the next simulation, it is found that the negative and positive sensitivity values affect the optimization of the iterative lattice without updating every design variable, and the fundamental reasons for the discontinuous optimization are analyzed.Considering the non-convexity of the objective function and using the conventional optimization criterion (OC), the optimization may lead to negative value of topological variables or fall into local optimal solution, so the moving asymptotic technique of mathematical programming is introduced to improve the OC method.Thus, all topological variables are incorporated into the optimization iteration process of the improved algorithm, the mathematical derivation process is calculated, and the concept of 鈭，

本文編號(hào)：1720506