温度对反对称铺设圆柱壳结构的双稳态特性的影响研究

发布时间：2018-12-24 14:04

【摘要】：反对称铺设复合材料圆柱壳结构具有两种不同稳定状态,可以通过机械载荷、智能材料或者温度场等外在驱动方式进行稳态之间的转变,因此被称为双稳态复合材料结构(Bi-stable Composite Structure)。双稳态复合材料结构具有轻质、承载能力优异以及可变形等特点,在航空航天的可变形机构和风力发动机叶片等诸多领域具有广泛的应用前景。当双稳态复合材料结构处于各种复杂的、极端的工作环境时,温度对结构的双稳态特性影响较大。目前,对于温度影响下反对称铺设圆柱壳结构的研究较少,限制了其在实际应用中的发展。本文采用理论推导、实验测试和有限元模拟等方法,研究了温度对反对称铺设圆柱壳结构的双稳态特性影响机理,得到了环境温度(整体温度场)、局部温度场以及温度梯度影响下圆柱壳稳态间相互转变过程、突变载荷和变形情况,并利用温度影响规律对结构变形进行了主动调控。最后,从宏观、微观角度对热暴露下双稳态结构变形特性进行了讨论和解释。主要研究内容和成果如下:1.在经典层合板理论的基础上,利用最小势能原理推导了温度影响下的反对称铺设圆柱壳结构的双稳态理论模型。在理论上预测了包括整体温度场和温度梯度的变化对反对称铺设圆柱壳结构的曲率的影响规律,并讨论了影响扭曲率变化的因素。2.采用实验方法,利用经改装的带有温控箱的拉伸试验机测试平台和自主研发的数字图像处理技术,得到温度影响下的反对称铺设圆柱壳结构的双稳态特性的变化规律。研究表明:整体温度场温度的增加会导致圆柱壳各个曲率都发生相应的增加;第一稳态转变到第二稳态的突变载荷不断减小,第二稳态回复到第一稳态的突变载荷反而有所增加;当在圆柱壳局部区域加热时,对结构的稳态转变过程以及曲率产生影响。3.通过有限元软件模拟了整体温度场、局部温度场以及温度梯度影响下反对称铺设圆柱壳结构的双稳态特性的变化情况,得到包括稳态转变过程的载荷—位移曲线以及两个稳态的曲率变化规律,计算结果与理论和实验结果较符合。温度梯度影响下的圆柱壳曲率变化特性的模拟结果表明:可以通过在圆柱壳上施加负方向的温度梯度来抑制由整体温度场导致的圆柱壳扭转变形的情况。4.利用恒温箱和拉伸试验机等实验测试平台,获得了不同温度、不同暴露时间后反对称铺设圆柱壳结构的双稳态特性的变化情况。通过热暴露实验,得到了宏观尺度下稳态转变、曲率变化和微观尺度下碳纤维、树脂基底的变化情况。
[Abstract]:The antisymmetric composite cylindrical shell structure has two different stable states, which can be changed between steady state by mechanical load, intelligent material or temperature field, etc. So it's called bistable composite structure (Bi-stable Composite Structure). Bistable composite structures have many advantages such as light weight, excellent load-carrying capacity and deformability. They are widely used in many fields, such as deformable mechanism of aeronautics and astronautics and blade of wind turbine. When the bistable composite structures are in various complex and extreme working environments, the bistable properties of the structures are greatly affected by temperature. At present, there is little research on antisymmetric cylindrical shell structure under the influence of temperature, which limits its development in practical application. In this paper, the influence mechanism of temperature on bistable characteristics of antisymmetric cylindrical shell structure is studied by means of theoretical derivation, experimental test and finite element simulation, and the ambient temperature (integral temperature field) is obtained. Under the influence of local temperature field and temperature gradient, the steady state transformation process, sudden load and deformation of cylindrical shell are studied. Finally, the deformation characteristics of bistable structures under thermal exposure are discussed and explained from macroscopic and microscopic perspectives. The main contents and results are as follows: 1. Based on the classical laminated plate theory, the bistable theoretical model of antisymmetric cylindrical shell structure under the influence of temperature is derived by using the principle of minimum potential energy. The influence of temperature field and temperature gradient on the curvature of antisymmetric cylindrical shell is predicted theoretically, and the factors influencing the distortion rate are discussed. 2. By means of the experimental method, the bistable characteristics of the antisymmetric cylindrical shell structure under the influence of temperature are obtained by using the test platform of the modified tensile testing machine with the temperature control box and the digital image processing technology developed by ourselves. The results show that the increase of the temperature of the whole temperature field will result in the corresponding increase of the curvature of the cylindrical shell. The sudden load from the first steady state to the second steady state decreases, while the second steady state returning to the first steady state increases. When heated in the local region of the cylindrical shell, the steady state transformation process and curvature of the structure are affected. 3. 3. The change of bistable characteristics of antisymmetric cylindrical shell structure under the influence of temperature gradient and the whole temperature field, local temperature field and temperature gradient are simulated by finite element software. The load-displacement curves including the steady state transition process and the curvature variation laws of the two steady states are obtained. The calculated results are in good agreement with the theoretical and experimental results. The simulation results show that the torsional deformation of cylindrical shell caused by the whole temperature field can be restrained by applying negative temperature gradient to the cylindrical shell under the influence of temperature gradient. The change of bistable characteristics of antisymmetric cylindrical shell structure with different temperature and different exposure time was obtained by means of an experimental test platform such as a constant temperature box and a tensile testing machine. The steady state transition, curvature change and carbon fiber and resin substrate change at macro scale and micro scale were obtained by thermal exposure experiment.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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