【作者】 李昊；

【导师】 杜善义； 戴福洪；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2015， 博士

【摘要】 先进复合材料由于其高比强度、高比刚度、耐腐蚀、耐疲劳和可设计性等优点,在航空航天领域内得到了广泛的运用。通常情况下,复合材料层板采用对称铺层以避免产生固化变形。然而,随着复合材料应用领域的拓展,复合材料层板的固化变形在特殊的应用背景下将有可能得到充分利用。双稳定层板是一种在内部残余热应力的作用下产生较大的固化变形,并具有两种稳定构型的复合材料结构。双稳定层板无需持续的能量来维持其稳定构型,并且在外力的驱动下能够发生构型转变并实现大变形,同时,双稳定层板在构型转变的过程中发生跳变现象并显示出负刚度特性。双稳定层板的双稳定特性和非线性特性,使其在可变形结构以及能量收集领域具有良好的应用前景。本文对双稳定层板进行了系统地研究,研究内容包括双稳定层板的构型预报和分叉行为分析、新型的混杂双稳定层板的设计、基于双稳定层板的多稳定结构、双稳定层板的新型热驱动方法、双稳定层板的动力学特性以及双稳定宽频能量收集系统。本文在层板的几何方程中引入冯卡门非线性项,并考虑非对称层板的拉弯耦合对中心面应变的影响,建立了基于多项式位移函数的6阶构型预测理论模型。当双稳定层板的尺寸较大时,基于多项式位移函数的构型预测模型具有较大误差。因此,建立了饱和曲率模型以预测大尺寸双稳定层板的稳定构型。利用理论模型和有限元方法,分析了层板的长宽比、厚度和尺寸对其分叉行为的影响,并预测了双稳定层板的双稳定临界尺寸以及中心点跳变临界载荷。通过在复合材料层板中的不同位置混杂金属层,提出了[0/90/Metal]混杂双稳定层板和混杂对称双稳定层板。建立了[0/90/Metal]层板的构型预测模型,预报并分析了层板尺寸、金属层厚度、金属层与复合材料层之间的滑移以及吸湿效应对[0/90/Metal]混杂双稳定层板的双稳定特性的影响。建立了对称混杂双稳定层板的9参数理论模型,并采用有限元方法和理论模型分析了几何参数和材料参数对混杂对称双稳定层板的稳定构型的影响。采用有限元方法研究了混杂对称双稳定层板在不同边界条件和载荷作用下的变形特性。提出了基于双稳定层板的多稳定格子结构。利用实验和有限元方法分析了多稳定格子结构中的机械连接对其跳变临界载荷的影响。研究了多稳定格子结构中格子结构单元的排列方式对其稳定构型的影响,并对多稳定格子结构的变形特性进行了有限元分析。在多稳定格子结构的基础上,构建了多稳定蒙皮结构,并采用实验和有限元方法分析了蒙皮结构的跳变临界载荷。提出了非对称双稳定层板的加热驱动方法,通过加热改变双稳定层板的局部残余应力进而驱动双稳定层板发生构型转变。针对不同形状和厚度的非对称双稳定层板,提出了两种加热策略,并进行了实验验证。利用有限元方法分析了加热驱动法的适用范围,结果显示加热驱动法能有效的驱动不同尺寸和厚度的非对称双稳定层板发生构型转变。基于加热驱动法,在层板的内部埋入电热材料,设计了单向和双向跳变的热驱动双稳定层板,并对其进行了实验验证和有限元分析。基于哈密顿原理,建立了非对称双稳定层板的动力学理论模型,采用理论模型和实验研究了非对称双稳定层板在一阶固有频率附近的动力学响应。建立了混杂对称双稳定层板的有限元模型,采用隐式动力学法和实验研究了混杂对称双稳定层板在其第一阶和第二阶固有频率附近的动力学响应。研究结果表明双稳定层板在振动过程中将出现刚度软化现象,当层板发生整体跳变或局部跳变时,其振动模式将从稳定的s ingle-well振动变为无规律的cross-well振动。设计了采用矩形非对称双稳定层板作为载体结构的宽频能量收集系统,利用矩形非对称双稳定层板基于其二阶模态的非线性振动带动压电陶瓷进行发电。通过实验研究了双稳定能量收集系统的振动模式,并测量了不同振动模式所需的激励加速度和对应的能量输出功率。采用有限元方法分析了双稳定能量收集系统的静力学非线性特性,并分析其非线性特性对其振动模式的影响。最后提出了双稳定压电能量收集系统的优化方案,并采用有限元方法对优化方案进行了验证。更多还原

【Abstract】 Advanced composite materials are widely applied in aerospace structures, due to their high specific strength, high specific stiffness, corrosion resistance and fatigue resistance. In general, laminated composite are designed to be symmetric to decrease the curing deformation. However, as the application range of composite materials is expanding, in the future it is possible to take advantage of the curing deformation of laminated composites in certain circumstance.Bistable composite laminates are laminated composite structures have two stable configurations, and are able to transform between stable configurations under external load, while no energy is needed to maintain the stable configuration. The bistability and nonlinear characteristics make bistable laminates be potential in application on morphing structures, energy harvesting and nonlinear vibration isolation. In this thesis a systematic study on the bistable laminates is conducted. The research contents including the configuration prediction and bifurcation analysis of bistable laminates, new hybrid bistable laminates, the heating actuation method, the dynamic characteristics of bistable laminates, the broadband vibration energy harvesting system based on bistable laminates and multistable structures based on bistable laminates.Using Rayleigh-Ritz method, the sixth-order theoretical shape prediction model is established. The influence of bending-stretching coupling on the mid-plane strains is considered in the theoretical model. For laminates with relative large sizes, saturated curvature model is established. Using theoretical model and finite element method, systematic parametric analyses are conducted to investigate the influences of aspect ratio, ply thickness and laminate size, on the bifurcation phenomenon of bistable laminates. Critical bistable dimensions and critical central load are predicted. The parametric analyses show the design space of bistable laminates.Novel hybrid bistable laminates are put forward and analyzed. By adding mental ply on the surface of cross-ply laminates, the two stable configurations of the [0/90/Al] bistable laminate curls to the same side. Using sixth-order theoretical model with 25 unknown parameters, the influence of dimensions, the slippery between mental ply and composite ply, and the moisture effect on [0/90/Al] laminates are investigated. By adding mental ply in the symmetric laminates, the novel hybrid symmetric bistable laminates(HSBL) are put forward. The two stable configurations of a HSBL curls in the same direction, and have identical curvatures with opposite signs. Theoretical shape prediction model with 9 unknown parameters is established. The design space of HSBL is investigated using the 9-parameter model and finite element method. The nonlinearity of HSBL under different boundary conditions is investigated by finite element method.A multi-stable lattice structure and a multi-stable wavy skin based on bistable laminates are developed. The multi-stable lattice structure consists of tri-stable lattice cell, which is assembled by 4 pieces of bistable laminates. The stability of tri-stable lattice cell is experimentally and numerically investigated. The influence of cell arrangement on the stable configurations of the multi-stable lattice structure is investigated. The snap-through processes among multiple states are simulated using finite element method. The results show a good correlation and give an intuitive understanding of multiple snap-through behavior. The feature highlights its potential application in morphing structures.A novel heating actuation method is put forward and verified. The heating actuation method changes the stability and the stable configurations of bistable laminates, by elevating the temperature of local area on the laminates. Two heating strategies are developed for bistable laminates of different shapes and different thicknesses. The heating actuation method is verified in experiments, and its adaptability is verified by finite element method. By embedding the electro-thermal material into bistable laminates, the thermal-driven bistable laminates(TDBL) are put forward. Two TDBLs are manufactured and verified. The experimental morphing processes of two TDBLs are compared with the simulated process, and good agreement between experiments and predictions are found.Theoretical kinetic model of unsymmetric bistable laminates is established. Experimental and theoretical studies on dynamic responses of four unsymmetric bistable laminates around the first vibration mode are conducted. The dynamic responses of two hybrid symmetric bistable laminates around the first and the second vibration modes are investigated by experiment and FEA. Results show that bistable laminates show soften stiffness in oscillation, and have two fundamental oscillation patterns including the single-well oscillation and cross-well oscillation. A bistable broadband vibration energy harvesting system is developed and analyzed. A rectangular bistable laminate is employed as the support structure of PZT. By exploiting the nonlinear oscillations around the second vibration mode, the bistable energy harvesting system(BEHS) is able to achieve broadband vibration energy harvesting at relative higher frequencies. The broadband characteristics and the considerable energy conversion efficiency of the BEHS are demonstrated in experiments. The static nonlinearity and the dynamic responses of the BEHS are investigated by finite element method. The optimization method of the BEHS is discussed and verified by finite element method.更多还原