舰船功能梯度石墨烯增强复合材料构件非线性行为和动力特性多尺度建模与分析

Functionally graded materials (FGMs) are a new generation of composite materials in which the microstructural details are spatially varied through non-uniform distribution of the reinforcement phase. Two kinds of FGMs are designed to improve mechanical behavior of beam/plate/shell structures. One is the functionally graded particles reinforced composite, like functionally graded ceramic-metal materials. Another one is the functionally graded unidirectional fibers reinforced composite. Graphene is the lightest and strongest two dimensional material that has been under the spotlight in the nanoworld. The concept of functionally graded material can also be utilized for the graphene-reinforced composite (RRC) by non-homogeneous distribution of reinforcing filler into the matrix with a piece-wise laminated type by volume fraction or weight fraction, so that the mechanical behavior of laminated beam/plate/shell structures can be improved. Like the functionally graded ceramic-metal materials, the material properties of functionally graded GRCs may be dependent of temperature..We propose a multi-scale approach to model and analysis the nonlinear bending, postbuckling behaviors and nonlinear dynamic responses of FG-GRC beam/plate/shell structures. From which the material properties of GRCs are estimated based on the extended Halpin-Tsai micromechanical model and the governing equations of beam/plate/shell structures are formulated based on the higher order shear deformation theory. The novel contribution of the present work is that both material property gradient and temperature-dependent material properties are taken into consideration in the nonlinear analyses. Numerical examples are carried out for different geometric and physical parameters and loading conditions, e.g. mechanical, thermal and their combination. The results presented explore for the first time the important issue of FG-GRC beam/plate/shell structures, and thus are greatly helpful to understanding for engineering design.

功能梯度材料是新一代的复合材料，其本质是非均匀复合材料。有两类功能梯度复合材料。一类是颗粒增强功能梯度复合材料。另一类是纤维增强功能梯度复合材料。石墨烯是纳米世界已知的最轻和最强的二维结构。将功能梯度材料的概念用于石墨烯增强复合材料层合结构，将每一单层石墨烯在基体中的体积含量按一定的方式分片梯度排布，从而使层合结构的力学性能得到改善。.本项目提出一种多尺度方法用于建模和分析功能梯度石墨烯增强复合材料梁板壳结构的非线性弯曲、后屈曲和非线性动力响应。石墨烯增强复合材料的物性参数由修正的Halpin–Tsai 细观力学模型估算。梁板壳结构的宏观控制方程基于高阶剪切变形理论。本项目的新贡献在于同时考虑材料的梯度属性和温度相关性。对功能梯度石墨烯增强复合材料梁板壳结构的非线性行为做出探讨。给出不同几何和物理参数及不同载荷条件下数值结果。为石墨烯增强复合材料在舰船和水下航行器中的应用提供必要的理论参考

功能梯度材料是新一代的复合材料，其本质是非均匀复合材料。石墨烯是纳米世界已知的最轻和最强的二维结构。将功能梯度材料的概念用于石墨烯增强复合材料层合结构，将每一单层石墨烯在基体中的体积含量按一定的方式分片梯度排布，从而使层合结构的力学性能得到改善。本项目的新贡献在于(1) 建立了功能梯度石墨烯增强复合材料层合结构的多尺度模型。层合结构由多层石墨烯增强复合材料构成，其中每一层的石墨烯含量可以不同，并沿厚度方向呈分片梯度分布。石墨烯增强复合材料的物性参数为正交各向异性，且假设为温度变化的函数，并由扩展的Halpin-Tsai细观力学模型给出。由于石墨烯增强复合材料制备中石墨烯的表面效应，应变梯度效应，分子间效应等小尺度效应的影响，经典的Halpin- Tsai 细观力学模型不能直接用于石墨烯增强复合材料物性参数的预测，为此我们引进石墨烯效能参数，该参数可以通过比照分子动力学的计算结果和用Halpin- Tsai细观力学公式的预测结果来获得。采用梁板壳的高阶剪切变形理论和 von Kármán应变-位移关系导出功能梯度石墨烯增强复合材料层合梁板壳的控制方程或运动方程。(2)分析功能梯度石墨烯增强复合材料梁板壳结构的非线性弯曲、后屈曲、非线性振动和非线性动力响应, 在分析中同时考虑材料的梯度属性和温度相关性。 (3)率先在国际上得到对应不同几何和物理参数及不同载荷条件下此类结构非线性问题的数值结果。为石墨烯增强复合材料在舰船和水下航行器中的应用提供必要的理论参考。