Design and Stiffness-Damping Optimizatino of Hybrid Coomposite Laminated Structures

该项目旨在开发、优化和验证具有优异阻尼和刚度性能的层压混合复合材料。混合复合材料包括商业碳纤维和表面生长的碳纳米管（CNTs）提供了有吸引力的替代纤维增强复合材料（frp）和更便宜的替代原始碳纳米管复合材料。混合复合材料还含有氧化钒（VO2），在振动引起的热环境中表现出负刚度行为。我们预计，由于碳纳米管的加入，杂化复合材料将获得高比刚度。提高了刚度（TPa级），同时通过VO2的负刚度以及固有的矩阵粘弹性阻尼特性获得增强的阻尼。采用有限元方法和多目标优化环境对复合材料的拓扑结构进行优化，以获得优异的刚度和阻尼性能。验证混合复合材料？动力学性能，实验室控制振动测试将进行，以开发其响应特定的激励。这些测试数据的分析将用于振动系统参数（阻尼、刚度和非线性参数）的表征和识别。振动会损害结构部件frp的安全性和耐久性。尽管frp具有良好的力学性能，但其低透厚的力学性能限制了其在结构中减轻面外动载荷的应用。开发的具有增强阻尼的混合复合材料对利用FRP的应用产生了影响，例如商用和军用飞机框架（例如波音787梦想飞机）、船舶、汽车工业、基础设施和体育用品。考虑到frp在民用基础设施（桥梁，柱子等）中的新兴应用，开发的材料提供了一种有吸引力和实用的解决方案，可以减轻地震中遇到的随机振动，并且可以延长这些结构的疲劳寿命。该项目的教育部分将使弗吉尼亚理工大学（VT）工程学院的三个系受益。现有的一门研究生课程将根据项目任务进行修改，包括理论和实践模块。一名研究生将参与混合复合材料的合成、制造、表征、拓扑优化、振动测试和参数识别的实践，攻读博士学位。

This project aims at developing, optimizing and validating laminated hybrid composites that possess excellent damping and stiffness properties. The hybrid composites comprising both commercial carbon fibers and surface-grown carbon nanotubes (CNTs) offer attractive alternative to fiber reinforce composites (FRPs) and cheaper alternative to pristine CNTs composites. The hybrid composites also incorporate vanadium oxide (VO2) that exhibits a negative stiffness behavior in thermal environments induced by vibrations. We anticipate the hybrid composite to acquire high specific stiffness due to the CNTs? elevated stiffness (TPa level) while gaining enhanced damping through the negative stiffness of VO2 together with the inherent matrix viscoelastic damping properties. Finite element methods and multi-objective optimization environment will be employed to optimize the topology of the hybrid composites to yield superior stiffness and damping properties. To validate the hybrid composites? dynamics performance, laboratory controlled vibration tests will be carried out to exploit their responses to specific excitations. The analysis of data from these tests will be used for characterization and identification of the vibrating system parameters (damping, stiffness and nonlinear parameters).Vibrations can compromise the safety and durability of structural components FRPs. Despite their attractive mechanical properties, the low through-thickness mechanical properties of FRPs have restricted their application in structures to mitigate out-of plane dynamic loads. The developed hybrid composites with enhanced damping have an impact on applications that utilize FRP such as commercial and military aircraft frames (ex. Boeing 787 Dreamliner), ship vessels, auto industries, infrastructures and sport goods. Considering the emerging applications of FRPs in civil infrastcrtures (bridges, columns, etc..) the developed materials offer an attractive and practical solution to mitigate random vibrations such as those encountered in earthquakes also they can extend the fatigue life of these structures. The educational components of the project will benefit three departments in the Virginia Tech (VT) College of Engineering. One existing graduate courses will be revised to include both theoretical and hands-on modules based on the project tasks. One graduate student will participate hands-on in the synthesis, fabrication,characterization, topological optimization, vibration testing and parametric identification of the hybrid composites toward a Ph.D. degree.