【作者】 江帆；

【导师】 杨忠清； 单杭英；

【作者基本信息】 南京航空航天大学 ， 机械， 2023， 硕士

【摘要】 随着碳纤维复合材料在无人机上的广泛应用,复合材料之间的连接就变得尤为重要。将碳纤维层压板二次胶接技术应用在中小型低速无人机机翼主承力结构上,降低机翼制造成本,提升产品经济效益。由于碳纤维复合材料结构的破坏形式多种多样,难以预估,缺乏成熟的分析方法和充足的设计使用经验,本文采用“积木式”研究方法,从元件、组件、部件等多个层次的试验与模拟,验证二次胶接技术在机翼主承力结构上应用的可行性,主要研究内容包括:首先,以碳纤维斜纹编织层压板/层压板(厚度均为2mm)二次胶接结构件为试验件进行元件级研究。通过拉伸剪切试验,采用理论分析、数值仿真和试验观测与验证相结合的方法,研究了胶粘剂类型、胶层厚度以及铺层方式薄层碳纤维层压板二次胶接强度的影响,并利用Abaqus软件中的cohesive单元对胶层单元进行了模拟,仔细比较了不同胶接参数下胶层的损伤起始、损伤演化、破坏形貌、极限载荷及其离散情况,得到了最适配的胶粘剂类型和最优的胶接参数,便于后续研究。接着,以碳纤维梁/蒙皮结构为试验件进行组件级研究。用薄层碳纤维斜纹编织预浸料制备了槽型梁和蒙皮,搭建了悬臂梁单点加载试验平台,对胶接、铆接和胶铆混接三种连接方式下的梁/蒙皮结构进行弯曲试验,分析了试验过程中的应变响应、结构破坏情况和位移载荷之间的关系,结果表明胶接连接是最优的连接方式。使用Abaqus软件对梁/蒙皮组件承载过程的损伤分布和演化情况进行仿真模拟,模拟结果与试验结果吻合良好。最后,以机翼盒段为对象进行研究。将无人机机翼简化后进行三维建模,导入计算流体动力学软件Star CCM+中,得到满足最大起飞重量和总体技术要求的气动载荷。然后将机翼模型导入有限元分析软件Abaqus中,将气动载荷映射到边界条件中。对某型号二次胶接成形的机翼受力盒段进行强度评估,在此基础上,细化蒙皮设计,使其在满足强度刚度的前提下,重量更轻。为二次胶接技术在中小型无人机主承力结构上的推广应用提供理论基础和实践经验。更多还原

【Abstract】 With the wide application of carbon fiber composites in UAVs,the connection between composites becomes especially important.Carbon fiber laminate secondary bonding technology is applied to the main bearing structure of small and medium-sized low-speed UAV wings to reduce the wing manufacturing cost and improve the economic efficiency of the product.Since the damage forms of carbon fiber composite structures are diverse and difficult to predict,and there is a lack of mature analysis methods and sufficient experience in design and use,this paper adopts a "building block" research method to verify the feasibility of the application of secondary bonding technology on the main bearing structure of the wing through tests and simulations at multiple levels,such as components,assemblies and parts.The main research contents include:Firstly,the secondary bonding structural parts of carbon fiber twill weave laminate/laminate(both 2 mm thick)were used as test pieces for component-level studies.The effects of adhesive type,adhesive thickness and lay-up method on the secondary bonding strength of thin carbon fiber laminates were investigated by combining theoretical analysis,numerical simulation and experimental observation and verification through tensile shear test,and the cohesive unit in Abaqus software was used to simulate the adhesive unit and carefully compare the damage initiation,damage evolution,damage morphology,ultimate load and its dispersion of the adhesive layer under different bonding parameters.The most suitable adhesive type and optimal bonding parameters were obtained to facilitate the subsequent study.Then,a component-level study was conducted using a carbon fiber beam/skin structure as the test piece.A cantilever beam single-point loading test platform was built,and the beam/skin structure was tested in bending with three connection methods: glued,riveted and mixed glued/riveted.The relationship between strain response,structural damage and displacement load during the test was analyzed,and the results showed that the glued connection was the optimal connection method.The damage distribution and evolution of the load bearing process of the beam/skin assembly were simulated using Abaqus software,and the simulation results were in good agreement with the test results.Finally,the wing box segment was studied as an object.The UAV wing is simplified and modeled in three dimensions and imported into the computational fluid dynamics software Star CCM+ to obtain the aerodynamic loads that satisfy the maximum takeoff weight and the overall technical requirements.Then the wing model was imported into the finite element analysis software Abaqus to map the aerodynamic loads to the boundary conditions.The strength of the force box section of a model of secondary bonding formed wing was evaluated,based on which the design was refined to make it lighter while meeting the strength and stiffness.It provides the theoretical basis and practical experience for the popularization and application of secondary bonding technology on the main bearing structure of small and medium-sized UAVs.更多还原