超声振动辅助的复合材料构件钛钉铆接机理研究

With the increasing performance of aircraft, the new emerging materials and structures are used in aircraft body’s manufacturing. Due to the excellent mechanical properties and anticorossion of titanium alloy, the titanium alloy rivets are more and more used in the composite materials strucrural components’ assembly of aircraft. In this project, the ultrasonic vibration is introduced into the riveting process, aiming at achieving high quality and reliability of titanium alloy riveting on composite materials structural components. Titanium alloy rivet’s texture rheological law, interfacial interaction mechnism and bulk forming rule are studied on multi-scale level, including microscopic, mesoscopic and macroscopoic scale.Then the strategy for suppressing interfacial damage and the method for geometrical contour forming of titanium alloy riveting are propsoed, increasing the life of structural components using titanium alloy riveting. The multi-scale numerical simulation will be performed by Finite Element Analysis software, and the riveting experimental platform assisted with ultrasonic vibration will be set up, on which riveting process’s experiments of titanium alloy assisted with ultrasonic vibration will be carried out. By analyzing the experiment results, the theory model will be modified by means of scienticfic method such as data processing. The proposed technologies will be applied to riveting process of composite materials strucrural components in a aircraft, and give theoretical and technological support to revealing the forming mechanism of titanium-alloy riveting with ultrasonic vibration aided.

随着现代飞行器性能的日益提高，机体制造中新材料、新结构不断出现，钛合金铆钉由于其具备优越的机械性能及抗腐蚀性，越来越多地应用于复合材料结构件的装配连接。本项目针对复合材料构件的钛合金铆钉高质量可靠连接问题，在铆接过程中引入超声振动辅助技术，从“微观-细观-宏观”多尺度层面研究复材构件铆接过程中钛钉的织构流变机理、界面作用机制和体积成形规律，进而提出钛钉铆接界面损伤抑制策略和几何轮廓成形控制方法，提升钛合金铆钉铆接结构的高服役性能。项目研究借助有限元分析软件进行跨尺度数值模拟，搭建超声振动辅助铆接试验平台，并开展钛合金铆钉超声振动辅助铆接工艺试验，对比分析试验结果，通过数据处理等科学手段修正相关理论模型。所提技术成果可应用于飞机复合材料构件铆接，为揭示超声辅助钛合金铆钉连接的成形机理提供理论与技术支撑。

基于碳纤维增强复合材料（CFRP）构件钛合金铆钉连接过程中，铆钉冷塑性差、应变率敏感、屈强比高等原因，引入超声辅助铆接工艺，在铆接过程中需要对金属材料的超声振动耦合软化的宏/微观特征演变规律以及超声软化机理进行深入研究，建立声塑性Johnson-Cook修正本构方程和仿真模型，检验并探究典型工况下铆钉成形几何轮廓控制方法，最终实现铆接干涉量的精准控制，项目的主要研究内容包括：（1）建立超声激励下钛合金铆钉的本构方程，得到超声振动、压铆载荷耦合作用下钛合金铆钉铆接成形流变特性；（2）探明超声振动铆接成形的几何轮廓变形特征与成形机理和连接界面的接触力学行为，揭示超声辅助下界面润滑效应的力学本质；（3）形成多尺度数值模拟方法，结合典型飞机壁板结构，掌握钛合金铆钉超声振动辅助铆接工艺中面向结构服役能力的工艺优化技术。本项目搭建了超声振动辅助铆接平台用于CFRP构件的钛钉铆接，提出了横向超声振动耦合效应软化模型，建立Ti-45Nb合金的横向超声振动的本构模型，基于能场参数、界面特征与材料流动轨迹的影响规律，提出铆钉成形几何轮廓控制方法，通过疲劳试验分析，提出不同服役条件下的最佳干涉量水平，得到CFRP构件横向超声振动辅助耐久性铆接最佳工艺参数。基于本项目的研究基础和成果，CFRP构件横向超声辅助铆接未来将在航空航天、舰艇船舶、等方面具有巨大的应用前景。