轻金属与纤维增强树脂基复合材料自冲铆接机理研究

Light-weight metal and fiber reinforced resin matrix composites have been widely used in vehicles such as automotive, train and spaceflight. In this project, self-piercing riveting (SPR) technology is purposed to connect light-weight metal and fiber reinforced resin matrix composites. Finite element method will be applied to simulate the riveting and static tension processes. Properties of resin and fiber materials, fiber laying format, layer, thickness in preparation of composite, rivet size and die shape will be taken as process parameters, and effect of these variables on forming quality, mechanical properties of joint and the material flowing discipline will be analyzed. The stress and strain distribution under tensile load and the damage failure mode of riveted joints will be studied by numerical simulation and digital image correlation (DIC). Scanning electron microscope and digital microscope will be employed to observe the morphology of engagement interface, accordingly the microcosmic connection mechanism of metal and composite material will be studied and optimized parameter matching will be obtained. Adhesive bonding technology will be incorporated with SPR for connection of metal and composite material. Meanwhile, aging and corrosion tests will be conducted, and failure mechanism of joint will be analyzed. Static and fatigue tests will be carried out, and effect of all the factors on shear and fatigue property of rivet joint will be researched. Eventually the optimal connection method and obtained process parameter will provide a certain theoretical basis for the popularization and application of SPR in connecting metal and non-metal materials.

在汽车、火车、航天等交通工具中轻金属和纤维增强树脂基复合材料的应用日趋广泛，本项目提出采用自冲铆接技术连接轻金属和纤维增强树脂基复合材料。采用有限元方法对铆接及拉伸过程进行数值模拟，以树脂材料、纤维材料的性能参数，复合材料制备过程中纤维铺设方式、铺层厚度以及铆钉尺寸，模具形状等作为变量，分析其对接头成形质量及力学性能的影响和材料流动规律。用数值模拟和数字图像相关法相结合研究应力-应变规律及连接件的破坏机制等。用扫描电镜和数码显微镜观察两种材料接合界面的形貌，研究微观连接机理，提出优化工艺参数匹配。在金属材料和复合材料的连接中综合运用自冲铆接和胶接技术，并进行时效及腐蚀试验等，分析接头的失效机理。进行静强度实验和疲劳试验，研究各因素对铆接接头剪切性能和疲劳性能的影响，得到铆接接头力学性能最优时的连接方法及工艺参数，为自冲铆接技术在金属与非金属连接中的推广应用提供理论依据。

采用真空辅助树脂传递模塑成型工艺，成功制备出玻璃纤维和碳纤维增强树脂基复合板。相比不饱和9321-VP树脂，饱和树脂R688复合板表现出更高的抗拉强度，其失效形式为纤维断裂。通过研究得到了纤维材料、铺层方式、铺层厚度、树脂对复合层板力学性能及失效形式的影响规律，优化了复合层板的制作工艺参数。随着固化时间延长，复合材料峰值载荷逐渐上升，当固化时间为24小时，复合材料力学性能较高，满足复合材料制备要求。.自冲铆接能够实现纤维增强树脂基复合材料与轻金属材料的有效连接。2.5mm碳纤维复合材料板作为上板，2.5mm5052铝合金板作为下板，铺层方式为[-45°/45°]4s，铆钉高度为7mm时，铆接接头的力学性能较好。运用DIC来测量接头应变，获得拉伸过程中铆钉四周在各个阶段的散斑分布图像。有限元分析了自冲铆接成形过程，得出铆钉头下沿和铆钉脚区域最容易出现应力集中，也是最容易失效的位置。自冲铆接成形过程中，铆钉和下板发生较大的塑性变形。铺层中含有±45°铺层时，自冲铆接接头受冲击后具有较高的静拉伸强度。.对胶铆接头，0.35 mm胶层厚度的胶铆接头具有较好的抗剪切及抗冲击性能，且冲击前的静力学性能最好。接头的疲劳失效形式为接头胶层的界面失效。碳纤维复合板和5052铝合金板自冲铆接件经历5周的盐雾腐蚀，接头拉伸失效模式均为铆钉失效导致环氧树脂碳纤维复合板和铝合金板的脱离。延长腐蚀，碳纤维复合材料板发生断裂损伤和纤维分层损伤，峰值载荷逐渐降低，弯曲率逐渐增大。.研究成果可以在航空航天，轨道交通，汽车等交通运输工具中应用。