Abstract

The mechanical properties of sandwich structures have drawn much attention from research and industrial application, while sandwich structures in the form of L-joint have been rarely addressed. In this paper, L-joint sandwich structures were experimentally tested under bending load to investigate the mechanical performance during structural deformation and damage evolution. The corresponding testing process was numerically simulated using finite element (FE) modeling. Nomex^® honeycomb was selected as the core material of the sandwich structure, with the outer facesheets made of thermosetting Carbon Fiber Reinforced Polymer (CFRP) prepreg. Sandwich structures in the form of thin-walled beams and L-joint were then manufactured with specially-designed molds. Quasi-static three-point bending tests up to failure were conducted on the sandwich panels. Experimental results revealed that the main failure mode of the sandwich panel was the fracture in the honeycomb wall. The stiffness and strength properties of the sandwich structure were analyzed with FE modelling results, which showed good agreement with the experimental data. The adhesively bonded and hybrid rivet-bonded sandwich L-joints were investigated under vertical crushing load, showing the main failure region located in the corner area of the L-joint. The proposed experimental-numerical method on the mechanical performance of sandwich structures can provide reliable guidance on the connection of the caravan floor and side walls in automotive industries.

摘要

夹层结构的力学性能引起了研究和工业应用的广泛关注，而 L 型接头形式的夹层结构却鲜有研究。在本文中，L 型接头夹层结构在弯曲载荷下进行了实验测试，以研究结构变形和损伤演变过程中的力学性能。使用有限元 (FE) 建模对相应的测试过程进行了数值模拟。诺梅克斯^®蜂窝被选为夹层结构的核心材料，外面板由热固性碳纤维增强聚合物（CFRP）预浸料制成。然后用专门设计的模具制造薄壁梁和 L 型接头形式的夹层结构。对夹芯板进行了直至失效的准静态三点弯曲试验。实验结果表明，夹芯板的主要失效模式是蜂窝壁的断裂。用有限元建模结果分析了夹层结构的刚度和强度特性，与实验数据吻合较好。在垂直挤压载荷下研究了胶粘和混合铆钉夹层 L 型接头，显示主要失效区域位于 L 型接头的拐角区域。