Polyamide mesh as an effective toughening interlayer for GFRP composites: insights into fracture behavior and mechanisms
Yunxiao Zhang, Hongchen Zhao, Yunfu Ou, Han Zhang, Xudan Yao, Dongsheng Mao
Abstract
The strategy of interlaminar toughening shows tremendous potential in addressing delamination failure in glass fiber-reinforced polymer (GFRP) composites. In contrast to commonly used particulate or nanofibrous interleaves, mesh structures feature a more continuous and uniform architecture, which confers notable benefits in terms of scalability. Despite this potential, there is currently a lack of systematic studies on the role of mesh structures in interlaminar toughening. Therefore, this study investigates the interlaminar toughening behavior of polyamide (PA) mesh, known for its excellent mechanical properties, as an interlayer in GFRP, focusing on the effects of different mesh densities and thicknesses. Through different fracture tests and failure analyses, the correlation between mode I/II fracture behaviors and characteristic parameters of PA6 mesh was elucidated. The results indicate that by introducing the PA6 mesh, the mode I and mode II fracture toughness can be improved by 109% and 69%, respectively. This enhancement is attributed to the structural toughening effect of the PA mesh, including PA fiber bridging, plastic deformation, and fracture, as well as its ability to induce controlled crack deflection and guidance. Upon analysis, the primary factor influencing the toughening efficiency of the PA mesh is the mesh porosity. Only within an appropriate porosity range (20% ~ 60%) can the interlaminar toughening effect of the PA mesh be activated. Under this premise, thickness, as the secondary dominant factor, has a positive regulatory effect on the interlaminar fracture toughness of the PA intercalated laminates.