On the mechanical performance of honeycomb-core sandwich L-joint under bending load: an experimental-numerical study

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.