Impact fracture behaviors of three-dimensional braided composite U-notch beam subjected to three-point bending

Abstract

Impact fracture behaviors of three-dimensional braided composites are critical to designing the braided composite parts. Here we report the impact fracture behaviors of three-dimensional braided composite U-notch beam tested on a modified split Hopkinson pressure bar. Crack mouth opening displacement, deformation process, and crack evolutions were recorded with high-speed photography camera. The digital image correlation method was used to calculate deformation contours of the braided composite. A microstructure model of the three-dimensional braided composite U-notch beam was established for analyzing damage evolution and fracture mechanisms. The histories of deformation, the load, and the crack mouth opening displacement were obtained from the impact fracture test and finite element analysis. It was found that the impact fracture resistance and morphologies were influenced by the braided structure and braided yarn orientations. The crack generated at the notch tip and then propagated along the braided angle direction rather than the perpendicular direction that often occurred for isotropic materials, such as the epoxy resin solid. The combinations of different braided angle and yarns are recommended for high impact fracture behavior design.

Low-velocity impact and residual flexural behaviors of 2.5-D woven composite under accelerated thermal ageing: Experiment and numerical modelling

“…An initial velocity is assigned to the indenter along loading direction according to the corresponding impact energy. While modeling the contact between the indenter and the specimen, ‘frictionless’ and ‘hard’ interaction properties (Shi et al., 2019) are adopted. After impact test, the deformed parts with damage was transported to the residual flexural testing model (as shown in Figure 3(b)).…”

Assessment of the fracture process zone in rocks using digital image correlation technique: The role of mode-mixity, size, geometry and material

“…In some researches, using DIC method, the displacement fields in the direction perpendicular to the crack propagation path have been used for measuring the FPZ length (Wu et al., 2011). Researchers have used different types of materials such as, concrete (Duan et al., 2007; Tejchman, 2010; Skarżyński et al., 2011), rock (Zietlow and Labuz, 1998), ceramic (Bažant and Kazemi, 1990) and asphalt (Li and Marasteanu, 2010) in their studies.…”

Multiple transverse impact damage behaviors of 3-D-braided composite beams under room and high temperatures

“…There is no doubt that the failure mode is more serious and the lateral displacement is greater with the decrease of the braiding angle and ambient temperature. For the beams with 20 and 30 , the resin cracks propagated along the braiding angle direction rather than the perpendicular direction that often occurred for isotropic materials (Shi et al, 2019), while the beam with 40 peeled off directly. Some beams ruptures at the clamped position at 90 C and 150 C. The possible reasons are the impact position and clamped positions of the beam have the maximum stress concentration at elevated temperatures, and the clamped position cannot withstand the large deformation.…”