Simulation and experimental study of bending mechanical properties and damage evolution of carbon/glass hybrid fiber reinforced titanium alloy laminates at room temperature

Abstract

This study aims to investigate the flexural mechanical properties and damage evolution behavior of carbon/glass hybrid fiber reinforced titanium alloy laminates (HFTLs) at room temperature through the combination of numerical simulation and experimental research. The three-point bending finite element model of HFTLs with 2/1 structure (the titanium alloys are used as the outer layer and the composite structure is the sandwich layer) is established, and the stress and strain evolution mechanisms are analyzed. Combining DIC online monitoring and SEM microscopic detection, the flexural response and failure behavior of HFTLs are discussed. Furthermore, the effect of the carbon/glass hybrid ratio (N_CG = 0 %, 25 %, 50 %, 75 % and 100 %) on the flexural properties of HFTLs is investigated. The results show that HFTLs exhibit significant stress gradient characteristics under bending loads at room temperature. When the upper titanium alloy layer is subjected to compressive stress, the lower titanium alloy layer mainly bears tensile stress, and the intermediate hybrid fiber layers mainly bear shear stress. Especially, the stress level of the hybrid fiber layers is lower than that of the titanium alloy layers, with an average stress reduction of approximately 76.4 %. By introducing hybrid glass fiber layers, the flexural strength and flexural modulus of HFTLs can be increased by 24.44 % and 12.90 %, respectively. The flexural failure of HFTLs primarily exhibits a mixed failure mode, which is closely related to the carbon/glass hybrid ratio. The failure modes manifest as brittle fracture of CFRP, matrix cracking, and delamination at the Ti/Gf and Gf/Cf interfaces.