A novel double-spring analytical model for hybrid GLARE joints: Model development, validation, parameter study and global sensitivity analysis

It is significant to theoretically evaluate the mechanical properties of hybrid (bonded/bolted) GLARE joint, especially under the condition of multiple assembly uncertainties. This work develops a double-spring analytical model that predicts the deformation of hybrid joints under the quasi-static load to solve this critical problem in the fabrication process of hybrid joints. Besides the mechanical properties of bolt, the stiffness of adhesive layers is introduced in this novel model in which the factors such as geometrics, properties of adhesive layer, bolt-hole clearance, laminate properties, contact condition, relaxation of pre-torque and types of materials are discussed in detail. Meanwhile, a Monte Carlo simulation (MCS) and a variance-based method are used to calculate their global sensitivity indices that have the ability to quantify the relative importance of those assembly factors in load distribution between the bolt and adhesive layer, fracture displacement at the initial stage and other mechanical properties. It is found that bolt-hole clearance, geometrics of laminate and properties of adhesive layer are the top three sensitive factors, the qualifies of which must be strictly controlled in the process of fabrication. This model is able to provide a powerful approach for the future design of hybrid joints to achieve higher reliability and load capacity.