Calibrated finite element and reduced-order models for efficient simulation of bolted composite–aluminium structures

Experimental characterisation of bolted joints is costly, time-consuming and difficult to scale across multiple joint configurations. Accurate modelling of joints in large composite–aluminium structures provides an alternative, but detailed finite element (FE) analysis of each fastener is computationally demanding and impractical. Reduced-order models, based on the Iwan formulation, offer an efficient approach that can mitigate these challenges. In this work, each bolt installation in a composite-aluminium joint with two fasteners is represented by a structural element incorporating an Iwan-type model. The corresponding model parameters are identified from force–displacement responses predicted by a detailed solid FE model, calibrated against experimental measurements. A large set of FE simulations, covering a range of joint geometries, is then used to construct a meta-model that estimates the relevant Iwan parameters. The resulting model provides a computationally efficient fastener representation suitable for both structural analysis and design optimisation in assemblies containing multiple bolted joints. The proposed modelling technique reduces reliance on extensive physical testing and detailed FE simulations.