Buckling instability analysis of delaminated beam-like structures by using the exact stiffness method

In multilayered structures, delamination not only reduces local strength but also induces buckling instability, compromising structural safety even before reaching the critical buckling load. This paper introduces a novel model for buckling analysis of structures with delamination damage. The model utilizes exact stiffness formulations derived from Timoshenko theory, enabling precising modeling of beam-like structures with through-thickness delamination. The Wittrick–Williams algorithm is utilized to calculate the critical buckling loads, which are validated against results from the finite element software ANSYS. Additionally, a modified Euler buckling formula for the approximate yet closed-form critical buckling load of delaminated beam-like structures is proposed, with comparisons made to the exact stiffness method results. The study investigates the effects of position and length of delamination and boundary conditions of beam on the critical buckling loads. The findings indicate that the buckling reduction factors of delaminated beam is primarily influenced by the thickness-wise position of the delamination, followed by the delamination length, and then the length-wise position of the delamination. Furthermore, the impact of boundary conditions becomes more significant when the delamination is near the beam’s end. This research provides practical guidelines for preventing buckling instability in delaminated beam-like structures.