Investigation of thermal bifurcation buckling in delaminated composite laminates: A combined global‐local ESL and LW theory approach

Abstract This paper investigates the thermal bifurcation buckling behavior of delaminated composite laminates by integrating equivalent single‐layer (ESL) theory and layerwise (LW) theory, aiming to balance computational efficiency and accuracy. While ESL theory is computationally efficient, it cannot adequately address the thermal buckling issues in delaminated laminates. Conversely, LW theories can handle these problems but at the cost of lower computational efficiency. This study combines these two approaches in both in‐plane and thickness directions, applying LW theory to delaminated regions and ESL theory to other areas. The buckling eigenvalues of the laminate are obtained using the principle of minimum potential energy, and the eigenvalue equations are solved using the finite element method to determine the critical buckling temperatures and modes for delaminated laminates. The results are validated against those obtained using full LW theory, showing good consistency while achieving improved computational efficiency. Finally, parametric studies are conducted to comprehensively analyze the effects of delamination shape, area, position, and quantity on the critical buckling temperature and modes of the laminates. The computational method and findings presented herein provide valuable references for understanding buckling phenomena in delaminated composite laminates.