Isogeometric thermal buckling analysis of variable-stiffness laminated plates with delamination using a multi-point constraint approach

Abstract Variable-stiffness laminated plates offer superior structural efficiency but are susceptible to delamination defects that significantly degrade their thermal buckling performance. This paper presents an isogeometric analysis (IGA) framework for the thermal buckling of VS laminated plates containing elliptical or rectangular delamination. The geometry and displacement field are discretized using non-uniform rational B-splines, which naturally satisfy the high-order continuity required by higher-order shear deformation theory and accurately represent curvilinear fiber paths. Delamination is modeled by a two-plate approach, dividing the plate into upper and lower sublaminates in the delaminated region. Multi-point constraints (MPCs) enforced via a penalty method are employed to guarantee kinematic compatibility along the intact interface. Fully clamped boundary conditions are applied on all four edges. The thermal buckling problem is reduced to a generalized eigenvalue problem, and the critical temperature is obtained as the smallest positive eigenvalue. Numerical verification against FEM results confirms the accuracy of the proposed model. Parametric studies investigate the effects of delamination shape, size, aspect ratio, in-plane location, and number of delaminations on the critical thermal buckling temperature. The proposed IGA-MPC framework provides an accurate and efficient tool for analyzing the thermal buckling of VS laminated plates with delamination.