Uncertain buckling characteristics of thermally loaded and internally defected variable fiber spacing composite laminates

The present investigation underscores the efficacy of laminated plates with variable fiber spacing (VFS) in the context of internal defects. The study involves the evaluation of the variability in buckling strength when faced with multiple tiers of damage; this is achieved through the implementation of an improved first-order shear deformation theory (IFSDT) within a finite element (FE) framework. Various types of fiber distribution (DT) are being examined to evaluate the effects of damage situated at both corner and mid locations. The application of a radial basis function network (RBFN)-based surrogate model demonstrates its potential as a feasible alternative to the computationally demanding Monte-Carlo simulations (MCS) for investigating the stochastic nature of buckling; the developed surrogate model requires reduced input sampling data to quantify buckling uncertainty. This study examines the stochastic nature of different material characteristics and observed that the uncertainty in the buckling response decreases with the increased damage severity. The assessment of the probability of failure is conducted subsequently. Following this, the damage ratios are influenced by randomness, leading to the pattern that an increased damage ratio corresponds to a more pronounced deviation in buckling uncertainty.