Assessment of new four variables 2D and quasi-3D higher order shear theories for bending analysis of different double curved FG shells

This study introduces a novel theory employing four unknowns to examine bending of a double-curvature functionally graded shells experiencing both uniform and sinusoidal pressure. This investigation utilizes 2D and quasi-3D higher order shear deformation theories, integrating a fresh model of a high-order displacement field. It focuses on exploring how geometric ratios, volume fraction and power law index influence the bending behavior, specifically examining their effects on the normal and shear stresses variation, along with their amplification-reduction impacts. The effectiveness of the developed model is evaluated by comparing its performance in simulating bending characteristics of plates, cylinders, spheres and ellipses with those presented in literature.