On The Simple Derivation of Stress-strain Relationship in Composite Laminated Material of Plate and Shell Structures

摘要

This study aimed to develop a model to accurately predict the stress-strain relationship and proposed for laminated composite material. Lack of accuracy of Classical Shells Theory (CST) in predicting the influence of transverse deformation occurs due to the line normal to the surface is assumed remain straight and normal to the mid-plane before and after deformation. This assumption overestimates the structures too stiff and the deflections too small. Anyway, for very thin structures CST still suitable for isotropic homogeneous material, but the shear transverse deformations were neglected, hence provide inaccurate results for thicker structures. These lacks had been revised by Constant Shear or First Order Shear Deformation Theory (CSDT/FOSDT), but still suffer shear locking phenomenon, because always have constant value in the shear term. This matter had been corrected by Higher Order Shear Deformation Theory (HOSDT) using refined assumption that the line normal to the surface in a parabolic function and not normal to the mid-plane, but normal to the surfaces so it fulfill the zero strain in the surfaces. The stress-strain relationship of laminated composite material is applied by using Higher Order Lamination Theory (HOLT) that adopted from HOSDT that was accurate for any thicknesses variation and complex material.