NONLINEAR ANALYSIS OF COMPOSITE CYLINDERS VIA MICRO-MECHANICS

A micro-mechanics-based nonlinear analysis of thick composite cylinders is presented. Composite material is described by one or the other of two competing micro-models. These are respectively, a Finite Element based Cylindrical (3-phase) Model (FECM) and a Simplified Square Cells Model @SCM). A modified Ramberg-Osgood type equation defined by three parameters is used to characterize the nonlinear behavior of the matrix. Models exhibit discrepancies in their prediction of nonlinear response of cylinders under hydrostatic pressure and axial compression. This raises the question of reliability of simplified micro-models in the nonlinear analysis of composite structures. Next, the model parameters for each micro-model are separately determined to fit an experimental shear stress-shear strain response of the composite material of the cylinder. The models thus calibrated tended to show noticeably less, but nevertheless significant, discrepancies in their prediction of the behavior of cylinders. The paper is concluded with a critique on the rationale and the practical value of such calibration.