Finite element analysis and experimental comparison of the crack opening displacement profile in the damaged cross-ply laminates

During the service life composite laminates undergo complex combinations of thermal and mechanical loading leading to microdamage accumulation in the plies. The most common damage mode and the one examined in this work is intralaminar cracking in layers. The crack opening displacement (COD) and the crack sliding displacement (CSD) during loading reduce the average stress in the damaged layer, thus reducing the laminate stiffness. These parameters depend on material properties of the damaged layer and surrounding layers, on layer orientation and thickness. Previously these parameters have been calculated using finite element method (FEM) assuming linear elastic material with idealized geometry of cracks. To validate these assumptions experimentally the displacement field on the surface of a [90/0/90], [90/0]s and [903/0]s carbon fiber/epoxy laminates specimens with multiple intralaminar cracks in the surface layer is studied. The profile of the COD along the width is investigated for each single crack. The specimen full-field displacement measurement is carried out using ESPI (Electronic Speckle Pattern Interferometry). The effect of crack interaction as well as the effect of the thickness of 90° layers on the COD is given in this paper.Godkänd; 2013; 20130930 (andbra