Investigation of delamination and damage due to free edge effects in composite laminates using cohesive interface elements

Abstract

Composite materials due to high strength and stiffness to their weight ratio are widely used in different structures. Hence, it is necessary to predict their failure behavior under loading. The delamination due to interlaminar stresses at free edges is one of the most important damage modes in laminated composites. In this study, this mode in cross-ply and angle-ply laminates has been investigated using a cohesive zone model. The advantage of this method is the possibility of modeling the delamination initiation and propagation without requirement to the presence of initial crack and remeshing. Hence, at first an interface element based on bilinear cohesive law was implemented in Ansys. Next, laminated plates with different lay-ups under uniaxial tension loading were modeled. Also Hashin's failure criteria were used to predict ply damage initiation. Numerical results show that in angle-ply laminates with small fiber angle orientation, delamination in the shear mode is the dominant mode in the loss of structural strength. The numerical and experimental results for global load-displacement response show a good agreement. Also numerical results show that in cross-ply laminates even under in-plane loading, the damage behavior extremely depends on the stacking sequence. Studies show that in cross-ply laminates under uniaxial tension, if 90o plies are inserted in top and bottom surface of the laminate, the mode I delamination and matrix cracking will start later.

Low velocity impact and fracture characterization of SiO2 nanoparticles filled basalt fiber reinforced composite tubes

“…51,52 This leads to a loss of stiffness in composites and reduces energy absorption. 53–57 For these reasons, the impact energy absorptions of composite specimens in the Charpy impact tests are thought to be lower than the low velocity impact tests.…”

Effect of fatigue loading on stiffness degradation, energy dissipation, and matrix cracking damage of CFRP [±45]3Scomposite laminate

“…[26][27][28][29] The initiation, growth, and postponing of matrix cracks in the vicinity of interface predominantly depends on layup sequence and loading condition. 13 This transverse matrix cracking and the intermediate distance has a significant effect on stiffness reduction. [30][31][32][33][34][35][36] Vassilopoulos and Philippidis reported a lower stiffness reduction for higher stressed specimens for various off-axis GFRP laminates.…”

“…The efficient prediction of crack growth rate, inter‐ply delamination, and residual life under low‐ or high‐cyclic fatigue loading is also possible through CZM approach . The initiation, growth, and postponing of matrix cracks in the vicinity of interface predominantly depends on lay‐up sequence and loading condition . This transverse matrix cracking and the intermediate distance has a significant effect on stiffness reduction .…”

“…The improper load distribution because of high‐density matrix cracking leads to catastrophic fracture of the composite. The evolution and growth of matrix cracks depend on certain variables like free‐edge stresses, residual stresses, delamination‐driven cracking, non‐uniform fibre distribution, stress intensity factor, and so on. Nairn and Zoller emphasised the consequences of residual stress‐driven matrix cracking on energy release rate for cross‐ply laminate and presented a master plot method to determine the effect of residual stress and toughness on experimental matrix cracking .…”

Experimental and numerical investigation of stiffener effects on buckling strength of composite laminates with circular cutout

“…To solve this problem, the cohesive zone model is used for prediction of delamination propagation under static, impact, and cyclic loading. [53][54][55][56][57][58][59][60] This method also has been used successfully for prediction of postbuckling behavior of delaminated plates. 61,62 In order to overcome the limitations of the traditional methods, in recent years, the novel and modified methods have been proposed for investigation of flexural and buckling behavior of the composite plates.…”