STUDY THE EFFECT OF STACKING SEQUENCE ON DELAMINATION MODE AT FREE-EDGE LAMINATED PLATE USING FEM

Composite laminates due to their high strength and stiffness to weight ratio are widely used in different load carrying structures. In order to obtain high stiffness laminates with complicated lay-up are used. The characteristics and advantages which carried by composite materials is of high importance, considering this fact has made them to be used more commonly as substitutes for other metal substances, during the last two decades, particularly as in space and aircraft industries. Laminates during the service are subjected to complex thermo-mechanical loading that causes delaminating. Delamination cause reduction in stiffness of laminate and accelerate the state of failure, this reduction in stiffness of laminate during delamination growth may made the structure unsafe. The first mode of damage is matrix cracking or so called transverse cracking. In some cases such damage is catastrophic for structures, for instance, it can cause leakage in pressure vessels and therefore it is not permissible. On the other hand, in structures where only stiffness is the main concern, this damage will cause certain stiffness degradation but it can be accepted at some extent. In order to design structure properly it is necessary to understand the damage process and to predict the level of degradation of mechanical properties in the present paper, analysis of interlaminar stresses in laminated structure at free edge effect with fibre orientation and stacking sequence is studied. Since those stresses act as primary reason for causing delamination problem at free-edge affect of laminated composite structure. In this work, the numerical modelling of the material, focusing on the damage behaviour for the different constituents, is described. In this paper delamination phenomenon in laminated composite material is investigated numerically. Laminated free-edge coupon is modeled in ANSYS finite element software for different fiber orientation and stacking sequence. The influence of variation of stacking sequence on interlaminar stresses particularly, delamination between adjacent layers is modelled. 3-D finite element models were done to analyze interlaminar stresses at a region were changing of stresses state exist free-edge affect in laminated coupons, and from these results, the effect of stacking sequence on the delaminating modes were obtained..

کلیدواژه ها:

Stress ، Composite ، Interlaminar ، Delamination ، Stacking Sequence