Study On Buckling And Postbuckling Of Composite Laminates With Delamination Damage

Composite materials are widely used in aviation,aerospace,transportation and other fields due to their high strength ratio,high modulus ratio,and high designability.In recent years,the worldwide demand for composite materials has increased year after year,and the field of its application has been gradually expanded.However,the composite material has a very obvious disadvantage relative to the traditional material,that is,the impact resistance of the composite is poor,the impact of small energy will bring great damage to the composite structure,among which the delamination is the most serious damage mode,which will cause a considerable reduction in compressive strength of the structure.Therefore,it is necessary to study the effect of delamination on the mechanical properties of composite materials qualitatively and quantitatively,which is of great significance to the engineering application of composite materials.Based on the finite element software ABAQUS,the progressive damage method of composite materials was introduced,and the self-embedded cohesive force interface in Abaqus was used to simulate the delamination damage between composite plies,which could effectively predict the buckling and post buckling behavior of laminated composite laminates and curved plates with delamination under compressive loading.Using this method,30 kinds of plates with different delamination radius and depths are calculated.The effects of delamination on the first-order buckling mode,critical buckling load,postbuckling deformation and ultimate load are analyzed.It is found that when the delamination position becomes closer to the middle of the thickness,the global buckling of the plate is more likely to occur,and the critical buckling load is closely equal to the critical buckling load of the intact plate without damage.The larger the circular radius is and the closer the delamination is to the plate surface layer,the more likely the local buckling occurs,resulting in the smaller critical buckling load.The effect of the layering radius on the ultimate load is greater than that of the layered position.That is,when the size of the delamination are the same,the ultimate loads of the plates with different delamination positions differ little,and while the size of the delamination have large difference,the difference of ultimate loads become larger.On the basis of the plate,three kinds of curved plates with different curvature and delamination damage are calculated respectively.Four kinds of damage and its gradual progress of the plate element in the loading process are analyzed.The influence of curvature,delamination radius and delamination position on the shape of curved plate and the ultimate load were studied.The results show that in a certain range,the greater the curvature of the plate,the greater the ultimate load,and the ultimate load value is closer to the ultimate load of the non-damaged curved plate.Compared to flat laminates with embedded delamination,delamination in curved laminates has relatively little effect on the ultimate load.