Study On Damage Of Composite Laminate Experienced Impactions Of Hail And Rigid Impactor

Composite materials are widely used in aerospace field because of their excellent mechanical properties such as high specific stiffness and high specific strength.With the extensive use of composite laminates on aircraft,the damage introduced by impaction from foreign object has attracted much attention.Composite laminates are vulnerable to impact loads.Impaction can cause various damages,e.g.delamination,fiber breakage and matrix cracking.These damages may lead mechanical properties of composite laminates seriously reduced,subsequently the load bearing capacity of aircraft structures obviously decreased which endangers flight safety.In this paper,impact tests and numerical research are carried out to investigate the impact damages of composite laminate.The main contents of this Master thesis are as follows:1?A strain rate hardening and hydrostatic pressure dependent dynamic elastic-plastic constitutive model of hailstones is established.The strain based Chang-Chang failure criterion and cohesive interface element are employed for representing in-plane failure and delamination of laminated composite.Based on the proposed model,the damage process of composite laminates induced by hailstones impaction is simulated.Compared with the available experimental results in the literature,it is proven that the proposed model is in good agreement with the experimental data and the error is within 10%.2?Low speed rigid body impact tests of composite laminate are carried out.The impact pit depth is measured with depth micrometer,damage area and shape are detected by ultrasonic C scan.The damages under conditions of different impact energy and different impactor shape are obtained in the tests.3?The low speed impact experiments above are numerical simulated.The influences of impact energy and impactor shape on impact damage mode and damage degree of composite laminate are investigated.Meanwhile,the dynamic response of composite laminate,e.g.load-time history curve,displacement-time history curve as well as load-displacement curve are also obtained.The numerical simulation of layered damage is close to the test data,and the error is within 17%.All the simulation model in this Master thesis have been implemented in the platform of commercial software package of ABAQUS,and a parameterized modeling module has been developed.