Analysis On Mechanical Properties Of GLARE Laminates With Holes Pulled-through

GLARE laminates is a kind of composite material,which is prepared by alternately arranging high-strength aluminum alloy plate and glass fiber resin layer under a certain temperature and pressure,which is widely used in the fairing and skin of aircrafts etc other structures.Due to the limitation of preparation technology and cost,the connection between components is essential,and mechanical connection is the most commonly used connection mode of composite materials.The mechanical connection will open holes in the composite material structure,after opening holes,the normal bearing capacity of the laminates will decrease,and the stress concentration phenomenon is easy to occur at the edge of the hole,under the action of external surface loading,the bolt fasteners and laminates are easy to occur tensile damage.In this paper,the mechanical properties of GLARE laminates with hole were analyzed by experimental analysis and finite element simulation.Firstly,this paper introduces the theory of mechanical connection of laminates,and carries out an external surface tensile test of GLARE laminates with straight holes and counterbore holes respectively.The pull-out tests of different hole diameters and hole types are described.The analysis results showed that the tensile damage stages of the laminated plate were approximately the same.In the first stage,the aluminum alloy and the fibrous layer were in the elastic stage,and the deformation was coordinated and synchronous;in the second stage,the aluminum alloy layer entered the plastic stage,and the deformation of aluminum alloy and fibrous layer were not longer coordinated any more;in the third stage,the fiber layer breaks and the laminated plate lost their bearing capacity.Comparative analysis of each group of experiments found that in the straight hole pull-off test,the larger the hole,the greater the ultimate load;the straight bolt hole pull-out limit load of the same hole diameter is larger than the countersunk bolt hole.Meanwhile,the failure mode of GLARE laminates was not single,including aluminum alloy breaking,interlamination delamination,fibrous layer breaking.Secondly,under the same testconditions,the finite element analysis modelling of GLARE laminates with holes was established by using the ABAQUS software,and the test results were compared with the finite element modelling results,achieving a good matching effect,confirming the correctness of the model.The stress distribution patterns in the radial and tangential direction on the each hole edge of test pieces were analyzed by using finite element software.Finally,the numerical simulation method was used to predict and analyze the influence of baffle distance,opening diameter,screw head diameter and layup angle on the mechanical properties of the GLARE laminates.The results showed that the bigger the distance of the baffle,the smaller the ultimate tensile loading of the laminated plate;the larger the hole diameter,the smaller the ultimate tensile loading;the larger the diameter of the screw head,the larger the ultimate tensile loading.