Analysis Of The Stress Around The Hole Of The Carbon Fiber Composite Bolt Connection

Carbon fiber and carbon fiber composites have many excellent properties and are widely used in the civil and aerospace fields at present.However,the structure of carbon fiber composite connection has been an important factor restricting its development,using the method of numerical analysis on hole edge stress and the stress distribution of the failure zone.It can save time and cost effectively.The main contents of this paper are as follows:Firstly,a finite element model of bolted connections of composite nails and multi nail connections is established,and typical failure criteria of composite materials are introduced.Secondly,the composite materials of typical failure modes are: tensile failure and shear failure,crushing,splitting failure,carbon fiber composite laminates around the hole stress state is complex,carbon fiber composite connection may also occur in combination type failure mode.The combined failure modes consist of two or more than two single failure modes,such as tensile shear failure,tensile crushing failure,and combined failure mode of compression shear failure.Thirdly,the distribution of radial normal stress,tangential normal stress and shear stress at the hole edge of the failure zone is obtained by using the appropriate pore edge stress function,and the relationship between the different failure modes(extrusion failure,shear failure and tensile failure)and the stress are analyzed.Then based on the three-dimensional finite element model of bolt connection,will get the results of finite element analysis and analytical results were compared,in good agreement with the calculation results of the analytical method and the finite element results,verify the composite bolt connection of different failure modes and the relationship between the stress.It shows that different failure modes of composite bolt connections are caused by different stresses.Finally,based on the classical laminated plate theory,laminated reference coordinate system,using the concept of stiffness of the eccentric shaft,respectively in different stacking sequence of the composite material bolt hole stress are analyzed separately.Were obtained around the hole of 0 degrees to 90 degrees in the region of the shear stress and radial stress and tangential stress distribution,verify the composite materials of different layers had great influence on the strength of bolt connection,the distribution of the hole edge stress is verifiedbased on the finite element model,the conclusion is a certain reference value to the project layer optimization design of Composite Bolted joints.