Research On Mechanical Properties Of The Winding Composite Lug

As an important part of the joint structure,the lug has been widely used in the field of aviation.Because of the disadvantages of heavy weight and high manufacturing cost in aviation metal joints,the composite lug has become a hot topic in recent years.In this paper,the composite lug is introduced and compared.Furthermore,the tensile mechanical properties of the winding composite lug are studied.Firstly,the structure and the static load analysis of the winding composite lug are conducted.Both progressive damage analysis method and cohesive interface theory are introduced as theoretical methods for the winding composite lug analysis.The constitutive relation of the composite is established with UMAT subroutine based on FORTRAN.Secondly,basic mechanical experiments of the composite material are carried out.And the mechanical properties of the unidirectional plate are obtained.By consulting literature,the adhesive behavior parameters of the adhesive layer are determined.Based on the material parameters,the finite element model of the winding composite lug subjected to axial tensile load is developed.Then,the simulation results are calculated.Thirdly,the results of finite element simulation are summarized.Based upon this,the damage and failure process of the winding composite lug is analyzed in detail.With the theory of elasticity,loop piles bearing capacity can be deduced.By comparing the simulation results with analytical solutions,the reliability of the finite element analysis method are verified.Finally,structural modification is carried out for the damage of the winding composite lug.The simulation and analysis of the winding composite lug with different structures are conducted.Then,the impacts of loop piles and middle laminates on tensile strength of the winding composite lug are studied in this thesis.Meanwhile,the advantages and disadvantages of various structural winding composite lugs are compared,which provide a certain research foundation for the design and optimization of composite lug.