Performance Study And Genetic Algorithm Optimization Of CFPR Laminate Ahesively Bonded Structure

In recent years,materials used in aerospace,automobiles,ships,and medical engineering are gradually transitioning from metal materials to composite materials.Carbon fiber reinforced polymer(CFRP)laminates are widely used because of their inherent excellent static and dynamic properties.At the same time,with the continuous improvement of integration,modularization and other technologies,the components in the above application fields are usually connected by different connection technologies,and adhesive connection is the simplest and most common connection method.In this paper,the experiment and simulation of single lap joints(SLJs)adhesively bonded structure of CFRP laminates are carried out in order to obtain its structural performance,the structure is optimized by multi-parameter and multi-objective optimization.Firstly,the SLJs of CFRP laminates with different overlap length,width and stacking sequences was prepared,and the tensile test was carried out on WDW-300universal tensile testing machine provided by Changchun Kexin.The experimental results divulged that,The tensile load at complete fracture of a CFRP single-lap test specimen becomes greater with increasing overlap width and length.and gradually increases with the decrease of the first and second ply angles of the laminate.There are many failure modes in the bonding zone.With the increase of the overlap length,the cohesive failure area decreases gradually,and the fiber delamination area becomes larger.However,the change trend of the failure mode corresponding to different overlap width is opposite to that of the overlap length,and the failure modes corresponding to different stacking sequences are also different.Moreover,based on ABAQUS 6.14,a three-dimensional finite element model(FEM)of CFRP laminate SLJs adhesively bonded structure was established.The ultimate failure load and strength of SLJs adhesively bonded structure,the failure modes of intra-laminar,inter-laminar and stress in and between layers were analyzed.It was shown that the relative errors of the numerical values and the expremental results are all below 7.34%,while the simulation failure mode and the exprement failure mode have the same trend.The connection stiffness of the SLJs increases with the increase of the overlap length and width,decreases with the increase of adhesive thickness,and increases with the decrease of the first ply angle.The normal stress between adhesive layer and inter-laminar is also related to different bonding parameters.Different bonding parameters have different effects on the tensile and shear strength of SLJs.Finally,the Latin hypercube sampling(LHS)was used to construct a quadratic polynomial response surface model of the tensile and shear strengths by taking sample points.A multi-parameter multi-objective optimization program based on genetic algorithm is written and optimized in MATLAB to obtain the Pareto optimal non-inferior solution set.The better solution in Pareto was obtained by the technique for order preference by similarity to ideal solution(TOPSIS).The results showed that the complex correlation coefficients R~2between the surrogate model and the numerical results were 0.9993 and 0.9999,The results of RSM shown that the variation trend of ultimate failure load with different bonding parameters was consistent with that of test and simulation results.and the optimal parameter combination of CFRP laminate SLJ structure was obtained,the overlap length,adhesive thickness and overlap width were 14.62 mm,0.08 mm and 10 mm respectively.The tensile and shear strength of CFRP laminate SLJ adhesive structure were increased by 2.65%and 17.24%,respectively.