Investigation On Effect Of Bonding Parameters On The Bonding Performance Of Adhesively Bonded Structure Of CFRP Laminates

Numerical modeling strategy and experimental tests have been performed on adhesively bonded single-lap joints of CFRP laminates.Numerical analyses have been performed on adhesively bonded double-lap joints of CFRP laminates.The effects of bonding parameters on the bonding performance of single-lap and doublelap joints were considered.Firstly,a tensile test platform for adhesively bonded single-lap joints of CFRP laminate was established.The single-lap joints with different lap lengths,lap widths,and stacking sequences were experimentally investigated.The effects of three bonding parameters on the ultimate failure load and failure forms of single-lap joints were analyzed.The tensile test results show that the ultimate failure load of the single-lap joints gradually increases with the increase of the lap length and the lap width;the failure forms of the single-lap joint with different lap lengths,lap widths,and stacking sequences are also different.Secondly,based on the continuum damage mechanics(CDM)mode,cohesive zone model(CZM)and 3D Hashin failure criteria,the numerical models of adhesively bonded single-lap and double-lap joints of CFRP laminates were established,and the model was calculated by ABAQUS finite element(FE)software.Based on this model,the effects of lap lengths,lap widths,stacking sequences,and adhesive thicknesses on the ultimate failure load and failure forms of single-lap and double-lap joints are investigated and analyzed.The numerical results show that the relative error of the ultimate failure load between the numerical,value and the experimental result is less than 5.7%,which verifies the validity of the numerical model;the numerical failure forms of single-lap joints is basically consistent with the failure forms of the experimental result,which further validates the accuracy of the model;the trend of the ultimate failure load of the single-lap and double-lap joints is basically the same,and the failure forms of the single-lap and double-lap joints with different bonding parameters are also different;compared with the single-lap joints,the bonding performance of the double-lap joints is higher.Finally,single-parameter and multi-parameter optimizations were performed for the three bonding parameters of single-lap and double-lap joints.Based on tensile strength and lap shear strength,the objective function of bonding strength of singlelap and double-lap joints was established.Single-parameter optimization was performed for lap length,lap width,and adhesive thickness to obtain the optimal value within a certain parameter range.The optimal lap length,lap width,and adhesive thickness of single-lap joints were 17 mm,22.9 mm,and 0.103 mm,respectively.The optimal lap length,lap width,and adhesive thickness of the doublelap joints were 19.3 mm,29.3 mm,and 0.107 mm,respectively.Based on Latin hypercube sampling and genetic algorithm,multi-parameter optimization was performed on single-lap and double-lap joints.Within a certain parameter range,the optimal lap length,lap width,and adhesive thickness of single-lap joints were 18.7 mm,35 mm,and 0.06 mm,and the optimal lap length,lap width,and adhesive thickness of the double-lap joints are 20 mm,20 mm,and 0.24 mm,respectively.Compared to original adhesively bonded single-lap and double-lap joints,the new adhesively bonded structures remarkably improves the bonding and tensile strengths.