Research On Strength Of Adhesive Bonded Composite Laminates

Superior to mechanical connection repair, adhesive bonding repair technology becomes the main research direction of composite repair. By taking patch-bonded repair and flush repair as the research object, a three-dimensional finite element model of composite laminates has been established to consider the interaction of the damage initiation and evolution of all the laminates, patch and adhesive layer during the entire analysis process. The main research contents are as follows:Firstly, based on the progressive damage analysis method, with commercial software ABAQUS as the platform, a user material subroutine(UMAT) is compiled for the implementation of the proposed composite lamina constitutive equation, damage initiation criterion and damage evolution criterion. The three-dimensional Hashin crietion is adopted as the damage initiation criterion. The adhesive layer element adopts second order strength criterion as the damage initiation criterion while the B-K energy criterion is presented as the damage evolution criterion.Secondly, the paper presented the 3D finite element model of patch-bonding repair and flush repair. Bearing capacity and damage evolution have been studied in comparison with the reference data. The analysis results have good agreement with the reference data. Based on the FEM, several main parameters of repaired laminates are discussed on the effect of ultimate strength.Thirdly, based on the analysis of patch-bonding repair and flush repair, repair scheme is analyzed and conducted with the final damage form and ultimate strength,which verifies the effectiveness of the repair scheme.