Research on stepped cohesive joint repair slope of composite laminates based on finite element numerical simulation

Abstract

The progressive damage analysis model of stepped adhesive repairing structure was established to study the ultimate load-bearing strength and failure mode of laminates under axial tensile load after stepped adhesive repairing, and the effect of different slope repairing technology on the strength of repaired laminate was further studied. By compiling VUMAT subroutine, failure criteria and stiffness degradation models of laminate and patch were set respectively, and cohesive element was selected to simulate the adhesive layer to complete progressive damage analysis of composite laminates with stepped adhesive repair structure. The results show that the ultimate tensile strength increases with the decrease of slope, but the strength recovery rate does not change much when the slope is 1:20 or less. The adhesive layer at the 0° laminate connection first occurs damage and extends along the direction perpendicular to the loading until failure, and then causes the damage of laminate and patch. The effective adhesive area of the cohesive layer increases with the decrease of the slope, which can effectively alleviate the stress concentration phenomenon; The tensile failure of laminate first occurs at the minimum radius of the damage area, and the tensile failure of fibers first occurs at the 0° laminate and then extends perpendicular to the loading direction.

Keywords

• composite
• adhesive repair structure
• progressive damage model
• vumat subroutine
• slope