Effect Of Repair Parameters On Low-velocity Impact Performance Of Single-sided Adhesive Bonding Repaired Composite Structures

The carbon fiber-resin composites are increasingly used in engineering because of their excellent properties.There are usually some minor damage in the composite materials that need to be repaired.Adhesive bonding repair is one of the widely repair methods.Since the composite materials are vulnerable to low-velocity impact in the process of using,it has a great influence on the structural bearing capacity.Therefore,this paper studies the damage treatment and low-velocity impact damage of single-sided adhesive repair structures.Firstly,a drop weight impact test system was built,and the influence of damage treatment methods on the impact resistance of laminate structure was studied.When the initial impact energy is the same,absorbed energy of AWJM specimens is relatively largest and the damage is also largest.The area of delamination for AWJM specimen is slightly larger than that for TD specimen,but the area of fiber breakage and matrix cracking for AWJM specimen is slightly smaller than that for TD specimen.The average damage area of AWJM specimens is 1386.5 mm~2,which is6.9%larger than TD specimens.Secondly,based on the ABAQUS platform,a user-defined material subroutine was edited.The damage criterion in the layers was considered and a theoretical model for the delamination and adhesive layer damage was determined.A three-dimensional finite element model for the single-sided adhesive repair of composites was established.The effect of different patch parameters on impact damage of repaired structures under low-speed impact loads is discussed.The repair effect of the structure is measured by parameters such as internal delamination area and absorbed energy of composite materials under impact loading.The results show that when the patch area is the same,the repaired structure of the circular patch has the smallest delamination area,the least impact damage,and the best repair effect.Increasing the size of the patch enhances the repair performance.However,when the patch area approaches to a convergent value,there is no significant improvement of the repair performance.Increasing the number of patch layers can enhance the repair performance,the effect of different repair positions on the repair performance is related to the position of the damage holes.Finally,the influence of patch sizes and patch shapes on the single-sided adhesive repair structure is tested on the built-down impact test platform to verify the correctness of the simulation calculation.