Research On Mechanism Of Delamination Defects In CFRP Laminates Based On Strain Monitoring

Composites material are widely used in military, aviation and various fields because of its excellent performance of light weight, high strength,high specific strength and stiffness.But its hardenability and the manufacturing technology of programmable laminated become the inducement of drilling defects. This paper focus on the drilling defect of FRP laminates and take the FRP laminates as research object to analyze the strain response during drilling laminates process with finite element method;According to the material failure criteria,this paper explain the mechanism of delamination of FRP laminates based on the evaluation of delamination area and contrastive analysis of simulation and experiment.The main contents include the following:Firstly,based on the mass papers research, the main reasons for each of the existing defects were analyzed and summarized after carding the defect of drilling.Therefore, delamination defect which is usually occurred on drilling process is selected to researchThen,using ABAQUS finite element software to establish a 2D impact CFRP laminates and 3D drilling finite element model.Based on PUCK and HASHIN materials failure criteria to develop the VUMAT user material subroutine, it also combine cohesive element technology to simulate 3D drilling laminate for Carbon Reinforced Plastics Fiber(CFRP). The relation of strain and its position would be analyzed by the stress and strain distribution given by 3D simulation.Thirdly,based on the simulation result to decide the sensor distribution,the test which sensors pasted on both inlet side and outlet side respectively on Glass-Fiber-Reinforced Plastic(GFRP) would be plan to analyze the characteristics of defect distribution and improve the experiment planFourthly,building strain experimental platform for monitoring CFRP laminates drilling response.This paper adopt improve twist of double tip angle to drill the CFRP laminates whether has plate supported or not,The result show that plate supported conducive to inhibit delamination and not only the orientation along the fiber is prone to defect but also the defect on outlet side is more serious.Finally,the defect of form and location basically agree well according to contrast analysis of simulation and experiment. Meanwhile,the differences among delamination factor on simulation and experiment do not exceed 5.8% based on the calculation on the method of max diameter ration Therefore,it has proved that the simulation model could predict drilling defect on CFRP laminate to some extent.