Experimental And Mechanism Research On Prepreg Tack Based On High-velocity Automated Placement Process

As a low-cost and efficient manufacturing technology,automated placement technology develops rapidly in the manufacturing industry of advanced polymer matrix composites.In the process of automated placement,prepreg tack is the key factor to determine the quality and efficiency of automated placement.Therefore,the characterization of prepreg tack,the influence of lay-up processing parameters on prepreg tack and the bonding mechanism between prepregs are basic problems to be solved urgently.On the background of automated placement technology(the National Basic Research Program of China,the formation mechanism of fiber morphology and precise control principle in automated placement process for large composite prepreg,project number,2014CB046501),the characterization method of prepreg tack was studied,a test system to characterize the prepreg tack during high-velocity automated placement process was designed,the bonding mechanism between prepregs was discussed,and the model of T-peel was established in this paper.With the typical prepreg for automated placement as the research object,the influence of lay-up processing parameters on prepreg tack was studied.The main research includes:A new test system which simulates the automated placement process to measure the prepreg tack during high-velocity automated placement process was designed.The test method called two-step method consisting of the automated placement process and peeling test has been developed.Peel force was used to characterize the value of prepreg tack quantitatively.According to the process characteristics of automated placement,the overall mechanical structure and control system were designed and built.The calibration of lay-up velocity,pressure and temperature was accomplished.The bonding mechanism between prepregs in high-velocity automated placement process was discussed.The bonding strength between prepregs was determined by the degrees of the resin flow and autohesion,and the models of the resin flow and autohesion were developed separately.Then the calculation formula of bonding strength between prepregs was deduced,and the influence of the lay-up processing parameters on the bonding strength was analyzed.The model of T-peel was presented,which established the relation between the bonding strength and peel force.The models indicated that the prepreg tack increases as the increase of the lay-up temperature and pressure,and decreases as the increase of the lay-up velocity,and the increase of bonding strength and peel rate results in the increase of peel force.Single factor experiments and orthogonal experiments were both carried out on the test system of prepreg tack to find the influence of lay-up processing parameters on the prepreg tack.Within experimental parameters,the results showed that the prepreg tack increases along with the increase of lay-up temperature and pressure,and decreases with the increase of lay-up velocity.The peel force increases with the increase of peel rate.The influence of lay-up temperature on prepreg tack is most significant,followed by the influence of lay-up pressure,and the lay-up velocity has the minimum influence.The results of experiments agree with the bonding model of prepreg and the T-peel model.This study provides a reliable reference for the determination of processing window in the automated placement process.