Research On Advanced Pultrusion Process For Composite Parts

Advanced pultrusion(ADP) is a low cost and automated manufacturing technology of composites parts,which can product the continuous parts in defined section shape with prepreg as raw materials and by pre-forming, hot pressing, and post-curing process, finally pull-out. As a new advanced composites manufacturing technology, ADP has advantages of high efficiency, limit-free fabrication in logitudinal direction, minimal void content, easy for secondary bonding etc. ADP has been used for A380, A350 and other large aircraft. Now the research on the ADP technology is in the initial stage in China. Based on the relevant literatures, the curing process of prepreg in ADP process was studied, details are as follows:(1) The curing kinetics of resin in the USN12500 prepreg was studied by differential scanning calorimetry (DSC) and the curing degree predicting model of the prepreg was established. The prediction results of the curing degree model were well coincident with the test results with the error less than 5%. Based on the curing degree model, an orthogonal test scheme for curing process study of ADP was designed.(2) In accordance with [0]16 ply stacking sequence, laminates were designed. Based on the existing equipments in the laboratory(oven and plate vulcanizing machine), the curing process of prepreg adopt with ADP was simulated. With interlaminar shear strength and flexural strength as the quality index, curing process scheme of pretreating the prepreg at 80℃for 15min, then curing at 130℃for 25min on certain pressure, and finally postcuring at 150℃for 1.5h was optimized.(3) In accordance with [(0 ,90)/02 /(0,90)/02/(0,90)]sply stacking sequence, laminates were designed and manufactured with the self-designed hot pressing device under pressure of 0.6MPa to verify above mentioned optimize curing process scheme. To decrease the void content in the laminates, the correlation between pressures, pressures apply time and void content was analyzed. The process schemes were designed and conducted with pressure values and pressures apply time as variables, with void content as the quality index. The final process scheme was optimized with pretreating the prepreg at 110℃for 20min, then curing at 130℃for 15min under pressure of 0.4MPa, and finally postcuring at 150℃for 1.5h. The test verificated that void content less than 2% in composites profiles can be prepared.