A LASER INTERFERENCE-BASED SURFACE TREATMENT OF ALUMINUM AND CARBON FIBER POLYMER COMPOSITES FOR ENHANCED BONDING

摘要

Due to its increased use in the automotive and aerospace industries, joining of Carbon FiberreinforcedrnPolymer matrix Composites (CFPC) to metals demands enhanced surface preparationrnand control of surface morphology prior to joining. In this study, surfaces of both composite andrnaluminum were prepared for joining using a new laser based technique, in which the laserrninterference power profile was created by splitting the beam and guiding those beams to thernsample surface by overlapping each other with defined angles to each other. Results arernpresented for the overlap shear testing of single-lap joints made with Al 5182 and CFPCrnspecimens whose surfaces prepared by (a) surface abrasion and solvent cleaning; and (b) laserinterferencernstructured surfaces by rastering with a 4 mm laser beam at approximately 3.5 Wrnpower. CFPC specimens of T700S carbon fiber, Prepreg – T70 epoxy, 4 or 5 ply thick, 0/90ornplaques were used. Adhesive DP810 was used to bond Al and CFPC. The bondline wasrn0.25mm and the bond length was consistent among all joints produced. First, the effect of thernlaser speed on the joint performance was evaluated by laser-interference structure Al and CFPCrnsurfaces with a beam angle of 3o and laser beam speeds of 3, 5, and 10 mm/s. For this sensitivityrnstudy, 3 joint specimens were used per each joint type. Based on the results for minimum,rnmaximum, and mean values for the shear lap strength and maximum load for all the 9 joint types,rntwo joint types were selected for further evaluations. Six additional joint specimens werernprepared for these two joint types in order to obtain better statistics and the shear test data wasrnpresented for the range, mean, and standard deviation. The results for the single-lap shear testsrnobtained for six joint specimens, indicate that the shear lap strength, maximum load, andrndisplacement at maximum load for those joints made with laser-interference structured surfacesrnwere increased by approximately 14.8%, 16%, and 100%, respectively over those measured forrnthe baseline joints. It was also found that joints made with laser-structured surfaces can absorbrnapproximately 150% more energy than the baseline joints.