An experimental study on low velocity impact behavior of thermoplastic composites repaired by composite patches

In this study, low velocity impact behavior of E-glass fiber-reinforced thermoplastic composites repaired by pressing external laminated composite patches was investigated by experimental methods. Thermoplastic composites were manufactured from polypropylene granules with two different fiber contents of 40 wt. % and 60 wt. %. Repaired specimens were prepared by using unidirectional E-glass reinforced polypropylene based thermoplastic prepregs. In order to compare the low velocity impact behavior of the repaired and unrepaired specimens, a number of single impact tests (ranging from energy levels of 10 J to 50 J) were carried out through a drop weight impact test machine with a hemispherical impactor. Low-velocity impact response of the specimens was investigated with cross-examining contact force-deformation curves and damaged specimens. Impact damages occurred in the upside and bottom surfaces of the composites were recorded from the visual inspection and compared for repaired and unrepaired specimens. According to experimental results, bending stiffness and maximum contact force of the specimens having fiber content of 60 wt.% are higher than those of 40 wt.%. Moreover, it was concluded that the patch repaired specimens have achieved a better performance in terms of maximum contact force and absorbed energy compared to the intact specimens.