Abstract
Composite materials have grown rapidly as the structural parts in many industrial sectors ranging from the advanced aerospace to electrical vehicles and leisure goods. The composite materials possess superior mechanical properties of high levels of strength-to-weight ratio, fracture toughness, corrosion resistance and abilities for adapting to a variety of shapes to meet the applications. Drilling is indispensable for building most load-carrying structure of composites. Owing to the peculiar property of composite laminates, delamination defect is usually produced at the exit of drilling, which leads to serious concerns of reliability and safety. This research presents an innovative method utilizing the internal expansive force during water icing to suppress delamination in drilling on wall of CFRP tubes which are made by pre-preg sheets and formed by vacuum forming process. The experimental results demonstrate the delamination extent can be reduced up to 43%, while the drilling feed rates can be also elevated more than 400% when maintaining the same level of delamination extent. Being more advantageous than the previous method of applying electromagnetic media inside the tube as back-up, the water icing is both clean and easily remelted as well as recycled leaving little environmental concerns after use. It requires no attention of cleaning the drill bits and composite tubes. The proposed innovative method is effective and inexpensive for industry.