Study of curved composites drilling behavior using time-domain acoustic signal analysis

In recent years, the use of layered composites has become very common in various industries due to specifications and properties like high strength, high strength to weight ratio and high corrosion resistance. One of the methods to construct the composite structures is the mechanical joining. To create these kinds of joints, the composite piece should be drilled. This drilling process results in the damages like interlayer delamination. Among the various methods for damage monitoring in composites, the acoustic emission test has the capability to detect the damages in composite pieces under loading due to high sensitivity, high detectability and the capability for online monitoring of the sample. Until now, extensive studies have been performed to analyze the damages during the drilling process of the composites with flat and smooth geometries. On the other hand, the utilization of curved composites is more common in the industry. There have been a few types of research for drilling of these kinds of composite materials. In this research, by using acoustic emission during the drilling process, the machining force behavior and also, interlayer delamination has been analyzed. According to the results, it has been shown that, count feature in acoustic emission method can presents different damage mechanisms.