Study of Tool Geometry on Ultrasonic Assisted Drilling of Composite Laminates

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Mehbudi, Pedram | 2013

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 43941 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Akbari, Javad
Abstract:
Delamination is a major problem in drilling of fiber-reinforced composite materials. Thrust force is an important factor leading to propagation of delamination during drilling process. One of effective methods to reduce machining forces is application of ultrasonic vibrations. In this study ultrasonic assisted drilling is applied to reduce thrust force in drilling of GFRP laminates. In order to conduct experiments a setup is designed and fabricated to apply both vibrations and rotation to drill bits. Using Taguchi method, a set of experiments is conducted with feed rate, spindle speed, point angle and ultrasonic vibration amplitude as control factors. The results show that applying ultrasonic vibration reduces the thrust force and therefore the drilling induced delamination dramatically. Furthermore using drill bits with smaller point angle leads to reduction in thrust force and delamination damage. The results obtained from twist drill tests were compared with results of stepped drill tests. It was observed that using drill bits reduces the effect of ultrasonic vibrations
Keywords:
Surface Roughness ; Taguchi Method ; Ultrasonic Assisted Deep Drilling ; Delamination ; Glass Fiber Reinfoced Polymer (GFRP) ; Point Angle

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