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A Criterion for Detection of Delamination in Laminated Composite Beams and Plates Based on Modal Analysis of Damaged Structure
,
Ph.D. Dissertation
Sharif University of Technology
;
Kouchakzadeh, Mohammad Ali
(Supervisor)
Abstract
In this study, irregularities of the mode shapes are utilized to determine the delamination situation in a composite laminated beam. Modal analysis is used to obtain the mode shapes of the beam; afterwards, the mode shapes are filtered to extract their irregularities. Presence of any delamination and its situation (number, size and location along the length and thickness of the beam) affects the extracted irregularities. Here, detection of delamination is based on these irregularities of the mode shapes. One of the most important advantages of this method is that unlike many other similar methods, in many cases, the mode shapes of damaged structure are sufficient and the exact mode shapes...
Effect of Ultrasonic Assisted Machining on Mechanical Properties of Carbon Fiber Composite Laminates
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
Ultrasonically assisted machining process has been introduced as an effective solution to improve machining quality of mechanical parts. This study aims to reduce the drilling induced delamination to increase mechanical properties of CFRP laminates. Delamination decreases the strength of laminates under static and dynamic loads. Drilling parameters (feed and spindle speed) and ultrasonic vibrations amplitude are chosen as design experiment factors. Taguchi design of experiments method is used to study the effect of input factors on drilling thrust force, delamination factor and residual strength of drilled laminates. Input factors are in three levels and Taguchi L9 array is utilized. To...
Synthesis of Graphene from Waste by Chemical Exfoliation and Study of It’s Physical Characteristics
, M.Sc. Thesis Sharif University of Technology ; Akhavan, Omid (Supervisor)
Abstract
One atom thick layer of pure carbon in bonded and hexagonal lattice is named graphene. graphene has unique mechanical, optical, thermal and electrical properties and because of these properties has grabbed attention. graphene has been made from high pure graphite by different methods such as CVD(chemical vapor deposition) , chemical exfoliation , micromechanical cleavage and colloidal suspension. through these methods, green methods for synthesis of graphene, using eco-friendly reductants during synthesis of graphene instead of hydrazine and recently using waste(not graphite) are attractive for synthesis of graphene. Following this idea , a group has produced graphene from wastes such as...