Thesis
Machinability of aerospace composites in drilling and structural integrity improvement of the pin-joined marine composites using experimental and finite element analysis techniques
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/101416
Abstract
Fiber reinforced plastics (FRP) composites have been increasingly used in the transportation industry because of their high strength-to-weight ratio and high stiffness-to-weight ratio. The FRP structural integrity requires the load carrying capability without failure happened. Hole generation for the mechanical joints and performance of the joints are very critical in manufacturing and design of the FRP structures. The fastener hole drilling process in hybrid carbon fiber reinforced plastics (CFRP) composite and titanium (Ti) stacked materials is difficult as they are very dissimilar materials and often causes machinability problems in tool wear and hole qualities. The coating materials are often applied on substrate carbide (WC) drills to improve tool wear resistance. In the first part of this thesis, the tool wear mechanisms have been studied in CFRP only, titanium only and CFRP-Ti stack drillings through the analysis of force, scanning electron microscope (SEM) and optical images. Cutting edge rounding by abrasion has been found to be the principal wear behaviors in CFRP drilling and the dominant wear in drilling CFRP-Ti stacks; while the chipping and titanium adhesion on drill cutting edge were observed in titanium and stack drilling. The AlCrN coated and uncoated carbide drills have been investigated and the best coated drills with the lowest tool wear and superior hole quality have been found. The pin loaded glass fiber reinforced plastics (GFRP) composite joints were investigated in in the second part of the thesis. Three nonlinear finite element (FE) models have been developed to simulate the contact problems in pin installation and bearing loading under different interference fit percentages. The stress and strain distributions have been investigated through experiments and FE analysis. Fiber damages have been analyzed with fractographs after pin installation and the higher interference-fit coupon showed more fiber damages. The higher interference-fit percentage showed smaller stress concentration in FE analysis. The average bearing strength in 0.6% interference-fit coupons has been found to be higher than these in 0% transition-fit and 1% interference-fit coupons. However, the maximum bearing strength and bearing stiffness increased with the increase of the interference fit percentage from both experimental and FE analysis results.
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Details
- Title
- Machinability of aerospace composites in drilling and structural integrity improvement of the pin-joined marine composites using experimental and finite element analysis techniques
- Creators
- Bin He
- Contributors
- Dave Kim (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525034201842
- Language
- English
- Resource Type
- Thesis