Thesis
Experimental and numerical investigations into hole generation and pin joints in carbon fiber reinforced polymer composites
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/101792
Abstract
With advancements in materials technology, carbon fiber reinforced plastics composite (CFRP) has become a vital material used across almost all industries. CFRP joining technology has been studied and one of the typical mechanical fastening methods is pin-joining which requires hole generation in the CFRP laminate. High precision hole generation in CFRP is challenging due to abrasive carbon fibers causing severe tool wear. This study aims to examine the effect of drilling parameters, spindle speed and feed rate, on hole quality, and the effect of hole quality on bearing stiffness and strength of pin-loaded CFRP laminates. To achieve so, a quasi-isotropic CFRP laminate was drilled with an inexpensive High-Speed Steel-Cobalt (HSS-Co) drill bit using four drilling parameter combinations. The same laminate was then drilled using two Diamond-Like Coating (DLC) drill bits to investigate the effect of DLC coatings on the machinability. Hole quality measurements were then taken using a Coordinate Measuring Machine (CMM) and surface roughness profiler. The study found that the setting with the fastest spindle speed, 4000 RPM, and slowest feed rate, 0.0254 mm/rev, produced the lowest drillings forces, and resultantly, the highest quality holes. The study also found that DLC coated HSS-Co drills did not perform significantly better than the uncoated HSS-Co drills in terms of drilling forces, which was attributed to coat chipping. However, DLC drills generated holes with improved hole quality over HSS-Co. To study the effect of hole quality on CFRP pin joint bearing stiffness and strength, nine CFRP coupons were produced with varying hole quality and interference fit by design. Stainless steel alloy pins were then pressed into the pre-drilled CFRP coupons and the pin-joints were subjected to quasi-static tensile loading until bearing failure occurred. The study found that hole size decreases with increasing number of holes drills due to severe tool wear, resulting in increased interference between the hole and the pin. Interference fit between a range of 0.20% and 0.47% resulted from the worn drills reduces the bearing stiffness and ultimate bearing strength of the CFRP pin-joints. The increasing weakness may be a result of increased hole damage that is associated with pressing pins into smaller diameter holes that contain fiber pull-out and delamination.
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Details
- Title
- Experimental and numerical investigations into hole generation and pin joints in carbon fiber reinforced polymer composites
- Creators
- Firas Mashary Balghonaim
- 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
- 99900525109501842
- Language
- English
- Resource Type
- Thesis