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    Abstract:
    Abstract. The Haiti region – bounded by two strike-slip faults expressed both onshore and offshore – offers a unique opportunity for an amphibious drilling project. The east–west (EW)-striking, left lateral strike-slip Oriente–Septentrional fault zone and Enriquillo–Plantain Garden fault zone bounding Haiti have similar slip rates and also define the northern and southern boundaries of the Gonâve Microplate. However, it remains unclear how these fault systems terminate at the eastern boundary of that microplate. From a plate tectonic perspective, the Enriquillo–Plantain Garden fault zone can be expected to act as an inactive fracture zone bounding the Cayman spreading system, but, surprisingly, this fault has been quite active during the last 500 years. Overall, little is understood in terms of past and present seismic and tsunami hazards along the Oriente–Septentrional fault zone and Enriquillo–Plantain Garden fault zone, their relative ages, maturity, lithology, and evolution – not even the origin of fluids escaping through the crust is known. Given these unknowns, the Haiti-Drill workshop was held in May 2019 to further develop an amphibious drilling project in the Haiti region on the basis of preproposals submitted in 2015 and their reviews. The workshop aimed to complete the following four tasks: (1) identify significant research questions; (2) discuss potential drilling scenarios and sites; (3) identify data, analyses, additional experts, and surveys needed; and (4) produce timelines for developing a full proposal. Two key scientific goals have been set, namely to understand the nature of young fault zones and the evolution of transpressional boundaries. Given these goals, drilling targets were then rationalized, creating a focus point for research and/or survey needs prior to drilling. Our most recent efforts are to find collaborators, analyze existing data, and to obtain sources of funding for the survey work that is needed.
    Keywords:
    Lithology
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    Measurement while drilling
    Citations (0)
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    Citations (0)
    This paper presents the application of a noncoated carbide drill having a sharp cutting edge and multistage point angle (drill A) for drilling carbon fiber reinforced thermoplastics (CFRTP). The cutting characteristics were evaluated by comparing the drill A with a diamond-coated carbide drill having a constant point angle (drill B). The influence of the contact state between the cutting edge and carbon fiber on the cutting force was evaluated using a CFRTP with a unidirectional fiber. The drill A exhibited a maximum thrust force at the drill rotation angle where the fiber orientation and cutting edge travel direction matched. It was found that the thrust force of the drill A was lower than that of the drill B at any drill rotation angle. Moreover, the thrust force of the drill A was always lower than that of the drill B during the drilling of the CFRTP with a plain-woven fabric. Additionally, the uncut fiber of the drilled hole obtained by the drill A was more satisfactory than that obtained by the drill B. The temperature of the area near the cutting point during the drilling was lower in the drill A than in the drill B. In the drill A, the thrust force tended to increase with the number of drilled holes. However, no considerable reduction in the drilled hole quality was observed at 200 holes.
    Citations (0)
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    Citations (0)
    Drilling is one of the most important method for hole making in composite materials. Drilling of polymer matrix composites causes substantial damage around the drilled hole. Damage free holes can be made using modified drill geometry. The present research investigation focuses on the drill geometry as candidate parameter that influence drilling forces and drilling-induced damage. The four different drill geometries (solid and hollow in shape) are used for drilling in composite materials. The cutting mechanism of these drill geometries is substantially different, and therefore influences the drilling-induced damage. The experimental results suggest a strong relationship between the drill point geometry and the drilling-induced damage.
    Citations (33)
    The accuracy of drill hole location is critical for implant placement in orthopaedic surgery. Increasing drill bit size sequentially has been suggested as a method for improving the accuracy of drill hole start location. The aim of this study was to determine whether sequential drilling or drill angulation would alter accuracy of drill hole start location. Three specialist veterinary surgeons drilled holes in synthetic bone models either directly, or with sequentially increasing drill bit sizes. Drilling was performed at 0 o , 10 o and 20 o to perpendicular to the bone models. Three synthetic bone models were used to mimic canine cancellous and cortical bones. Sequential drilling resulted in greater inaccuracy in drill hole location when assessing all drilling angles together. There was no influence of surgeon or synthetic bone density on drilling accuracy. The combination of drill angulation and sequential drilling increased inaccuracy in drill hole start location. We conclude that sequential drilling decreased accuracy of drill hole location in the synthetic bone model when drilling was angled. Inaccuracy associated with the drill hole start location should be taken into account when performing surgery, although the magnitude of inaccuracy is low when compared with other sources of error such as angulation.
    Drill bit
    Cancellous bone
    Drill hole
    Citations (4)
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    Drill bit
    Breakage