Laboratory Drill Rig Design for Bit Wear & Vibration Study

Drilling operations is a costly operation and any factors that contribute to the delaying of work operation would be unwanted by the industry. Among the many factors that contribute to problems are bit wear and vibration. Besides currently there are no real time monitoring of bit wear in the oil and gas industry. The main objective of this project here is to design a safe laboratory scale test rig that is capable of assimilating the actual drilling operations and conditions out in the field. Thorough study of material selections and decision making processes such as the weighted evaluation matrix and also analytic hierarchy process (AHP) are used in order to complete the study and thus providing a proper conceptual design of the laboratory scale test rig. A design concept is also generated together with general static analysis of the designed concept. With the lab scale test rig, studies on the bit wear and also vibrations could be done and thus further optimization of drilling practices could be done at a lower cost rather than practicing out in actual drilling operations. This work would illustrate the advantages of varying the parameters for better drilling results in the oil field

Experimental and numerical investigations of bone drilling for the indication of bone quality during orthopaedic surgery

Bone drilling is an essential part of many orthopaedic surgical procedures, including those for internal fixation and for attaching prosthetics. Drilling into bone is a fundamental skill that can be both very simple, such as drilling through long bones, or very difficult, such as drilling through the vertebral pedicles where incorrectly drilled holes can result in nerve damage, vascular damage or fractured pedicles. Also large forces experienced during bone drilling may promote crack formation and can result in drill overrun, causing considerable damage to surrounding tissues. Therefore, it is important to understand the effect of bone material quality on the bone drilling forces to select favourable drilling conditions, and improve orthopaedic procedures. [Continues.

Destructive disassembly of bolts and screws using impact

Disassembly, the process of separating parts or components at the end of their useful life is complex due to a variety of fastener shapes and variability in their damage during use. As a natural solution, mechanical impact has been suggested as a cost-effective method for destructive disassembly of joining elements. The objective of this research is to improve the efficiency of impact disassembly process by studying the characteristics of elastic waves caused by impact. This research presents a new method for increasing the shear stress applied on the bolt head without increasing the energy input invested on launching striker. The equations are developed for the elastic waves in one-dimensional bar that transfers the impact energy to a protruded bolt head mounted on an infinite elastic medium or structure. These equations represent the stress wave for each period when the stress wave caused by impact travels back and forth between the struck end and the other end that is in contact with the bolt head mounted on an elastic body. The equations determine the impact load exerted on the bolt head and also the impact force generated to shear-off the bolt head. Since these equations are developed based on the assumption that the stress waves reflect at the bolt-contacting surface with a constant ratio, the reflection characteristics significantly affect the precision of the analysis. The reflection characteristics from a bolt head are found to be more complex than expected, and they affected the experimental result deviate from the analytical result

Modeling parallel robot kinematics for 3T2R and 3T3R tasks using reciprocal sets of Euler angles

Industrial manipulators and parallel robots are often used for tasks, such as drilling or milling, that require three translational, but only two rotational degrees of freedom ("3T2R"). While kinematic models for specific mechanisms for these tasks exist, a general kinematic model for parallel robots is still missing. This paper presents the definition of the rotational component of kinematic constraints equations for parallel robots based on two reciprocal sets of Euler angles for the end-effector orientation and the orientation residual. The method allows completely removing the redundant coordinate in 3T2R tasks and to solve the inverse kinematics for general serial and parallel robots with the gradient descent algorithm. The functional redundancy of robots with full mobility is exploited using nullspace projection

Laboratory Drill Rig Design for Bit Wear & Vibration Study

Drilling operations is a costly operation and any factors that contribute to the delaying of work operation would be unwanted by the industry. Among the many factors that contribute to problems are bit wear and vibration. Besides currently there are no real time monitoring of bit wear in the oil and gas industry. The main objective of this project here is to design a safe laboratory scale test rig that is capable of assimilating the actual drilling operations and conditions out in the field. Thorough study of material selections and decision making processes such as the weighted evaluation matrix and also analytic hierarchy process (AHP) are used in order to complete the study and thus providing a proper conceptual design of the laboratory scale test rig. A design concept is also generated together with general static analysis of the designed concept. With the lab scale test rig, studies on the bit wear and also vibrations could be done and thus further optimization of drilling practices could be done at a lower cost rather than practicing out in actual drilling operations. This work would illustrate the advantages of varying the parameters for better drilling results in the oil field

Compliance analysis of a 3-SPR parallel mechanism with consideration of gravity

By taking gravity and joint/link compliances into account, this paper presents a semi-analytical approach for compliance analysis of a 3-SPR parallel mechanism which forms the main body of a 5-DOF hybrid manipulator especially designed for high-speed machining and forced assembling in the aircraft industry. The approach is implemented in three steps: (1) kinetostatic analysis that considers both the externally applied wrench imposed upon the platform and the gravity of all moving components; (2) deflection analysis that takes both joint and link compliances into account; and (3) formulation of the component compliance matrices using a semi-analytical approach. The advantage of this approach is that the deflections of the platform caused by both the payload and gravity within the given task workspace can be evaluated in an effective manner. The computational results show that the deflection arising from gravity of the moving components may have significant influence on the pose accuracy of the end-effector

Human-robot cross-training: Computational formulation, modeling and evaluation of a human team training strategy

We design and evaluate human-robot cross-training, a strategy widely used and validated for effective human team training. Cross-training is an interactive planning method in which a human and a robot iteratively switch roles to learn a shared plan for a collaborative task. We first present a computational formulation of the robot's interrole knowledge and show that it is quantitatively comparable to the human mental model. Based on this encoding, we formulate human-robot cross-training and evaluate it in human subject experiments (n = 36). We compare human-robot cross-training to standard reinforcement learning techniques, and show that cross-training provides statistically significant improvements in quantitative team performance measures. Additionally, significant differences emerge in the perceived robot performance and human trust. These results support the hypothesis that effective and fluent human-robot teaming may be best achieved by modeling effective practices for human teamwork.ABB Inc.U.S. Commercial Regional CenterAlexander S. Onassis Public Benefit Foundatio

Hydraulic fracturing experiments to investigate circulation losses

In recent years the oil and gas industry has been drilling more challenging wells due to long deviated wells, drilling through already depleted reservoirs, sub salt wells and increasing water depth. A major challenge these wells create is to prevent fluid loss into the formation and wellbore breakouts by having accurately determined the mud weight operational window. In addition to accurately determine the fracture gradient, additives in the drilling fluid have been used to enhance the fracture gradient in an industry process named wellbore strengthening. In order to study the phenomenon of fracture gradient alteration, a hydraulic fracturing apparatus was developed to replicate downhole conditions. Different lithologies were tested by performing hydraulic fracturing experiments in order to compare and contrast their original breakdowns and re-opening pressures. Results showed that original breakdown pressures for non-permeable cores tend to vary depending on which fracturing fluid is used. The more viscous fluids, the higher breakdown pressure was obtained. A re-opening pressure cycle was performed after reaching breakdown pressure. The values obtained for re-opening pressures do not present a large variation with respect to the fracturing fluid. Thus, it can be said that the re-opening pressure does not have a significant change with respect to the mechanical properties of the core as well as fluid properties --Abstract, page iii

Numerical investigation of cavitation in twin-screw pumps

In order to investigate the flow characteristics and the formation process of cavitation in twin-screw pumps, three-dimensional computational fluid dynamics numerical analysis has been carried out. A conformal structured moving mesh generated by an in-house code SCORG was applied for the rotor domain. The volume of fluid method has been adopted for dealing with the liquid-gas two-phase flow, while the bubble dynamics was handled by a homogenous cavitation model. By changing the rotation speed and discharge pressure, the intensity, distribution area and variation of cavitation at different rotor angle were obtained. The effects of rotation speed and discharge pressure on cavitation characteristics have been analysed. Calculation results with cavitation model are compared with the results without cavitation and the experimentally obtained values. The influence of cavitation on the performance of a screw pump in terms of the mass flow rate, pressure distribution, rotor torque and the shaft power has been analysed and discussed. For analysis of cavitation in clearances, a 2D numerical model which includes radial and inter-lobe clearances was used. The relationship between volumetric efficiency and cavitation intensity was developed by variation of boundary conditions