bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Prediction of the Flow, Pressure and Holding Force Generated by a Bernoulli Handling Device
Authors: Brun Xavier F. , Melkote Shreyes N.
Published: July 2009

This paper presents the modeling and prediction of the air flow, pressure and holding force produced by a non-contact Bernoulli gripper, which is essentially a radial air flow nozzle, used to handle small and large, rigid and non-rigid materials. Previous studies have demonstrated the turbulent behavior of the flow and the presence of a flow separation region at the nozzle of the gripper. Here, a Reynolds stress model has been implemented in a finite volume based segregated Reynolds-Averaged Navier-Stokes solver. Compressible air is modeled to capture the effect of the high flow velocities generated by the nozzle. In addition an experimental set up is designed to validate the model. Experimental results of air pressure and force agree favorably with those predicted by the model. This model could be used to understand the influence of handling variables such as the stand-off distance and air flow rate on the suction pressure distribution and lifting force acting on the handled object.
Design of a Stamping Test for Investigating Surface Distortion in Sheet Metal Parts
Authors: Fu Zhengchun , Hu Ping , Wang Hui-Ping , Zhao Kunmin
Published: July 2009

Surface distortions/deflections are frequently introduced into the Class “A” surfaces during sheet metal stamping processes. However, the origins of the draw die related surface distortion/deflection have not been well understood. This paper presents our design of a stamping test for the investigation of the distortion phenomenon. Five geometric parameters are first identified to represent basic geometry of typical automobile outer panel depression features around the surface distortions. Experimental stamping dies are then designed to reflect various combinations of these five geometric parameters with the assistance of numerical simulations to ensure that the designed dies are able to replicate the surface distortion phenomenon. Also, real-time dynamic measurement techniques are designed to collect historical data of strains and deflection on the stamping panels. Our preliminary tryouts show that the designed stamping test successfully replicates the distortion phenomenon observed in production stamping processes. It provides a platform for the investigation of the root-cause of the draw die related surface distortions.
An Innovative Polymeric Material for Microhandling
Authors: Pagano Claudia , Fassi Irene
Published: July 2009

The rationales for the use of microsystems are numerous, including the reduction of consumables (less chemicals in Lab-on-a-Chip), a faster response time (airbag sensors), the enhanced portability (RF-MEMS), the higher resolution (Inkjet printer head), and the higher efficiency (micro-chemical reactor); moreover their application sectors are numerous. For this reason, during the past decades many improvements have been done concerning the design and manufacturing of microsystems and several products have been fabricated for a great variety of applications in the traditional fields, including the medical and biomedical sectors (e.g.: pacemakers, analysis equipments, microtweezers for minimally invasive surgery, micro drug delivery systems), automotive (sensors for safety in cars e.g. electrostatic field sensors for controlling airbags), aeronautics and aerospace (lightweight distributed sensors for micro crack detection), IT (ink jet printers, reading caps for hard disk, micropumps for microprocessor cooling) and telecommunication (e.g. micro optical switches) as well as in more innovative areas, such as household appliances, entertainment and sport equipment (noise canceller ear plugs, variable stiffness tennis racket, skis equipped with piezoelectric active dampers). Nevertheless microproducts have still great difficulty in penetrating the market, mainly due to the limits of the fabrication processes. Indeed, the two main approaches, monolithic and hybrid, show both many issues to overcome. On one side, the monolithic approach has the consolidate expertise of lithographic processes for the manufacturing of electronic devices on one hand, but on the other hand it has the difficulty in producing three dimensional microdevices with good mechanical properties. On the other side, the hybrid approach is suitable for the fabrication of three dimensional microscopic structures but often fails in assembling processes (12). In order to overcome these issues, new materials have often been studied at microscale to extend the manipulation principles of macroproducts to microsystems (e.g. SMA microgripper (1)), but the techniques imported from the assembly of macro components are, usually, not adaptable for microcomponents, which are subject to very strong superficial forces (3). Therefore new techniques for the manipulation of microcomponents, based on innovative principles, have been conceived and have to be further developed. In this paper the use of new materials in combination with a new handling principle has been proposed and the preliminary results concerning the study of the electrostrictive behavior of a dielectric polymeric smart material, which is promising for the assembly of microcomponents, has been presented.
Inferring Hardness From High-Speed Video of the Machining Process
Authors: Hush Don R. , Bement Matthew T. , Wong Tim K.
Published: July 2009

This paper presents the results of a study to assess the feasibility of inferring workpiece material hardness from high-speed video data of chip formation obtained during a turning operation. The motivation for assessing hardness in situ comes from the fabrication of shaped charges, where spatial variation in hardness is known to affect the performance of the shaped charge. While other in-process data could be used for this purpose, video data are analyzed here because of the stand-off, non-contact advantages afforded. This is especially relevant for highly qualified machining processes for small-lot, high value parts where any interference with the process (e.g., introduction of cables near the machine tool) is undesirable. A multistep image processing procedure is presented which is used to extract several features from the video data. These features are then used to develop a classifier which can be used to predict work-piece hardness. Multiple classifier designs (Knn and Ratchet) are considered.
A New Computationally Efficient Method in Laser Hardening Modeling
Authors: Orazi Leonardo , Fortunato Alessandro , Tani Giovanni , Campana Giampaolo , Ascari Alessandro , Cuccolini Gabriele
Published: July 2009

Laser hardening is a laser assisted process devoted to the surface hardening of the mechanical components. This process is highly suitable for medium carbon steels with carbon content comprised between 0.2 – 0.6% or for low alloy steels which are usually surface hardened during their manufacturing process. Laser hardening technology is gaining a great industrial interest in the last years in fact, the possibility of integrating the heating source directly on the production line, together with the absence of the quenching medium, meets the production needs of modern industries. Laser hardening optimization could be complex especially when tempering due to multiple passes effects must be considered. Many research studies have been proposed in the last years aimed at predicting the optimal laser process parameters such as beam power density, beam velocity and scanning strategies. Many Authors agree with the assumption that the whole austenite resulting from the heating is transformed into martensite during the quenching. This is a valid approximation for single pass but could be a rough hypothesis in multiple-passes when the cooling rate could be not so high. Moreover hysteresis phenomena, due to the severe heat cycle occurring in laser hardening, should be taken into account for pearlite to austenite and martensite to austenite transformations during heating and for martensite tempering during multiple passes. In this paper the crucial problems to be faced regarding laser surface hardening modeling are discussed with respect to current literature. In particular, partial austenitization of the pearlite is suggested as a solution of the hardness prediction of the profile depth. Then three transformation parameters are proposed in order to take into account the hysteresis phenomena in martensite and pearlite transformations into austenite and in martensite tempering. Finally several experimental examples are proposed in order to validate the mentioned assumptions.
Embedding of Micro Thin Film Sensors Into Polycrystaline Cubic Boron Nitride (PCBN) for Potential Tooling Applications Via Diffusion Bonding
Authors: Werschmoeller Dirk , Li Xiaochun
Published: July 2009

Polycrystalline cubic boron nitride (PCBN) is increasingly being used in manufacturing processes to increase tool life and processing speed. Existing sensors in PCBN tools are unable to provide accurate time- and space-resolved measurements of the thermo-mechanical phenomena at and near the tool-work interface. Using microfabrication techniques along with diffusion bonding, thin film palladium-13wt% chromium (PdCr) alloy micro strain gage sensors were successfully embedded into PCBN structures for potential tooling applications. This article reports on the design, fabrication and characterization of a sensor consisting of three PdCr sensing elements embedded into a PCBN sample. The embedded sensors show good linearity and sensitivity.
Pulsed Laser Micro Polishing of Microfabricated Nickel and Ti6Al4V Samples
Authors: Perry Tyler L. , Werschmoeller Dirk , Li Xiaochun , Pfefferkorn Frank E. , Duffie Neil A.
Published: July 2009

The objective of this work is to improve our understanding of pulsed laser micro polishing (PLμP) by studying the effects of laser pulse length, pulses per mm, and workpiece material on surface roughness. PLμP experiments are conducted with a multi-mode Nd:YAG laser (1064 nm wavelength) that is focused down to approximately 50 μm diameter and scanned over the stationary workpiece surface. Simulation results presented here and previous work suggest that longer laser pulses are better for polishing. Results on microfabricated nickel samples using laser pulse lengths of 300 ns and 650 ns test this hypothesis. Additionally, a surface artifact introduced by the PLμP process will be investigated. Results on the microfabricated nickel sample prove that longer laser pulses yield a higher reduction in surface roughness; 300 ns and 650 ns pulses reduce the Ra of the sample by 30% and 50%, respectively. The artifact introduced by the PLμP is found to be directly related to the number of laser pulses per mm. Successful polishing is achieved on Ti6Al4V and the surface roughness (Ra) of the sample is reduced from 0.250 μm to 0.058 μm. It is also shown that the presence of argon shielding gas is necessary to avoid surface cracks. The results presented here further validate the simplified thermal and fluid flow modeling of the PLμP process and demonstrate the effectiveness of PLμP on a broadly used titanium alloy, Ti6Al4V.
Real-Time Diagnostics, Prognostics and Health Management for Large-Scale Manufacturing Maintenance Systems
Authors: Barajas Leandro G. , Srinivasa Narayan
Published: July 2009

Traditional technologies emphasize either experience or model-based approaches to the Diagnostics, Prognostics & Health Management (DPHM) problem. However, most of these methodologies often apply only to the narrow type of machines that they were developed for, and only support strategic level assessments as opposed to real-time tactical decisions. By enabling widespread integration of diagnostics and prognostics into our manufacturing business processes, we have reduced spacio-temporal uncertainties associated with future states and system performance and therefore enabled more informed and effective decisions on manufacturing activities. For large-scale systems, the usual approach is to aggregate multidimensional data into a single-dimensional stream. These methods are generally adequate to extract key performance indicators. However, they only point to observable effects of a failure and not to their root causes. An integrated framework for DPHM requires the availability of bidirectional cause-effect relationships that enable system-wide health management rather than just predicting what its future state would be. This paper summarizes best practices, benchmarks, and lessons learned from the design, development, deployment, and execution of DPHM systems into real-life applications in the automotive industry.
A Comparability Study of a Wireless Electret Accelerometer to a Traditional Piezoelectric Accelerometer
Authors: Jones Joshua J. , McNeal Timothy A. , Salandro Wesley A. , Roth John T. , Suprock Christopher A. , Fussell Barry K.
Published: July 2009

Traditional piezoelectric accelerometers used for machine condition monitoring are expensive and represent a capital risk when placed in the harsh environment of a cutting process. Additionally, these components require signal conditioning hardware and are sampled on a PC via an independent data acquisition interface (DAQ card). The goal of the research discussed herein is to test an industrial-friendly electret-based accelerometer that can perform tasks similar to a traditional piezoelectric accelerometer. The sensor will be adapted to utilize Bluetooth wireless data capabilities, further enhancing the sensors industrial practicality. The output of this electret-based sensor will be compared to the output of a traditional piezoelectric accelerometer and accompanying DAQ. More specifically, the study will focus on the effects of elevated temperature on the sensor. To achieve this, a comparison of both the electret and piezoelectric accelerometer response spectra will be observed over a range of 21°C to 77°C. To further validate the sensor, turning data is collected wirelessly from the sensor and compared to the output of the traditional piezoelectric sensor. Finally, the performance of the sensor for monitoring a tool’s condition during turning is evaluated and presented. The generated trend is contrasted to the comparable trend developed from the piezoelectric-based accelerometer.
Spatially Resolved Characterization of Geometrically Necessary Dislocation Dependent Deformation in Micro-Scale Laser Shock Peening
Authors: Wang Youneng , Vukelic Sinisa , Kysar Jeffrey W. , Yao Y. Lawrence
Published: July 2009

As the laser spot size in micro-scale laser shock peening is in the order of magnitude of several microns, the anisotropic response of grains will have a dominant influence on its mechanical behavior of the target material. Furthermore, conventional plasticity theory employed in previous studies needs to be reexamined due to the length scale effect. In the present work, the length scale effects in microscale laser shock peening have been investigated. The crystal lattice rotation underneath the shocked surface was determined via Electron Backscatter Diffraction (EBSD). From these measurements, the geometrically necessary dislocations (GND) density that the material contains has been estimated. The yield strength increment was then calculated from the GND distribution by using Taylor model and integrated into each material point of the FEM simulation. Finite element simulations, based on single crystal plasticity, were performed of the process for both with and without considering the GND hardening and the comparison has been conducted.
Medical Device Coating Using Ink-Jet Technology
Authors: Walsh Gareth
Published: July 2009

Labcoat has incorporated Ink-Jet technology into its JAC System™ to target the location and quantity of coating applied to a medical device and more particularly in the case of a stent implant to apply a low dose of drug and carrier to the desired surfaces only of the device.
Model and Information Theory Based Diagnostics for Machinery and Gears
Authors: Bryant Michael D. , Choi Ji-Hoon
Published: July 2009

Machines focus power. We view a machine as a “machine communications channel,” wherein components along the channel organize power and information flow. Errors from broken or degraded components disrupt this organization and the implicit information processing. Our model based diagnostics approach constructs detailed physics models of the machine having direct physical correspondence to components and faults, measures states off the real in-service machine, simulates states and sensor outputs of the machine under same service loads, compares simulated sensor outputs to real sensor outputs, and adjusts (tunes) the model’s parameters until simulated outputs closely mimic real outputs. The tuned model now contains information on the real system’s health condition. By comparing the numerical values of parameters to those of an ideal model—an exemplar of perfect health—faults are detected and located. To assess machine functional condition, Shannon’s theorems of information theory are applied as a health metric to the machine communications channel. For prognosis of future health, plots of the model’s parameter values extrapolated forward in time predicts future parameter values. Simulation of the machine channel model predicts “future” machine behavior, and future machine functional condition, using the aforementioned methods. This article applies these methods to a gearbox with tooth root cracking.
Single- and Multi-Stand Chatter Models in Tandem Rolling Mills
Authors: Zhao Huyue , Kornel F. Ehmann
Published: July 2009

Many different modes of chatter and their possible causes have been identified after years of research, yet no clear and definite theory of their mechanics has been established. One of the most important reasons for this can be attributed to the fact that only oversimplified models with a single input and a single output were historically used to formulate chatter in rolling. Such a situation has hindered a complete analysis of the underlying mechanisms. In this paper, a state-space representation of single- and multi-stand chatter models will be proposed in a rigorous and comprehensive mathematical form for stability analysis of the various chatter mechanisms. First, a dynamic model of the rolling process that utilizes homogeneous deformation theory will be established that includes the material strain-hardening and work roll flattening effects. By coupling this dynamic rolling process model with a structural model for mill stands, a single-stand chatter model in a state-space representation will be proposed. Based on the single-stand chatter model, a multi-stand chatter model will be formulated by incorporating the inter-stand tension variations and the time delay effect of the strip transportation. A simulation program will also be presented for the study of the dynamic rolling process in the time domain and for verifying the results from stability analysis.
Review of Intelligent Energy Field Manufacturing (EFM)
Authors: Zhang Wenwu
Published: July 2009

The long cycles of modern economy is driven by technology innovations. New methodologies are needed to increase the efficiency of technology innovations. Intelligent Energy Field Manufacturing is one of such methodologies. The evolution and the fundamentals of Intelligent Energy Field Manufacturing (EFM) are reviewed in this paper. One issue in technology innovation is that the importance of manufacturing process innovations is underestimated. The other issue is how and why shall manufacturing Go Green to increase long-term sustainability. These should be the important topics in the research of Intelligent EFM.
ERP Systems Supporting Lean Manufacturing: A Literature Review
Authors: Halgeri Pritish , Pei Z. J. , Iyer Karthik S. , Bishop Kendal , Shehadeh Ahmad
Published: July 2009

ERP (Enterprise Resource Planning) and Lean manufacturing are two production control methodologies. ERP systems were once considered as hindrance to Lean manufacturing efforts. The explosive growth of e-business is forcing many companies to revisit where they stand in relation to these two methodologies. Vendors of ERP systems begin to recognize the power and advantages of Lean manufacturing and then explore ways to build Lean-related features into their ERP systems. The main objective of this paper is to answer the question “Can ERP and Lean co-exist?” To accomplish this, the paper first discusses the misconception about ERP and Lean and then summarizes the differences between the two methodologies that led to the misconception. The paper discusses the importance of linking ERP and Lean methods and summarizes some of the key Lean toolsets that are offered in some ERP systems. From a list of ERP vendors offering Lean enabled modules three vendors are discussed in details. They are Oracle, TTW WinMan and Pelion systems.
Potential Theory Based Blank Design for Deep Drawing Irregular Shaped Components
Authors: Jianjun Wu
Published: July 2009

A computer aided blank design method based on the potential theory and boundary element methods is presented. The potential theory approximately describes the material flow involved in deep drawing processes. Using the CAD model of an irregular shaped component, a specific number of cross sections at different heights can be generated. In order to obtain the blank shape, the outermost contour is determined by developing these sections gradually. This blank design procedure is like an imaginary reverse material flow governed by the potential theory. In addition, the boundary element method provides a good computational efficiency. This computer aided design method has been found effective by a manufacturer and the proposed approach can be used for a wide variety of complicated deep drawing components.
Sheet Metal Forming Limit Under Stretch-Bending
Authors: Xia Z. Cedric , Zeng Danielle
Published: July 2009

The Forming Limit Diagram (FLD) as developed by Keeler etc. has been widely used to assess sheet metal failure during a variety of forming operations. Its theoretical and empirical foundation is based on localized necking under biaxial loading for the sheet metal. While the in-plane deformation is generally the dominant mode for most forming operations, sheet metal bending is inevitably coupled to the deformation process, and the traditional Forming Limit Diagram has to be modified to take into account the bending effect, especially when the bending radius becomes smaller. This paper presents a theoretical formulation for the Bending-Enhanced Forming Limit model. The deformation theory of plasticity is employed for the instability analysis, and the bending is assumed only in the direction along one principal loading. The obtained results show that the forming limit is enhanced by the bending effect, consistent with experimental observations.
Development of the Process of Honeycomb Seal for Gas Turbine
Authors: Han K. T.
Published: July 2009

In this research, numerical approach for modeling the behavior of honeycomb seal material is studied. Also, the optimal forming process of the honeycomb core is developed and the rolling process is analyzed. The part of the honeycomb is modeled using the commercial S/W, CATIA. And the rolling process is simulated using finite element code, DEFORM™-3D. The standard honeycomb has a uniform hexagonal structure defined by the material, cell size, cell wall thickness and bulk density. The simulation results are reflected to the forming process design for the honeycomb core.
Experimental Investigation of Surface Roughness in Cylindrical Wire Electro Discharge Machining (CWEDM)
Authors: Mohammadi Hossein , Fadaei Tehrani Alireza , Hamadani Ali Z. , Mohammadi Aminollah
Published: July 2009

In this paper the effects of machining parameters on the surface roughness (Ra) in cylindrical wire electro discharge machining (CWEDM) are investigated. CWEDM is a new technology in which a rotary axis is added to a usual Wire EDM machine. In this process, a new machining parameter, such as rotational speed, is introduced, which changes the normal machining conditions in conventional wire electrical discharge machining (WEDM). Current paper investigates the effects of main parameters of CWEDM including power, voltage, pulse-off time, rotation speed of rotary axis and form factor (cone angle) on the surface roughness in CWEDM. This has been done by means of the technique of design of experiments (DOE); the three levels fractional factorial method (3k−p) was used for studying the selected factors which allows us to carry out the above-mentioned analysis performing a relatively small number of experiments. Analysis of Variance (ANOVA) has been used to determine significant factors; also an equation based on data regression has been presented. Results from ANOVA show that power is a significant variable to surface roughness of cylindrical wire-EDMed AISI D3 cold worked steel parts. The surface roughness of test specimen increased as power and voltage increased and pulse off time and rotation speed decreased. Surfaces of the cylindrical WEDM parts were examined using Scanning Electron Microscopy (SEM) to identify the macro-ridges and craters on the surface. Cross-sections of the EDM parts are examined using the SEM to quantify the sub-surface recast layers and heat-affected zones under various process parameters and to determine their relation with surface roughness of parts.
Separation Characteristics Study on Hydrocyclone-Filter
Authors: Li Feng , Jiang Minghu , Zhao Lixin , Zhang Yong
Published: July 2009

In order to improve the oilfield waste water treatment efficiency, a new type separation equipment hydrocyclone-filter is developed. With the main separating structure manufactured with PE-X series capillary material, the hydrocyclone-filter’s separating capability and the relationship between the oil concentration in the filtered water and the filtering speed are all discussed in detail. The tests in lab indicate that the top separating efficiency 99.5% can be gained when the split-ratio is 15% on the PE-8 capillary material cyclone body, and the value 15% is the optimal split-ratio to all type cyclone separating body (PE-X series).The new equipment hydrocyclone-filter offers a new measure to the sewage treatment in oil field.
Hydroelastic Response of a Subsea Production Platform
Authors: Olunloyo Vincent O. S. , Osheku Charles A.
Published: July 2009

The use of subsea production platforms and systems is widely employed in the course of deep and ultra deep waters exploration and exploitation activities. The increasing importance of these structures is driven in part by the global prospecting effort for deep and ultra deep waters oil/gas resources. Nonetheless, these structures and systems are constantly under the influence of hydrodynamic forces that prevail in such locations. In this paper, the nonlinear hydroelastic response of a subsea production platform idealized as a rectangular template supported on four cylindrical tensioned legs that are partly buried in a moving nonlinear elastic medium is investigated analytically. By employing singular perturbation with multiple scales and integral transforms, the effect of waves and the subsoil layer characteristics on the natural frequency of the systems and dynamic response interaction are reported for design analysis and application.
Tuned Mass Damper for Vibration Control in Steel Jacket Platforms
Authors: Golafshani A. A. , Gholizad A.
Published: July 2009

Considering the stress cycles in joints and members due to wave induced forces on offshore platforms, fatigue analysis is therefore one of the most important analyses in offshore platforms design. Most of steel jacket type platforms located in areas with relatively high ratios of operational sea-states to maximum design environmental events; fall in acceptable safety margin in inplace and seismic analyses. But in fatigue analyses they will face critical condition. Therefore it seems that utilizing control mechanisms with the aim of increasing fatigue life in such platforms will be more preferable to merely deck displacement control. Investigation of tuned mass dampers adjustable parameters optimality for vibration control of wave excited structures implies that optimum tuning and damping ratios are strongly dependent to sea-state in addition to system parameters. The efficiency of optimally designed tuned mass damper for fatigue damage mitigation in realistic steel jacket platforms has been evaluated in this study. Full stochastic spectral analysis method has been employed to estimate the maximum fatigue damage as objective function to be minimized. This leads to a min-max problem which has been solved with Micro Genetic Algorithm. Furthermore the efficiency of a variable TMD with different optimum mass for each sea-state has been evaluated in comparison with a TMD with constant parameters.
Numerical Modeling of Launching Steel Jackets With Consideration of Water Entry Forces
Authors: Nourpanah Nikzad , Pirooz Moharram D.
Published: July 2009

In this paper, a numerical model describing launching of offshore jackets from barge is developed. In addition to commercial software’s, water entry forces on jacket members and an implicit Newmark solution technique are included in the model. The results are in general agreement with other numerical software’s available (SACS). Special attention is paid to the fluid forces acting on jacket and the importance of each one. Also it is observed that water entry forces on horizontal jacket elements are very significant and may locally govern the design of these members. This force is more important for horizontal slender members near the mud-line, which do not experience significant environmental loading in operating conditions. Therefore the water entry impact force with large magnitude can cause over-stress and/or ovalling. It is also observed that taking water entry forces in account modifies the jacket trajectory in little extent.
Research on Transient Mechanics Behavior of Pumping Rod in Pumping System
Authors: Zhu Jun , Zhou Rui Fen
Published: July 2009

More than 75% pumping rod well accounted is artificial lifting production well. With the development of the oilfield, eccentric wearing of rod is becoming the main problem. Numerous factors influencing eccentric wearing of rod heighten the difficulties in the prediction and comprehensive analysis. In the past, it is emphasized on the avoiding and curing measures application, and short of system analysis in respect of flectional reason, flectional conformation and influencing factors. In order to reduce eccentric wearing of rod and show the flectional conformation, the transient mechanics behavior research of pumping rod should be researched deeply. The pumping rod is the extra slender flexible rod. Its working state back and forth moving in the process of the pumping oil, the mechanics behavior is very complex including geometric nonlinear, contact nonlinear and dynamics state. The kinematics equations of pumping rod are deduced adopting the updating lagrange based on the finite deformed theory and the contact constraint equation is confirmed by contact theory. The discrete form of equations can be acquired by using the finite element method. The contact dynamics equation can be obtained by coordinates transformation and elements integration. It is shown the flectional modality and the contact state with the load incremental method and Newmark method utilized in the equation solved. Basing on the research, the swab parameters can be optimized and the centralizer can be rational installed to guarantee normal work and extend the inspecting pump cycle.
Hybrid Catenary Riser for Spar Application
Authors: Chang S.-H. Mark , Cheng Yongming , Vass Malcolm , Ledoux Vincent
Published: July 2009

Porches or pull tubes are typically used as conventional hang-off systems for catenary risers suspended from spars. The Hybrid Catenary Riser (HCR) is a novel hang-off alternative to suspend risers from spars where conventional hang-off systems are not available. The HCR consists of a section of flexible pipe suspended from the spar deck and running down to a location about 120 ft below the keel, where it is connected to regular Steel Catenary Riser (SCR) pipe. The flexible pipe passes through intermediate guides in the spar structure, a receptacle protruding from the spar keel, a curved guide pipe attached to the receptacle, and exits a bend stiffener attached to the curved pipe. The curved guide pipe controls the riser departure angle. During pull-in, a bend stiffener connector (BSC) will lock the bend stiffener to the curved pipe while the flexible pipe slides freely through the bend stiffener allowing the pipe to be pulled up to the spar deck. Feasibility of the HCR configuration is verified through state-of-the-art computer modeling. Installation procedures are developed to demonstrate installability. This paper presents the concept in detail and identifies its technical and economic advantages.
Free-Fall Lifeboats: Experimental Investigation of the Impact of Environmental Conditions on Technical and Human Performance
Authors: Simo˜es Re´ Antonio , MacKinnon Scott , Veitch Brian
Published: July 2009

Free-fall lifeboats offer a means to evacuate a ship or offshore installation rapidly, without the lowering operations associated with conventional davit launched lifeboats on wire falls. The performance of free-fall lifeboats during launch and sail-away has been investigated using a model test campaign. The main focus of the experimental evaluation was on the performance of this evacuation system in a range of different weather conditions. Measurements were also made of motions during the launch process, which are relevant to occupational safety issues. Examples of the tests are presented with a focus on results that warrant scrutiny in terms of human health and performance. The results lead us to question the IMO criteria used to assess the occupational safety of free-fall lifeboats.
Comparative Test Research on Different Type Energy-Saving Pumping Unit
Authors: Guo Zhao , Yu Gao
Published: July 2009

Beam pumping unit is the uppermost artificial lifting equipment in the oilfield exploitation. In order to reduce its energy consumption and to cut down the oil production costs, many manufacturers have developed a lot of types of the energy-saving pumping unit. With different energy-saving principle, the energy-saving effects are quite different. It is becoming very important how to justly and reasonably evaluate the energy-saving effect of a pumping unit. Hydrodynamic simulated experiment well is used to compare the energy-saving effects of four types of pumping units. In the process of the experiments, water is taken as the medium, offset pumping unit is as the reference body, system efficiency and electricity-saving ratio is as the evaluating goal and all the experiments are executed at the same condition. The relative curves of the lifting height with the system efficiency and the electricity-saving ratio are drawn for the four types of the pumping units. Testing results indicate that the double horse-head pumping unit has the best effect, and then the compound-balanced pumping unit with downward beam balance weight. According to the comparative results, it is put forward the pumping unit selecting suggestions.
Hydrodynamics of a SPAR-Type FPSO Concept for Application as a Production Platform
Authors: Srinivasan Nagan , Chakrabarti Subrata , Sundaravadivelu R. , Kanotra Rahul
Published: July 2009

A state of the art non-ship-shaped FPSO vessel for the applications to the frontier fields, including arctic, deepwater and harsh environment, is introduced in this paper. Its application towards arctic field is described more elaborately. The need for such a vessel and its feasibility are emphasized herein. As a first phase of the study, extensive physical large scale model test is performed with dis-connectable turret mooring for application in the arctic summer environment in shallow water. The arctic environment with ice conditions require turret mooring system for the vessel with the capability that the platform is removable in emergency conditions e.g., approaching icebergs. Here, the motion behavior of the vessel in waves with 100% turret mooring is determined physically in the tank test. For wave conditions in another field location in the world with clear water, the vessel is also needed to be designed with a 100% conventional mooring system. Hence, the effect of different kinds of mooring system, including 50% vessel and 50% turret mooring, on the vessel behavior is studied. Key results on the comparison of test vs. analysis results are presented in this paper. These results are considered of immense interest and add value to the Oil and Gas industry.
Experimental Research on the Vibration Reduction and Impact Resistance Performances of Offshore Structure Based on Magnetorheological Damper
Authors: Deng Zhongchao , Zhang Dagang , Yao Xiongliang
Published: July 2009

This paper presents a new kind of vibration reduction and impact resistance isolator system based on magnetorheological technique, and its experiment results. The vibration and impact experiments were designed using MTS hydraulic loading system. There were many load cases being applied in the experiment with different mass of the model, exciting forces, and controllable electricity of MR damper (Magnetorheological Damper). The experiment results indicate that this isolator system can control the vibration response very well, especially near the natural frequency of the system; and the isolator system has a good performance in the impact experiment too, the response acceleration was evidently reduced, but the characteristic of MR damper was different form its performance in vibration experiment.
Drag Reduction of Recess Type Moonpool Under Vessel’s Forward Speed
Authors: Son Hye-Jong , Choi Soon-Ho , Kim Man-Hwan , Hwangbo Seung-Myun
Published: July 2009

Recess type moonpools are vertical wells with step frequently found in Samsung drillship. The recess moonpool was originally invented in order to move the drilling equipments without hull interferences. It was also verified that the recess type moonpool had good performance on reduction of relative motion inside the moonpool during zero speed operation. However, once the ship is under forward speed, the moonpool brings a large drag due to the oscillation of water inside the structure. In this research, a drag reduction method of the moonpool was investigated through analyzing the flow behavior inside the moonpool at the Samsung Ship Model Basin. As a result, the moonpool was modified through numerical and experimental study, which was obtained more than ten percents of drag reduction compared to normal rectangular moonpools.
Bending Fatigue Tests Using a Suitable NDT Method to Determine Lifetime of Large Diameter Wire Ropes for Offshore Lifting Applications
Authors: Vennemann Olav , To¨rnqvist Rikard , Ernst Bjo¨rn , Winter Sven , Frazer Ian
Published: July 2009

Wire rope for installations of subsea components offshore have been used for years in different configurations as single-fall or multi-fall. With greater water depths multi fall solutions become more challenging as even low torque ropes induce some torque and great technical effort has to be made to overcome this problem. An alternative solution is the use of a single-fall system employing a large diameter wire rope. Installations are often carried out with the aid of a heave compensation system to keep the load steady during final approach or to pass through resonance zones. As a result such a large diameter wire rope is subjected to frequent bending. It is well known that cyclic bending over sheave (CBoS) can significantly reduce the lifetime of ropes depending on rope utilisation factors and sheave diameters. While there is a lot of data available for smaller rope sizes, very limited data has been generated with large diameter ropes. It was therefore considered necessary to build a bending fatigue test rig and perform bending fatigue tests with the aim of reducing the uncertainty in the fatigue life of large diameter wire ropes. This paper presents the bending fatigue test rig capable of testing O̸109 mm wire rope to up to 330 t, describes the bending fatigue tests carried out and presents bending fatigue test results. Furthermore, results from non-destructive tests, which were frequently performed during the fatigue tests to obtain further information of rope deterioration over its lifetime, will be presented in this paper.
Improving the Motions of a Semi by the Addition of Heave Plates
Authors: Chen Cheng-Yo , Ding Yun , Mills Trevor , Murray John
Published: July 2009

Similar to the manner in which heave plates provide a Truss Spar with low global motions, a heave plate system can be used to significantly mitigate the motions of a conventional semi-submersible. This paper will focus on the global performance of a conventional semi-submersible that has been properly configured with heave plates. The design case is a Gulf of Mexico deepwater environment similar to that for a Spar located in 5,600 feet of water. The system has eight top-tensioned risers (TTR) supported on the top of the semi hull with tensioners, a spread mooring and a 10,000-ton operating payload. Extensive global motion analyses and comprehensive model testing have been carried out to validate the in-place behavior of such a solution. This paper presents the validation results from the analytical prediction and the model test. A semi-submersible with properly configured heave plates can be used as a viable deepwater dry-tree floating solution in such harsh environments as in the Gulf of Mexico. Because of its superior motion characteristics, this solution is also more SCR friendly and can be a better wet-tree application as compared to conventional semi-submersibles. The analytical and model test results demonstrate that the excitation of a semi-submersible hull by wind, wave and current can be adequately mitigated by the proper placement and sizing of a heave plate system. The analysis and testing also indicates that to achieve suitable motions in a cost effective manner requires incorporating fabrication and installation issues into the heave plate system. The in-place behavior of this solution has been validated and thus proving the concept provides a viable cost effective dry-tree floating solution for deepwater developments.
Non Linear System Identification of Offshore Floating Structures
Authors: Varadarajan Nadathur P. , Nagarajaiah Satish
Published: July 2009

Floating structures such as spar platforms are typically designed to be compliant or move with environment loadings, rather than resisting them. Hence they are designed so that there is no dynamic amplification in wave frequency response. However, higher order nonlinear effects are produced in low frequency wind excited regions, especially in Spar platforms. It is difficult to separate the nonlinear behavior of the model response from the loading using conventional methods. In this paper, Empirical Mode Decomposition and Hilbert Transform (EMD/HT) is used to identify the nonlinear response of a spar from the model test results. From the measured response the dynamic parameters are estimated as follows: 1) The multi-component response of the floating structure is decomposed into IMF components. 2) Hilbert transform of the input and the IMF signal in the time domain is done to extract the instantaneous dynamic characteristics. 3) Amplitude and frequency dependent frequency response function is used to represent the result of HT identification. The EMD method can identify any changes in system properties in real time and can be effectively used for repair and retrofit.
Durability of Aramid Ropes in a Marine Environment
Authors: Derombise Guillaume , Van Schoors Laetitia , Davies Peter , Dussud Loic
Published: July 2009

This paper presents first results from a study of the long term marine durability of aramid fibers. The program was started based on the experience of IFREMER using aramid fiber ropes for instrumentation and deep sea handling lines, which is described here. Instrumentation lines showed no degradation after recovery, but results from testing of handling ropes after service indicated significant strength reduction. This led to the development of specific test facilities to study bend-over-sheave performance. The overall aim is to improve understanding of the roles of both the fiber and the rope construction in a marine environment, in order to improve long term strength retention of aramid marine ropes.
Dynamic Response Analysis of a Spar Platform Subjected to Wind and Wave Forces
Authors: Leira Bernt J. , Myrhaug Dag , Voll Jarle
Published: July 2009

Results from a study on dynamic response analysis of a floating production unit (FPSO) excited by wave and wind forces are presented. The FPSO is examplified by a Spar platform considering the motion in surge and pitch. The wind gust is modelled with the Harris [4] and Ochi and Shin [7] wind gust spectra. The effect of the wave age on the wind gust spectrum is included by adopting the Volkov wave age dependent sea surface roughness parameter [10]; the wave age independent Charnock roughness parameter [2] is also used as a reference. Examples of results demonstrate clear effects of wave age on the dynamic response. Moreover, for high mean wind speeds the total wind response is much smaller than the wave response, but for low mean wind speeds the wind appears to be more important.
Fatigue Assessment of Side Shell Details of an FPSO Based on Non-Collinear Sea and Swell
Authors: Andersen Odd Jan , Haver Sverre , Oma Narve , Rognebakke Olav , Sado´ Octavi
Published: July 2009

A methodology to calculate the fatigue damage in non-collinear wind generated sea and swell has been proposed for weather vaning turret moored FPSO’s. The methodology consists in specifying long-term distributions of sea and swell conditions by directional wave scatter diagrams of Hs and Tp and extracting the swell – and wind wave contributions by use of the Torsethaugen double-peaked wave spectra. By assuming the wind sea induced response and the swell induced response to be independent narrow banded processes, response spectra for the combined processes are established. The wave loads are calculated from a hydrodynamic analysis and a closed form approach is used to calculate the fatigue damage summation. The fatigue damage of selected side longitudinal stiffener fillet welds is calculated by using the proposed methodology for a Norwegian Sea FPSO at three different hull girder cross-sections. The relative contributions from sea and swell to the total damage are identified as well as the sea-states and headings that contribute most to the total damage. In addition, the proposed methodology is compared with the more traditional approach, assuming both wind sea and swell to come from the same direction. For the traditional approach, the corresponding resulting wave spectrum used is a single peaked type, i.e. Pierson Moskowitz.