bluuebunny/crossref_metadata_2025 huggingface dataset:
The “GD&T Knowledge Gap” in Industry
Authors: Watts Dean
Published: May 2009

Mechanical designs in industry typically do not include adequate specification of allowable part geometry variation. Poorly applied Geometric Dimensioning and Tolerancing (GD&T), ambiguous plus/minus location or orientation controls, and sometimes no variation specifications (only a 3D CAD body) are commonly all that is done. Since improper specifications cause confusion, and since functional requirements are likely either more precise, or less precise, than the manufacturing process will deliver, excessive costs of dealing with geometry variation result. Specifications which unambiguously capture the functional needs of critical part features, combined with properly gathered and consistently reported measurement data would provide a competitive advantage for any company producing a precise mechanical product. The need to capture functional requirements, and also the improved part designs that result when thinking includes the cost & quality issues clarified by GD&T makes this subject an important element of design focused mechanical engineering education. Especially when tolerance analysis and measurement process quality considerations are included, there is sufficient academic rigor to justify additional coursework. The critical seed needed to remedy industry’s knowledge gap regarding dimensional specifications and associated data is to include two academic quarters of GD&T and Dimensional Management design electives as part of every mechanical engineering curriculum.
The Revision of Tooth Surface in Order to Compensate the Load Derivation of the Circular Arc Gears
Authors: Liu Huran , Liu Quanhong , Zhao Dongfu , Song Deyu , Wang Jiande
Published: May 2009

Based on the torsion deformation the gear body and the contact deformation of tooth surface, the fundamental equations of load of the gear was presented, thus established the theoretical basis of the load derivation of the gearing. In this paper, the torsion deformation of the circular arc gears is analyzed first. Then the second order differential equation for the tooth surface load distribution of the involutes gears has been deduced. The equation is applied for the situation where the load is acting on non-continuous engaged point. This forms the theoretical basis for the derivation load calculation of the Novikov gears. Finally, the revision equation to compensate the derivation of the circular arc gears is presented.
Phonon Prediction in Toroidal Carbon Nanotubes Using a Continuum Finite Element Approach
Authors: Leamy Michael J. , DiCarlo Anthony A.
Published: May 2009

This work develops a tensor-based, reduced-order shell finite element formulation used to predict the phonon behavior of toroidal carbon nanotubes (CNTs). Displacements referencing two covariant basis vectors lying in the toroid’s tangent space, and one basis vector orthogonal to the tangent space, capture the kinematics of the toroidal CNT. These basis vectors compose a curvilinear coordinate system. Although specific attention is on toroidal CNTs, the formulation can be quickly adapted to cylindrical or other curvilinear CNTs by appropriate replacement of the metric tensor components and Christoffel symbols. The finite element procedure originates from a variational statement (Hamilton’s Principle) governing virtual work from internal, external (not considered), and inertial forces. Internal virtual work is related to changes in atomistic potential energy accounted for by an interatomic potential computed at reference area elements. Small virtual changes in the displacements allow a global mass and stiffness matrix to be computed, and these matrices then allow phonons to be predicted via the general eigenvalue problem. Results are generated for example toroidal CNTs documenting zero-energy behavior (rigid body motion) and the lowest phonons, which include the expected breathing-like and bending-like phonons.
A New Class of Asynchronous Rotordynamic Response in High-Speed Rotors
Authors: Ehrich Fredric F.
Published: May 2009

Virtually all of the nonlinear rotordynamic phenomena studied in the past result in excitation of rotor response at a dominant frequency at or near the critical frequency at rotational speeds other than the critical speed. In experimental work on a “macro-rig” of a micro-rotor in development some years ago at the Gas Turbine Laboratory of MIT, an unforeseen array of asynchronous response frequencies at other than the critical were noted when the rotor was operated at both subcritical and supercritical speeds. However, those responses were not explored in detail at the time. The patterned responses were apparently related to subharmonic and ultra-subharmonic response, but at frequencies lower than the critical frequency. More recently, the author noted a similar pattern of rotordynamic response in the course of operation at subcritical of an experimental turbomachinery component which was experiencing a local rub between the rotor and stator of an interstage seal. Data from that incident revealed a pattern of asynchronous response that had a very similar appearance to the earlier observation. Using a simple numerical model of a rotor employing a single mass mounted on a massless shaft and a piecewise linear (that is, a bilinear) bearing support stiffness to represent the system, it was possible to replicate the response at individual representative points over a range of sub-, trans-, and supercritical high-speed rotor operation. A generalized expression was derived inductively to represent the individual data points. The resultant pattern of data replicated the patterns of data from the two test vehicles which originally inspired the investigation and suggested the means of their suppression where their presence might be undesirable.
Topology Optimization for Synthesizing Extrusion Based Nonlinear Transient Designs
Authors: Patel Neal M. , Renaud John E. , Mozumder Chandan
Published: May 2009

Concept designs synthesized using conventional topology optimization methods are typically not easily manufacturaed, in that multiple finishing processes are required to construct the component. A manufacturing technique that requires only minimal effort is extrusion. Extrusion is a manufacturing process used to create objects of a fixed cross-sectional profile. Extrusion often minimizes the need for secondary machining, although not necessarily of the same dimensional accuracy as machined parts. The result of using this process is lower costs for the manufacture of the final product. In this paper, a non-gradient hybrid cellular automaton (HCA) algorithm is developed to synthesize constant cross section structures that are subjected to nonlinear transient loading. Examples are presented to demonstrate the efficiency of the proposed methodology in synthesizing these structures. The methodology is first demonstrated for elastic-static modeling. The novelty of the proposed method is the ability to generate constant cross section topologies for plastic-dynamic problems since the issue of complex gradients can be avoided using the HCA method.
Kinematics of a 5-DoF 5-RRR(RR) Prototype
Authors: Zhu Si-Jun , Huang Zhen , Zhao Ming-Yang
Published: May 2009

A fully-symmetrical 5-DoF 3R2T parallel manipulator has three rotational and two translational freedoms. It may be adopted in motion simulation for a spinal column. However, kinematics of these manipulators has not been studied very well because of their short history. To study the characteristics of these manipulators, a 5-RRR(RR) prototype is manufactured. Both forward/reverse position solution and singularity are analyzed in this paper. The work presented in this paper will be helpful for understanding the property of other fully-symmetrical 5-DoF 3R2T parallel manipulator because of their similar constraint relationship.
Self-Organising Features of Rotor-Dynamic Faults
Authors: Vyas Nalinaksh S. , Kumar Ankur
Published: May 2009

Artificial Neural Networks offer an efficient platform for devising condition monitoring strategies in machinery and plants where the number of components and processes are too many and complex to be mathematically modeled appropriately. Self-Organizing Map (SOM) is an interesting artificial neural network algorithm which produces an ordered low dimensional representation of an input data space. The basic Self-Organizing Map (SOM) can be visualized as a sheet-like neural-network array, the cells (or nodes) of which become specifically tuned to various input signal patterns or classes of patterns in an orderly fashion. This work describes a study on application of such topographic mapping for rotordynamic faults. A variety of rotor faults like unbalance, bearing damage, cocked rotor etc., are simulated on an experimental rig in a controlled manner. Vibration Signals obtained from various sensors on the rig are processed to train a Self-Organising Neural Network. It is has been shown that input neurons from the same fault get mapped together in clusters in both two-dimensional and three-dimensional grid spaces and each individual fault occupies a distinct zone on the grid.
Interaction Between Single Unit Trucks and Concrete Barriers in High Speed Impacts
Authors: Reid John D. , Faller Ronald K.
Published: May 2009

Single Units Trucks (SUT’s) are commonly used for hauling many things and typically have a loaded mass between 8,000 to 10,000 kg (18,000 and 23,000 lbs). Concrete barriers are commonly used on high volume traffic highways that have very little median space between opposing traffic lanes. The interaction between SUT’s and concrete barriers during impacts at speeds between 80–90 km/h (50–56 mph) at angles up to 15 degrees is of importance not only to the driver, but also to the surrounding traffic. Of particular concern is the vehicle rolling-over the barrier. This study investigates some recent full-scale crash testing and simulation of SUT’s into concrete barriers. Information gained from this study is being used to help determine the next generation of recommended practices and procedures for designing and testing concrete barriers, as well as other types of barriers, like bridge-rails.
Investigation on Piston Secondary Dynamics: A Model That Considers Translation Along the Wrist-Pin and Second Land Interactions With the Cylinder Bore
Authors: Panayi Andreas P. , Schock Harold J.
Published: May 2009

In recent years several efforts have been made to model piston secondary dynamics in an attempt to assess piston performance accurately. In all these efforts, piston translation along the wrist-pin was ignored, and the piston land interactions with the cylinder bore were not considered. In this paper the authors present a model for piston secondary dynamics that considers piston translation along the wrist-pin and piston land interactions with the cylinder bore. A previously developed piston finite element program has been refined further to incorporate piston secondary dynamics. As its predecessor this model uses a full piston model to perform the analysis over a four-stroke cycle. The model is capable of considering an elastic skirt with deformations induced by thermal, inertial, combustive, hydrodynamic and contact effects. In the current model only the interactions of the second land with the cylinder bore are considered. Unlike the skirt, the land is assumed to be rigid. A brief discussion on the model development is presented. Piston secondary dynamics, hydrodynamic and contact forces, and piston wear results are shown. A comparison is made between the results obtained via three different piston secondary dynamics modeling approaches; no translation along the wrist-pin, translation along the writ-pin, and translation along the wrist-pin as well as second land-cylinder bore interactions.
Active Vibration Control of Active Fuel Management Engines Using Active Engine Mounts
Authors: Shin Kwang-Keun
Published: May 2009

Given the realities of today’s world, the goal of achieving vehicular fuel economy is of paramount importance. One cost effective solution to improve fuel economy without major modification of engines is using Active Fuel Management (AFM), which refers to on-demand cylinder activation and deactivation. One general characteristic of AFM engines is higher level of ignition force resulting in higher torque variation. Consequently the noise and vibration (N&V) performance of a vehicle with an AFM engine can reach an unacceptable level with aggressive cylinder deactivation. One solution to improve fuel economy without degrading N&V performance is the use of Active Engine Mount (AEM). This paper studies the control methods for active engine mount. Both open-loop and closed-loop control are developed based upon single-tone adaptive feed-forward control framework. The details of the algorithm are discussed and the stability and the robustness are examined. Integrated open-loop and closed-loop control is proposed to ensure fast response, enhance performance and robustness. A series of simulations are performed to demonstrate the control algorithm. It is shown that the integrated open-loop and closed-loop control algorithm yields the most promising results.
Cost-Effective Structural Anti-Ram Security Barriers: New Design, Computer Modeling and Test Validation
Authors: Omar Tarek , Bedewi Nabih E. , Hylton Timothy
Published: May 2009

Terrorist attacks became a major threat to the safety, security, and economy of our nation in the last few years. The Attacks against important facilities could have different techniques; however the main source of ground attacks is the application of excessive amount of energy to the designated facility through a vehicle intrusion and/or a blast. In the current research, a new approach of using steel-structure barriers is presented. Several new structural anti-ramming barriers are designed and analyzed using nonlinear Finite Element Analysis (FEA). In this new design, commercial steel-structural components were used in order to reduce the manufacturing cost. These new steel-structure security devices have proven an excellent capability to sustain severe impacts by spreading substantial amount of the impact energy throughout the entire structure and the supporting soil/concrete. In the current research, three anti-ramming bollard systems, for K4, K8 and K12 impact conditions, were presented. The bollard systems were made of commercial steel unites connected together to produce the entire bollard structure. The FE modeling and simulation results of the bollard systems were presented in details in this paper. The FEA for the K4 bollard was validated by comparing the simulation results with the actual test results. The FE simulation results correlated very well with the actual test results. The steel-structure barriers could have much less shallow foundation to account for the in-city utility restrictions. It also has the advantage of easier and faster installation minimizing the required digging and installation time inside the city. The design could also be modified to account for different threat levels and different sites’ restrictions.
3D Road Geometry Based Optimal Truck Fuel Economy
Authors: Huang Wei , Bevly David M. , Li Xiaopeng , Schnick Steve
Published: May 2009

This paper investigates the benefit of using a 3D road geometry based optimal powertrain control strategy in reducing the fuel consumption of heavy trucks. The optimal control, which applies a sequential quadratic programming (SQP) method, is designed to predict the optimal truck velocity trajectory, based on the road geometry with the consideration of fuel consumption and travel time. The fuel consumption baseline is developed based on an engineering drive cycle. Computer simulations of a Class 8 truck are conducted with Intermap real 3D road geometry. Simulation results show that the optimal control strategy is able to reduce the fuel consumption with equal or even shorter travel time, when compared to the defined baseline.
Mechanical/Naval Design of an Underwater Remotely Operated Vehicle (ROV) for Surveillance and Inspection of Port Facilities
Authors: Rami´rez Juan A. , Va´squez Rafael E. , Gutie´rrez Luis B. , Flo´rez Diego A.
Published: May 2009

This paper presents the mechanical/naval design process of an underwater remotely operated vehicle (ROV), required to obtain reliable visual information, used for surveillance and maintenance of ship shells and underwater structures of Colombian port facilities. The design was divided into four main subsystems: mechanical/naval, hardware, software and guidance, navigation and control. The most relevant design constraints were evaluated considering environmental conditions, dimensional restrictions, hydrostatics, hydrodynamics, degrees of freedom and the availability of instrumentation and control hardware. The mechanical/naval design was performed through an iterative process by using computational tools, including Computer Aided Design CAD, Computer Aided Engineering CAE, Computational Fluid Dynamics CFD and a high level programming environment. The obtained design ensures that the reliable operation of the robot will be achieved by using a consistent construction process. The new ROV constitutes an innovative product in Colombia, and it will be used for surveillance and oceanographic research tasks.
Robust Control of Active Suspensions
Authors: Kum Dongsuk , Peng Huei
Published: May 2009

Active suspension has been widely studied in recent decades but the implementation of the single-input, single-output (SISO) force-control architecture that many of the prior studies use has had limited success due to the lightly damped zeros. The inherent trade-off between robust stability and road disturbance attenuation for SISO control architecture is the main culprit. In this paper, we study whether the single-input, two-output (SITO) control architecture provides sufficient degrees of freedom in the control synthesis. First, a quarter car model with an electromagnetic motor is derived and the improved LQG/LTR design technique is employed to simultaneously recover both stability robustness and disturbance attenuation properties at the expense of measurement noise sensitivity. It was found that if the control system is restricted to SISO architecture, sprung mass acceleration is the most promising choice among practical measurements. Both classical and modern control approaches are used to analyze the effectiveness of the proposed method and its closed-loop performance. Simulation results show that stability robustness and disturbance attenuation can be dramatically improved by the SITO architecture over its SISO counterpart.
Model-Based Control for Diesel Engine Start-Stop Operations With a Belted Starter/Alternator
Authors: Canova Marcello , Porembski Joseph , Sevel Kris , Guezennec Yann , Yurkovich Steve
Published: May 2009

The coupling of an internal combustion engine with a starter/alternator is one of the most easily realizable hybrid electric vehicle configurations to achieve significant fuel economy savings in urban driving. A successful implementation of the starter alternator technology includes controlling the electric motor to start and stop the engine quickly and smoothly, without compromising the vehicle noise, vibration and harshness (NVH) signature. The issue becomes more critical in the case of Diesel hybrids, as the peak compression torque is much larger than in automotive spark ignition engines. This paper presents a model-based approach in control design for engine start/stop operations with a belted starter/alternator. Starting from previous modeling and experimental results, a nonlinear model of a belted starter/alternator coupled with a Diesel engine is developed for control algorithm development. With the introduction of a feed-forward control action proportional to the instantaneous engine torque, the starter/alternator controller is capable of consistently reducing the large torque fluctuations during the engine start. With this feedforward control action, the engine start control problem can be translated into a simpler disturbance rejection problem, given a prescribed speed trajectory. This facilitates a linearization of the complex nonlinear model to produce a control-oriented model on which feedback control can be designed. Using the control-oriented model thus developed, different linear control designs have been developed and compared. Further, a robustness study is conducted to evaluate the effect of noise and uncertainties common to such systems. The final results are tested on the original nonlinear truth model, demonstrating the capability of starting and stopping the engine with very limited torque and speed fluctuations.
Experimental Validation of a Model for Control of Drivability in a Hybrid-Electric Vehicle
Authors: Koprubasi Kerem , Westervelt Eric R. , Rizzoni Giorgio , Galvagno Enrico , Velardocchia Mauro
Published: May 2009

This paper describes the development and validation of a control-oriented drivability model for a power-split hybrid-electric vehicle (HEV). The HEV model is capable of identifying drivability issues under critical conditions such as pedal tip-in tip-out, change of operating modes, and gear shifting. The model is useful for the design, improvement and calibration of control strategies. The model is implemented in Simulink® and is validated using data collected from a test vehicle.
Control of Multi-Plate Torque Converter Clutch With an Aggressive Schedule in an Automatic Transmission
Authors: Lee Chunhao Joseph , Samie Farzad , Hebbale Kumaraswamy , Kao Chi-Kuan , Otanez Paul
Published: May 2009

In an automatic transmission, torque converter is the main device that transmits torque from the engine to the gear train. An open converter relies on fluid coupling to transmit torque, which causes energy loss and also causes engine to run at a higher speed. A single-plate locking or slipping clutch has been used between the pump and turbine of a torque converter so that the slip across the converter can be reduced to a level that increases the efficiency of the converter. This slip control, called Electronically Controlled Capacity Clutch (ECCC), also provides necessary damping to the driveline to ensure pleasant driveability similar to an open converter. New legislative and environmental pressures on car makers to improve fuel economy have resulted in aggressive use of ECCC in their automobiles. However, the controllability and heat capacity of the single-plate clutch limit the ability to engage the torque converter clutch (TCC) more aggressively (in earlier gears and lower vehicle speeds). At GM, an experimental multi-plate toque converter was designed, fabricated, and implemented in a RWD transmission. It was demonstrated in a 6-speed vehicle that driving pleaseability can be maintained with a more aggressive ECCC strategy. For this purpose, a control algorithm was developed to control the slip speed of the clutch and allow early ECCC starting in second gear. This paper describes in detail hardware implementation of the multi-plate clutch, development and implementation of the aggressive ECCC control strategy, and some vehicle test results.
A Linearized Vehicle Dynamics Model for Global Chassis Control
Authors: Deur Josˇko , Assadian Francis , Hancock Matthew
Published: May 2009

The paper presents an analytical linearized vehicle dynamics model for global chassis control. Use of the following vehicle dynamics actuators is anticipated: active front and rear steering, active rear and central differential, and drive-by-wire power plant. The linearized model takes into account the tire effects of combined slip and variable normal force. The transfer function form of the linearized model is used for an analysis of control authority of different actuators. The influence of lateral tire relaxation length is also analyzed and incorporated in the model. Characteristic features of the transfer function model with respect to yaw rate output are revealed and used for model order reduction. The presented linearized model is validated against nonlinear models of different complexity.
A Comprehensive Physics-Based Model for Medium-Duty Diesel Engine With Exhaust Gas Recirculation
Authors: Joshi Alok A. , James Scott , Meckl Peter , King Galen , Jennings Kristofer
Published: May 2009

Physics-based models of diesel engines with exhaust gas recirculation and a variable geometry turbine (EGR/VGT) have been developed extensively in the control system design community. However, these models omit the heat transfer effects of the charge-air cooler and the recirculated exhaust gas cooler in order to avoid the added complexity in model order for online implementation. Generally, there is no need to include these effects if the purpose of the model is to control the target variables, such as boost pressure and air-to-fuel ratio. In this paper, after surveying the existing state of physics-based models for the EGR/VGT subsystem, a comprehensive model of the EGR/VGT subsystem is developed. This model includes heat transfer effects in the coolers, pressure drops across air filters and pipes, and mass flow rate calculations for a variable geometry turbine and an exhaust gas recirculation control valve. The purpose and scope of this work is offline modeling-for-diagnostics. Such models, though complex, will assist in the fault sensitivity analysis of a subsystem while avoiding any destructive testing when a major design modification in the EGR/VGT subsystem is proposed. For example, the impact of charge-water or EGR cooler degradation on the boost pressure and the air-to-fuel ratio can be studied with such models to further help in designing diagnostic reasoning strategies. Simulation performed using the proposed physicsbased model demonstrates a dominant failure effect of an EGR cooler coolant leak over a charge-water cooler water leak on the properties of the intake air.
Active Front Steering Damping Control
Authors: Lin William C. , Chen Shih-Ken
Published: May 2009

This paper investigates the feasibility of steering-wheel damping enhancement control of an active front steer (AFS) system without the benefit of closed-loop feedback control and actuator control parameter adjustment. Through a comprehensive modeling and analysis of the AFS system, a simple, yet effective solution is reached to incorporate an additional control term to the actuator angular displacement command, which permits the fine-tuning of the steering wheel damping characteristics as a function of vehicle operation states beyond the pre-determined specification. Furthermore, the analysis also identifies a fundamental relationship between steering effort and the damping control, and thus leads to a proposed fine tuning of the Variable-Effort Steering for further development and implementation.
Two-Stage Turbocharger Modeling for Engine Control and Estimation
Authors: Shu Yong , van Nieuwstadt Michiel
Published: May 2009

The increasingly stringent emissions regulations and needs for higher power density for both turbo-diesel passenger vehicle and commercial vehicles have demanded significant alterations to the basic architecture of turbochargers. An attractive option for providing a high-boost system is the use of two-stage turbocharger which consists of two different size turbochargers connected in series that may or may not utilize bypass regulation. The exhaust mass flow is expanded by the high pressure turbine to the low pressure turbine, and on the other side the air flow is compressed through the low pressure compressor to the high pressure compressor. This increases the complexity of the air-charging system and requires new methodologies for modeling and control. A two-stage turbocharger model is presented in this paper. The total efficiency of the two-stage compressor, which poses the biggest problem in two-stage turbocharger modeling, was derived based on a second law analysis. A new parameter, compressor temperature ratio, was introduced as a linkage between the two stage compressors and also used to predict the two-stage compressor outlet temperature. Extrapolation to lower turbocharger speeds and compressor flow rates by using curve fitting methods was also discussed. The model for a two-stage turbine with a bypass valve is derived in the same way. Engine dynamometer tests have been performed to identify the model parameters and to validate the model structure. The test results show a good agreement between the model predictions and test data. In conclusion, this two stage turbocharger model is suitable for turbocharger control design and the estimation of some key turbocharger parameters.
Engine Start Simulation on an Engine Transient Test System: Hardware and Controls
Authors: Krosschell Brian D. , Klick Stephen J. , Moskwa John J.
Published: May 2009

The goal of this research is to use a hydrostatic transient dynamometer combined with new control techniques to replicate multi-cylinder engine dynamics which occur while the engine is started by an electric starting system. The transient engine dynamometer test system in the Powertrain Control Research Laboratory (PCRL) uses a torque tube and extremely stiff driveline in order to provide a very high bandwidth of torque actuation. The design and nature of this low inertia, stiff system requires that a standard electrical starting system be omitted. One of the objectives of this research was to assemble a new engine on the hydrostatic dynamometer and model the starting dynamics which occur during an engine cold start. The other objective was to verify and compare data collected by the PCRL and Ford to validate testing. This information will then be used in support of development of a cold start testing procedure on the single-cylinder engine transient test system in the PCRL.
IC Engine Transient Heat Transfer System Hardware and Simulation
Authors: Klick Stephen J. , Krosschell Brian , Moskwa John J.
Published: May 2009

One of the ongoing goals of the Powertrain Control Research Laboratory (PCRL) at University of Wisconsin-Madison is to expand the capabilities of the single-cylinder internal combustion research engine by bringing its operation closer to that of its multi-cylinder counterpart. The PCRL has already replicated the rotational dynamics and intake manifold dynamics of a multi-cylinder engine on a single-cylinder research engine. This paper covers the development of an addition to the single-cylinder test system that will allow the replication of transient heat transfer that normally occurs in a multi-cylinder engine from the engine to the coolant. This system will include physical hardware as well as real time hardware-in-the-loop control strategies using MATLAB/Simulink and dSPACE software.
A Simple Vehicle Model for Path Prediction During Evasive Maneuvers and a Stochastic Analysis on the Crash Probability
Authors: Kim Taewung , Bang Kyukwon , Jeong Hyun-Yong , Decker Stephen
Published: May 2009

Active safety systems are being developed in automotive industry, and an analytical vehicle model is needed in such systems to predict vehicle path to assess the crash probability. However, the bicycle model cannot result in a good correlation with test data and ADAMS simulation results, and other analytical vehicle models which have 8 or 14 degrees of freedom need more computation time. Therefore, in this study a simple analytical vehicle model was proposed to predict vehicle path especially during evasive maneuvers. The analytical vehicle model can predict a vehicle’s path based on the given vehicle speed and steering angle. In the analytical vehicle model, two different moment arms were used for inboard and outboard wheels, and lateral and longitudinal load transfers were taken into account. In addition, the magic formula tire model was used to estimate the lateral force. The analytical vehicle model has been validated with a sophisticated ADAMS model, and it resulted in a good correlation with test data. Using the simple analytical model, a stochastic analysis was conducted to analyze the effect of the initial offset amount and the heading angle on the crash probability. Another stochastic analysis was also conducted to analyze the effect of a sensing error on the false negative rate (FNR) and the false positive rate (FPR). It was found that the initial offset amount and the heading angle played a key role in the crash probability, and only FPR was affected noticeably by a sensing error.
Multibody Dynamics Simulation and Bogie Structure Evaluation for Active-Bogie Steering Truck
Authors: Miyajima N. , Matsumoto A. , Suda Y. , Sato Y. , Ohno H. , Michitsuji Y. , Komiyama M. , Tanimoto M. , Kishimoto Y. , Sato Y. , Nakai T.
Published: May 2009

Railway truck is necessary to have excellent curving performance as well as high speed hunting stability, but generally they are contrary to each other. In order to realize the compatibility, many trucks with passive steering mechanism have been studied, and some of them are realized on service operation. In order to realize further improvement of bogie steering ability on sharp curve, active steering control can give effective performance, and is considered as the latest topic. As an example of the active steering bogie, the bogie with actuators between wheelsets and bogie frame is considered. The bogie mechanism realizes effective steering but requires many actuators results in complex mechanism. The truck treated here has simple but effective mechanism: Actuators are attached only between car body and truck frame. When railway trucks negotiate sharp curve running, the rolling radius difference between inside and outside wheels cannot be obtained sufficiently, and the attitude of the truck becomes so-called “insufficient steering condition”. Considering the phenomena, if the truck frame is steered by actuators toward “radial steering position of the truck”, the improvement of curving performance of the truck can be realized. This is the first concept of active-bogie-steering (ABS) truck. In this paper, detailed study and evaluation for ABS (Active-Bogie-Steering) bogie will be presented. Validity tests were carried out with the bogie on rolling test stand in NTSEL (National Traffic Safety and Environment Laboratory), which can simulate curve-running condition including transition curve. Bogie parameters and steering actuator characteristics are elaborately identified in order to compare the experimental results with multi-body dynamics simulation. According to the test results and numerical simulation, the effectiveness of the proposed bogie mechanism and control are proved.
Roll Stability Indicator Incorporating Roll Center Movement
Authors: Jung Jongchul , Shim Taehyun , Gertsch Jamie
Published: May 2009

Predicting impending vehicle rollover is essential for rollover prevention systems but it is not a simple task. In describing roll motion, the roll center movement becomes important as the vehicle roll angle increases, and thus affects the performance of rollover warning devices. This paper proposes a dynamic roll stability indicator incorporating roll center movement. A robust parameter identification algorithm is designed to estimate the horizontal and vertical movement of the roll center. This estimate is used in the roll stability indicator to update its rollover threshold value. The effectiveness of the proposed roll stability indicator is demonstrated through simulations.
Flow Field Characteristic Analysis and Structural Optimization of a Centrifugal Gas-Liquid Separator
Authors: Zhao Lixin , Zhu Baojun , Zhang Yong
Published: May 2009

Based on computational fluid dynamic (CFD) method, the simulation of a normal vertical-vessel type centrifugal gas-liquid separator was carried out, by using Gambit and FLUENT soft packs. It is found that the axial symmetry of the flow field is bad, the gas-content near underflow outlet is higher, which indicates the separating effect of the separator is not satisfied. Through structural optimization, including changing the underflow outlet from side to bottom, designing double inlets, reducing the vessel diameter, extending the overflow tube to the bottom of inlet tube, changing the bottom part of the separator from cylindrical to conical structure, etc., so as to improve the axial symmetry of the separator flow field, including gas phase distribution, then to enhance its separation effect. CFD analysis result of velocity distribution is in accordance with Laser Doppler Anemometer (LDA) result qualitatively. All of these will provide some reference on structural optimization. It is concluded that CFD aided optimization design is very helpful for fluid machinery design, which can guide experimental work and decrease the experimental time and cost to a great extent.
Two-Dimensional Numerical Simulation of Vortex Induced Vibration of a Circular Cylinder
Authors: Wanderley Juan B. V. , Souza Gisele H. B. , Levi Carlos
Published: May 2009

Vortex induced Vibration (VIV) plays a very important role in the offshore petroleum exploration. For example, risers used in oil extraction from the bottom of the sea to the offshore platforms are subjected to marine flows that may trigger dangerous VIV oscillations. Many researches have been spending a lot of efforts to understand the complicated flow around bluff bodies to control or even eliminate the VIV occurrence. Numerical simulations have been unsuccessful to predict the VIV amplitudes mainly because of the diffusive nature of the numerical methods. The present two-dimensional numerical investigation is a continuation of previous efforts trying to predict correct amplitudes of the VIV oscillations. The Beam and Warming scheme is used to solve the governing equations written in general curvilinear coordinates and the Boussinesq Hypothesis and the K-ε turbulence model are used to simulate the turbulent flow in the wake of a circular cylinder. The numerical results agreed qualitatively well with other data from the literature, but poor quantitative agreement was obtained confirming the difficulty of predicting amplitudes reported by other authors.
Ship Hull Drag Reduction Using Bottom Air Injection
Authors: Fakhraee Ahmad , Rad Manoucher , Amini Hamid , Rishehri Mehdi
Published: May 2009

Air cavity ship concept has received some interest due to its potential on viscous resistance reduction for high speed craft. Air-cavity ships (ACS) are advanced marine vehicles that use air injection at the wetted hull surfaces to improve a vessel’s hydrodynamic characteristics. Air is supplied through nozzles under a profiled bottom to generate an air cavity beneath such a ship, so that a steady air layer separates a part of the bottom from contact with water, consequently reducing hydrodynamic resistance. Resistance tests were conducted with two forms: first of which was planning catamaran hull form, and second one was an alternative form with an air cavity injection under its bottom which was tested both without any air injection and with three different air injection ranges. Dead rise angle was fixed to 23 degree during both model tests. Frictional resistance was calculated from wetted surface area and compared with total resistance. It is clear from these results that improvements in high speed planning catamarans can be realized by using bottom air injection. Drag reduction achieved on these model is within 13–23 percent.
A Physical and Numerical Modeling for Launching of Jackets: Case Study on Balal PLQ Platform
Authors: Honarvar M. R. , Pirooz Moharram D. , Bahari Mohammad R.
Published: May 2009

Platform structures are commonly utilized for various purposes including offshore drilling, processing and support of offshore operations. A jacket is a supporting structure for deck facilities stabilized by leg piles through the seabed. In a jacket design, operational and environmental loads are very important and must be investigated intensively to secure the stability of structures during their operational life, as well as installation phase. The main purpose of this research is to evaluate and compare the results of physical and numerical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform. Both physical & numerical modeling basics are described and they are performed on Balal PLQ (Production and Living Quarter) platform that is one 8-legged, 1700-tone main jacket of Balal oil field, located in the center of Persian Gulf, some 100 kms distance from Iranian Lavan Island. It is found that both methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. Then, the inequalities are evaluated to be due to the Froude-type parameters chosen for modeling purpose. The most important result achieved in this research is the necessity of choosing Reinolds-Froude type for physical modeling of launching, instead of Froude-type. This is due to the effect of viscosity in drag hydrodynamic force in addition to the importance of gravitational and inertial forces. It should be noted that viscosity and consequently drag coefficient in Froude type modeling is not quite correct and causes the difference between the results of physical and numerical modeling. To our knowledge, based on the surveyed done in the literature, although there was no results found on the physical modeling of jacket launch to be addressed, but it seems that Reynolds-Froude modeling could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model.
Effect of Skirts on the Behavior of a Mono-Column Structure in Waves
Authors: Masetti Isaias Quaresma , dos Santos Costa Ana Paula , Matter Gerson Beraldo , Barreira Rodrigo Augusto , Sphaier Sergio Hamilton
Published: May 2009

Petrobras, through its Research Center and in cooperation with Universities and Research Institutes, has invested in the development of new concept of platform, aiming to minimize the movements of the structure to work in the field of oil and gas in ultra-deep water. One of these developments is related with a Mono-Column conception provided with a moonpool. In the OMAE2005 Conference, an experimental study of the behavior of this concept was presented, showing the influence of the diameter of the opening of the moonpool base in the heave and pitch motions. A new experimental program was carried out in LabOceano/COPPE/UFRJ, to study the influence of different skirts and the influence of variation of the external diameter along the vertical axis in the behavior of the monocolumn in waves. In this new experimental program a storage unit was tested.
Cyclic Flow Experiments of a Fine Particle Separation Hydrocyclone
Authors: Zhao Lixin , Jiang Minghu
Published: May 2009

Basic separating principle of hydrocyclones and the cyclic experimental research facilities are introduced. The difficulty of separating fine particle is described. Based on a solid-liquid hydrocyclone used for separating fine particles, effect of cyclic flow condition on hydrocyclone’s performance is studied. Effects of cyclic period ratio, cyclic flowrate amplitude ratio, Reynolds number, gas liquid ratio, and the cyclical signal type on the hydrocyclone’s fine particle separation performance, especially on relative overflow purifying rate were studied in detail. The results show that the separation efficiency of the hydrocyclone operated under cyclic flow condition can be higher than that in steady condition, when the cyclic period ratio is about 0.68 and the cyclic flowrate amplitude ratio is about 2%. Rectangular wave seems to be the best cyclic signal for enhancing the hydrocyclone’s separation efficiency. The cyclical change of flowrate leads to the increasing of hydrocyclone’s energy consumption to some extent, while the increasing amount is very less, which is no more than 3% in general.
Statistical Analysis of Channel Siltation Amount on the Silt-Sandy Beach
Authors: Kong Lingshuang , Cao Zude , Dong Sheng
Published: May 2009

The connection of wind and channel siltation is derived. Coefficient of the equation is ascertained using observed data. The annual maximal sudden siltation of channel of 1979∼2003 of Huanghua harbor is calculated using the derived formula and statistical analysis is carried out. The P-III type and Log-normal distributions are used to compute the return period of siltation amount.
Ormen Lange Gas Field, Immediate Settlement of Offshore Rock Supports
Authors: de Vries Guus , van der Meer Joop , Brennodden Harald , Wendel Stein
Published: May 2009

Located approximately 120 km offshore, Ormen Lange, with an estimated 400 billion m3 of natural gas, is the second-largest gas discovery on the Norwegian shelf. The water depth is up to 850 meters, making Ormen Lange the first deepwater project on the Norwegian Continental Shelf. The development of Ormen Lange is under shared operatorship between Norsk Hydro and Shell. Ormen Lange’s untreated well stream will be transported to shore in two 120 km long, 30-inch diameter pipelines to a processing plant at Nyhamna, Norway. From there, gas will be exported via a 42” 1200 km sub sea pipeline (Langeled) to Easington at the east coast of the UK. The pipelines have to pass over the Storegga slide edge which rises 200–300 meters toward the continental shelf in very steep slopes, which are also encountered in the nearshore Bjo¨rnsundet area. The uneven and steep seabed conditions require the use of approximately 2.8 million tons of rock to support and stabilize the pipelines. The sea bottom conditions on the Norwegian continental shelf are characterized by many outcrops as well as very soft clay deposits. The immediate settlement of the rock supports during installation form a significant amount of the total required rock volume. In this paper a procedure is presented on how to assess these immediate settlements recognizing four contributing components all being discussed separately. The calculation results are compared to a back-analysis, performed during the execution of the Ormen Lange rockworks, proving the suitability of the calculation method.
The Influence of Different Scenarios of Supply Ship Collision on the Dynamic Response of a North-Sea Jacket-Pile-Soil System
Authors: Emami Azadi M. Reza
Published: May 2009

In the present study, the influence of various scenarios of supply ship collisions, namely, bow, stern and also broad-side impacts on a jacket-pile-soil system is investigated. In the previous study of ship impact on an 8-leg North-Sea Jacket Platform by Amdahl et al. [2] and also other authors, the effect of jacket-pile-soil interaction was not considered. The collision points on the jacket structure are also taken as joints and mid-span of leg, horizontal and vertical braces, namely, hard and soft impact points. The speed and the weight of the colliding vessel are also varied for typical supply vessels. Several supply ship collision analyses are carried out for bow, stern and broad-side impact scenarios on an 8-leg North-sea Jacket platform It is observed that by taking into account the jacket-pile-soil interaction effects, in particular in softer clay soils the amplitude of displacement response after supply ship impact at the deck level is increased due to yield in the upper soil layers. Contrary to this finding, less linear dynamic effects can be seen in the studied jacket-pile-soil system subjected to the supply ship impact. It can also be concluded that for soft impact scenario, the dynamic effects in the global response of the platform located in the mainly OC clayey soil may be much less than those for hard impact scenario on the same platform. For instance, for a brace impact at its mid-span, a less significant dynamic effect has been observed than for a leg impact. The duration of impact in such cases is shown to play an important role in determining the dynamic influence of the platform response. The relative energy absorption of the platform is shown to be more for broad-side loading. It is shown that the global response of the jacket platform during the collision with a supply vessel might depend largely on the scenario of the impact and to some extent on the pile-soil behavior. It is found that for the bow and stern impact scenarios, the energy contribution of the local member dent or buckling might be more significant than for the broad-side loading for which the global frame energy contribution and the overall inertia effect of the platform might be a dominant factor.