bluuebunny/crossref_metadata_2025 huggingface dataset:
Guide to Using the New Generation of IEEE Standards for Railcar Procurements
Authors: Dietz James H.
Published: June 2009

In 1996, the Rail Transit Vehicle Interface Standards Committee was formed as a sponsor committee under IEEE. In IEEE jargon, a sponsor committee is a clearing-house for standards development in a particular subject area. Up to 1996, there was no committee that was actively developing rail transit standards in the electrical arena. This new committee was tasked with the goal of developing standards in an industry that has frequently been keen on customization. Over the last 11 years, the committee has developed 14 standards and has 14 additional standards that are near to completion. The end product will be a suite of standards that cover aspects of railcars, signal systems, overhead contact systems, and traction power substations. While these standards offer the collective advice of the industry, they cannot be blindly implemented. This paper will lay out the scope of the various published standards and provide a roadmap to their use.
Twenty-Five Years of Track Geotechnology Research
Authors: Chrismer Steven M.
Published: June 2009

In the early 1980’s the railroad industry increased funding to the AAR track research program to finds ways to mitigate the expected damage from the eventual introduction of heavy axle load (125-ton) freight cars. This research has provided valuable insights into the behavior of the geotechnical components of track (ballast, subballast, and subgrade) allowing certain long-held but erroneous assumptions about these components to be put to rest, such as the canard that fouling “muddy” material in the ballast resulted from subgrade material pumping upward. Analysis showed that typically the fouling material originated predominately from within the ballast layer itself due to ballast particle wear. With such improved understanding of substructure behavior the railroad industry was able to reduce costs by choosing more appropriate track maintenance and remediation methods. As understanding of track geotechnology has continued to advance, track substructure design and maintenance planning has become less empirical, less trial and error. The paper describes how, with today’s more scientific approach, it is now possible to better address such track substructure problems as unstable “track transitions”, soft subgrade, determining when ballast must be replaced, and more durable track geometry correction methods.
Analysis of Railroad Tank Car Shell Impacts Using Finite Element Method
Authors: Jeong D. Y. , Gordon J. E. , Tang Y. H. , Perlman A. B. , Yu H.
Published: June 2009

This paper examines impacts to the side of railroad tank cars by a ram car with a rigid indenter using dynamic, nonlinear finite element analysis (FEA). Such impacts are referred to as shell impacts. Here, nonlinear means elastic-plastic material behavior with large deformations. Several computational issues are addressed. The dynamic response of the shell structure coupled with the sloshing response of fluid inside the tank is characterized through various mesh formulations. Puncture of the tank is calculated using a material failure criterion based on the general state of stress in the shell structure in terms of stress triaxiality. The FEA models were verified and validated in previous work. In the present work, the verified and validated FEA framework is applied to examine the effect of various factors on the structural response of the tank. These factors include shell thickness and indenter geometry.
Rail Car Tracking Device Selection and Power Consumption
Authors: Gray Robert , Grisier Richard
Published: June 2009

Since its introduction, consumer GPS has made the tracking of critical items in the transportation chain more popular. Shipment of items via rail car is one link in the chain that serves to benefit from GPS technology. This paper discusses a wireless communications system suitable for tracking rail cars. In particular, the power source selection and system testing are described. The system was limited to one device and one power source, a battery. Findings show that the lithium battery selected will power the device for one to three years, depending on transmission activity. Recommended areas of additional research include: battery recharging techniques, effects of connecting sensors to the device, and investigating other communications devices as they become available.
Electrical Transients Analysis for Conductor Rail Gaps of Taipei Rapid Transit System
Authors: Chen Nanming , Shih Wen-Lin , Tzeng Yii-Shen
Published: June 2009

The design for the conductor rail gaps of a rapid transit system complies with service and maintenance criteria for crossovers, pocket track turnouts, walkway side variations, terminal stations, and different power supply sections. The collector shoes of a moving train passing the gaps will produce mechanical abrasion and switching transient characteristics. If the transient voltage is very large, it will produce electrical erosion on the leaving termination of the conductor rail. Maintenance technicians must often replace the damaged components beside the gaps with a new one to maintain service quality, thus, deciding the position and the type of the gaps to reduce arc voltage is very important. This study analyzed transient voltage of Taipei transit train passing crossovers, pocket track turnouts, and the distinct power supply section from deducing electrical circuits. If non-bridgeable gaps are replaced with bridgeable gaps, the bridgeable gaps will produce more arcing current than non-bridgeable gaps for the circuit from transient to steady state. The analysis results indicate that the magnitude of transient voltage depends on the charge and discharge time of the line impedance, the train operation speed and the overlap time of the two collector shoes touching the two sides of the conductor rail.
Feasibility Study for an Ultrasonic Sensor for Monitoring Wheel Flange Contact
Authors: Lewis R. , Dwyer-Joyce R. S. , Yao C.
Published: June 2009

If the contact between the wheel and rail occurs at the flange, a high degree of slip is inherent. This can result in excessive wear and the potential for rolling contact fatigue cracking. Multi-body dynamics software is useful for predicting the bogie and track characteristics that may lead to flange contact occuring. However, there is a shortage of experimental tools available to validate such models or to assist in vehicle and track condition monitoring. In this study, the feasibility of a new approach is investigated. The method is based on an ultrasonic sensor mounted on the wheel. The concept is that the sensor emits an ultrasonic pulse which is designed to impinge on the wheel flange. If there is no contact the pulse is fully reflected back at the flange and picked up by the same sensor. If flange contact takes place, a proportion of the pulse amplitude will be transmitted into the rail. The signal reflected back to the sensor is therefore reduced. The amount by which this signal reduces indicates how much flange contact occurs. Test specimens were cut from sections of wheel and rail, and a 2MHz ultrasonic contact transducer was bonded onto the wheel in a position best suited to detect the flange contact. The specimens were pressed to together in a bi-axial loading frame to generate differing degrees of head and flange contact. The reflected signal was monitored as the normal and lateral loads were varied. It proved possible not only to detect the onset of flanging, but also to record a signal that varied monotonically with both normal and lateral applied load. A map of reflected ultrasound against the applied loading is presented.
A Rail Mounted Ultrasonic Sensor for Contact Patch Measurement
Authors: Dwyer-Joyce R. S. , Lewis R. , Drinkwater B. W. , Zhang J. , Yao C.
Published: June 2009

Failure of a wheel/rail contact is usually by wear or fatigue and both of these depend on the size and location of the contact patch. One contact measuring approach that shows promise is by the use of ultrasonic reflection. If the wheel and rail surfaces make contact and are under high stress they are more likely to transmit an ultrasonic pulse. However, if there is no contact or the contact is under low stress then the wave is completely or partially reflected. By measuring the proportion of the wave reflected it is possible to deduce the extent of the contact area and also estimate the pressure distribution. In previous work [1] static specimens of wheel and rail were measured by scanning a transducer to build up a 2D map of the contact. Whilst this produced good results and agreed well with contact modeling, it is a time consuming process (typically takes 30 minutes for a scan) and could in no way be used for the measurement on-line. In this paper we describe a method that potentially could be used at line speeds and so provide wheel rail contact measurements in field trials. The 2D scan is achieved by using an array transducer that performs a simultaneous line scan. This coupled with the speed of travel of the contact patch over the sensor location can achieve a map of the contact. Specimens were cut from wheel and rail sections and loaded together hydraulically in a biaxial frame. An array transducer was mounted beneath the rail specimen. The array transducer consisted of 64 ultrasonic elements that may be pulsed independently, simultaneously, or with controlled phase difference. In this work all transducers were pulsed simultaneously at repetition rates of 20 kHz. The signals were reflected back from the contact to effectively produce a line scan. The transducer was physically moved, to simulate the translation of the contact patch and so generate a series of reflection profiles. Contacts under a range of normal and lateral loads have been measured and compared with some simple results using pre-inked paper. The paper concludes with a discussion of how this array measurement procedure might be implemented at full line sped and what accuracy could potentially be achieved.
Influence of Passenger Car Suspension Design on Carbody Roll and on Wheel Unloading on Curves at Unbalance Speeds
Authors: Strong Philip M.
Published: June 2009

Analytical results indicate that there is a wide variation in roll and lateral behavior on curves at unbalance speeds, for passenger car suspensions in use today. This paper categorizes passenger car types and analyzes behavior under the action of quasi-static lateral forces such as can occur on curves. Understanding this behavior can be important in providing guidelines for developing new designs that operate at relatively high unbalance speeds while still retaining safe operation, good ride quality and other performance related to suspension system design. The approach taken is to develop equations of motion in terms of the physical parameters that must be known in order to determine carbody roll and lateral motions due to lateral loads and laterally offset component weights. These equations are then rearranged in terms of parameters that characterize quasistatic and dynamic performance in a form that facilitates making general statements about the comparative influence of categories of cars on carbody roll and lateral motions, and the resultant increase in wheel unloading, as functions of lateral load. Results are presented for ranges of cars in each category. Roll and lateral motions of existing designs can be estimated by using the physical parameters of the existing design to calculate the parameters used in the equations presented in the paper and then using those equations to calculate estimates of the roll and lateral motions. For contemplated new designs either physical parameters can be selected and motions calculated, or values of the parameters used in the equations presented in the paper that result in desirable levels of roll and lateral motions can be used as trial values for initial and later iterations of the design. The analytical approach has been subjected to limited correlation with static lean test results with good agreement found.
Measurement of Vertical Track Modulus: Field Testing, Repeatability, and Effects of Track Geometry
Authors: El-Sibaie Magdy , GeMeiner William , Clark Dwight , Al-Nazer Leith , Arnold Richard , Farritor Shane , Fateh Mahmood , Lu Sheng , Carr Gary
Published: June 2009

The heavy axle loads and high speeds of modern freight trains produce high track stresses leading to quicker track degradation. Track loads can be increased by variations in vertical track stiffness — the relationship between vertical rail deflection and the vertical applied load — and vertical track modulus. Both low track modulus and large variations in track modulus (leading to increased dynamic loading) cause accelerated track degradation and associated increased maintenance requirements. The University of Nebraska, under sponsorship from the Federal Railroad Administration, continues to develop a method to measure vertical track deflection and modulus from a rail car traveling at revenue speed. This paper first summarizes past work to develop a method to measure vertical track deflection from a moving rail car. The measurement is made by attaching a beam to the sideframe of a loaded hopper car that extends along the rail toward the car’s center. Then the deflection of the rail is measured approximately four feet from the inner wheel using a camera/laser system. The measurement determines the offset between the rail and the line established by the two wheel/rail contact points. These deflection measurements can then be used to estimate track modulus. Results are presented for repeated tests on approximately three hundred miles of heavy axle load freight line over a period of about ten months. These results have shown that the measurements of the above system are extremely repeatable and are not significantly related to train speed. The measurements also show seasonal variations in track modulus caused by factors such as variations in subgrade moisture and ambient temperature. The system has shown a notable ability to identify locations at high risk of derailments. After each of the four tests, a “top ten” list was created indicating the largest changes in relative deflection in descending order (one top ten list corresponding to each of the four tests). The lists were created based on exception criteria presented by the authors at last year’s conference. Four derailments occurred over this ten month period and three of those derailments appear in the top ten lists (#2, #10, in list one and #1 in list four). Finally, simulation and experimental analysis that quantify and assess the co-relation between this system and track geometry is presented. Extreme track geometry variations can create errors as the relative deflection measurement is mapped into a specific value of track modulus. This effect is also quantified and described.
Multifunctional Sensor-Based Monitoring System for Identifying Vehicle Characteristics
Authors: Mgebrishvili Nikolozi
Published: June 2009

The intensification of investments into international transportation and the resulting intense growth of traffic volume and speed of railroad consists predetermines the need for increased safety and reliability of railroad operation. Current safety requirements revealed the urgent need for monitoring safety of rolling stock. The author designed a multifunctional wayside monitoring system that allows to identify the type and speed of passing vehicles, count the number of axles in the consist, and also determine the condition of car wheels and axles that may potentially present the risk to safe operations. The monitoring system is based on the use of intelligent sensors. Four such sensors are placed along the rail. The number of sensors is driven by the different distances between axles for commuter, passenger and freight trains operated in the countries of Former Soviet Union. For a given direction of the train the distance between the first sensor and the following other three sensors corresponds to the distances between axles of different types of vehicles. The electrical signals generated in each sensor are registered in the computer-based system that is located nearby and is hard-wired with the sensors. The computation system keeps count of number of axles passed, and computes the speed of the train. At the same time, the analog signals from the sensors, the magnitude of which represents the magneto-inductive characteristics of the wheel set depending on the state of their wear, are processed by the diagnostic system that determines the level of wheel wear. A special algorithm, developed by the author is used for identifying a type of the wheel wear. The system developed by the author is unique. It is patented in Russia and Georgia. There are no analogous technical solutions for the system to perform the named above multiple tasks. The monitoring system can be used for train location determination, for wayside diagnostics of rolling stock, for identification the type of vehicles and monitoring their movements in tunnels, for controlling the speed of vehicles, especially on steep descents, and for identification of the type and amount of passing vehicles in yards, repair facilities, depots and sidings. Equipping certain segments of railroad tracks with such monitoring devices will increase the effectiveness of railroad operation since the most vital characteristic of the passing vehicles will be monitored, which would allow to prevent potential accidents.
Predicting Railway Tapered Roller Bearing Life Using Measured Residual Stress and Retained Austenite Data
Authors: Wilson Brent M. , Dick Matthew G. , Magner Scott H.
Published: June 2009

A predictive life tool for case-carburized railcar tapered roller bearings, called the Service Load Factor (SLF), makes use of residual stress and retained austenite data to assess the condition of bearings as a result of service history. It is well known that the interaction between retained austenite transformation and the development of residual stresses are primary factors contributing to cone bore growth and decreased resistance to raceway spalling. This paper attempts to quantify these changes throughout the life of a bearing to provide insight into the predicted remaining service life of the bearing. Also, this paper will cover the use of the SLF as a failure analysis tool in order to quantify bearing damage due to shifted lading or worn adapters.
Correlation of Ultrasonic Inspection of Bearing Components With Bearing Fatigue Life
Authors: Wilson Brent M. , Ghoshal Goutam , Turner Joseph A.
Published: June 2009

One of the most important issues for bearing grade steels is the cleanliness of the steel. Impurities present in a cast steel can manifest as hard/brittle inclusions, which are detrimental to a bearing in service. An advanced ultrasonic measurement technique is developed to determine the inclusion size and density in bearing components. Using ultrasonic C-Scan, a map of the inclusions can be developed that pinpoints the worst areas in an entire cone or cup section nondestructively. A threshold is developed for determining good or bad locations so that specific gate settings can parse those discontinuities considered to be detrimental to rolling contact performance. In addition, multiple transducer sizes and frequencies are investigated to determine an optimized scanning configuration. This protocol can then be adapted to perform quality control specific scans capable of investigating numerous parts and determining a failure rate using the rejection criteria.
Some New Correlations Between Wheel Tread Defects and Their Potential Effects on Wheel Bearing Performance
Authors: Cheng Li , Harrison Harold D. , Snyder Todd
Published: June 2009

Impact wheels and their effects on track have been studied extensively and used to justify the wide-scale deployment of wheel impact measurement systems to improve management and prevention of impact related damage to the infrastructure. Impact data has also been found to correlate with car failures including brake beams and bearings. While it is true that a disproportionately high percentage of catastrophic bearing failures have been associated with high impact wheels, it is also true that there are thousands of high impact wheels that do not result in catastrophic bearing failures. This paper examines both the effect of high impact wheels on roller bearing temperatures throughout their service life as measured using wayside bearing temperature detectors and the idea that a ‘braking event’ may start the long process of wheel deterioration.
Forging and Heat Treating Process Upgrades for a Wrought Railroad Wheel Manufacturing Facility
Authors: Ames George , Lonsdale Cameron , Leghorn John
Published: June 2009

This paper describes a major capital project that was recently completed at a North American wrought railroad wheel manufacturing facility. The overall goals and concept of the project are outlined. Upgrades and improvements to band saws, the 10,000 ton forging press, rolling mill, and associated hydraulic systems, are described with emphasis on improvements in process speed. Installation of new wheel handling robots, which replaced an additional number of older, less robust wheel handling robots, is reviewed. Further, a new in-line wheel heat treating process, which provides for rim quenching and tempering of the wheel shortly after the forging and rolling process is completed, is described in detail. The new computer-controlled heat treating process features a rotary heating furnace to austenitize the wheels, several rim spray stations for quenching, a slot-in-the roof tempering furnace, controlled cooling operations, and automated Brinell testing. Important equipment maintenance concerns that were addressed are also reviewed. Finite element analysis (FEA) results for the new wheel heat treating process are discussed, along with other process considerations.
Quasi-Static and Dynamic Sled Testing of Prototype Commuter Rail Passenger Seats
Authors: Severson Kristine , Perlman A. Benjamin , Stringfellow Richard
Published: June 2009

In support of the Federal Railroad Administration’s (FRA) Railroad Equipment Safety Program, tests have been conducted on prototype commuter rail passenger seats which have been designed for improved occupant protection during commuter train accidents. Quasi-static tests were conducted to evaluate the moment versus rotation behavior of the seat back and to improve the fidelity of the finite element seat model. Dynamic sled tests were conducted with instrumented Hybrid III anthropomorphic test devices (ATDs) to evaluate occupant protection under collision conditions and to improve the fidelity of seat/occupant computer models. The three-passenger prototype seats were designed to meet the following dynamic test requirements: 1. Seats must remain attached to the test fixture. 2. Occupants must be compartmentalized between seat rows. 3. Injury criteria for the head, chest, neck and femur must be within tolerance thresholds specified by the automotive industry. 4. All seat components, including seat cushions, must remain attached. Test conditions were specified for two dynamic sled tests as follows: three forward-facing 50th percentile male Hybrid III ATDs subjected to an 8G, 250 millisecond triangular crash pulse; and three rear-facing 50th percentile male Hybrid III ATDs subjected to a 12G, 250 millisecond triangular crash pulse. The 8G crash pulse is specified in the existing American Public Transportation Association (APTA) Standard for Row-to-Row Seating in Commuter Rail Cars [1] and in the Federal Code of Regulations 49 CFR 238.233 [2], and represents nominal collision conditions. The 12G crash pulse represents the collision environment measured in the cab car during a previous full-scale train-to-train impact test of passenger rail cars incorporating crash energy management [3, 4]. The final test results indicate that all test requirements were met: the seats remained attached to the test sled; the ATDs were compartmentalized; all the injury criteria were within accepted tolerance thresholds; and all the seat cushions remained attached.
Update on Ongoing Tank Car Crashworthiness Research: Predicted Performance and Fabrication Approach
Authors: Carolan Michael , Tyrell David , Talamini Brandon
Published: June 2009

Research is currently underway to develop strategies for maintaining the structural integrity of railroad tank cars carrying hazardous materials during collisions. This research, sponsored by the Federal Railroad Administration (FRA), has focused on four design functions to accomplish this goal: blunting the impact load, absorbing the collision energy, strengthening the commodity tank, and controlling the load path into the tank. Previous papers have been presented outlining the weight and space restrictions for this new design, as well as the approach being taken in developing the design. The performance goals for the new car have also been outlined. A key goal for the new design is the ability to contain its lading at four times the impact energy of the baseline equipment. Presently, a preliminary design has been developed that will incorporate these four functions together. This new design features a conventional commodity tank with external reinforcements to strengthen the tank. The reinforced tank is situated on a structural foam cradle, within an external carbody. This carbody has been designed utilizing welded steel sandwich panels. The body is designed to take all of the inservice loads, removing the commodity tank from the load path during normal operations. Additionally, the carbody panels will serve as an energy-absorbing mechanism in the event of a collision. Preliminary steps for fabricating and assembling the new tank car design have been outlined. These steps were developed with the intention of paralleling existing tank car fabrication process as much as is practical. Using the commercial finite element analysis (FEA) software ABAQUS/Explicit, the improved design has been analyzed for its response to an impact by a rigid punch. Simulations of two generalized impact scenarios have been made for this rigid punch impacting the improved tank car head as well as the improved tank car shell. Results of these analyses, including the force-displacement curves for both impacts, are presented within this paper. These results show that an improved-design tank car can contain the commodity for a head impact with eight times the energy of the baseline car, and four times the energy for a shell impact.
Post Test Review of a Single Car Test of Multi-Level Passenger Equipment
Authors: Priante Michelle
Published: June 2009

In support of the Federal Railroad Administration’s (FRA) Railroad Equipment Safety Program, a full-scale dynamic single car impact test of multi-level passenger equipment was conducted on October 2, 2007. The purpose of the test was to evaluate the crashworthiness performance of a multi-level car. The car struck the test barrier at 36.6 miles per hour (mph). Instrumentation on the car measured the deformations of critical structural elements; the vertical, lateral and longitudinal accelerations of the car body and trucks; and the suspension displacements. The structure of a multi-level car is different from that of a single level car or bi-level car. The underframe for single level cars and bi-level cars are straight. In a multi-level car, the underframe is at one level for the mezzanines, and at a lower level at the midsection. A transition structure, or gooseneck, connects the levels. Two passenger train incidents in the last few years have shown that multi-level cars deform in different modes from single level cars under dynamic loading conditions. In two separate collisions in Placentia and Glendale, CA, the gooseneck crushed. During the test, the most damage occurred in the draft sill. The gooseneck was beginning to hinge. The truck connections at both the leading and rear truck failed. Test results show that the multi-level car had a higher average force than the single level car. The secondary impact velocity is higher for the conventional multi-level car than in the conventional single level car. The multi-level car crushed approximately 2 feet during the test, 3 feet less than the single level car crushed.
Three-Piece Half-Truck Multibody Dynamics Models for Freight Train Suspensions
Authors: Ballew B. , Chan B. J. , Sandu C.
Published: June 2009

A three-piece bogie acts as a support for the freight train car bodies so that they can run on straight and curved tracks. It also absorbs the vibrational energy generated by the track. The three main parts of a traditional three-piece bogie are two side frames and a bolster. The side frames run parallel to the rails and are connected to each other by the bolster, which runs perpendicular to the rail. The side frames are connected to the axles, which are directly connected to the wheels that run on the track through the primary suspension. The primary suspension includes the bearing adapter and pedestal roof. The secondary suspension, which includes the friction wedge and load coils, connects and provides damping on each end of the bolster at its intersection with the side frame. Moreover, the friction wedge aids in warp resistance of the bogie. Because of the wedge’s non-linear frictional characteristics and load sensitive behavior, accurately capturing its dynamics in a computational model proves difficult. Previous work at the Railway Technology Laboratory (RTL) at Virginia Tech focused on better capturing the dynamics of the friction wedge modeled as a 3D rigid body. The current study extends that work to a half-truck model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the side frame. The half-truck model created in MATLAB is a 3D, dynamic, stand-alone model comprised of four rigid bodies: a bolster, two friction wedges, and a side frame assembly. The model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and side frame), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the side frame have only a vertical translation degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialized with a pre-defined static yaw (rotation around the vertical axis) and the side frame may be initialized with a predefined pitch/toe geometry (rotation around the lateral axis). The model simulation results have been compared with results from NUCARS®, an industrially used train modeling software developed by the Transportation Technology Center, Inc., for similar inputs.
Evaluating Different Railway Wagon Alternatives for Timber Transportation by Discrete Event Simulation
Authors: Toikka Tero , Hilmola Olli-Pekka , Saranen Juha P.
Published: June 2009

Finland with Sweden is one of the most important pulp producing countries in Europe, and in paper production these two countries are accompanied with Germany and France as being most important countries of production. For the production of pulp, most important parts are (1) the quality and scale of production process as well as (2) cost efficient and high quality raw material. In addition to using its own raw material sources, Finland purchases wood from various different regions, including Russia. In a frequent number of cases raw material transports is completed with rail transports, especially in the case of Russia where distances are relatively long for transports (several thousand kms). Until now Russian timber has had a cost advantage in comparison to Finnish raw material. The availability of a cheaper alternative has also kept the price of domestic raw material at a relatively low level. However, Russia has announced a schedule to increase tariffs for timber exports. As a consequence the exporters of Russian timber need to examine and fine tune their cost structure of timber procurement to correspond to this new demanding environment. In this paper we examine the transportation cost of forest industry raw material using different types of railway wagons. The case network consists of four Russian terminals and two mills located in Finland. The evaluation is based on a discrete event system simulation model concentrating on timber transport within the case network in question. To make this evaluation even more interesting, Russian railway deregulation has its own special feature: Railway customers are allowed to own railway wagons, but nationally owned RZD owns the locomotives and charges for traction. Our research results show that the traction charge of RZD and competing road transport prices are the most influential factors, when determining the most cost efficient wagon type and network structure for timber transportation.
Loss of Preload in Threaded Fasteners With or Without Rotation
Authors: May Robert L.
Published: June 2009

It is well known that a loss of preload tension in a threaded fastener frequently leads to a fatigue failure of the fastener. Loss of preload in threaded fasteners is usually attributed to rotation of the fastener due to vibration; however under some conditions preload may also be lost without relative rotation between the male and female components in a joint. In these cases, preload is lost due to embedment and relaxation of the joint members. Given that loss of preload is normally associated with rotation, there are numerous methods of “safetying” threaded fasteners to prevent rotation. Many of these methods are in-fact ineffective as they only prevent gross rotation, but allow sufficient rotation to cause a loss of preload. This paper discusses the shortcomings of several traditional fastener “safetying” methods such as safety wire, lock washers, and locking tabs. It also presents the factors that can lead to a loss of preload due to embedment and relaxation. A case study is presented where it is believed that a recurrent joint failure occurred because the inclusion of a traditional anti-rotation safety device in the design contributed to a total loss of preload due to embedment and relaxation.
Root Cause Analysis of Passenger Side Door System
Authors: Clark Wade , Cook Jeff , Madden Chris
Published: June 2009

This paper presents a real-world application of Root Cause Analysis methods that were applied to analyze and resolve a side door problem that was occurring on a particular fleet of coach cars operated by Amtrak. The foundation of a Root Cause Analysis program is a disciplined engineering process designed to identify physical, human and latent roots of chronic or sporadic problems. This paper presents the engineering challenges encountered while conducting root cause analysis of a complex coach car side doors problem. The coach car side doors system exhibited undesirable characteristics when in service. Mechanical staff received multiple reports that during station stops all of the open side doors would unexpectedly close even though the train speed was at zero. During this unexpected side door closing sequence all of the obstacle detection systems were disabled presenting a potential hazard to the traveling public. The side doors Root Cause Analysis team found the Physical Root cause of failure to be located in the door system software code — a finding that was never suspected following years of trouble with the side doors. As a result of this finding, the door manufacturer corrected the software and issued revised software to be installed fleet-wide. The Human and Latent Root causes were addressed through the development of a standard operating procedure and training for conductors and crew on the proper operation of side doors. The Root Cause Analysis method proved to be a powerful and productive process for achieving a solution to a chronic passenger side door problem.
Preparation of Pulp for Screen Printing ZnO Nanoneedles and Field Emission Properties
Authors: Yu Ling-Min , Zhu Chang-Chun , Qi Li-Jun
Published: June 2009

To solve the problem that Various post-treatment technologies were needed to improve the field emission in the current preparation of screen printing carbon nanotubes (CNTs) film, a novel pulping process without post-treatment for screen printing ZnO nanoneedles was presented. Carboxymethyl cellulose (CMC) was used for pulping agent and water was used for dissolvent in this process. The measurement of field emission revealed that the ZnO nanoneedles film prepared by mass ratio 3:5 of ZnO nanoneedles to the paste agent had the lowest turn-on field 2.25V/μm at the current density of 1μA/cm2, and the uniform distribution and great density of luminance points of the ZnO nanoneedles was obtained at the applied field of 4V/μm. This method had a good utility value in the fabrication of ZnO nanoneedles field emission display.
Preparation and Characterization of Pt/WO3 Nano-Film and Its Hydrogen-Sensing Properties
Authors: Hou Changjun , Dong Jiale , Xu Yan , Huo Danqun , Tang Yike , Yang Jun
Published: June 2009

Tungsten trioxide is an n-type semiconductor, which has been extensively used for the development of metal oxide semiconductor gas sensors. The hydrogen gas sensing performance of platinum (Pt) catalyst activated WO3 thin films were investigated here. All of the Pt/WO3 films membranes are sensitive to hydrogen gas and the sample by sol-gel and DC reactive magnetron sputtering methods. X-ray diffraction results indicate that the tungsten trioxide is cubic crystal, and the AFM analysis shows molecular structures of the samples are tetrahedron. It means the four consecutive quadrilateral forms we observed in the 9nmx9nm molecular structure are scattergram of tungsten-ions and oxide-ions on 106 sides in WO2.9 structure cell, and the lost one oxide-ion resulted in the transition of WO3 to WO2.9. With anneal temperature rising, the membranous poriness decreasing. The higher crystal degree is, the lower gasochromic efficiency is. The change of combining environment and content of O−2 ions in colorized / decolorized state WOx films was observed in XPS analysis of Pt/WO3 film, the peak shape had changed greatly. As a result, the explanation to this phenomenon is available here according to XPS chemical shift of electric potential model theory.
Back-Side Wafer Grinding Quality Affecting Back-End Assembly Process for LCD Driver ICs
Authors: Wang Mu-Chun , Hsieh Zhen-Ying , Huang Kuo-Shu , Chen Shuang-Yuan , Huang Heng-Sheng
Published: June 2009

Die size and thickness of IC substrate typically vary as a result of the various market demands while the semiconductor process and the product applications develop fast. In order to satisfy the market concerns, the improvement of wafer grinding and dicing saw technology is necessary to provide lighter, thinner and more reliable ICs. Generally, most of previous commercial ICs almost demonstrate the square profile, but some special applications such as liquid-crystal-display (LCD) driver ICs request approximate rectangle shape. Furthermore, the ratios of length / width of these drivers are near 14:1, therefore, it is easy to be broken during IC assembly process and induce some reliability defects. However, the growth rate of digital panel displays is gradually increased. This global market is more and more impressed. In this study, how to promote the die strength and investigate the wafer grinding process for the previous LCD products is the main target. Through the analysis of data collection in die sizes, the suitable wafer grinding process is recommended in assembly line and some predictable trends for future panel IC applications are also exposed.
Investigation of Dicing Saw Methods Impacting Back-End Assembly Process
Authors: Wang Mu-Chun , Hsieh Zhen-Ying , Huang Kuo-Shu , Chen Shuang-Yuan , Huang Heng-Sheng
Published: June 2009

The chip size, substrate material and package type of ICs are continuously changed due to the advanced process development. In order to satisfy these needs, it is necessary to cut wafers as discrete chip shape. Recently, the cutting technology cardinally relies on the thinner diamond blade plus some variable dicing saw parameters to obtain the separate chips. Although the cutting process is similar to that with traditional mechanical cutting, the accuracy and the quality are totally different. The previous is better than the last. Therefore, the cutting cost is not easily reduced more, except promoting the cutting yield. At the same time, if the utility rate of the cutting machine in one day is increased, this is an alternative to possibly decrease the cost. In present and commercial species of cutting machine, there are single cut, double cut, and laser cut. Except some advanced products or special wafers with laser cut method, most of commercial ICs are still cut with single-cut machine. In this study, we investigate the recent wafer cutting methods and how to protect the pad quality on ICs and probably decrease the assembly price. During this effort, we expect that one is to increase the cutting yield and the other is to practically reduce the assembly-line cost.
Avoidance of Bonding Pad Contamination Affecting Back-End Assembly Process
Authors: Wang Mu-Chun , Huang Kuo-Shu , Hsieh Zhen-Ying , Chen Shuang-Yuan , Huang Heng-Sheng
Published: June 2009

While the process fabrication and the electronic applications develop quickly, the die size and the package type also confront the improvement from the customers’ request to achieve the better signal performance in IC products. In cost consideration and marketing competition, most of commercial IC products still adopt the wire-bond technology, except some high performance products with solder/gold balls adhesion process. For consumer ICs, the gold wire is the major material to connect the IC chip and the lead frame through the bondability technology. In the recent era, the bond pad size and pitch is always shrinking. Therefore, the bond performance strongly depends on wire bond machine to provide lighters, thinner, and more reliable IC. After pad size shrinkage, the quality of pad is more impressed for wire bond reliability, especially in fine-pitch assembly process. It’s a challenge in reliability requirement. In this study, the root cause and promising solution of bond pad contamination were investigated. One is to improve the bonding yield in wire-bond process; the other is to promote the bonding reliability after the whole assembly process.
Nanotechnology in Textile Industry and Advantages
Authors: Chow Charlie
Published: June 2009

Nanotechnology can be applied to various industries and textile industry is one of the foremost industries benefited. Starting 1997, textile industry pioneers with foresight already using the nanometer particles to coat on yarns, fibre and fabric to give innovation to the industry. There was estimation that in 2007, the market for the nanometer particles application, electronic textiles and wearable electronics had reached US$13.6 billion and projected to hit US$115 billion in 2012 (1). Despite this great potential, the textile industries find themselves like swimming in the big ocean when applying nanotechnology to their products. Consumers are hesitated to accept the nano-treated garments as they have little knowledge when comes to nanotechnology. A poll was taken out in August, 2007 showed that in United States, many Americans know little to nothing about nanotechnology. Only 6% of Americans have “heard a lot” about nanotechnology and 42% have heard “nothing at all” (2, 3).
Experimental Investigations on the Nano-Damping Durability
Authors: Suciu Claudiu Valentin
Published: June 2009

Connected to the nano-technological development, solid-liquid interfaces have been used to dissipate surface energies, in systems where the solid is liquid-repellent. Such interfaces are able to store, release or transform the mechanical energy. For instance, some modified silicas and zeolites in association with water have been used to build efficient ecological dampers and springs. Regarding this attractive kind of storage and loss of energy, some practical aspects, such as the endurance limits need to be clarified, and measures to augment the nano-damping durability to values required by usual machine elements (106−107 working cycles) await validation. Thus, in this work endurance tests are performed on nano-porous silica gel micro-particles by using a compression-decompression chamber. When the colloidal mixture of water and silica gel was supplied directly into the test chamber, the nano-damping performances abruptly reduced at augmentation of the number of working cycles due to the colloid leakage at the seals. Such severe leakage occurred since the clearance between the piston and cylinder (hundreds of microns), prescribed by the seals makers, was one order of magnitude larger than the diameter of silica gel particles (tens of microns); accordingly, a few layers of silica gel penetrated the gap, producing damage by abrasive wear of the seals and even of the piston surface during about 105 working cycles. In order to augment the nano-damping durability, colloidal mixture of water and silica gel is introduced inside of a tank that is separated by micro-filters from the main cylinder, in which only water is supplied. One discusses the influence of filtration on the nano-damping performances and the variation of durability versus the ratio of the filter pore’s diameter to the mean size of the silica gel particles. During a few working cycles the silica gel grains are not damaged, since the uniform pressure distribution in the liquid surrounding the particles prevent them from premature fracture, even at high-pressurization. However, silica gel grains that undergo gradually fatigue fracture are able to pass the filter and then, to escape at the test chamber seals; this produces a continuous reduction of the silica gel quantity inside of the pressurization chamber and accordingly, a proportional reduction of dissipation. On a logarithmic scale, a slight linear decreasing of the damping occurs until a critical number of working cycles; this is followed by an abrupt linear reduction of dissipation, with a slope that decreases when the diameter of the filter orifices is diminished. Despite the undesired decreasing of the nano-damping performances at augmentation of the number of working cycles, using appropriate filters the durability can be extended to reach the required life of an actual machine element.