New Publications are available for Ballistics and mechanical impact (mechanical engineering)
http://dl-live.theiet.org
New Publications are available now online for this publication.
Please follow the links to view the publication.Experimental and simulated force-displacement relations under cyclic bending deformation of copper-based spring materials
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0637
The reliability of connector is depending on the contact force, generated by the spring in terminals of connectors. The springs are commonly formed by stamping from a strip of the spring material. Therefore, the prediction of its force-displacement relation by the finite element method (FEM) is very important for the design of terminals. For the simulation, the accurate model of stress-strain (s-s) responses of the materials is required. When the materials are deformed in forward and the following reverse directions, almost all the spring materials show different s-s responses between the two directions, due to the Bauschinger effect. This phenomenon makes the simulation difficult because the s-s response depends on the prior deformation of the material. The authors reported the mathematical description of s-s responses of the materials by the Yoshida-Uemori model, which is a constitutive model having high capability of describing the elastic and plastic behavior of cyclic deformation. In this paper, a new measurement method for cyclic bending of actual strips of the materials will be presented. The experimental force-displacement relations were in good agreement with the corresponding simulation results using Yoshida-Uemori model. Therefore, the use of this model for the FE simulation would be recommended for the more accurate prediction of force-displacement relation of the spring.Use of real time creep force estimation data for assessment of low adhesion in the wheel/rail contact
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0614
Low adhesion in railway vehicle wheel/rail contact can create large cost and punctuality issues for train operators and users. There is currently a lack of real time knowledge of the running conditions on networks, therefore the work reported here proposes a method of detecting dynamically the adhesion conditions underneath a rail vehicle using modest cost sensors and advanced model based monitoring of the creep forces. The estimated creep forces are then post processed to give an estimation of the current adhesion condition. (6 pages)A robotic system for non-destructive evaluation of RCF cracks in rails using an ACFM sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0611
The growing use of heavier and faster trains means that more consideration must be given to routine inspection of rails. Inspection trains, dual purpose road/track vehicles and hand held trolleys utilising ultrasonic, eddy current, alternating current field measurement (ACFM) or magnetic flux leakage sensors are the techniques which are currently employed in the rail industry. The vehicle mounted systems generally provide information on defect locations but provide less dependable data about defect sizes, which has to be ascertained by hand-held systems. However, the hand held systems require expert operators to interpret the collected data and, hence, are more costly and time consuming to use. Therefore, in order to address the requirements of higher axle weight and faster trains, the rail inspection system needs to be improved. In this research, a robotic system has been proposed for detection and characterisation of rolling contact fatigue (RCF) cracks on in-service rail tracks. The system consists of a mechanised trolley, an FS02N Kawasaki robot arm and a commercially available AMIGO ACFM system, supplied by TSC Inspection Systems. The RCF defects will be located while the ACFM sensor is fixed in position and the trolley moves at a controlled speed. The detected defects are then re-visited and the robot arm is utilised to perform a detailed scan over the defects (for characterisation) while the trolley is stationary. This paper summarises experimental results obtained when the trolley is stationary and the robot arm is used to survey the rail head. The results suggest that the proposed system has the potential to improve the quality of RCF crack characterisation and to be used autonomously to inspect the rail tracks. (6 pages)Detection of wheel-rail conditions for improved traction control
http://dl-live.theiet.org/content/conferences/10.1049/ic.2010.0036
Novel detection techniques of wheel-rail contact condition, that exploit the dynamic properties of the conventional solid axle wheelset in response to changes at the wheel-rail interface, are studied in this paper. The main aim is to develop an ability to identify/predict adhesion limit to overcome the problem of wheel slip/slide in poor contact conditions where the adhesion is low. Two possible solutions are introduced. One of the proposed methods detects the wheel slip indirectly from the wheelset dynamic changes caused by the wheelsets operating in the unstable region of the non-linear contact characteristics as a consequence of wheel slip. The second method estimates the contact force saturation and identifies the maximum adhesion using a model based technique that involves the use of multiple Kalman filters. (6 pages)Green manufacturing technologies of CrTiAIN composite coatings as an alternative to chromium electroplating for piston rings
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0459
As an alternative to chromium electroplating for piston rings, one green manufacturing technology of CrTiAIN composite coatings has been introduced in this paper. In addition the mechanical and tribological properties of CrTiAIN composite coatings have been compared with chromium electroplating and CrN films. During the deposition of CrTiAIN composite coatings, the three processing steps in deposition involved were plasma ion cleaning, buffer layer deposition, and multi-component layer deposition. During the final deposition step, nitrogen concentration was controlled at 0~50 %. The metallic ratio of Cr,Ti,and Al was varied by adjusting the target currents. The nano-indenter, ehergy dispersive X-ray(EDX), scanning electron microscopy and X-ray diffraction instrument were used to investigate the mechanical property and microstructure of the coatings. The experimental results showed that the optimized quaternary Cr-Ti-AI-N coating performs better than binary CrN as well as the conventional hard chromium plating in teams of hardness and wear resistance, which was suited to use under the high temperature condition of piston rings, and they can be proposed as an alternative to hard chromium platings.Research on cutting remanufacture deposited materials in the impactive condition
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0431
Orthogonal experimental were carried for cutting remanufacture deposited Materials in the impactive condition. By the experiments analysis, it can be known that the cutting capability of tools were determind by toughness of tools when the hardness of deposited materials is low. And the hardness of tools becomes the main roles for improving cutting capability when the hardness of deposited materials arrives to HRC56. At the same time, orthogonal design-direct analysis shows that the impact resistant capability of tools does not always means improvement in cutting capability. The comprehensive balance between strength of tools and impacts in the process is favorable method to improve cutting capability of tools.Approach to toughen polypropylene processed by plane compression
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1348
An approach which formed sheet structure through plane compression processing in the bulk of polypropylene (PP) polymer was suggested and the mechanism was presented based on a series of experiment. The variety of super-molecular structure that the spherulite deformed into ellipse even fractures piece in the pressure field helped to increase the impact resistance and changed the thermo performance. In the polar reign of spherulite, the lamellae underwent a slight deformation, and the lamellae broke into fraction and then slid each other along the flow direction in the equatorial region. Finally, the lamellae in the sample aligned along the flow direction, and the sheet structure which was packed each other by lamellae was built up by plane compression processing.Simulative analysis of cyclist's head impact point in vehicle-electric bicycle rear-end crashes
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1122
In order to study the characteristics of cyclist head impact point in vehicle-electric bicycle rear-end crashes, we build the models of cyclist, electric-bicycle and vehicle based on PC-Crash, in which three types of vehicle, namely compact car, SUV and sports car are selected, and the impact point between vehicle and electric-bicycle is located in the middle of the bumper and the collision angles are 0°, 30° and 60°, respectively. Major analysis is based on the governing factors such as vehicle types, collision angels and collision speeds. The results indicate that the hood height is a significant factor affecting the head impact point on the vehicle, i.e. the head impact point becomes closer to the front of the vehicle with the hood height increasing. In addition, the head impact point on the vehicle in car to electric-bicycle rear-end crashes is also highly dependent on the collision angle and speed, namely, the impact points is located in the lower middle of the windshield with a larger collision angle at higher collision speeds.Research on electromagnetic crack heat arrest and laser repaired in hot die metal
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1319
The hot die steel contacted with hot metal are easy to produce surface cracks with higher impact and heating and cooling repeated.. This paper uses the electromagnetic heating effect theory,It pulse discharge which make the crack tips passivated and form welded joints to prevent further expansion of the crack.Then using loser cladding repairs the cracks.Consequently, the hot die steel could be arrested and repaired.Dynamics characteristic study of the visco-elastic suspension system of construction vehicles
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1508
Due to the environmental protection laws and regulations being strict day by day now, how to resolve the problems of serious vibration and impact construction vehicles, the poor driving comfortableness and the noise pollution occurring in the vehicles, have become a new urgent task, which affects the development of the heavy duty construction vehicles. The new visco-elastic suspension can not only buffer serious vibration and impact, but also dissipate most of vibration and impact energy into heat, which improves the driving and working condition of the vehicle. However, because of the complex structure of viscoelastic suspensions used in construction vehicles, it is considerable difficult to make model and analyse the characteristics of parameters. In the paper, the semi-car model of tracked vehicle suspension system is built in accordance with the visco-elastic suspension system of structural characteristics and the feature of components. The characteristics of stiffness-damping of suspension dampers is studied by using finite element. And the loading of suspension is analyzed by applying the loading of tracked pin. Lastly, for the example of a 246 kW tracked tractor, the dynamic responding of whole machine is researched in representative working condition. The results show that the model can better reflect the characteristics of vibration damping reduction about the visco-elastic suspension system. (4 pages)The Asset Protection Supersite (APS)
http://dl-live.theiet.org/content/conferences/10.1049/ic_20080337
Asset protection sites are used to detect a variety of conditions from wheel wear and over speed impacts to truck hunting, vertical impacts, and temperature/pressure changes. They protect rolling stock and track infrastructure and help to prevent damage and costly repairs, traffic hold-ups and derailments. (5 pages)Signature analysis on wheel-rail interaction for rail defect detection
http://dl-live.theiet.org/content/conferences/10.1049/ic_20080342
Fibre Bragg Grating (FBG) sensors have been installed along an existing line for the purposes of train detection and weight measurement. The results show fair accuracy and high resolution on the vertical force acted on track when the train wheels are rolling upon. While the sensors are already in place and data is available, further applications beyond train detection are explored. This study presents the analysis on the unique signatures from the data collected to characterise wheel-rail interaction for rail defect detection. Focus of this first stage of work is placed on the repeatability of signals from the same wheel-rail interactions while the rail is in healthy state. Discussions on the preliminary results and hence the feasibility of this condition monitoring application, as well as technical issues to be addressed in practice, are given. (6 pages)Wayside monitoring of metro lines
http://dl-live.theiet.org/content/conferences/10.1049/ic_20080339
A case study of need, development and implementation of a Wheel Condition Management System. Wayside monitoring was implemented in an Australian metropolitan area in Australia in response to rail damage and environmental concerns. Wheel condition monitoring was well established in the freight industry but the implementation on a suburban network highlighted unique problems and requirements. The successful implementation of a Wayside Monitoring System required changes to instrumentation and the strategies for using the data that is produced by these instruments (see Fig 1). These modifications included classic "process" control and improvement methods that involved engineers for the rolling stock division working closely with the repair centres. The program included the initial recovery and control phases, the search for root cause (see Fig 2), the steady state management phase and finally the new early intervention strategies that involve using a "step-change" alarm method. The manner in which minor wheel defects were repaired also changed - these changes included the introduction of trim blocks to service the wheels when early "minor" wheel defects were detected thus avoiding the need for wheel machining. The introduction of Wayside Detection has included a significant reduction in rail damage, noise pollution, the rail network now exhibits fewer new wheel defects and has resulted in the improved passenger comfort and perception of quality of the system by all stakeholders. (8 pages)Condition monitoring of pantograph contact strip
http://dl-live.theiet.org/content/conferences/10.1049/ic_20080343
A common issue in electric railway operation is the wear of the pantograph contact strip. This is especially pronounced with ice or rime frost on the overhead line that causes arcing between the contact strip and the contact wire. To monitor the contact strip it is possible to utilise the fact that arcing between the contact strip and the overhead line generates a DC component in the AC locomotive current. The paper presents a method for condition based maintenance of the contact strip. The wear of the contact strip is predicted by monitoring the running distance of the pantograph as well as the DC component of the locomotive current. To evaluate the method, measurements have been carried out on a Swedish Re locomotive during winter conditions. (6 pages)A new approach of assessing rail roughness
http://dl-live.theiet.org/content/conferences/10.1049/ic_20080322
Rail roughness with a broad spectrum of wavelengths is always present on the running surfaces of the rails. It has been shown that there is a high dependence between the amplitude and the wavelength of the roughness. Further, the magnitude and frequency of the vertical wheel-rail contact force is depending on the amplitude and wavelength of the roughness. The standards used for monitoring roughness all use constant values as thresholds in large wavebands, see for example the coming EU standard prEN 1321-3 that controls the condition after grinding. However, in the ISO standard ISO EN 3095 the track quality has to satisfy a rail roughness limit that is based on one-third octave bands. The standard is used when measuring noise levels from railbound vehicles ensuring a minimal spread in noise level between different tracks. A new approach to present rail roughness has been implemented at the Swedish Railway Administration, Banverket. It is based on a transformation of the measured longitudinal rail profile to a one-third octave band spectrum, and a weighting of the spectrum against the limit described in ISO 3095. The result is presented as a spectrogram. By applying spectrograms on the results received, the rail roughness can be presented with both spatial and wavelength resolutions. This gives a good overview of the track quality. A handbook has been written on how to interpret the spectrograms. In the handbook, a threshold is given to assess the need for grinding. (5 pages)A time domain wheelflat/track FE model
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060057
A time domain wheelflat/track FE model is presented. The model includes rail, rail pad, sleepers, ballast, wheel and primary suspension of the vehicle. The model allows calculating dynamic loads and rail accelerations due to wheel defects, particularly wheelflats. Wheelflat modelling is specifically studied and compared with measurements of real wheels. A parametric study, which includes the study of the influence of train speed, defect size and railpad stiffness, is presented. The results from this parametric study show that, in general, the higher the speed, the size or the stiffness, the larger impact load and rail accelerations and that the dependence is not linear. This results are used in a track monitoring system for the detection of vehicles having wheelflats.Research on a novel approach to multi-axis line contact milling
http://dl-live.theiet.org/content/conferences/10.1049/cp_20061003
The principle of a novel multi-axis milling is presented. Peripheral edges of a cutter are in contact with the theoretical profile of a work-piece, and rotation of spindle drum imitates turning. Thus, the theoretical profile can be achieved with the minimum reciprocating movements of the cutter and the shortest cutter path length. It is a novel efficient numerical control (NC) machining approach that combines the high efficiency of line contact machining with low roughness of turning. A whole developable ruled surface can be processed with only one NC code by lifting, swinging, shifting, and rotating of the spindle drum. Two rotating movements adjust the vector of the cutter axis. The lifting of the spindle drum makes the tangent point of the cutter moves along the drive curve of surfaces while the peripheral edges of the cutter are tangent to the theoretical surfaces. The milling methods, efficiency and machining precision to process various curved surfaces are contrasted. Comparing the efficiency and machining accuracy in the approach with those of 5-coordinate point contact machining and 5-coordinate line contact machining, the results show that the approach excels the others.Study on high performance driving P/M gear for engine
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060900
Aimed at the failure mode for heavy-duty diesel engine driving gear, the calculation and analysis of bend strength, contact fatigue strength for the oil-pump driving gear was conducted. A new P/M warm compaction material of high wear-resistant was developed and its friction and wear test was also performed. Its wear-resistance increased apparently in comparison with the alloy steel material of 38CrMoAl; The method of P/M die with warm compaction die wall lubrication was adopted to make oil pump driving gear, the distribution of density is uniform. The simulation result is consistent with the experimentation under the conditions of three-dimension finite analysis of gear with big strain and stress. Furthermore, manufacture cost, machine processing and materials using rate between metallurgy warm compaction gear and alloy gear were compared, the total cost of warm compaction gear has been reduced about 35% compared with the alloy gear. At last, the experiments on break of the teeth, reliability of the oil pump and durability of the gear were also carried out. And the results show that during the life-span of engine, the driving gear of powder metallurgy warm compaction is very wear-proof and of the great strength. The gear meets the requirements of the heavy-duty diesel engine.Simulation system of operating performance of hypoid gears
http://dl-live.theiet.org/content/conferences/10.1049/cp_20061034
A performance simulation program of hypoid gears that can accept measured form deviation of real tooth flank form is developed and gear dynamic performance such as transmission error, contact pattern under load and no-load, normal load distribution on tooth flank, tooth contact stress, tooth root stress, flash temperature, vibrational excitation for actual production gears can be simulated. In this simulation program, a new method has been proposed to determine the reference surface for the tooth contact analysis of bevel and hypoid gears. The gear reference surface use the theoretical tooth flank coordinate calculated from the machine settings and the pinion reference surface use a virtual conjugate pinion surface. The concept of composite error surface has been introduced by using conjugate reference surface and measured real tooth flank form. The deformation of tooth and rim of hypoid gears calculated by FEA, and the approximation equation for the compliance of cylindrical involute gear tooth is modified to that of hypoid gear tooth. The results of loaded contact pattern calculated by simulation program were also compared with the experimental results and showed good agreement.Contact simulation and sensitivity research of quasi-transverse-double-circular gears
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060817
The contact simulation, sensitivity research, and enhanced stress analysis of quasi-transverse-double-circular gears is presented; the shape of the contact region as well as the stress distribution is investigated. The approaches proposed for modification of conventional circular gears are based on transverse-circular and normal-circular. We call it after quasi-transverse-double-circular gear. It both is different with the transverse-circular arc gear and is different with the normal-circular arc gear. Quasi-transverse-double-circular-profile means deviation of profile from a transverse-circular and normal-circular one. Using the method developed, the sensitivity of the change of centre distance in comparison with normal-circular gear is reduced. Finite element analysis of the contact and bending stresses is performed by application of general purpose computer program. Design parameter β<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0</sub> of quasi-transverse-double-circular gears is designated for sensitivity studies, and result of contact and bending stresses is obtained with β<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0</sub>'s change. The theory and method are proved valid through designs.Research on plastic removal mechanism of engineering ceramics grinding with ultrasonic assistance
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060757
Plastic removal mechanism of engineering ceramics was discussed based on the method of micro-indentation, and the formula of critical wheel depth of cut and the model of material removal ratio were established. In comparison with traditional grinding, the experiment on the characteristics of ductile-regime grinding engineering ceramics with/without ultrasonic assistance were carried out using engineering ceramic Al<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub>, zirconia-toughened alumina (ZTA) and nano-ZrO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> workpiece respectively. Experimental results showed that the material removal ratio in machining engineering ceramics with ultrasonic assistance was increased by one time. Meanwhile, the ductile-regime critical wheel depth of cut was up to 9-12μm and the surface roughness on ground workpieces was improved 1-2 grades. According to analysis of surface topography, grinding-induced cracks on Al<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> workpiece were almost as a result of intercrystalline crack, while cracks on ZTA and ZrO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> workpiece were mainly owing to trans crystalline crack.The technique of paralleling motivation with impact and vibration for impact roller
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060845
In this paper a new kind of compaction device and system is introduced for the impact roller. It could generate strongly impact fore and high frequency vibration to soil at the same time but no additional force to roller oneself. A series of problem has been solved that proceed from the present impact roller. The principle and action mode has been introduced, which can create multiple impact and vibration motivation. Reasonable structure parameter has been chose by dynamic optimization design. The impact energy can be switch over compression energy of soil at the full. The research has also analyzed the resistance fluctuation condition and the variety rule of the traction peak when working wheel rolling by 3-d simulation technique, and the life of machine is estimated. The stable load characteristic can lead the drawbar power of impact roller to reduce 25%, and the life of mechanical part can increase by 100%. It is a valid method of compaction construction with high-efficiency, high- quality and lower energy.Topological optimization of axisymmetrical bodies on water entries
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060789
This paper focuses on modeling of axial symmetrical bodies which is formalized and generalized by the approach of topological optimization. Both constant velocities of their striking the water surface and arbitrary angles of water-entry are utilized to topological design within non-regular design domain and on the fixed loading surface. The topological optimization is based on the adoption of the solid isotropic microstructure with penalty (SIMP) approach and minimum compliance as the design objective subjective to volume constrain. The initialization of variables is the ratio of material volume limited to the total volume; and the values of variables out of the design domain always evaluate zeros. Numerical examples of water-entry bodies are investigated based on the topology optimization method. The optimum models with actual loads presented and the SIMP models are proved to be reliable and practical at the conceptual design phase of axisymmetric bodies on water entries by applying the topological optimization to a hemispheroid, wedge, and plate.Estimating the ballistic coefficient of a re-entry vehicle
http://dl-live.theiet.org/content/journals/10.1049/iet-rsn_20060064
Theoretical bounds for estimating the ballistic coefficient of a ballistic object during the re-entry phase have been addressed. One essential characteristic of the vehicle trajectory is its deceleration when it reaches dense atmospheric layers. The intensity of the phenomenon is proportional to a scalar, called the ballistic coefficient. This leads to an highly nonlinear time-varying dynamic. To understand the dimensioning parameters for estimating the ballistic coefficient, accurate approximations of the Fisher information matrix are developed. The main result is a closed-form expression of a lower bound for the variance of the ballistic coefficient estimate.What you can do? [building design]
http://dl-live.theiet.org/content/journals/10.1049/et.2011.0403
Some of the world's most extensive sea defences did little to protect Japan's coast from the devastating tsunami so is it time to develop buildings that can withstand the impact when it comes?The Japanese government has invested heavily In seawalls and breakwaters, which stretch along some 40 per cent of the country's 30,000km coastline. The policy reflects a general belief by authorities in tsunami prone regions around the world that concrete barriers offer the best hope of protection from the sea. Indeed. that may be true for smaller storms, but the disaster in Japan illustrates that seawalls offer precious little protection against the most ferocious tsunamis. Many coastal engineers are now calling for a shift in policy. Rather than trying to keep the sea out by building ever higher walls, more lives might be saved by designing buildings that can withstand the waves - an a research that up to now has received little funding.