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1
He, Zhihang, Wei Wang, Huaping Ruan, Yanzhang Yao, Xuelong Li, Dehua Zou, Yu Yan, and Shaochun Jia. "A two-wheel load balance control strategy for an HVTL inspection robot based on second-order sliding-mode." Industrial Robot: the international journal of robotics research and application 46, no. 1 (January 21, 2019): 83–92. http://dx.doi.org/10.1108/ir-10-2018-0212.
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Purpose Overhead high-voltage transmission line (HVTL) inspection robots are used to inspect the transmission lines and/or maintain the infrastructures of a power transmission grid. One of the most serious problems is that the load on the front wheel is much larger than that on the back one when the robot travels along a sloping earth wire. Thus, ongoing operation of the inspection robot mainly depends on the front wheel motor’s ability. This paper aims to extend continuous operation time of the HVTL inspection robots. Design/methodology/approach By introducing a traction force model, the authors have established a dynamic model of the robot with slip. The total load is evenly distributed to both wheels. According to the traction force model, the desired wheel slip is calculated to achieve the goal of load balance. A wheel slip controller was designed based on second-order sliding-mode control methodology. Findings This controller accomplishes the control objective, such that the actual wheel slip tracks the desired wheel slip. A simulation and experiment verify the feasibility of the load balance control system. These results indicate that the loads on both wheels are generally equal. Originality/value By balancing the loads on both wheels, the inspection robot can travel along the earth wire longer, improving its efficiency.
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O'Connor, Colin, and Tommy Hung Tin Chan. "Dynamic Wheel Loads From Bridge Strains." Journal of Structural Engineering 114, no. 8 (September 1988): 1703–23. http://dx.doi.org/10.1061/(asce)0733-9445(1988)114:8(1703).
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Kim, Sang-Hyo, Kwang-Il Cho, Moon-Seock Choi, and Ji-Young Lim. "Development of a Generation Method of Artificial Vehicle Wheel Load to Analyze Dynamic Behavior of Bridges." Advances in Structural Engineering 12, no. 4 (August 2009): 479–501. http://dx.doi.org/10.1260/136943309789508474.
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In this study, artificial wheel loads are proposed which reflect the dynamic effects of running vehicles and road roughness to overcome shortcomings of vehicle modeling methods. To derive a suitable artificial load from the moving vehicle model, a parametric study is conducted regarding span lengths, types of bridges, road roughnesses, vehicle speeds and consecutive vehicles. After that, Power Spectral Density (PSD) analyses of wheel loads are performed using Maximum Entropy Method (MEM). Based on the result, a representative PSD function is proposed considering the cumulative energy distribution and the area of the PSD curve. The artificial wheel loads are generated based on this PSD function. Also, dynamic analyses of a bridge are performed using the artificial wheel loads. The probabilistic characteristics of dynamic responses are evaluated by comparing the results with the existing moving vehicle model. The results show that the dynamic responses through the proposed method are slightly overestimated. It is concluded that the proposed method is a simple and reliable procedure for engineers to perform a dynamic analysis in practical design.
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Dolipski, Marian, Eryk Remiorz, and Piotr Sobota. "Determination of Dynamic Loads of Sprocket Drum Teeth and Seats by Means of a Mathematical Model of the Longwall Conveyor / Wyznaczenie Obciążeń Dynamicznych Zębów I Gniazd Bębna Łańcuchowego Za Pomocą Modelu Matematycznego Przenośnika Ścianowego." Archives of Mining Sciences 57, no. 4 (December 1, 2012): 1101–19. http://dx.doi.org/10.2478/v10267-012-0073-7.
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Abstract Scraper conveyors are one of the key machines forming part of mechanised longwall systems. They are currently the only means of transporting the mined rock from longwalls in hard coal mines. The hauling force caused by the drive is transmitted onto a link chain through drive wheels with their external shape corresponding to a geometric polygon. The number of teeth (seats) in such wheels ranges between 5 and 8. The horizontal links running on the drum are arranged in the drive wheel seats and are meshing with the teeth segments. The geometric relationships between the sprocket drum and the links are decisive for the position of the chain links in the seats. The abrasive wear of the chain parts and of the drive drum parts occurring due to conveyor operation is increasing the chain pitch and decreasing the wheel pitch. The position of a link in the seats changes as a result along with the load on the sprocket drum teeth and seats. Sprocket drums are the weakest element in longwall conveyors. It is, therefore, urgently necessary to determine the dynamic loads of such drums’ teeth and seats. The article presents a physical model and a mathematical model of a longwall conveyor created for the purpose of determination of dynamic loads of the sprocket drum teeth and seats. The results of computer simulations are also presented (dynamic loads: in chains, dynamic loads of sprocket drums and dynamic loads of sprocket drums’ teeth and seats) carried out using the created mathematical model for a 350 m long face conveyor.
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Nallusamy, S., N. Manikanda Prabu, K. Balakannan, and Gautam Majumdar. "Analysis of Static Stress in an Alloy Wheel of the Passengercar." International Journal of Engineering Research in Africa 16 (June 2015): 17–25. http://dx.doi.org/10.4028/www.scientific.net/jera.16.17.
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The vehicle may be towed without the engine but it is not possible without the wheels. Road wheel is a significant structural member of the vehicular suspension system that supports the static and dynamic loads encountered during vehicle operation. As in the case of an automobile wheel maximum load is applied on the alloy wheel. Proper analysis of the alloy wheel plays a significant role for the safety of the passenger cars. Alloy wheels which are intended for normal use on passenger cars, undergo three tests and have to pass before going into the production: Dynamic Cornering Fatigue Test, Dynamic Radial Fatigue Test and Impact Test. Most of aluminium alloy wheels manufacturing companies have done several testing of their product however information of their method on simulation test is often kept limited. During a part of research a static and fatigue analysis of aluminum alloy wheel A356.0 was carried out using FEA package. The 3-D model was imported from CATIA into ANSYS using the appropriate format. Finite element analysis (FEA) is carried out by simulating the test conditions to analyze stress distribution and fatigue life of the aluminium alloy wheel rim of passenger car. Experimental analyses are carried out by radial fatigue testing machine for evaluation of fatigue life under influence of camber angle. The test indicates that integrating FEA and nominal stress method is a good and efficient method to predict alloy wheels fatigue life. In this paper by observing the results of both static and dynamic analysis the aluminium alloy is suggested as better material.
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Husaini, Ali Nurdin, Abdillah Sofian, and Nuzan Rizki Muhammad. "Comparison of Hardness and Microstructure of Cast Wheel and Spoke Wheel Rims of Motorcycles Made of Aluminum Alloy Alloy." Key Engineering Materials 892 (July 13, 2021): 81–88. http://dx.doi.org/10.4028/www.scientific.net/kem.892.81.
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The rim is one of the main components in a motorized vehicle system, both two and three wheels. Rim loads when used are dynamic and often even shock. This study aims to study the mechanical characteristics, especially the hardness properties of spoke wheel rims and cast wheel rims made of aluminum alloy used in motorcycles and compare the results. Hardness testing is carried out on the spoke wheel and cast wheel specimens, using the Rockwell method with an identifier of 1/16 ball and a spectrometer used for both microstructure observations. The result of the average hardness test for the spoke wheel is HRB 99.3, while for the cast wheel is HRB 76.5. From the hardness test, it can be concluded that the hardness of the spoke wheel type is higher than the cast wheel type due to the difference in the manufacturing process. Cast wheel rims can withstand a load of 3 tons (30000 N) and the value of rim tension that can be accepted until the fracture is 45.84 MPa. Meanwhile, spoke wheel rims have the ability to withstand smaller compressive loads than cast wheel rims, which are 2 tonnes (20000 N) and the rims can accept the stress of 66.04 MPa until they break.
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Vale, Cecilia. "Wheel Flats in the Dynamic Behavior of Ballasted and Slab Railway Tracks." Applied Sciences 11, no. 15 (August 2, 2021): 7127. http://dx.doi.org/10.3390/app11157127.
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Wheel flats induce high-impact loads with relevance for the safety of the vehicle in operation as they can contribute to broken axles, hot axle boxes, and damaged rolling bearings and wheels. The high loads also induce damage in the track components such as rails and sleepers. Although this subject has been studied numerically and experimentally over the last few years, the wheel flat problem has focused on ballasted tracks, and there is a need to understand the phenomena also for slab tracks. In this research, a numerical approach was used to show the effects of the wheel flats with different geometric configurations on the dynamic behavior of a classical ballasted track and a continuous slab track. Several wheel flat geometries and different vehicle speeds were considered. The nonlinear Hertzian contact model was used because of the high dynamic variation of the interaction of the load between the vehicle and the rail. The results evidenced that, for the same traffic conditions, the dynamic force was higher on the slab track than on the ballasted one, contrary to the maximum vertical displacement, which was higher on the ballasted track due to the track differences regarding the stiffness and frequency response. The results are useful for railway managers who wish to monitor track deterioration under the regulatory limits.
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Sadeghi, J. M. "Experimental evaluation of accuracy of current practices in analysis and design of railway track sleepers." Canadian Journal of Civil Engineering 35, no. 9 (September 2008): 881–93. http://dx.doi.org/10.1139/l08-026.
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This research investigates the accuracy of the assumptions made in the current method of analysis and design of railway track sleepers. This study consists of a comprehensive field investigation into the response of sleepers in a railway track system to static and dynamic loads. In the experiments, several load cells (load gauges) are installed under a rail seat and beneath a B70 concrete sleeper for the purpose of monitoring the response of the sleeper to vertical loads. The dynamic coefficients factor, the ratio of the rail seat load to the wheel load and the pressures between the sleeper and the ballast are measured. The results are used to evaluate the current approaches for the analysis and design of concrete sleepers, in particular those proposed by the Americans (AREMA) and Europeans (UIC). New models are proposed for the calculation of dynamic load factors, correlations between wheel loads and rail seat loads, and load distribution patterns beneath sleepers.
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Zolotarevskaya, D. I. "Analysis of the influence of the main factors on the characteristics of the elastic properties of elastic wheels of tractors." Traktory i sel hozmashiny 85, no. 4 (August 15, 2018): 71–78. http://dx.doi.org/10.17816/0321-4443-66415.
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The work is devoted to the theoretical study of the elastic properties of tractor wheels and the analysis of the effect of air pressure in the tires and vertical loads on the wheel axles. According to the developed computer program, which allows to implement the method of calculating the characteristics of the elastic properties of tractor wheels with pneumatic tires proposed in this work, one-factor and complete factor computer experiments of two types were carried out. In computer experiments of the first type, the dependences of the elasticity coefficients of a number of elastic wheels were investigated when operating on the practically non-deformable basis of tractors MTZ-82 and MTZ-142 from the air pressure in the tires at different values of the vertical dynamic loads on the axes of the corresponding wheels of tractors. In computer experiments of the second type, the dependences of the elasticity coefficients and the normal deflection of the wheels with tires of different sizes from the air pressure in the tires at constant values of the vertical dynamic loads on the wheel axles were investigated. In computer experiments of both types, the deviations of the elastic properties of elastic wheels found by calculation are within the limits of the accuracy of measurements of the experimental data. Based on the results of computer experiments of the first type, regression equations were obtained reflecting the dependence of the elasticity coefficients of the elastic wheels studied on the air pressure in the tire for various values of the vertical dynamic loads on the wheel axes. According to the results of computer experiments of the second type, equations of regression of the coefficients of elasticity and normal deflection of wheels with tires of different sizes from air pressure in tires at constant values of vertical dynamic loads on the wheel axle are obtained. The high correlation values for these regression equations indicate the high importance of the relationships in the found correlation dependencies. The application of the proposed calculation method makes it possible to simplify and shorten the work on the choice of tires of optimum sizes to different tractors, taking into account the specific conditions of their operation. It was calculated that wheels with tires 18.4R38 are optimal on the rear axle of the MTZ-82 tractor.
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Savinkin, Vitaliy V., Zaure Zh Zhumekenova, Andrei Victor Sandu, Petrica Vizureanu, Sergey V. Savinkin, Sergey N. Kolisnichenko, and Olga V. Ivanova. "Study of Wear and Redistribution Dynamic Forces of Wheel Pairs Restored by a Wear-Resistant Coating 15Cr17Ni12V3F." Coatings 11, no. 12 (November 24, 2021): 1441. http://dx.doi.org/10.3390/coatings11121441.
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The relevance of this study lies in the need to research the wear process of the elements of dynamic systems and to establish the dependence of the geometric and structural characteristics of wheels restored by plasma surfacing with a coating of 15Cr17Ni12V3F on dynamic, cyclically varying loads. The study was aimed to establish the dependencies between the deviation of the wear area, the formation of contact and fatigue stresses, and the change in the phase structure of the wheel defect. It is important to justify the permissible limits of wear of the transverse profile in the contact zone of a wheel and ridge. The object of the study was the dynamic interaction of the “wheel–ridge–rail contact surface” system. To achieve the goal, the following methodology was adopted: kinematic analysis, strength calculation, the use of mathematical analysis in dynamic system modelling, virtual modelling in the SOLIDWORKS software environment of the GearTrax application, experiment planning, and model correction through the results of metallographic studies. The results of the study are presented as reasonable prediction criteria that consider contact cycles during the formation of fatigue stresses at the stage of defect origin. The process of the dynamic interaction of the contact worn profile of a wheel with a railway rail is explored. Polynomial equations are proposed to substantiate the optimal design and technological parameters of designing a railway carriage wheel. The permissible limits of wear of the transverse profile in the contact zone of the wheel and the ridge are justified while taking the coefficient of the reduction of contact stresses in the metal into account. The dependences of the change in static load on the utilization factor of the railway carriage load capacity are established. The dependences of changes in fatigue stresses on the design deviation of the contact area of wheel wear are established. It is confirmed that the stress concentration under cyclic loads is formed in the ferritic layers of the material structure before the appearance of wear.
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Van Dyk, Brandon J., J. Riley Edwards, Marcus S. Dersch, Conrad J. Ruppert, and Christopher PL Barkan. "Evaluation of dynamic and impact wheel load factors and their application in design processes." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, no. 1 (August 4, 2016): 33–43. http://dx.doi.org/10.1177/0954409715619454.
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A sustained increase in heavy axle loads and cumulative freight tonnages, coupled with increased development of high-speed passenger rail, is placing an increasing demand on railway infrastructures. Some of the most-critical areas of the infrastructure in need of further research are track components used in high-speed passenger, heavy haul and shared infrastructure applications. In North America, many design guidelines for these systems use historical wheel loads and design factors that may not necessarily be representative of the loading currently experienced on rail networks. Without a clear understanding of the nature of these loads and how design processes reflect them, it is impossible to adequately evaluate the superstructure in order to make design improvements. Therefore, researchers at the University of Illinois at Urbana-Champaign are conducting research to lay the groundwork for an improved and thorough understanding of the loading environment imparted into the track structure using wheel loads captured by wheel impact load detectors. This paper identifies several design factors that have been developed internationally, and evaluates their effectiveness based on wheel loads using several existing and new evaluative metrics. New design factors are also developed to represent the wheel-loading environment in a different manner. An evaluative approach to historical and innovative design methodologies will provide improvements to designs, based on actual loading experienced on today’s rail networks.
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Zhu, X. Q., and S. S. Law. "Dynamic axle and wheel loads identification: laboratory studies." Journal of Sound and Vibration 268, no. 5 (December 2003): 855–79. http://dx.doi.org/10.1016/s0022-460x(02)01557-2.
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Dong, R. G., S. Sankar, and R. V. Dukkipati. "A Finite Element Model of Railway Track and its Application to the Wheel Flat Problem." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 208, no. 1 (January 1994): 61–72. http://dx.doi.org/10.1243/pime_proc_1994_208_234_02.
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To study the dynamic interactions between the railway vehicle and track, a finite element model of infinitely long track is developed. The track is represented by a Timoshenko beam on discrete pad-tie-ballast supports. The non-linear factors such as loss of wheel-rail contact, rail lift-off from the tie and tie lift-off from the ballast are taken into account. A multi-point wheel-rail contact model is also proposed. The dynamic forces on the track and the strains on the rail are directly calculated from the model. The vehicle could travel on the track forever with an arbitrary time-dependent speed. The steady-state response of a vehicle-track system for a perfect wheel carrying a constant load and travelling at a constant speed over a track with no irregularities is studied using the finite element model and is presented. The impact loads due to wheel flats are also studied with this model. The results show a good correlation with the experimental data available in the literature. Influences of system parameters on the impact loads due to a wheel flat are also investigated. T***he results show that the axle load and vehicle speed are the important factors affecting the wheel-rail impact loads. The impact forces transferred from the rail to the tie are strongly affected by the pad stiffness and tie mass.
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Hua, Liang, and Run-dong Zhou. "Damage and Fatigue Life Evaluation for Laser Cladding Remanufactured Wheel." Advances in Materials Science and Engineering 2022 (March 3, 2022): 1–7. http://dx.doi.org/10.1155/2022/2060564.
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Owing to high speeds and heavy loads, the wheels of trains and locomotives undergo gradual but significant damage. Conventionally, these damaged wheels are repaired using the rotatory repair method; however, this approach results in large amounts of material waste. To address this issue, in this study, laser cladding remanufacturing technology was employed to repair a damaged wheel. The contact stress and creep characteristics of the cladded wheel were determined using Simpack, a dynamic simulation software program. The existing damage function model, which is based on the wear number, was modified, and this modified model was used to perform damage assessments for the remanufactured wheel. Furthermore, a life evaluation model for wheels remanufactured using this laser cladding technology was established. The service life of the cladded wheel calculated using this model was in good agreement with the design life of the wheel.
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Wang, Dong, Guoyu Lin, and Weigong Zhang. "Design of real-time filter for the wheel force transducer." Sensor Review 35, no. 2 (March 16, 2015): 174–82. http://dx.doi.org/10.1108/sr-06-2014-657.
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Purpose – Wheel force transducers (WFTs) have performance characteristics that make them attractive for applications in endurance evaluation of road vehicles, ride and handling optimization, tire development and vehicle dynamics. As a WFT is mounted on the the driven wheel, the loads on the wheel and the outputs of WFTs are usually nonlinearly related. Thus, a real-time filter is needed to measure the true loads on the wheel. Design/methodology/approach – In this paper, a new nonlinear filtering algorithm utilizing quadrature Kalman filter (QKF) is proposed to track the actual loads in real time through establishing the specific observation equations with Singer models. Findings – The simulation results show that the accuracy and the rapidity of QKF outperforms the capability of the unscented Kalman filter (UKF). Then, the dynamic tests on the MTS testing platform give the comparisons between the real-time QKF and the wavelet transform, where the former has superior dynamic accuracy. Finally, the practical tests of shifting and braking on a real vehicle confirm the effectiveness of QKF, which further validates the proposed method fitting reality. Originality/value – In this paper, a newly improved algorithm with QKF for WFT has been proposed and tested experimentally. As the wheel loads are always time-varying and complex, introducing Gaussian noise in the outputs of the transducer, WFT-suitable Singer model and WFT measurement equation base on a QKF are established. The experiment results show that QKF has advanced performance than the traditional UKF. Also, the road wheel test bed produced by MTS has been exploited as the test platform to demonstrate the dynamic efficiency of the proposed real-time filter under various operating conditions for a wide range of loads. And, the practical tests with the real vehicle are accomplished to verify the value and effectiveness of the proposed method.
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Pletz, Martin, Werner Daves, and Heinz Ossberger. "A wheel passing a crossing nose: Dynamic analysis under high axle loads using finite element modelling*." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 226, no. 6 (May 29, 2012): 603–11. http://dx.doi.org/10.1177/0954409712448038.
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A finite element model for the process of a wheel passing a crossing is presented. In the dynamic model, one wheel, the wing rails and the crossing nose (frog) are modelled. The bogie, the complete wheel set and the support of the crossing are represented as a system consisting of masses, springs, dampers and friction-generating elements. The rolling/sliding behaviour between the wheel and crossing is studied using the proposed model. Due to the conical shape of the wheel tread and multiple contacts between the wheel and the crossing parts, sliding occurs during the transition of the wheel from the wing rail to the crossing nose or vice versa. At the same time, an impact occurs that produces high contact forces. The parameters of the model are the train speed and passing direction, the wheel and the crossing geometry, the axle load and the support of the crossing. In this paper, the crossover process is studied for high axle loads and compared with results of simulations using a normal axle load. Further parameters are three train velocities, both directions of passing and different crossing materials. The loading of the crossing nose is calculated for all cases (axle load, train speed and direction) and materials.
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Joubert, Nicolas, Maxime Boisvert, Carl Blanchette, Yves St-Amant, Alain Desrochers, and Denis Rancourt. "Frame loads accuracy assessment of semianalytical multibody dynamic simulation methods of a recreational vehicle." Multibody System Dynamics 50, no. 2 (July 27, 2020): 189–209. http://dx.doi.org/10.1007/s11044-020-09756-8.
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Abstract The design of a vehicle frame is largely dependent on the loads applied on the suspension and heavy parts mounting points. These loads can either be estimated through full analytical multibody dynamic simulations, or from semi-analytical simulations in which tire and road sub-models are not included and external vehicle loads, recorded during field testing, are used as inputs to the wheel hubs. Several semi-analytical methods exist, with various modeling architectures, yet, it is unclear how one method over another improves frame loads prediction accuracy. This study shows that a semi-analytical method that constrains the vehicle frame center of gravity movement along a recorded trajectory, using a control algorithm, leads to an accuracy within 1% for predicting frame loads, when compared to reference loads from a full analytical model. The control algorithm computes six degrees of freedom forces and moments applied at the vehicle center of gravity to closely follow the recorded vehicle trajectory. It is also shown that modeling the flexibility of the suspension arms and controlling wheel hub angular velocity both contribute in improving frame loads accuracy, while an acquisition frequency of 200 Hz appears to be sufficient to capture load dynamics for several maneuvers. Knowledge of these loads helps engineers perform appropriate dimensioning of vehicle structural components therefore ensuring their reliability under various driving conditions.
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Johansson, A., and J. C. O. Nielsen. "Out-of-round railway wheels—wheel-rail contact forces and track response derived from field tests and numerical simulations." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 217, no. 2 (March 1, 2003): 135–46. http://dx.doi.org/10.1243/095440903765762878.
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The influence of different types of railway wheel out-of-roundness (OOR) on the vertical dynamic wheel-rail contact force and track response is investigated through extensive field tests and numerical simulations. The response from a freight train, provided with a number of different types of severe wheel tread damage, is studied. Two different axle loads are used in combination with different train speeds in the range 30-100km/h. The wheel defects are wheelflats, local spalls due to rolling contact fatigue cracking, long local defects and polygonal wheels (periodic OOR). The vertical wheel-rail contact force was measured using a strain gauge based wheel impact load detector. Strain gauges and accelerometers were positioned on rails and sleepers to measure the track response. Most of the magnitudes of measured impact forces were found to be lower than the current impact load limit that is used in Sweden to determine when a defective wheel should be removed for repair. Only the long local defect caused larger force magnitudes than the wheel removal criterion. Measured responses are used to calibrate and validate numerical models for simulation of train-track interaction. Results from one linear and one state-dependent track model are compared.
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Remennikov, A. M., M. H. Murray, and S. Kaewunruen. "Reliability-based conversion of a structural design code for railway prestressed concrete sleepers." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 226, no. 2 (September 12, 2011): 155–73. http://dx.doi.org/10.1177/0954409711418754.
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Ballasted railway track is very suitable for heavy-rail networks because of its many superior advantages in design, construction, short- and long-term maintenance, sustainability, and life cycle cost. An important part of the railway track system, which distributes the wheel load to the formation, is the railway sleeper. Improved knowledge has raised concerns about design techniques for prestressed concrete (PC) sleepers. Most current design codes for these rely on allowable stresses and material strength reductions. However, premature cracking of PC sleepers has been found in railway tracks. The major cause of cracking is the infrequent but high-magnitude wheel loads produced by the small percentage of irregular wheels or rail-head surface defects; both these are crudely accounted for in the allowable stress design method by a single load factor. The current design philosophy, outlined in Australian Standard AS1085.14, is based on the assessment of permissible stresses resulting from quasi-static wheel loads and essentially the static response of PC sleepers. To shift the conventional methodology to a more rational design method that involves a more realistic dynamic response of PC sleepers and performance-based design methodology, comprehensive studies of the loading conditions, the dynamic response, and the dynamic resistance of PC sleepers have been conducted. This collaborative research between several Australian universities has addressed such important issues as the spectrum and the amplitudes of dynamic forces applied to the railway track, evaluation of the reserve capacity of typical PC sleepers designed to AS 1085.14, and the development of a new limit states design concept. This article presents the results of the extensive analytical and experimental investigations aimed at predicting wheel impact loads at different return periods (based on field data from impact detectors), together with an experimental investigation of the ultimate impact resistance of PC sleepers required by the limit states design approach. It highlights the reliability approach and rationales associated with the development of limit states and presents guidelines pertaining to conversion of AS 1085.14 to a limit states design format. The reliability concept provides design flexibility and broadens the design principle, so that any operational condition could be catered for optimally in the design.
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Kawatani, Mitsuo, and Chul-Woo Kim. "Computer simulation for dynamic wheel loads of heavy vehicles." Structural Engineering and Mechanics 12, no. 4 (October 25, 2001): 409–28. http://dx.doi.org/10.12989/sem.2001.12.4.409.
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Siddique, Zahidul Q., and Mustaque Hossain. "Portland cement concrete pavement roughness and dynamic wheel loads." International Journal of Vehicle Design 36, no. 2/3 (2004): 233. http://dx.doi.org/10.1504/ijvd.2004.005358.
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Zhu, Shengyang, Jun Luo, Mingze Wang, and Chengbiao Cai. "Mechanical characteristic variation of ballastless track in high-speed railway: effect of train–track interaction and environment loads." Railway Engineering Science 28, no. 4 (November 30, 2020): 408–23. http://dx.doi.org/10.1007/s40534-020-00227-6.
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AbstractDue to the fact that ballastless tracks in high-speed railways are not only subjected to repeated train–track dynamic interaction loads, but also suffer from complex environmental loads, the fundamental understanding of mechanical performance of ballastless tracks under sophisticated service conditions is an increasingly demanding and challenging issue in high-speed railway networks. This work aims to reveal the effect of train–track interaction and environment loads on the mechanical characteristic variation of ballastless tracks in high-speed railways, particularly focusing on the typical interface damage evolution between track layers. To this end, a finite element model of a double-block ballastless track involving the cohesive zone model for the track interface is first established to analyze the mechanical properties of the track interface under the loading–unloading processes of the negative temperature gradient load (TGL) followed by the same cycle of the positive TGL. Subsequently, the effect of wheel–rail longitudinal interactions on the nonlinear dynamic characteristics of the track interface is investigated by using a vehicle-slab track vertical-longitudinal coupled dynamics model. Finally, the influence of dynamic water pressure induced by vehicle dynamic load on the mechanical characteristics and damage evolution of the track interface is elucidated using a fluid–solid coupling method. Results show that the loading history of the positive and negative TGLs has a great impact on the nonlinear development and distribution of the track interface stress and damage; the interface damage could be induced by the wheel–rail longitudinal vibrations at a high vehicle running speed owing to the dynamic amplification effect caused by short wave irregularities; the vehicle dynamic load could produce considerable water pressure that presents nonlinear spatial–temporal characteristics at the track interface, which would lead to the interface failure under a certain condition due to the coupled dynamic effect of vehicle load and water pressure.
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Xiao, Xiang, and Wei-Xin Ren. "A Versatile 3D Vehicle-Track-Bridge Element for Dynamic Analysis of the Railway Bridges under Moving Train Loads." International Journal of Structural Stability and Dynamics 19, no. 04 (April 2019): 1950050. http://dx.doi.org/10.1142/s0219455419500500.
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There has been a growing interest to carry out the vehicle–track–bridge (VTB) dynamic interaction analysis using 2D or 3D finite elements based on simplified wheel–rail relationships. The simplified or elastic wheel–rail contact relationships, however, cannot consider the lateral contact forces and geometric shapes of the wheel and rails, and even the occasional jump of wheels from the rails. This does not guarantee a reliable analysis for the safety running of trains over bridges. To consider the wheel–rail constraint and contact forces, this paper proposes a versatile 3D VTB element, consisting of a vehicle, eight rail beam elements, four bridge beam elements, and continuous springs as well as the dampers between the rail and bridge girder. With the 3D VTB element matrices formulated, a procedure for assembling the interaction matrices of the 3D VTB element is presented based on the virtual work principle. The global equations of motion of the VTB interaction system are established accordingly, which can be solved by time integration methods to obtain the dynamic responses of the vehicle, track and bridge, as well as the stability and safety indices of the moving train. Finally, an illustrative example is used to verify the proposed the versatile 3D VTB element for the dynamic interactive analysis of railway bridges under moving train loads.
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Igwemezie, Jude O., M. Saeed mirza, and J. F. Scott. "Field test of an open deck railway bridge with concrete ties." Canadian Journal of Civil Engineering 16, no. 4 (August 1, 1989): 417–25. http://dx.doi.org/10.1139/l89-071.
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Prestressed concrete ties offer an alternative to the timber ties which are used presently on North American open deck railway bridges. This paper presents the results of a field study of an open deck railway bridge equipped with precast prestressed concrete ties subjected to a special work train and regular railway traffic. The results of the study show that a train with smooth wheels does not overload the bridge deck. When wheel defects are present, the bridge deck loading is speed-dependent and consists of distinct static and dynamic components. Test results show that the tie design loads are underestimated. The impact on the bridge deck due to the defective wheels was also found not to amplify the response of the bridge longitudinal steel girders. Key words: bearing pads, impact load, railway bridge, load distribution, dynamic load factor, open deck, precast prestressed concrete, ties, wheels.
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Mu, Jian, Jing Zeng, Qunsheng Wang, and Hutang Sang. "Determination of Mapping Relation between Wheel Polygonalisation and Wheel/Rail Contact Force for Railway Freight Wagon Using Dynamic Simulation." Shock and Vibration 2021 (October 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/4677851.
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The polygonal wear around the wheel circumference could pose highly adverse influences on the wheel/rail interactions and thereby the performance of the vehicle system. In this study, the effects of wheel polygonalisation on the dynamic responses of a freight wagon are investigated through development and simulations of a comprehensive coupled vehicle-track dynamic model. The model integrates flexible ballasted track and wheelsets subsystem models so as to account for elastic deformations caused by impact loads induced by the wheel polygonalisation. Subsequently, the vehicles with low-order polygonal wear, whether in empty or loaded conditions, are simulated at different speeds considering different amplitudes and harmonic orders of the wheel polygonalisation and thus the mapping relation between wheel/rail impact force and wheel polygonalisation is obtained. The results reveal that the low-order wheel polygonalisation except 1st order and 3rd order can give rise to high-frequency impact loads at the wheel/rail interface and excite 1st-bend modes of the wheelset and “P2 resonance” leading to high-magnitude wheel/rail contact force at the corresponding speed.
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Luong, Van Hai, Tan Ngoc Than Cao, J. N. Reddy, Kok Keng Ang, Minh Thi Tran, and Jian Dai. "Static and Dynamic Analyses of Mindlin Plates Resting on Viscoelastic Foundation by Using Moving Element Method." International Journal of Structural Stability and Dynamics 18, no. 11 (October 22, 2018): 1850131. http://dx.doi.org/10.1142/s0219455418501316.
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Presented herein is a novel computational approach using the moving element method (MEM) for simulating the dynamic response of Mindlin plate resting on a viscoelastic foundation and subjected to moving loads. The governing equations and the element mass, damping and stiffness matrices are formulated in a convected coordinate system in which the origin is attached to the point of the moving applied load. Thus, the method simply treats moving loads as ‘stationary’ at the nodes of the plate to avoid updating the locations of moving loads due to the change of the contact points on the plate. To verify the accuracy of the proposed computational approach, static and free vibration analyses of plates are investigated first. Next, the dynamic response of plate resting on a viscoelastic foundation subjected to a moving load is examined. A parametric study is performed to determine the effects of the load’s velocity, foundation damping and foundation stiffness on the dynamic response of a plate. Finally, the comparisons of the dynamic response of plates resting on viscoelastic foundation and subjected to moving vehicles with three models of load (single-wheel, single-axle and tandem-axle) are discussed.
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Liu, Peng-Fei, Wan-Ming Zhai, Kai-Yun Wang, Quan-Bao Feng, and Zai-Gang Chen. "Theoretical and experimental study on vertical dynamic characteristics of six-axle heavy-haul locomotive on curve." Transport 33, no. 1 (May 4, 2016): 291–301. http://dx.doi.org/10.3846/16484142.2016.1180638.
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This paper presents a method to study the vertical dynamic characteristics of a heavy-haul locomotive in curve. A quasi-static analysis model based on the static force equilibrium relationship is established to investigate the load bearing characteristics of suspension system when the locomotive runs through the curve. Then a locomotive–track coupled dynamics model is used to analyse the dynamic characteristics of wheel load in curves. Finally, a field test in curve is carried out to validate the simulated results. The theoretical analysis results indicate that due to the different twist shapes of track on the entry and exit transition curves, for some specific position in the suspension system or wheel arrangements, the corresponding vertical load along the curve length presents an asymmetry about the section of circular curve. The asymmetry is predominantly caused by the Superelevation Angle Differences (SADs) between car body, bogie frames and wheelsets. A distinct phenomenon is that the outer wheel–rail vertical load of the first axle increases when the locomotive enters the transition curve and then reduces when it exits. These results are expected to provide theoretical guidance to the design of the heavy-haul railways. It is suggested that the asymmetric characteristics of the wheel loads can be improved by some measures, such as adopting a low vertical stiffness in the secondary suspension and increasing the transition curve length.
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Kulkarni, Ambarish, Sagheer A. Ranjha, and Ajay Kapoor. "A quarter-car suspension model for dynamic evaluations of an in-wheel electric vehicle." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 9 (October 5, 2017): 1139–48. http://dx.doi.org/10.1177/0954407017727165.
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Electric vehicles (EVs) are an alternative architecture in the automotive industry that provide reduced emissions. This research has developed a switch reluctance motor (SRM) in-wheel drivetrain for an EV. SRM drivetrains are cheaper and do not use rare earth elements unlike a permanent magnet motor (PMM). Conversely, the in-wheel SRM has a drawback of an increased mass on the suspension when compared with an equivalent power output PMM drivetrain. This situation results in an increased mass at the wheels; hence, a suspension analysis is required. This paper discusses the suspension dynamics evaluated using a quarter-car simulation of an in-wheel SRM EV and compares it to the internal combustion engine (ICE) vehicle. The simulation used step loads derived design scenarios, namely (1) sprung, (2) unsprung and (3) driver’s seat. Further Bode plot analysis techniques were used to determine the ride comfort range for the developed EV.
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Sych, Tatyana, and Andrey Kolomeets. "Methods of determination of forces in the “wheel-rail” system." MATEC Web of Conferences 216 (2018): 03009. http://dx.doi.org/10.1051/matecconf/201821603009.
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Increase in the volume of heavy traffic on railways updates the requirements for ensuring transportation safety in conditions of continuous increasing in axle loads on the track. The purpose of the study is to review methods for determining the dynamic forces arising from interaction between the wheel and the rail during rolling stock movement. The numerical method is used to determine the values of relative strain of the rail web at the transducers locations. Model verification and estimation of the calculation accuracy for several methods of determining forces in the “wheel-rail” system has been performed. Methods for determining the loads arising in the wheel and rail system, as well as the results of calculating the three load components were obtained. Simulation tests of the proposed forces control method have been performed.
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Uppal, A. S., S. H. Rizkalla, and R. B. Pinkney. "Response of timber bridges under train loading." Canadian Journal of Civil Engineering 17, no. 6 (December 1, 1990): 940–51. http://dx.doi.org/10.1139/l90-106.
Full textAbstract:
Timber bridges are still commonly used by several North American railroads. For short spans, they offer an attractive alternative to other types of bridges, as they are economical, faster to construct, and easy to maintain. Current design practices do not allow an independent consideration of the effects of the dynamic loads in sizing the bridge components, because very little information is available on the subject. Dynamic tests were carried out at two timber railroad bridge sites under the passage of trains at speeds varying from crawl, i.e., 1.6 km/h (1 mph), to 80.5 km/h (50 mph). The loads at wheel–rail interfaces, the vertical displacements, and the accelerations were measured at several locations on the bridge spans, the bridge approaches, and the normal track sections. The maximum values of the dynamic load factors obtained were 1.50, 1.65, and 1.85 for bridge, bridge approach, and normal track, respectively; and the corresponding maximum values of the dynamic displacement factors obtained were 1.30, 1.00, and 1.20. The main objective of this paper is to describe the experimental work and the influence on the measured values of the train speed and other factors. Key words: railroad, timber, bridge, wheel–rail interfaces, load, deflection, frequency, load factor, dynamic displacement, track modulus.
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Sankar, S., A. Dhir, and V. S. Shankhla. "Simulation and Field Testing of Tracked Vehicle Suspension Dynamics." Journal of Dynamic Systems, Measurement, and Control 116, no. 4 (December 1, 1994): 764–73. http://dx.doi.org/10.1115/1.2899276.
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A nonlinear, in-plane ride dynamic simulation model of a typical off-road tracked vehicle is developed assuming constant forward vehicle speed and nondeformable terrain surface. The ride model includes nonlinear suspension characteristics, wheel/track-terrain interactions, and dynamic track loads. An equivalent damper and continuous radial spring formulation is employed to model wheel/track-terrain interactions, whereas dynamic track loads are modeled in view of track belt stretching and initial track tension. Typical simulation results are presented for a conventional armoured personnel carrier traversing discrete half round obstacles, and a random course, and are validated against field measurements. The predicted ride responses exhibit generally good agreement with field test data.
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Zhang, Mengxi, Xiaoqing Zhang, Lei Li, and Chengyu Hong. "Experimental study on dynamic response of model shield tunnel induced by moving-axle loads of subway train." International Journal of Distributed Sensor Networks 14, no. 10 (October 2018): 155014771880278. http://dx.doi.org/10.1177/1550147718802785.
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A new testing method was introduced to apply moving-axle loads of a subway train on a track structure. In order to investigate the dynamic responses of the shield tunnel subjected to moving-axle loads, a series of laboratory model tests were conducted in a 1/40 scale model tunnel. The influences of the axle load, the wheel speed, and the cover depth of the shield tunnel on the vertical displacement and acceleration of the lining were presented and discussed. Parametric studies revealed that the vertical displacement–time history of the lining presents a “W” shape due to the combined action of two axles of a bogie. The peak value of the vertical displacement increased with the axle load linearly, while it decreased with the increase in the cover depth. Moreover, response time of the displacement decreased with the increase in the wheel speed, but the peak values remained stable at the same level. Finally, a three-dimensional dynamic finite element model was adopted to simulate the movement of the axle loads and calculate the responses of the lining. The numerical results analysis agrees well with experimental results.
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Kaynardag, Korkut, Giuseppe Battaglia, Chi Yang, and Salvatore Salamone. "Experimental Investigation of the Modal Response of a Rail Span during and after Wheel Passage." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 12 (October 16, 2020): 15–24. http://dx.doi.org/10.1177/0361198120966931.
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This paper examines the vibrations of a rail span (rail section between two consecutive sleepers) during and after the passage of a rail car’s wheel as well as under impact hammer excitation. In literature, the dynamic response of railway tracks under moving loads has been studied extensively. Many of these studies focus on the responses in relation to displacement/force-time histories and wave propagation parameters. These responses are investigated for the time instants when rail car wheels transverse over the rail spans of interest. In this context, an investigation of responses in relation to modal parameters during and after moving loads might provide additional information. Such information can be used to examine how the loading and additional masses induced by the moving wheels affect the dynamic responses. To this end, field tests were carried out at Transportation Technology Center Inc. (TTCI) facility in Colorado, U.S. First, to find the flexural modes of a rail span under no loading, data was collected from three accelerometers placed on the span under vertical impact hammer excitation. Next, the accelerometers were placed underneath the rail span, and data was collected while a rail car traveled over the span. The signal segments corresponding to during and after a wheel passage were analyzed for the identification of modal parameters. The comparison of the results demonstrated that the frequencies of the rail span increased as the loading induced by the wheel increased.
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Abu El-Maaty, Ahmed Ebrahim, Ghada Mousa Hekal, and Eman Muhammed Salah El-Din. "Modeling of Dowel Jointed Rigid Airfield Pavement under Thermal Gradients and Dynamic Loads." Civil Engineering Journal 2, no. 2 (February 1, 2016): 38–51. http://dx.doi.org/10.28991/cej-2016-00000011.
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Concrete pavements have been widely used for constructing runways, taxiways, and apron areas at airports. The aviation industry has responded to increased demand for air travel by developing longer, wider, and heavier aircraft with increasing numbers of wheels to support the aircraft while in ground operation. Many researchers developed their models based on the finite element method (FEM) for the analysis of jointed concrete pavement. Despite the notable improvement, important considerations were overlooked. These simplifications may affect the results of the developed models and make them unrealistic. Sensitivity studies were conducted in this study to investigate the effect of the loading parameters on the load transfer efficiency (LTE) indictors where concept of LTE is fundamental in airfield design procedures. The effect of main gear loading magnitudes in different wheel configurations combined with positive and negative thermal gradients was investigated. The verification process was presented to increases the confidence in the model results. Understanding the response of rigid airfield pavement under such circumstances is important developing a new pavement design procedure, as well as implementing a suitable remedial measure for existing pavements. The results obtained that utilizing a dynamic load allows studying the fatigue cycles that pavement can be subjected under different wheel configurations. Moreover, the change in the thermal gradient from positive to negative significantly changed the slab curvature shape.
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Boycho Marinov. "Full dynamic reactions in the main links of big band saw machines." Global Journal of Engineering and Technology Advances 9, no. 3 (December 30, 2021): 092–104. http://dx.doi.org/10.30574/gjeta.2021.9.3.0162.
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In this study, the full dynamic reactions in the bearing supports of the leading wheel of big band saw machines are determined. These reactions are caused by both the external loads and the kinematic and mass characteristics of the rotating disk. Expressions for calculating the dynamic reactions caused by external forces and moments that occur in the operating mode are obtained. The influence of the kinematic and mass characteristics of the rotating disk is studied and expressions for calculating the dynamic reactions caused by these characteristics are obtained. Expressions for calculating the full dynamic reactions that load the bearing supports of the leading wheel are obtained. With the help of these expressions, the parameters of the band saw machine can be selected in such a way as to ensure a minimum load on the shaft and bearings.
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Barrett, D. A., and T. M. Hrudey. "An investigation of hoist-induced dynamic loads on bridge crane structures." Canadian Journal of Civil Engineering 23, no. 4 (August 1, 1996): 926–39. http://dx.doi.org/10.1139/l96-899.
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A series of tests were performed on a bridge crane to investigate how the peak dynamic response during hoisting is affected by the stiffness of the crane structure, the inertial properties of the crane structure, the stiffness of the cable-sling system, the payload mass, and the initial conditions for the hoisting operation. These factors were varied in the test program and time histories were obtained for displacements, accelerations, cable tension, bridge bending moment, and end truck wheel reactions. Values for the dynamic ratio, defined as peak dynamic value over corresponding static value, are presented for displacements, bridge bending moment, and end truck wheel reactions. A two degree of freedom analytical model is presented, and theoretical values for the dynamic ratio are calculated as a function of three dimensionless parameters that characterize the crane and payload system. The predicted dynamic ratios are found to be conservative when compared with the test results. A general format is suggested for dynamic factors in design standards that apply to bridge cranes with constant speed motors. Key words: bridge crane, hoist, dynamic load.
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Schwering, Jane M., Mila J. E. Kanevsky, M. John D. Hayes, and Robert G. Langlois. "Atlas motion platform split-axle mecanum wheel design." Transactions of the Canadian Society for Mechanical Engineering 44, no. 4 (December 1, 2020): 492–500. http://dx.doi.org/10.1139/tcsme-2019-0169.
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The Atlas motion platform was conceptually introduced in 2005 as a 2.90 m diameter thin-walled composite sphere housing a cockpit. Three active mecanum wheels provide three linearly independent torque inputs enabling the sphere to enjoy a 100% dexterous reachable workspace with unbounded rotations about any axis. Three linearly independent translations of the sphere centre, decoupled from the orientation workspace, are provided by a translational three degree-of-freedom platform. Small-scale and half-scale demonstrators introduced in 2005 and 2009, respectively, gave us the confidence needed to begin the full-scale design. Actuation and control of the Atlas full-scale design is nearing completion; however, resolution of several details have proven extremely elusive. The focus of this paper is on the design path of the 24 passive mecanum wheels. The 12 passive wheels below the equator of the sphere help distribute the static and dynamic loads, while 12 passive wheels above the equator, attached to a pneumatically actuated halo, provide sufficient downward force so that the normal force between the three active wheel contact patches and sphere surface enable effective torque transfer. This paper details the issues associated with the original twin-hub passive wheels and the resolution of those issues with the current split-axle design. Results of static and dynamic load tests are discussed.
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Blanchette, Carl, Maxime Boisvert, Nicolas Joubert, Denis Rancourt, and Alain Desrochers. "Dynamic input loads evaluation of a recreational vehicle frame using multibody dynamics hybrid modeling validated with experimental and full analytical modeling data." Advances in Mechanical Engineering 13, no. 8 (August 2021): 168781402110346. http://dx.doi.org/10.1177/16878140211034608.
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Knowledge of frame loads at the limits of the intended driving conditions is important during the design process of a vehicle structure. Yet, retrieving these loads is not trivial as the load path between the road and the frame mounting point is complex. Fortunately, recent studies have shown that multibody dynamic (MBD) simulations could be a powerful tool to estimate these loads. Two main categories of MBD simulations exist. Firstly, full analytical simulations, which have received great attention in the literature, are run in a virtual environment using a tire model and a virtual road. Secondly, hybrid simulations, also named semi analytical, uses experimental data from Wheel Force Transducers and Inertial Measurement Units to replace the road and tire models. It is still unclear how trustworthy semi analytical simulations are for frame load evaluation. Both methods were tested for three loads cases. It was found that semi analytical simulations were slightly better in predicting vehicle dynamic and frame loads than the full analytical simulations for frequencies under the MF-Tyre model valid frequency range (8 Hz) with accuracy levels over 90%. For faster dynamic maneuvers, the prediction accuracy was lower, in the 50%–80% range, with semi analytical simulations showing better results.
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Wang, Yingjie, Zuzana Dimitrovová, and Jong-Dar Yau. "Dynamic responses of vehicle ballasted track interaction system for heavy haul trains." MATEC Web of Conferences 148 (2018): 05004. http://dx.doi.org/10.1051/matecconf/201814805004.
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In this study, the dynamic responses of ballasted tracks subjected to heavy haul trains are investigated. The vehicle ballasted track interaction (VTI) model can be divided into three parts, which are vehicle model, ballasted track model and wheel/rail contact model. The vehicle is modelled as a multi-body system with 10 degrees of freedom. The ballasted track consisting of rail, sleeper, ballast, sub-ballast and sub-grade is modelled as four elastic components. The vehicle model and ballasted track model is linked by the wheel/rail contact model, which is determined by the nonlinear Hertzian theory. The VTI model is solved by an iterative procedure and validated with some field experiments. The dynamic responses of the vehicle/track system are compared with those from the moving load model. Moreover, the wheel/rail contact force, the force from rail to sleeper and the force from sub-ballast to subgrade are computed for different axle loads of 25t, 30t, 35t and 40t. It is deduced that maximum values of these forces increase in a linear form with the increasing of axle load.
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Li, Yun Sheng, Li Li Shi, and Shuai Li. "Research on Impact Factor of Simple Composite Box Beam under Vehicle Loads." Advanced Materials Research 382 (November 2011): 471–76. http://dx.doi.org/10.4028/www.scientific.net/amr.382.471.
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Commonly the vibration due to vehicle loads has no apparently impact on highway bridges, but it is unneglectable when the heavy vehicles load on highway bridges. The impact factor is usually used to define the dynamic effect under vehicle loads in most design code. In this paper, the models of simple composite box beams with different span and the models of two simplified heavy vehicles are established respectively. The impact factors are calculated when the heavy loads pass though bridges at different speed under different load conditions. In addition, the change laws of the impact factors and the influence of different vehicle models on the impact factors are analyzed. Analysis results show that, not only the impact factor are increased with vehicle speed, but also the amplitude and period are all increased. In normal speed range, the influence of speed on the impact factors appears rising trend overall. For the bridge with same span, the impact factors under the double wheel load are smaller than that under single wheel load.
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Wright, Jason, S. Sonny Kim, and Bumjoo Kim. "Stiffness and Strength Improvement of Geosynthetic-Reinforced Pavement Foundation Using Large-Scale Wheel Test." Infrastructures 5, no. 4 (April 3, 2020): 33. http://dx.doi.org/10.3390/infrastructures5040033.
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Laboratory cyclic plate load tests are commonly used in the assessment of geosynthetic performance in pavement applications due to the repeatability of testing results and the smaller required testing areas than traditional Accelerated Pavement Testing facilities. While the objective of traditional plate load testing procedure is to closely replicate traffic conditions, the reality is that rolling wheel loads produce different stresses in pavement layers than traditional cyclic plate load tests. This two-fold study investigates the differences between the stress response of subgrade soil from a rolling wheel load (replicating rolling traffic conditions) and a unidirectional dynamic load (replicating traditional plate load test procedures) in order to obtain a more realistic stress response of pavement layers from rolling wheel traffic. Ultimately, results show that the testing specimens that experienced rolling wheel loading had an average of 17% higher pressure measurements in the top of the subgrade than vertically loaded (unidirectional dynamic load) specimens. The second segment of this study is used in conjunction with the first to analyze aggregate base material behavior when using a geosynthetic for reinforcement. The study aimed to determine the difference in the post-trafficked strength and stiffness of pavement foundation. A Dynamic Cone Penetrometer and Light Weight Deflectometer were utilized to determine material changes from this trafficking and revealed that all specimens that included a geosynthetic had a higher base stiffness and strength while the specimen with geotextile and geogrid in combination created the highest stiffness and strength after large-scale rolling wheel trafficking.
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Edwards, J. Riley, Aaron Cook, Marcus S. Dersch, and Yu Qian. "Quantification of rail transit wheel loads and development of improved dynamic and impact loading factors for design." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, no. 10 (April 27, 2018): 2406–17. http://dx.doi.org/10.1177/0954409718770924.
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An increase in the number of rail transit track construction and rehabilitation projects in North America has generated increased interest in optimizing the design of the track infrastructure and its components. Many rail transit track component design guidelines use historical wheel loads and loading factors that were derived from freight railroad design practices. These design factors may not be representative of the loading experienced on the rail transit networks today, leading to over-designed, sub-optimal infrastructure components. Therefore, researchers at the University of Illinois at Urbana–Champaign are conducting research to lay the groundwork for improved understanding of the loading environment entering the track structure using wheel loads data obtained from recently deployed field instrumentation and existing wheel impact load detectors. This paper evaluates the existing design impact factors and assesses their effectiveness when applied to the rail transit sector, using data from three representative rail transit agencies in the United States. New dynamic loading factors are also proposed to represent the rail transit loading environment more accurately. A quantitative approach to addressing design factors may provide economies in future designs and facilitate the use of probability of exceedance and other metrics that relate to factors of safety.
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Burrow, Michael P. N., Jin Shi, Mohamed Wehbi, and Gurmel S. Ghataora. "Assessing the Damaging Effects of Railway Dynamic Wheel Loads on Railway Foundations." Transportation Research Record: Journal of the Transportation Research Board 2607, no. 1 (January 2017): 62–73. http://dx.doi.org/10.3141/2607-09.
Full textAbstract:
Dynamic train wheel loads, which can be significantly greater than static loads, occur because of a variety of factors and unless they are properly considered in track structural design, significant unplanned maintenance and premature track failure may result. This is particularly so for traditional ballasted railways built on soft foundations, because although ballast lends itself to maintenance, it is often problematic and costly to repair damaged foundations. A novel rigorous analytical–numerical approach is described to predict and characterize, for the first time, the damage to which railway foundations can be subjected as a result of dynamic loads. The approach marries a sophisticated three-dimensional dynamic model of the train–track system incorporating vertical track quality, foundation soil distress models, statistical analysis methods, and results of field investigation. The resulting analyses demonstrate that the magnitudes and distributions of dynamic loads are a function of train speed and track quality, and that specific locations experience significantly higher amounts of damage, which can lead to a variety of track faults. The approach is illustrated via a study of a heavy haul railway line in China where the wheel loads and tonnage carried are set to increase significantly. Findings from the study suggest that the thickness of the ballasted layer would need to increase by over 20% to prevent premature foundation failure provided that the track is maintained in good condition, and by significantly more should the track condition be allowed to deteriorate.
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Mazov, Yuriy Nikolaevich, Aleksey Alekseevich Loktev, and Vyacheslav Petrovich Sychev. "Assessing the influence of wheel defects of a rolling stockon railway tracks." Vestnik MGSU, no. 5 (May 2015): 61–72. http://dx.doi.org/10.22227/1997-0935.2015.5.61-72.
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Transfer of the load from the wheels on the rail occurs at a very small area compared with the size of the wheels and rails. The materials near this site have a very large voltage. Determination of contact stresses is complicated by the fact that the magnitude of these stresses in the rails under actually revolving wheel load exceeds the yield and compressive strength of modern rail steel. We should note that the metal of the rail head, experiencing contact stresses, especially when the location of the pads is closer to the middle of the rail head, works in the conditions close to the compression conditions, and therefore can withstand higher voltage without plastic deformation than the standard compressible sample. But, as a rule, the observed hardening of the metal in the zone of contact stresses and lapping at the edges of the rail head indicates the presence of plastic deformation and, consequently, higher stresses in the wheel-rail contact zone than the yield strength of the metal rail even in the conditions of its operation in the rail head.The use of the design equations derived on the basis of the Hertz theory for metal behavior in elastic stage, is valid. The reason is that each individual dynamic application of wheel loads on the rail is very short, and the residual plastic deformation from the individual loads of the pair of wheels on the rail is actually small. This elastic-plastic deformation of the rail becomes visible as a result of gradual gaining of a missed tonnage of rails and wheels respectively. Irregularities on the running surface of the wheels are of two types. The most common are the so-called continuous bumps on the wheel, when due to the uneven wear of rail the original shape of the wheel across the tread surface distorts. But nowadays, more and more often there occur isolated smooth irregularities of the wheel pairs, due to the increased wear of the wheel because of the stopping and blocking of wheels of the vehicles - slides (potholes), etc.The motion of the wheels with irregularities on the surface of the rail leads to vertical oscillation of the wheel, resulting in the forces of inertia, which is an additional load on the rail. In case of movement of the wheel with isolated roughness on the tread surface of the slide there is a strike, having a very large additional impact on the rail. Such attacks can cause kinked rails, especially in the winter months when there is increased fragility of rail steel, because of lowered temperatures. This is an abnormal phenomenon and occurs relatively rarely, at a small number of isolated irregularities on a wheel of the rolling stock. As correlations connecting the contact force and local deformation in the interaction of the wheel-rail system, we use the quasi-static Hertz’s model, linear-elastic model and two elastoplastic contact models: Alexandrov-Kadomtsev and Kil’chevsky. According to the results of Loktev’s studies ratios of the contact Hertz’s theory are quite suitable for modeling the dynamic effects of wheel and rail for speeds up to 90 km/h for engineering calculations. Since the contact surface is homogeneous and isotropic, the friction forces in the contact zone are not taken into account, the size of the pad is small compared to the dimensions of the contacting bodies and characteristic radii of curvature of the undeformed surfaces, the contacting surfaces are smooth.When train is driving, the position of the wheelset in relation to the rails varies con- siderably, giving rise to different combinations of the contact areas of the wheel and rail. Even assuming constant axial load the normal voltage will vary considerably because of the differences in the radii of curvature of the contacting surfaces of these zones. Thus, the proposed method allows evaluating the influence of several types of wheel defects on the condition of the rail and the prospects of its use in the upper structure of a railway track on plots with different speed and traffic volumes. Also the results can be used to solve the inverse of the considered problems, for example, when designing high-speed highways, when setting the vehicle speed and axle load, and the solution results are the parameters of the defects, both wheelsets and the rails, in case of which higher require- ments for the safe operation of railways are observed.
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Uppal, A. S., R. B. Pinkney, and S. H. Rizkalla. "An analytical approach for dynamic response of timber railroad bridges." Canadian Journal of Civil Engineering 17, no. 6 (December 1, 1990): 952–64. http://dx.doi.org/10.1139/l90-107.
Full textAbstract:
In the 1970s, it was reported that there were approximately 3700 track kilometers of timber railroad bridges in the United States and Canada. For short spans, they offer an attractive alternative to other types of bridges, as they are economical, faster to construct, and easy to maintain. Current design practices do not allow an independent consideration of the effects of the dynamic loads in sizing the bridge components, because very little information is available on the subject. Dynamic tests were carried out in 1986 on timber bridge spans at two test sites using test trains consisting of a locomotive unit, two loaded hopper cars, and a caboose. This paper gives a brief description of the analytical approach employed for determining the dynamic response of timber bridge spans under railway vehicles travelling at a constant speed. The model comprises a multi-degree-of-freedom system with each vehicle having bounce, pitch, and roll movements. Two parallel chords, each having its distributed mass lumped at discrete points, were used to idealize the bridge spans. A computer program developed on this basis was used to predict the loads at the wheel–rail interfaces and the vertical displacements at the discrete points on the spans. The predicted loads at wheel–rail interfaces and the maximum vertical displacements were found to be in agreement within about 20% and 16% respectively of the measured values. The program was utilized to study the effect of speed and other factors on the dynamic response of open-deck and ballast-deck bridges. Key words: analytical approach, timber railway bridge, railway locomotive and cars, constant speed, wheel–rail interface, loads, displacements, accelerations, dynamic response.
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Bošnjak, Srđan, Nenad Đ. Zrnić, Vlada M. Gašić, Zoran D. Petković, and Aleksandar Simonović. "External Load Variability of Multibucket Machines for Mechanization." Advanced Materials Research 422 (December 2011): 678–83. http://dx.doi.org/10.4028/www.scientific.net/amr.422.678.
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This paper discusses the problems of identifying external loads of multibucket machines for mechanization. External loads are dominantly dynamic with distinguished stochasticity in certain cases. The paper presents the procedures for determining external loads caused by resistance-to-excavation (for bucket wheel excavators) or grabbing soil (for bridge-type coal stacker-reclaimers), as well as a short description of the model upon which is based and defined the response of the stacker-reclaimer to the external changeable load. It points to the significance of the problem of identifying the external load, as well as to the potentially very detrimental and dangerous consequences of eventual shortcomings during solving the mentioned problem.
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Radulovic, Milovan, Dejan Popovic, and Novak Jaukovic. "Optimal control of a two-wheeled mobile robot: Simulation for selecting of the motors." Facta universitatis - series: Electronics and Energetics 16, no. 1 (2003): 55–65. http://dx.doi.org/10.2298/fuee0301055r.
Full textAbstract:
This paper presents how a novel simulation package for optimal control based on dynamic programming can be used for selecting the drives once the constraints are known: range of speeds, trajectory (minimum radius for turns), load that will be carried by the mobile robot and its position on the platform (inertia! properties of the mobile robot with the load). We calculate the necessary driving torques at the wheels of the mobile robot for various trajectories having a shape of the figure eight within a given time. The simulation uses fully customized dynamic model of the mobile robot that is propelled by two independent wheels and has third non-powered wheel that freely rotates around the vertical shaft to ensure three degrees of freedom. Dynamic programming and the discrete mathematic model allow simulation of the non-holonomic system. We presented in this paper only one possible application, that is, the analysis of three different loads carried along the same trajectory. The simulation clearly shows the relation between the tracking error and required diving torque; thereby, allow selection of the adequate driving motors for a given load and vice versa.
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Kim, In Tai, and Erol Tutumluer. "Unbound Aggregate Rutting Models for Stress Rotations and Effects of Moving Wheel Loads." Transportation Research Record: Journal of the Transportation Research Board 1913, no. 1 (January 2005): 41–49. http://dx.doi.org/10.1177/0361198105191300105.
Full textAbstract:
The latest research findings on stress rotations caused by moving wheel loads and their effects on permanent deformation or rut accumulation in pavement granular layers are presented. Realistic pavement stresses induced by moving wheel loads were examined in the unbound aggregate base and subbase layers, and the significant effects of rotation of principal stress axes were indicated for a proper characterization of the permanent deformation behavior. To account for the rutting performances of especially thick granular layers, a comprehensive set of repeated load triaxial tests was conducted in the laboratory. Triaxial test data were obtained and analyzed from testing aggregates under various realistic in situ stress paths caused by moving wheel loading. Permanent deformation characterization models were then developed on the basis of the experimental test data to include the static and dynamic stress states and the slope of stress path loading. The models that also considered the stress path slope variations predicted the stress path dependency of permanent deformation accumulation best. In addition, multiple stress path tests conducted to simulate the extension–compression–extension type of rotating stress states under a wheel pass gave much higher permanent strains than those of the compression-only single path tests. The findings indicated actual traffic loading simulated by the multiple path tests could cause greater permanent deformations or rutting damage, especially in the loose base or subbase, when compared with deformations measured from a dynamic plate loading or a constant confining pressure type laboratory test.
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Mishra, Debakanta, Huseyin Boler, Erol Tutumluer, Wenting Hou, and James P. Hyslip. "Deformation and Dynamic Load Amplification Trends at Railroad Bridge Approaches." Transportation Research Record: Journal of the Transportation Research Board 2607, no. 1 (January 2017): 43–53. http://dx.doi.org/10.3141/2607-07.
Full textAbstract:
Railroad track transitions such as bridge approaches may experience differential movements due to variations in track stiffness; impact loads due to train speed and excessive vibration; ballast settlement from fouling, degradation, or both; tie–ballast contact condition and gap; and settlement of fill, subgrade, and foundation layers. A research study completed recently at the University of Illinois focused on identifying the major causes of this differential movement and implementing suitable rehabilitation measures to mitigate recurrent problems with settlement and geometry. Transient and permanent deformation trends were observed in track substructure layers at two instrumented bridge approaches along the Amtrak Northeast Corridor. Multidepth deflectometer systems installed through crossties successfully recorded both permanent (plastic) and transient deformations of individual track substructure layers. Strain gauges mounted on the rail effectively measured vertical wheel loads applied during train passage and monitored the support conditions under the instrumented crossties. Track settlement (or permanent deformation) data revealed that the ballast layer was the primary source of differential movement contributing to recurrent settlement and geometry problems. Transient layer deformations recorded under train passage were higher in the ballast than in any other substructure layer. Transient displacement and wheel load data were consistently higher at near-bridge locations than at open-track locations. Rail-mounted strain gauges indicated that load amplification levels were significantly higher at near-bridge locations than at open-track locations.
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Javad Taherinezhad, M. Sofi, Priyan Mendis, and Tuan Ngo. "Strain Rates in Prestressed Concrete Sleepers and Effects on Cracking Loads." Electronic Journal of Structural Engineering 17 (January 1, 2017): 65–75. http://dx.doi.org/10.56748/ejse.17220.
Full textAbstract:
Prestressed concrete sleepers (PCSs) play an essential role in structural response and performance of ballasted railway tracks. Due to defects in track or train components, high magnitude dynamic loads may generate at the rail head and transfer to the PCSs which can generate cracks in PCSs. Cracking from dynamic loads have been reported as the most critical problem of PCSs around the world and impose an early replacement of sleepers which is a financial burden to the rail industry. This paper investigates the effects of strain rates on the strength enhancement of PCS. By using available measurements, the strain rates are calculated at two critical points of the PCSs, the rail seat and midspan. Considering the dynamic increase factor (DIF) of concrete, the cracking loads of a PCS are calculated and are compared with commonly occurring dynamic loads. Results show that the maximum strain rates at both rail seat and midspan are about 0.08 and 0.016 1/s, respectively. The increase of cracking wheel load due to the strain rate effects is about 5 to 26 percent. The results are also shown to be able to demonstrate the level cracking from dynamic loads with very short return periods.