1,720,982 research outputs found
Integration of the measure of the primary suspension deflection into a dynamometric wheelset equipped with strain gauge bridges
No full textA hybrid method for the integration between an instrumented wheelset and the measure of the deflection of the primary suspension
Full text linkPortable Device for Rail Bending and Torsion measurement
No full textA portable device for assessing rail bending and torsion as well as the relative wheel-rail position was designed and tested. The main requirement for this device is that its first eigenfrequency should be well above the first bending eigenfrequency of the rail in order not to dynamically amplify rail bending motions. Thus, a minimum target frequency of 100Hz is set. Another requirement is to design a device that could be easily mounted on different track sections in order to assess also the influence of vehicle type and speed. Thus, a portable device based on laser sensors was produced that does not require any operations on the rails (contactless sensors) and allows to place the sensors at a reasonable distance from both the rail and the passing by wheel. Tests were performed on a dedicated test track in Czech Republic both at low speed (20km/h on a 150m radius curve) and at medium speed (90km/h on a 600m radius curve) with two axle and four axle wagons. Installation was extremely easy and acquired signals were post-elaborated to assess rail vertical and lateral bending as well as torsion
A new method for the improvement of the accuracy of the estimation of wheel-rail contact forces using instrumented wheelsets
No full textEvaluation of the metrological characteristics of an instrumented wheelset for the measurement of wheel-rail contact forces
No full textThe actual European regulations in matter of rail vehicle homologation prescribe to measure not only accelerations but also contact forces exchanged at wheel-rail interface, in order to state the level of running safety, track loading and vibration behaviour. It is important to point out that the standards do not prescribe any specific method to measure forces, nevertheless define any metrological requirement of the measuring system. Aim of this paper is to investigate the metrological properties of a dynamometric wheelset in order to determine the associated measurement uncertainty and to verify its readiness in the range of frequencies where the force analysis have to be performed. With reference to a specific instrumented wheelset, the calibration procedure was performed using a dedicated test-rig developed in the laboratories of the Department of Mechanical Engineering - Politecnico di Milano. The test-rig allows a static calibration of the system. Dynamic tests have been performed, imposing a random or an impulsive excitation to the wheelset, in order to define the bandwidth of the measuring system
An Application of the Interactive Multiple Model to the Measurement of Wheel-Rail Contact Forces
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DEVELOPMENT OF A NEW ALGORITHM FOR WHEEL-RAIL CONTACT FORCE ESTIMATION USING REDUCED MEASUREMENT SETS
No full textIn the present work, the problem of the contact forces measure is analysed with a particular focus on the dynamometric wheelset method. Knowing the state of deformation on the wheelset, it is possible to reconstruct the forces that caused it after a calibration process. In this research, the definition of the minimal measurements sets required for a consistent estimation of the forces is defined, highlighting the need of six independent measurement sections for the estimations of the vertical and lateral forces. It is important to point out that dynamometric wheelset are very delicate systems and may suffer of damages or drifts on some measurement sections, which can affect or compromise the possibility to estimate correctly the wheel-rail contact forces. It is indeed important to derive a method for the measurement of the forces also in case of degraded conditions of the dynamometric wheelset in order to increase the reliability of the measuring system. By means of a proper partitioning of the calibration test-plan, it is possible to achieve a series of calibration matrices, each one suitable for a specific calibration conditions. These calibration matrices can provide good results in terms of estimation precision even though the measurement set is reduced below the minimal conditions. At this point, a method based on the fuzzy logic is derived in order to recognise properly the conditions encountered by the dynamometric wheelset. This method is capable to identify between the calibration models the most suitable. Eventually, the algorithm is also capable to mix the models in order to cover the regions out of the calibration ranges. The effectiveness of the method is tested by means of quasi-static tests performed on a full-scale dedicated test-rig highlighting the possibility to increase the performances of a non-optimally instrumented wheelset in terms of both forces reconstruction and measurement precision
Improvements of the estimation of wheel-rail contact forces using instrumented wheelsets
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