Blanco, B. (Blas)

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    Panhead accelerations-based methodology for monitoring the stagger in overhead contact line systems
    (Elsevier Ltd., 2022-05) Errandonea, I. (Itxaro); Alvarado-Videira, U.(Unai); Blanco, B. (Blas); Arrizabalaga-Juaristi, S. (Saioa); Beltrán, S. (Sergio)
    The monitoring of overhead contact lines (OCL) is a key part of railway infrastructure maintenance. This paper proposes a methodology to assess the lateral geometry of contact wire, the so-called stagger, by using the dynamic response of a pantograph. The methodology is tested in a validated virtual environment that resembles the behaviour of the pantograph when it interacts with the OCL. A signal processing is developed to define features relating the lateral position of the contact wire with the vertical acceleration of the contact strip. It is demonstrated that these features have a clear and close connection with the lateral position of the contact wire. Subsequently, model-driven machine learning algorithms are defined using these features to address the OCL stagger prediction and the detection of out-of-range lateral displacement due to a faulty steady-arm. The methodology shows a good prediction performance in the estimation of the stagger amplitude/central position and the steady-arms diagnosis. The prediction of the stagger amplitude is performed with a root-mean-square error of 4.7(10) mm. In addition, the area under the Precision-Recall curve is 0.952 CI95 [0.940, 0.962] for the steady-arms diagnosis.
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    Effect of lubrication on the mechanical behavior of magnetorheological elastomers in compression mode
    (Elsevier, 2022) Kari, L. (Lefi); Gil-Negrete, N. (Nere); Wang, B. (Bochao); Erenchun, A. (Aitor); Blanco, B. (Blas)
    The effect of the lubrication on the mechanical behavior of magnetorheological elastomers (MREs) in compression mode is experimentally studied. According to ISO 7743, there are two procedures to characterize specimens in compression mode. Differences in the properties of these materials between lubricated and non- lubricated conditions must be considered if devices such as vibration absorbers and isolators are to be devel- oped. With lubrication, compression is said to be uniaxial and homogeneous, thus material properties can be obtained. Without lubrication, tests are easier to perform but results are strongly dependent on the piece shape. In this study isotropic and anisotropic MREs with iron particle volume concentrations of 10, 20, 30 and 40% are tested under different strain amplitudes, prestrain and magnetic fields for a frequency range up to 300 Hz, with and without lubrication. Important design parameters like amplitude, frequency and magnetic field dependency are showed to be dependent on lubrication.