Improved Railway Track Irregularities Classification by a Model Inversion Approach
Over time railway networks have become complex Systems characterized by manifold types of technical components with a broad range of age distribution. De facto, about 50 percent of the life cycle costs of railway infrastructures are made up by direct and indirect maintenance costs. A remedy can be provided by a condition based preventive maintenance strategy leading to an optimized scheduling of maintenance actions taking the actual aswell as the expected future infrastructure condition into account. A prerequisite is, however, that the thousands of Kilometers of railway tracks are almost continuously monitored. Thus, a promising approach is the usage of low-cost sensors, e.g. accelerometers and gyroscopes, which can be installed on common in-line freight and passenger trains. Due to ambiguous data records a credible classification of railway track irregularities directly from these data is challenging. Alternatively to this pure data-driven approach, in this paper a novel hybrid Approach is presented. To this end, a simplified vehicle Suspension model is applied for the purpose of railway track condition monitoring by analyzing the dynamic railway track - Train interactions. The inversion of the model can be used to recalculate the actual inputs (irregularities) of the monitored system (rail surface) which have caused recorded System Responses (dynamic vehicle reactions and acceleration data, respectively). These recalculated inputs are a sound Basis of subsequent data-driven condition monitoring analyses. In this preliminary study, a classification algorithm is implemented to identify a simulated railway track irregularity automatically.
Zustandsüberwachung mit kostengünstigen Multi-Sensor-Systemen
Flexible, skalierbare und kostengunstige Multi-Sensor-Systeme auf Schienenfahrzeugen ermoglichen auch fur die Betreiber kleinerer Streckennetze eine datengestutzte Zustandsuberwachung des Gleisoberbaus. Am DLR wurde ein Prototyp zur georeferenzierten Erfassung von Achslagerbeschleunigungen aufgebaut und auf einer Rangierlokomotive im Braunschweiger Hafen im operativen Einsatz erprobt. Aus den Messdaten gewonnene Informationen geben einen kontinuierlichen und aktuellen Uberblick uber den Zustand der Infrastruktur. Veranderungen oder Schaden im Gleisnetz konnen fruhzeitig erkannt werden, so dass teure Ausfalle vermieden und Wartungsarbeiten zielgerichteter durchgefuhrt werden konnen.
Tests of composite beams with web holes
Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount of shear connection between slab and steel section in the region of a web hole, and on the effect of construction loads acting on the steel section prior to composite action being effective.It is shown that limited shear connection at the hole will significantly affect the strength when loading produces a high shear-to-moment ratio, and a theory is presented which conservatively takes this into account. The effect of construction loads on unshored construction is shown to be small when these do not exceed 60% of the non-composite beam resistance at the hole.