Percorrer por autor "Frigeri, Ary Vinicius Nervis"
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- Prediction models for rail temperatures validated with experimental measurementsPublication . Frigeri, Ary Vinicius Nervis; Minhoto, Manuel; Piloto, Paulo A.G.; Silva, Dyorgge AlvesRail temperatures play an important role when understanding and predicting rail track instabilities. A rail temperature energy balance model was used, validated with FEA analysis, and compared with field-collected data. Both simplified and Finite Element Analysis (FEA) model are in good agreement. Compared with the collected data, the model reaches an R² of 0.83. Boundary conditions improvements are needed.
- Prediction models for rail temperatures validated with experimental measurementsPublication . Frigeri, Ary Vinicius Nervis; Minhoto, Manuel; Piloto, P.A.G.; Pereira, Ana I.Rail temperatures play an important role when understanding and predicting rail track instabilities. A rail temperature energy balance model was used, validated with FEA analysis, and compared with field-collected data. Both solution methods are in good agreement. Compared with the collected data, the model reaches an R² of 0.83. Boundary conditions improvements may be required.
- Prediction models for rail temperatures validated with experimental measurementsPublication . Frigeri, Ary Vinicius Nervis; Minhoto, Manuel; Piloto, Paulo A.G.; Silva, Dyorgge AlvesRail temperatures play an important role when understanding and predicting rail track’s instabilities. An energy balance model called CNU was used to simulate rail temperatures, validated with FEA analysis, and compared with field-collected data. The model uses weather data and accounts for the solar position to improve temperature prediction. In addition, a python package is developed to solve the thermal lumped model including specific modifications on the model. Both simplified and Finite Element Analysis (FEA) models are in good agreement. Compared with the collected data, the model reaches an R² of 0.914.
- Thermal and mechanical behavior of railway tracksPublication . Frigeri, Ary Vinicius Nervis; Minhoto, Manuel; Piloto, P.A.G.; Silva, Dyorgge A.Railways are infrastructures subject to open weather conditions and also to temperature changes during the day and over the season. Due to this change, internal stresses may appear, whether tensile or compressive depending on the stress-free temperature and the current measure. High compressive stress may lead the track to buckle, meanwhile tensile stress can cause brittle failure. Given the importance of the temperature on railways, many models have been developed to correlate weather conditions and rail temperatures, in order to avoid the occurrence of mechanical instabilities which cause major problems in the operation of railroads. The present work validates one model developed by CNU university by comparing it with nite element solutions and also with experimental data of a rail track in the city of Mirandela-Portugal. A python package was developed to solve the model and is available to download. The model shows a good correlation between measured and simulated rail temperatures. In addition, by utilizing weather information of other locations in Portugal, the maximum expected rail temperatures were determined. Furthermore, mechanical analyses were made to analyze the critical temperature to reach the buckling mode of instability without the e ect of rolling loads and also the important parameters that a ect this phenomenon. The simulations show that the quality of the ballast and the initial miss-alignment of the track are the most important. Keywords:
- Thermal buckling of railwaysPublication . Piloto, Paulo A.G.; Frigeri, Ary Vinicius Nervis; Minhoto, ManuelThis manuscript presents the results of numerical research regarding the thermal buckling on railway tracks. High temperatures may cause thermal buckling on the railways and due to this fact speed restrictions are often issued to reduce the probability of derailments. Railways are subject to thermal and mechanical loads in which, given some circumstances, buckling may take place. Continuous welded rail (CWR) is more prone to this effect than jointed rails since the longitudinal displacement is restrained. This research is focused on the effect of the track gauge, rail profile, initial imperfection amplitude, sleeper's elasticity modulus, torsional resistance of fastenings, and ballast resistance on the thermal buckling of railways. A total of 144 simulations were developed, concluding that the imperfection level and ballast resistance are the most affecting parameters on the buckling temperature.
- Validation of a rail temperature model with experimental measurementsPublication . Piloto, P.A.G.; Frigeri, Ary Vinicius Nervis; Minhoto, Manuel; Silva, Dyorgge A.Rail temperature is a key factor when studying the effects of thermal buckling. Many models have been developed to simulate rail temperatures under various weather conditions. This work is based on the model developed by the Chungnam National University (CNU), which includes the shadow effect on the rail and the solar position to improve the temperature prediction during several periods of the day, validates it with experimental data, and compares it with a finite element model. Furthermore, a python library is developed based on the lumped thermal model with small adaptations, called railtemp. The python package has slightly better performance over the original CNU model, reaching a correlation factor R2 of 0.947 and a root mean square error of 2.6°C. Furthermore, a new proposal is presented to determine the temperatures on rail tracks based on air temperature.