Both effects involve economic costs. Moreover, if the excessive deformation of rails is not detectable in time, the consequences can be very serious, not only from an economic point of view but also from the point of view of passengers’ safety. Long-term monitoring of the tracks offers solutions for the early detection of excessive deformation and therefore, allows in-time planning of maintenance actions necessary to ensure safety and decrease economical losses.
To monitor the structural behavior of the railway tracks of high-speed trains in Taiwan, fiber optic technology-based monitoring systems SOFO® and DiTeSt® are proposed. The standard sensors are easy and fast to install, but they require additional protection, notably if exposed to direct sun rays, wind, rodents, and vandalism. Good and safe protection can involve a slowdown of installation, an increase of costs, and an increase of the size of the installation. Therefore, new packaging for the sensor is being developed. This packaging is designed to allow fast and easy installation, but also to insure good and durable protection of the sensor over long terms, even in aggressive environments. The new packaging consists of the integration of the optical fibers into a glass-fibers reinforced thermoplastic composite profile or tape, which guarantees safe and easy installation and good long-term protection of the sensor. Prototypes of the tape were tested first in the laboratory and then on-site. The sensing tape is called SMARTape and can be used with both systems (SOFO and DiTeSt). All the deformation sensors (SMARTapes and Standard SOFO Sensor) are installed by gluing, using Araldite glue. The thermocouples were only simply fastened using the self-gluing tape (scotch). The one-meter-long Standard SOFO Sensor was installed using the L-brackets. First, the rust was cleaned, then the glue was applied and the L-bracket bonded to the rail. The same procedure was repeated for both L-brackets. When the glue had set, the sensor was installed. In the case of the SMARTape, a special procedure was developed. As in the case of the L-brackets, first, the rail was cleaned. The SMARTape was first glued to the scotch tape, and then the layer of Araldite was applied to it. Afterward, both the SMARTape and the scotch tape were glued to the rails. The scotch tape was not necessary after the setting of the glue, but it was however kept since it protected the SMARTape from direct exposure. The loading of the rail was performed using an empty wagon (W=19 tons). The wheel of the wagon was placed approximately in the middle of the sensors. The static measurements were performed once before the load was applied (zero measurements), once during the loading, and once after the load was removed. The full loading test was repeated two times, in two successive days.
Aim of monitoring:
The on-site test was performed with the following aims:
- To test the applicability of the Standard SOFO Sensor onto the rails in real conditions
- To test the applicability of SMARTape onto the rails in real conditions.
- To test the sensing performances of SMARTape
- .To compare two sensors (Standard SOFO Sensor and SMARTape)
At the present stage static test is performed. The following conclusions are carried out: ·The Standard SOFO Sensor can successfully be used for rail monitoring. The issue of sensor protection in the long term was not considered by the tests. ·The SMARTape can successfully be used for rail monitoring. The measurements collected using the SMARTape are comparable with those collected by Standard Sensor, proving excellent resolution and transfer of strain from the rail to the sensor. ·Due to the small dimensions of the cross-section and due to the material combination (fiber-reinforced thermoplastic composite tape) the protection of the SMARTape in long term is not an issue. ·A curvature of 8.14×10-4 m-1 (bending radius of 1228.5 m) was successfully measured. Long-term performance testing of SMARTape continues. The quality of interaction between the rail and the SMARTape is regularly controlled. The SMARTapes will remain installed onto the rail for their long-term testing and characterization.
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