Rail Temperature Stress, Measured With A Capacitive Displacement Sensor

This paper present a method based on strain theory to test temperature stress ofseamless rail and the design of the intelligent stress measure instrument.Rail is the important part of railroad. While rail temperature changing alone withenvironment temperature, stress may be appear in the rail. Oversize stress will causethe rail bent or ruptured, which serious influence the safety of railroad. In recent years,many measure instruments were developed to test temperature stress of seamless rail,however, simple, universal and effective instruments or methods don't appear up tonow. This paper present a measure method based on strain theory and the generaldesign of displacement sensor, interface circuit and software arithmetic.1. The paper presents a theoretic deduce to the stress measurement based onstrain theory, and worked out the mathematic formulas of the measurement.2. The design of measure instrument sufficient applied the technology of newtype capacitance signal convert circuit and micro controller, which can improve thefunction and capability of the instrument.3. The interface capacitance of capacitive sensor, non-linear output and warp ofconvert circuit are all amended. The anti-jamming and system self diagnoses designsguarantee stability and reliability of the measurement instrument. An intelligentdigital filter arithmetic having programmable judgement was used in paper, whichsince have better smooth capability, and then have fast respond speed.4. Designed perfect intelligent software for measure system. The softwareactualized auto-plus control, auto-adjust and temperature expiate, and so on, whichfarther improve the measure precision.The development of this new type measure instrument of temperature stressfulfilled fast and precise measurement. The instrument has the characteristics ofsimple, low cost, credible and fast respond, which make the instrument having appliedvalue.