PSI - Issue 32

G. Gusev et al. / Procedia Structural Integrity 32 (2021) 49–55 Gusev G.N./ StructuralIntegrity Procedia 00 (2019) 000 – 000

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The bunker receives ore from an elevator, which lifts it from a depth of 800 meters. Figure 6a shows the results of strain evolution for this control point over the entire measurement period for the final version of the sensor. Figure 6b shows the cycle of ore pouring into a hopper and pouring ore onto a conveyor. Figure 6b clearly shows that the sensor feelsthe ore transportation cycle. The amplitude of deformation change for a given column is about 8 mkStr, which is in good agreement with the finite element model. This fact allows to speak about the work of the deformation measurement system with the required accuracy and discreteness. This fact deserves attention, since

this sensor was developed individually. 4. Application experience analysis

Several basic provisions for measuring deformations in aggressive conditions based on the experience gainedwere achieved. The experience gained is valuable as it will help prevent the described errors in the future. The main theses that describe the approach derived from the analysis below was presented. First. The duration of the experiment and the features of the external environment completely determine the design, method of installation and use of strain gauges. Ignoring this fact leads to the use of solutions that have been tested in practice. There is no guarantee that the turnkey solution will meet current operating conditions. We are promoting the principle that suitable measuring instruments should be developed for each unique environment. Second. The increasing complexity of the sensor design leads to the complication of the methods of its installation at the monitoring object. It can also lead to errors. The installation technology should be worked out as efficiently as the calibration of the sensor itself. Technology validation should be carried out under conditions that are similar to future conditions of use. It is important to evaluate and prevent all factors that affect the quality installation of measuring devices. Third.It is necessary to be confident in every single component of the strain gauge, as well as in their perfect collaboration under the current conditions. For this, it is important to conduct appropriate verification tests at all stages of production. It is very important to control the manufacture of the sensor and test it. Fourth. The most important aspect of the reliable operation of the sensor is its complete waterproofing. In the conditions of the plant, highly aggressive potash brines are present, which in the most negative way affect the performance of all measuring devices. It is important to be able to separate the degradation of the electrical signal of the measuring bridge from the degradation of the bearing capacity of the structure itself. For this, it is very important to create a mathematical model and work out various scenarios for the evolution of the stress-strain state. Taking into account all the described experience, the developed sensor and the installation technology allow to solve the problem of exposure to an aggressive environment and ensure the specified measurement accuracy. Unlike ready-made sensors, our development allows to evaluate deformations in metal bearing elements with an accuracy of up to 0.05% of the measurement range. This is confirmed by tests on a laboratory bench and comparison with the results of numerical modeling. Given that our solution is completely protected from the external environment, there are no analogues of such a sensor. The complexity of the manufacturing and installation technology of such sensors does not allow them to be used en masse. But this is the most suitable solution for analyzing the stress-strain state of structures in the mining and processing industry. The next step in the development of these devices is an attempt to implement an internal control scheme for the state of the sensor itself. Adding a feedback loop to the measurement circuit will allow you to evaluate the sensor's performance remotely. Acknowledgements The study was performed as part of a government-sponsored program (the state registration number of the topic is AAAA-A19-19012290100-8). References Gusev, G. N., Shardakov, I. N. Monitoring of stress-strain state in steel oil storage tanks. Features of strain gauges transducers application in severe environment, Procedia Structural Integrity, Proceedings Paper. 2020. Volume – 28, 2328-2334 p.DOI: 10.1016/j.prostr.2020.11.080