The Influence of Construction Features of a Thin-Layer Sensor on Pressure Distributions Recorded in an Elastohydrodynamic Contact

This paper presents the experimental study of the construction features of a thin-layer sensor on the accuracy of pressure measurements in an EHD contact. Two common types of transducer shapes and isolating layers of the sensor, made of SiO are considered. The measurements were carried out on a two-disc machine, with the use of two mating lubricated steel cylindrical disks. On the outside surface of one of the discs, a pressure sensor was deposited with two transducers of different shapes, symmetric and asymmetric, located close to each other. The pressure transducer has an active part in the form of a layer contraction, and two wider parts of the layer serves as electrical leads (connections). In the symmetric transducer, the active part is located in the middle of the connections width and in the asymmetric transducer the active part is located along the edge of connections. In case of no current supply for the measurement bridge, the measurement signals from the sensor were observed. The occurrence of these signals indicated piezoelectric properties of the insulation layers of the sensor. The investigations showed that the shape of the transducer has a significant influence on the accuracy of pressure measurements. In the case of the asymmetric transducer, the measurement signal distortions caused by the piezoelectric effects and changes in the electric capacitance of the sensor were much larger than in the case of the symmetric transducer. Measurement signal courses coming from the asymmetric transducer were significantly influenced by the transition velocity of the sensor trough the contact, by the value of the current supplying the measurement bridge and by the rotation direction of the disc with the sensor.