Abstract
In this paper, a sensing layout for the real-time in-situ monitoring of the length of a gear root crack is presented, suitable for use in powertrains where high reliability is expected. The sensing layout is based on the principle that electrical potential difference measurements between different positions on a tooth will be affected by a propagating crack and may be used to characterise the crack parameters. Mechanical finite element analysis (FEA) of spur gear teeth loaded at their highest point of single tooth contact (HPSTC) was performed and the location of the critical cross-section as well as the crack path was determined. Two measuring electrodes were placed in selected positions over the gauge area of a spur gear tooth and their readings were associated with the actual position of the crack tip by means of electrostatic FEA on cracked tooth geometries. The optimum position of the two measuring electrodes was determined by means of parametric simulation studies of the electrical field. With only two current electrodes and two sensing electrodes, the developed sensing array is simpler and more accurate than Boolean-type crack gauges using multiple wires.