Numerical Analysis of Response Time for Thin Film Temperature Sensors in Lubricated Contact

Thin film temperature sensors integrated onto mechanical component surface are promising for real-time machine condition monitoring. In this paper one-dimensional heat conduction model has been developed to study the response time of the thin film sensors designed for monitoring of temperature distribution in elastohydrodynamic lubrication contact. A control volume approach was used to numerically analyze the effects of film thickness (from 0.1 μm to 100 μm), sensing materials, and substrate materials on the transient time response of the thin film sensor. Validation of the numerical model was compared to an analytical solution in a semi infinite domain. The time constants are obtained based on a constant heat load and sensor sensibility is studied when a typical dynamic pressure in lubricated contact is applied. The faster response time and the short time delay for a thin film sensor are expected in lower conductivity of substrate. It is also clear that the response time decreases with increasing film thickness and the conductivity of the substrate. Results show that when thickness of the sensor is less than 1 μm, the sensor is feasible to capture the transient temperature profile in real-time for machine health monitoring under various operating condition.