In the context of intelligent components in industrial applications in the automotive, energy or construction sector, sensor monitoring is crucial for security issues and to avoid long and costly downtimes. This article discusses component-inherent thin-film sensors for this purpose, which, in contrast to conventional sensor technology, can be applied inseparably onto the component’s surface via sputtering, so that a maximum of information about the component’s condition can be generated, especially regarding deformation. This article examines whether the sensors can continue to generate reliable measurement data even after critical component loads have been applied. This extends their field of use concerning plastic deformation behavior. Therefore, any change in sensor properties is necessary for ongoing elastic strain measurements. These novel fundamentals are established for thin-film constantan strain gauges and platinum temperature sensors on steel substrates. In general, a k-factor decrease and an increase in the temperature coefficient of resistance with increasing plastic deformation could be observed until a sensor failure above 0.5% plastic deformation (constantan) occurred (1.3% for platinum). Knowing these values makes it possible to continue measuring elastic strains after critical load conditions on a machine component in terms of plastic deformation. Additionally, a method of sensor-data fusion for the clear determination of plastic deformation and temperature change is presented.

Bearings play a crucial role in a broad range of engineering applications, such as automotive, aerospace and renewable energies. Particularly when it comes to larger and/or hard to replace/repair bearings, such as those in wind turbines, condition monitoring and load control are essential due to their complex and expensive conditions for maintenance and repair. Conventionally, different sensors are used, which are typically positioned outside of the bearing. Thus, a rather low depth of information is achieved, and the bearing condition cannot be assessed optimally. Therefore, this article focuses on the production and evaluation of directly deposited thin-film strain sensor arrays on a rolling bearing within and close to the tribomechanical contact between roller and raceway. The sensor production was carried out using sputtering, photolithography and etching processes. After the static strain gauge characterization concerning temperature, strain and pressure sensitivity on different substrates, a sensor-integrated 81212 thrust roller bearing was investigated in an FE8 bearing test rig. After data processing, the dynamic measurements with a maximum Hertzian pressure of 1 GPa revealed negative sensor resistance changes of up to −1.4 ‰ in the tribomechanical contact and up to 3.8 ‰ positive resistance change right next to the contact zone. Due to the fact that these sensors were subject to wear, sensors were also positioned at a greater distance from the contact that still showed a measurable signal of 0.5 ‰ resistance change that can be used after critical loads when their signal has been correlated to the other sensors in the contact zone when the latter are worn. Furthermore, the time-resolution enables the precise measurement of the rotational speed, and deviations in the roller geometries can be detected as well due to different sensor amplitudes. The location-resolved measurements allow important information about the tribomechanical contact to be derived in real-time, thus enabling intelligent component control, for example concerning rotational speed, lubrication and load before a damage occurs.

The article shows the production and evaluation of directly deposited thin-film temperature sensors on a thrust cylindrical roller bearing washer in and near the tribo-mechanical rolling contact. The production was carried out using sputtering, photolithography and etching processes. Due to the frictional forces, a 12 % (3.6 °C) higher temperature was measured in the mechanical rolling contact and a 5.3 % (1.6 °C) higher temperature near the mechanical rolling contact compared with the conventional temperature sensor on the outside of the bearing washer.