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Friction welding is a popular process for joining metal and polymer work pieces by rubbing them against each other. This way, friction heat is generated in a zone of the faying surfaces, thinner than 1 mm. After cooling down, the heated surfaces establish a tight and strong bond. To improve this joining process, a method is desirable allowing measuring generated temperature and shear stress in the zone between the joining work pieces. Unfortunately, this is a very difficult task because the welding zone cannot be accessed with a sensor without significantly altering the process and thereby the desired measurement results. This paper describes how shear stress and temperature change generated by rubbing polymer pieces in a friction welding machine have been measured between the faying surfaces by employing sensor foils from the piezoelectric and pyroelectric polymer polyvinylidene fluoride (PVDF). This way, heating and cooling rates, pressure rise of the pneumatic system, frequency rise of the starting machine, the duration of starting and stopping, the damping of the vibrations after the drive was stopped, and the stress generated by the pullback of the machine head have been measured. A careful characterization of the sensor was necessary to enable distinguishing the measured voltage due to straining, shearing and temperature change.

A time of flight sensor has been equipped with a sensing wire parallel to the flow direction (flow parallel wire, FPW). A heat pulse is generated with a coil in the flow channel. The FPW has a center tap allowing its upstream and downstream parts to join in a half bridge. When a heat pulse passes the FPW, a large output peak is generated. The time between heat pulse generation and recording the peak maximum is only marginally affected by the properties of the fluid. With a combination of two FPWs, a measuring range of approximately 0.01–0.5 m/s can be achieved.

Ultrasonic hot embossing is a new process for fast and low-cost production of micro systems from polymer. Investment costs are on the order of 20.000 € and cycle times are a few seconds. Microstructures are fabricated on polymer foils and can be combined to three-dimensional systems by ultrasonic welding.

The structural integrity of the rotors of wind power stations can be monitored by a variety of sensors. However, the power supply of the employed sensors should not be connected by cable because lightning strikes are provoked that way. Therefore, energy harvesting systems are an interesting alternative. Three concepts for electrical power generation by harvesting the energy from the movements inside of rotor blades of wind power stations are described and compared to each other. Inside of such rotor blades, large vibration amplitudes of up to 15 cm are available but only at a frequency of a few Hertz. The available space is on the order of 20 × 20 × 40 cm3. A beam equipped with piezos and repelling magnets turned out being the most promising solution.