The invention relates to a device and a method for detecting the mechanical forces at the welding pin tip during friction stir welding, having the following features: a) a strip-shaped sensor (3) at a long side of a tool cup (9) holding a welding pin pen (12) by way of a pin shaft (13) using a tool receiving cone (14), and also holding a welding shoe (11); b) a conical narrowed portion (20) in the further region of the tool-receiving cone (14), which serves to receive a sensor (18) for detecting the axial force, the torque and the bending moment at the welding pin pen (12); c) a further narrowed portion in the front region of the tool-receiving cone (14), having three sensors (24) distributed across the circumferences at a distance of 120 degrees; d) a sensor signal amplifier having a rotor antenna (19) for receiving, amplifying and forwarding all detected measurement values, said measurement values being forwarded by a static antenna (17) to a machine control; and e) an inductive power supply system.

A crystal unit includes: a crystal blank; an excitation electrode formed on the crystal blank and excites a main vibration of the crystal blank; a housing that accommodates the crystal blank; and a sub-vibration electrode formed on the housing and excites a sub-vibration of the crystal blank.

And a method for inspecting a crystal unit, the method includes: generating a sub-vibration in a crystal blank by applying an input signal to a sub-vibration electrode formed on a housing, which accommodates the crystal blank, via external electrodes which are electrically coupled to the sub-vibration electrode and formed on the outer surface of the housing; obtaining an output of the crystal unit via the external electrodes; obtaining frequency characteristics of impedance between the external electrodes based on the output; and comparing the obtained frequency characteristics with the reference frequency characteristics indicating the quality of the crystal unit.

It is provided an arrangement for detecting a shaft break. The arrangement comprising a shaft, a bearing on which the shaft is mounted so as to be rotatable about a rotational axis, a force sensor which is arranged on the bearing and is configured to measure an axial force component, applied by the shaft, in parallel with the rotational axis of the shaft, and an evaluation unit which is configured to receive measured values of the force sensor and to determine, on the basis of comparison of a plurality of measured values, whether there is a change in the axial force component, in order to detect a shaft break of the shaft.

It is provided a control system for a gas turbine engine. Therein, at least one piezoelectric, in particular piezoresistive element arranged at a bearing adapted to support a shaft of the gas turbine engine is provided, wherein the piezoelectric element is adapted to provide information indicative for a force acting on the bearing to a processing unit, wherein the processing unit is adapted to determine a thrust force of the gas turbine engine based on the information provided by the piezoelectric element.

A physical quantity detecting device includes a vibrating element and a charge amplifier. The vibrating element includes a first detection electrode, a second detection electrode, a third detection electrode, and a fourth detection electrode. The first and fourth detection electrodes have the same electrical polarity, the second and third detection electrodes have the same electrical polarity, and the first and second detection electrodes have opposite electrical polarities. The first and fourth detection electrodes are connected to the charge amplifier, and the second and third detection electrodes are connected to the charge amplifier.

An electrical component having: a sensor cell; the sensor cell being configured to, firstly, detect a physical quantity and output an electrical measurement signal having at least three differentiable states based on the detected physical quantity and to, secondly, provide electrical energy when the physical quantity is applied.

A crystal unit includes: a crystal blank; an excitation electrode formed on the crystal blank and excites a main vibration of the crystal blank; a housing that accommodates the crystal blank; and a sub-vibration electrode formed on the housing and excites a sub-vibration of the crystal blank. And a method for inspecting a crystal unit, the method includes: generating a sub-vibration in a crystal blank by applying an input signal to a sub-vibration electrode formed on a housing, which accommodates the crystal blank, via external electrodes which are electrically coupled to the sub-vibration electrode and formed on the outer surface of the housing; obtaining an output of the crystal unit via the external electrodes; obtaining frequency characteristics of impedance between the external electrodes based on the output; and comparing the obtained frequency characteristics with the reference frequency characteristics indicating the quality of the crystal unit.

An illustrative example embodiment of a sensing device includes a force sensor that detects a force and provides an output indicative of the detected force. An acceleration sensor detects acceleration and provides an output indicative of the detected acceleration. A processor receives the output from the force sensor and the acceleration sensor. The processor provides an indication of a relationship between the detected force and the detected acceleration.

A physical quantity detecting device includes a vibrating element and a charge amplifier. The vibrating element includes a first detection electrode, a second detection electrode, a third detection electrode, and a fourth detection electrode. The first and fourth detection electrodes have the same electrical polarity, the second and third detection electrodes have the same electrical polarity, and the first and second detection electrodes have opposite electrical polarities. The first and fourth detection electrodes are connected to the charge amplifier, and the second and third detection electrodes are connected to the charge amplifier.

The disclosure provides a method, system, device and medium for online monitoring of a plane stress field without baseline data based on a piezoelectric transducer array. Since Lamb waves have complex multi-mode characteristics, a suitable excitation frequency needs to be selected according to geometric dimensions of the structure to be measured, and then, only low-order mode Lamb waves are excited inside the measured structure to avoid serious waveform aliasing. For isotropic measured objects, anisotropic characteristics will be generated under the action of pre-stresses, that is, the propagation velocities of ultrasonic waves in all directions are different, but there is a linear relationship between velocity changes in different propagation directions and stresses. Therefore, there is still a linear relationship between the difference of velocity changes in different propagation directions and the stress. According to this characteristic, a characterization method of an absolute stress field without baseline data can be implemented. The method of the disclosure can make full use of the low attenuation characteristics of the Lamb waves to realize online monitoring of the plane stress field with a large coverage area.