Abstract:
A vibrating beam force transducer includes a piezoelectric beam structure supported at first and second ends, and an oscillator for inducing a vibration in the piezoelectric beam. To permit adjusting the bias frequency of the beam, an adjustment mass is formed at the center of the beam, the adjustment mass made of piezoelectric material. Part of the adjustment mass can be broken off to adjust the bias frequency. The first and second ends are attached to the a support structure by first and second legs at each end of the beam, the legs having an angle therebetween, thereby forming an A-frame mount.
Abstract:
A force and pressure transducer comprises a plate-like crystal. Two separate portions of the crystal are maintained in oscillation at separate frequencies by a circuit. The force to be measured, is applied by a seating to a part of the crystal edge such that compression in one of the oscillating portions causes the frequency of that oscillating portion to change substantially whereas the frequency of the other portion changes only minimally.In the past it has been difficult to manufacture crystals in which the frequency versus temperature response of each of the two oscillating portions was sufficiently well matched to permit the difference frequency between the portions to be used as the instrument output signal.This invention resides in the application of a second fixed force by a spring via a seating to a second part of the crystal edge in such a way as to influence the frequency of oscillation of this second portion. In so doing the second seating can be adjusted to cause the frequency change due to temperature of the second oscillating portion to become as nearly as possible matched to the frequency versus temperature response of the first oscillating portion of the crystal thus providing a frequency change derived by computing the difference frequency between the two portions. This difference frequency forms the instrument output and responds only to the force applied to the instrument and not to the ambient temperature of the instrument.
Abstract:
A mounting structure for double-bar resonators to ensure symmetrical loading of the resonator responsive to external forces. In one embodiment, the resonator is connected to a pair of mounting pads through compliant coupling members. The coupling members allow longitudinal, force-induced displacements of the mounting pads to load the resonator while making the resonator insensitive to spurious transverse displacements of the mounting pads. In another embodiment, a force is applied to a load-sensitive, double-bar resonator through a force-transmitting bar which is mounted on an elongated flexure hinge. The hinge is compliant about an axis of rotation which is perpendicular to the longitudinal axis of the resonator so that the hinge attenuates any force component acting perpendicular to the longitudinal axis of the resonator which would otherwise non-symmetrically load the resonator.
Abstract:
A system for isolating the mounting pads of a vibrating beam or tuning fork force transducers from longitudinal vibrations generated by transverse vibrations of the beam or tuning fork tines which extend between the mounting pads. The system includes an arrangement of longitudinally resilient support links and masses that flex responsive to change in the length of the beam or tines as the beam or tines vibrate transversely. The support links and masses thus isolate the mounting pads from the longitudinally vibrations of the beam or tuning fork tines while allowing transmission of forces applied between the mounting pads which vary the force dependent resonant frequency of the beam or tuning fork.
Abstract:
A stress estimation method for a machine structure according to an embodiment is provided with a calculation step of calculating a relationship between the stress generated at the evaluation target position and a physical quantity including a sound pressure or vibration generated at a detection position different from the evaluation target position during vibration of the machine structure. The stress estimation method for a machine structure is provided with a detection step of detecting the physical quantity generated at the detection position during operation of the machine structure. The stress estimation method for a machine structure is provided with an estimation step of estimating the stress generated at the evaluation target position during operation of the machine structure on the basis of the relationship calculated in the calculation step and the physical quantity detected in the detection step.
Abstract:
A method for determining sensor parameters of an actively-driven sensor system may include obtaining as few as three samples of a measured physical quantity versus frequency for the actively-driven sensor system, performing a refinement operation to provide a refined version of the sensor parameters based on the as few as three samples and based on a linear model of an asymmetry between slopes of the measured physical quantity versus frequency between pairs of the as few as three samples, iteratively repeating the refinement operation until the difference between successive refined versions of the sensor parameters is below a defined threshold, and outputting the refined sensor parameters as updated sensor parameters for the actively-driven sensor system.
Abstract:
A procedure for measuring a measured variable in a process step of a manufacturing process uses a measurement chain with an evaluation unit and a plurality of measurement units having a sensor, a converter unit and a secondary antenna. The evaluation unit has a primary antenna. A measurement unit is positioned for measuring the measured variable and automatically coupled to the evaluation unit by establishing a transmission connection between the secondary antenna and the primary antenna. The sensor automatically generates measurement signals indicative of the measured variable. The converter unit automatically converts the measurement signals into measurement data, which the secondary antenna automatically transmits to the primary antenna.
Abstract:
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.