Integrated beam strain gauges

We consider the results of development of silicon strain-gauge transducers. We present the technical characteristics for different types of integrated silicon strain-gauge transducers. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 36–37, March, 1994.     

Resistance strain gauges on thermoplastics

Analysis of structural problems with the aid of scale models constructed in low–modulus thermoplastic materials such as Perspex, Vybak and Darvic is now well established. Measurements of strain and deflexion are complicated, however, by the structure creeping under load and by the effects of changes in ambient conditions of temperature and humidity. Experience shows that these difficulties can usually be overcome by the use of suitable testing techniques, but strain measurements using resistance strain gauges are sometimes regarded critically because these measurements are said to be influenced by the heating effect of the bridge current and the low thermal conductivity of thermoplastics. One aspect of this could be a softening of the model material with heat causing a variation in the value of Young's modulus. At the Naval Construction Research Establishment, Dunfermline, thermoplastic model testing has for many years been a feature of the work in support of structural and theoretical analyses and the information derived from this work shows that the criticisms are unjustified.     

J-integral evaluation by resistance strain gauges

Under plane stress, the contour integral $\text{J}$ is evaluated using strain gauge measurements on a cracked test specimen. Results compare favorably with the conventional compliance technique for experimental $\text{J}$ evaluation except at relatively small loads. The technique holds the potential for real-time, single-specimen $\text{J}$ evaluation.     

GaN based high temperature strain gauges

Gallium Nitride based electronic devices have several unique properties such as robustness to high temperature, and both strong spontaneous and piezoelectric polarization fields. The polarization effects of Gallium Nitride are stable at high temperatures; therefore, it is an ideal material to fabricate high temperature strain gauges. In this work we have fabricated metal-insulator-semiconductor(MIS) capacitors to be used as a high temperature strain gauge. GaN based MIS capacitors were fabricated and tested both at room and high temperature. The gauge factor was measured to be 75 at room temperature. AlGaN/GaN heterostructures were also used to make MIS capacitors for testing at both room and high temperature. The gauge factors were measured on these devices to be 575 at room temperature, and 361 at 400 °C.     

Pressure measurement with FKM strain gauges

Measurement Techniques -     

The calibration of CERL-Planer capacitance strain gauges

CEGB-Planer capacitance strain gauges are used extensively for monitoring the deformation of components operating in the creep range. However, there are significant differences between the way the gauges are installed for use and the way they are installed for calibration. This paper describes the various types of calibrations that have been carried out to identify the errors associated with these differences and the results show that, providing the manufacturers' recommendations are adhered to, the errors are acceptably small.     

Characterization of lithographically printed resistive strain gauges

This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain-sensitive structures manufactured using a modified printing process and conductive inks is addressed. The performance of a "single-ink" strain-sensitive structure when printed on six alternative substrates (GlossArt, PolyArt, Teslin, Mylar C, Melinex, and Kapton) is analyzed. Though not intending to compete with conventional gauges in high-tolerance measurement, the structures exhibit properties that indicate suitability for novel applications.     

The behaviour of post yield strain gauges

The calibration of post yield electrical resistance strain gauges in tension shows that their behaviour is strongly dependent upon gauge construction, bond strength, the presence of instability and the mechanism of plastic deformation. For medium tensile strains in the range 0-5% the calibrations reveal that the gauge sensitivity factor consists of separate elastic and plastic components which are respectively identified with recoverable and irrecoverable strain components.