Measurement with strain gauge

A die stamping was produced in just one action. Stock (2) was fed into die (1) and the deformation to obtain a cup was performed by a stamp (3) which moved in a sleeve (4) driven by a piston of a hydraulic cylinder. The strain obtained was measured with strain gauge (5). The temperature of the deformed alloy was maintained by heating device (7) and controlled with sensor (8). After the deformation was completed shedder (9) driven by a piston (10) of hydraulic cylinder (11) ejected the cup. The whole press ram rested upon base (12). 

CPT soundings are one of the most versatile and widely used in situ tests. The standard CPT cone consists of a 1.4-in.-diameter cone with an apex angle of 60°, although other cone sizes are available for special apph-cations (Figure 7.3a). The cone tip resistance beneath the 10 cm cone tip and the friction along the 150 cm friction sleeve are measured with strain gauges and recorded electronically at 1- or 2-cm intervals as the cone is advanced into the ground at a rate of about 2 cm/s. In addition to the tip and sleeve resistances, many cones also are instrumented to record pore water pressure or other parameters as the cone is advanced. 

It should be noted that the stresses in components are typically measured with strain gauges from which the loads still have to be calculated. Despite this fact, strain-related failure criteria are only occasionally applied to very brittle plastics. 

A pin on flat apparatus (Fig. 2) was used to measure wear rate under concentrated contact and reciprocating motion. The square plate is made of alumina, zirconia or alumina/zirconia nanocomposite ceramics. The pin of medical grade alumina had an end face with 10 mm spherical radius. The lower plate oscillates while the vertical load is applied to the pin by dead weights. Friction force is measured with strain gauges attached to the double leaf springs. Applied load is 30 N, oscillation frequency is 2 c/s, stroke is 10 mm and mean sliding velocity is hence 40 mm/s. Wear test was performed in 30 vol.% bovine serum solution kept at 37 °C. Wear volume of the pin was calculated from the area of the wear surface while the wear volume of the disc was calculated by the weight loss. 

Some presses are equipped with strain gauges at key points in the overall feed—compress—eject cycle. Thus, these measure compression and ejection forces. Tight specifications for punch lengths and weU-designed and prepared granulations have led to better control of variations in tablet weight. In fiiUy automated presses, weight variations are adjusted by computer. 

Before a torsion shaft with strain gauges was employed to determine the torque on a rotating stirrer shaft, a swiveling motor had to be used and the torque measured by weighing. 

Power measurements require the measurement of the torque and the rotational speed. The torque can be measured using a torsion shaft with strain gauges, electrically with eddy-current torque transducers, or mechanically with a swiveling motor. The speed of rotation can be measured using mechanical, electrical (photocell), or optical (stroboscope) instruments. 

To measure load distribution, standard aerospace bolts were fitted with strain gauges. Both shear and axial load could be measured. A three-dimensional finite element model with linear elastic material properties was developed for calculation of load distribution prior to initiation of material failure and comparison with instm-mented bolt results. Model details are similar to those of the single-bolt model above, with a full contact analysis being performed for all bolts, washers and holes. 

As an interim measure operational constraints were imposed as the frequency of failures could have invalidated the risk analysis in the safety report, and hence jeopardised the authorisation to operate the plant. Meanwhile the AHXs were heavily instrumented with strain gauges and thermocouples to identify the cause of the problem and indicate a solution. 

To measure Poisson s ratio, a sample must be instrumented with strain gauges in both transverse and longitudinal directions, which are monitored while the sample is deformed below its elastic limit in either tension or compression. 

Consideration should be given to alternative methods of pressure measurement that may provide greato safety than the direct use of pressure gauges. Such methods include the use of seals or other isolating devices in pressure tap hues, indirect obsa-vation devices, and remote measurement by strain-gauge transducers with digital readouts. 

Inductive sensors for displacement measurement are based on the fact that inductance of a cod, L = n Gfi, where n = number of turns of coil, G = form factor, and ju = effective permeability of the medium. Each of these three parameters can be changed by mechanical displacement. Linear variable differential transformer inductive sensors show good linearity over a large range of displacement, high resolution, and better sensitivity compared with strain gauge [11]. 

In view of the facts that in young tritides essentially all of the generated He remains in the samples " and that a He atom needs more space than the T atom it replaces it is readily understandable that such tritides will swell. There are a number of advantages to measure this swelling effect in flat, bulk samples at ambient temperatures with strain gauges > ... 

The situation becomes even more obvious by a recent paper by Tsiok et al. (1991) who measured on SmSe and SmTe very precisely (with strain gauges) the volume change and, via conductivity, the energy gap under pressure. It became evident, as shown in fig. 46, that the energy gap was driven to zero before a softening of the lattice occurred. This clearly shows again that it is the concentration of carriers which triggers the lattice-related properties and not vice versa. 

The vane probe (Smith, 1985) has been used with success to detect cavity type. A probe with a small vane fitted with strain gauges is mounted in the turbine discharge stream, and the different cavity types are indicated by characteristic frequency spectra of the strain gauge signals. Cavity type can also be implied from power draw measurements if the ungassed power number of the impeller and the power losses in the motor and drive are known. 

Figure 22-19 ImpeUa- with strain gauges to measure biade bending ioads.

It is common practice to measure elastic constants and their temperature dependence experimentally, either via static (e.g. three- or four-point bending, XRD or neutron scattering in connection with strain gauges) or via dynamic tests (e.g. sound velocity methods or resonant frequency techniques). It is well known from solid state physics, cf e.g. [Ashcroft Mermin 1976, Kittel 1988], that the elastic constants determine the velocity of sound waves in solids. For example, the velocity of transversal waves (shear waves) Vj, is given by... 

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