Differential transducer, linearly variable LVDT

Linear-Variable-Differential-Transformer and Reluctive Pressure Transducers. In ahnear-vatiable-differential-transformer (LVDT) pressure transducer, the pressure to be measured is fed to a Bourdon tube or diaphragm. The motion of this element is transferred to the... 

Fig. 39. Schematic of the TA Instmments model 2940 thermomechanical analyzer. LVDT = linear variable differential transducer.

Linear-variable-differential-transformer (LVDT) transducers, 20 652-653 Linear velocity, exponents of dimensions in absolute, gravitational, and engineering systems, 8 584t Lineatin, 24 473 Line-block coders, 7 691 Line-edge roughness (LER), 15 181 Line exposures, in photography, 19 209-210 Linen... 

An associated type of transducer is the Linear Variable Differential Transformer (LVDT) which is essentially a transformer with a single primary winding and two identical secondary windings wound on a tubular ferromagnetic former. The primary winding is energised by an a.c. source (see Fig. 6.13). 

The operation of proximity sensors can be based on a wide range of principles, including capacitance, induction, Hall and magnetic effects variable reluctance, linear variable differential transformer (LVDT), variable resistor mechanical and electromechanical limit switches optical, photoelectric, or fiber-optic sensors laser-based distance, dimension, or thickness sensors air gap sensors ultrasonic and displacement transducers. Their detection ranges vary from micrometers to meters, and their applications include the measurement of position, displacement, proximity, or operational limits in controlling moving components of valves and dampers. Either linear or angular position can be measured ... 

Linear variable differential transformer (LVDT, Fig. 2) is a device that produces voltage proportional to the position of a core rod inside a cylinder body. It measures displacement or a position of an object relative to some predefined zero location. On tablet presses, LVDTs are used to measure punch displacement and in-die thickness. They generally have very high precision and accuracy, but there are numerous practical concerns regarding improper mounting or maintenance of such transducers on tablet presses. 

Tensile and compressive tests were performed at room temperature with a tensile testing machine (DY25, Adamel-Lhomargy). For the tensile tests, strain measurements were performed with an extensometer (EX-10) at a strain rate of 3.3 x 10-4 s-1, using ISO-60 standard specimens. Samples of dimension 20 x 12 x 6 mm were deformed in a compression cage between polished steel plates. The nominal strain was determined by averaging the results from two linear variable differential transformer (LVDT) transducers. The strain rate used was 8.3 x 10"4 s-1. 

Changes in the dimensions of a sample are detected by a mechanical, optical or electrical transducer although the transducer is usually a linear variable differential transformer (LVDT). The sample may be positioned either vertically or horizontally. The latter usually introduces friction between the sample and the support tube, which may be reduced to acceptable levels but never totally eliminated (l). Vertical dilatometers overcome the prob-... 

LVDT linear variable differential transducer MB mercaptobenzimidazole... 

The heart of this system is a pair of parallel, balanced sample support arms which oscillate freely around flexture pivots. Designed for low friction and precise balance, the natural frequency of the sample support system is less than 3 Hz, minimizing system contributions to damping. A schematic of this device is shown in Fig. 1. To make a measurement, a material of known dimensions is clamped between the two sample arms. The sample-arm-pivot system is oscillated at its resonant frequency by an electromechanical transducer. Frequency and amplitude of this oscillation are detected by a linear variable differential transformer (LVDT) positioned at the opposite end of the active arm. The LVDT provides a signal to an electromechanical transducer, which in turn keeps the sample oscillating at constant amplitude. 

Displacements of the test specimen relative to the table or relative displacements between parts of the specimen are monitored either with Celesco draw wire displacement transducers or with Linear Variable Differential Transformers (LVDT), whichever is most convenient... 

Figure 14.6. Schematic diagram of the three-point support flexural test h, sample thickness LVDT, Linear Variable Differential Transformer displacement transducer R = 46.75 mm [69]...

Linear/Rotational variable differential transducer (LVDT/RVDT)... 

On the other hand, there may be instances when seemingly unstable fractures are in fact valid stable fractures. The inability to adequately detect stable crack extension results in the appearance of an unstable test and the presumption of an invalid result. A variety of methods have been used to verify stability such as load-point displacement (LPD) as determined from the linear variable differential transducer (LVDT) used to control the test system actuator center-point displacement (CPD) as determined using an LVDT or capacitance extensometer placed in or near the flexure fixture a time record as generated with an XY recorder or strain as monitored with a strain gage centered about the crack plane on the compressive or back-face of the test specimen [12,13]. In addition, laser extensometers have also been used [14]. 

The displacement transducer shown in Fig. 5 is generally one of two types. A linear-variable differential transformer (LVDT) is effectively a transformer where the coupling to the secondary winding(s) is a function of the position of a movable magnetic core. A capacitive displacement transducer (CDT) is a capacitor where the... 

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