Que1.18. Explain the construction and working of optic encoder for relegation dimension with suitable illustration.
Answer 1. An optic encoder is an electromechanical device which has an electrical affair in digital form commensurable to the angular position of the input shaft. 2. optic encoders enable an angular relegation to be converted directly into a digital form. An optic encoder is an angular position detector. 3. It has a shaft mechanically coupled to an input motorist which rotates a slice strictly fixed to it. 4. Light from infrared emitting diodes reaches the infrared receivers through the transparent gashes of the rotating slice. 5. also electronically, the signal is amplified and converted into digital form. This signal is also transmitted to the data processor. 6. It comprises of a slice with three concentric tracks of inversely spaced holes. 7. Three light detectors are employed to descry the light passing through the holes. 8. These detectors produce electric beats which give the angular relegation of the mechanical elemente.g. shaft on which the optic encoder is mounted. 1.18.1. Construction and working of optic encoder. 9. The inner track has just one hole which is used detect the’ home’ position of the slice. The holes on the middle track neutralize from the holes of the external track by one- half of the range of the hole. This arrangement provides the direction of gyration to be determined. 10. When the slice rotates in clockwise direction, the beats in the external track lead those in the inner; in counter clockwise direction they lag before. 11. The resolution can be determined by the number of holes on slice. With 100 holes in one revolution, the resolution would be, °/ 100 = 3.6 °
Que1.19. What are cargo cells? What are its types?
Answer cargo cell A cargo cell is a force hand that consists of a transducer that is used to produce an electrical signal whose magnitude is directly commensurable to the force being measured. Types Curvaceous Hydraulic Strain hand Piezoresistive Magnetostrictive.
Que1.20. What’s strain hand? Give its principle.
Answer 1. Strain hand cargo cells are a type of cargo cell where a strain hand assembly is deposited inside the cargo cell casing to convert the cargo amusement on them into electrical signals. 2. The weight on the cargo cell is measured by the voltage change caused in the strain hand when it undergoes distortion. 3. The resistance of a strain hand varies with applied force and, it converts parameters similar as force, pressure, pressure, weight,etc. into a change in resistance that can be measured latterly on. 4. Whenever an external force is applied to an object, it tends to change its shape and size thereby, altering its resistance. 5. The stress is the internal resisting capacity of an object while a strain is the quantum of distortion endured by it. 6. Any introductory strain hand consists of an separating flexible backing that supports a metallic antipode pattern. 7. The hand is attached to the object under stress using an glue. The distortion in the object causes the antipode to get distorted which eventually changes the electrical resistivity of the antipode. 8. This change in resistivity is measured by a Wheatstone ground which is affiliated to strain by a volume called, hand factor. 9. A strain hand works on the principle of electrical conductance and its dependence on the captain’s figure. 10. Whenever a captain is stretched within the limits of its pliantness, it does n’t break but, gets narrower and longer. 11. also, when it’s compressed, it gets shorter and broader, eventually changing its resistance.
Que1.21. How do you measure strain with a strain hand?
Answer 1. Strain gauges work on the principle of the captain’s resistance which gives you the value of hand factor by the formula Hand factor( GF) = ( R/( RG *))
2. Now, the change in the strain of an object is a veritably small volume which can only be measured using a Wheatstone ground.
3. A Wheatstone ground is a network of four resistors with an excitation voltage, VEX that’s applied across the ground. The Wheatstone ground is the electrical fellow of two resemblant voltage separator circuits with R1 and R2 as one of them and R3 and R4 as the other bone.
4. The affair of the Wheatstone circuit is given by VO = (( R3/ R3 R4) –( R2/ R1 R2)) × VEX.(1.21.1) 5. Whenever R1/ R2 = R4/ R3, the affair voltage VO is zero and the ground is said to be balanced. Any change in the values of R1, R2, R3, and R4 will, thus, change the affair voltage. 6. still, indeed a minor change If you replace the R4 resistor with a straingauge.in its resistance will change the affair voltage VEX which is a function of strain.
7. The original strain affair and voltage affair always have a relation of 2 1.
8. In a cargo cell, these resistors are replaced by strain needles in interspersing pressure and contraction measures. When a force is applied to the cargo cell, the resistance in each strain hand changes and VO is measured.
9. From the performing data, VO can be fluently determined using the eq.(1.21.1).
Que1.22. Explain the characteristics of strain needles.
Answer 1. They’re largely precise and do not get told due to temperature changes. still, if they do get affected by temperature changes, a thermistor is available for temperature corrections.
2. They’re ideal for long distance communication as the affair is an electrical signal.
3. Strain needles bear easy conservation and have a long operating life. 4. The product of strain needles is easy because of the simple operating principle and a small number of factors.
5. The strain needles are suitable for long- term installation. still, they bear certain preventives while installing.
6. All the strain needles are hermetically sealed and made up of pristine sword therefore, leakproof. 7. They’re completely reprised for protection against running and installation damage. 8. The remote digital readout for strain needles is also possible.
Que1.23. Give the operations of strain needles.
Answer 1. Strain needles are extensively used in experimental stress analysis and opinion on machines and failure analysis.
2. They’re principally used formulti-axial stress fatigue testing, evidence testing, residual stress and vibration dimension, necklace dimension, bending and deviation dimension, contraction and pressure dimension and strain dimension.
3. Strain needles are primarily used as detectors for machine tools and safety in automotive.
4. In particular, they’re employed for force dimension in machine tools, hydraulic or curvaceous press and as impact detectors in aerospace vehicles.
Que1.24. Explain the working of LVDT grounded diaphragm pressure detector.
Answer 1. The diaphragm pressure hand uses the elastic distortion of diaphragm i.e. membrane) rather of a liquid position to measure the difference between the unknown pressure and a reference pressure.
2. A typical diaphragm pressure hand contains a capsule divided by a diaphragm, as shown
3. One side of diaphragm is open to the external targeted pressure,PExt., and the other side is connected to a given pressure, PRef. The pressure difference PExt – PRef, mechanically deflects the diaphragm.
4. The membrane of the diaphragm is connected to LVDT as shown in 1.24.2.
5. Due to operation of pressure on diaphragm, a relegation is applied on core or primary winding of LVDT. As a result a voltage is convinced in the secondary winding of LVDT. This convinced voltage is directly commensurable to applied pressure.