LECTURER PROF.Dr. DEMIR BAYKA AUTOMOTIVE ENGINEERING LABORATORY I

VARIOUS TRANSDUCERS AND SENSORS STRAIN DISPLACEMENT VELOCITY ACCELERATION AND VIBRATION FORCE TORQUE PRESSURE TEMPERATURE FLUID FLOW

MEASUREMENT OF STRAIN WHEN A FORCE (TENSILE, COMPRESSIVE OR RADIAL) IS APPLIED TO A MACHINE ELEMENT IN ONE DIRECTION ANY ONE OF THE DIMENSIONS (L) OF THE ELEMENT SLIGHTLY CHANGE BY ( d L )

e IS RELATED TO STRESS BY Hooke’s Law E = Modulus of elasticity (Young’s modulus)

D L F F

Let us take the logarithm of both sides

Differentiating the above equation ;

L DLDL DWDW W FF FOR A PRISMATIC ELEMENT

ALSO DEFINE : (Poisson’s Ratio)

If the temperature is held constant, the change in resistivity is approximately proportional to the strain.

F = GAGE FACTOR

MEASUREMENT OF DISPLACEMENT POTENTIOMETER L x Slider Vs Vo

CAPACITIVE TRANSDUCERS D x A W Permitivity for vacuum :

Rotary Capacitive Displacement Transducer Angle Sensor

MEASUREMENT OF VELOCITY Winding 1 DC Voltage Output Winding 2 South Pole North Pole Permanent Magnet Core

MEASUREMENT OF PRESSURE

Strain-Gage Based Pressure Cell

Capacitance-Based Pressure Cell Differential pressures as low as 0.01 inches of water can readily be measured. They are also quite responsive, since the distance the diaphragm is displaced is only a few microns.

Typical Piezoelectric Pressure Sensor When pressure, force or acceleration is applied to a quartz crystal, a charge is developed across the crystal that is proportional to the force applied

DIFFERENTIAL PRESSURE MEASUREMENT BY MANOMETERS U-TYPE İncluding the density of air

WELL TYPEINCLINED

MEASUREMENT OF FLUID FLOW 1.Collect certain amount of liquid at measured time interval 2.Disc, Rotary-Vnae, Impellar flowmeters Positive Displacement

PRESSURE DIFFERENCE METHODS

VENTURIMETER

ORIFICE METER

LAMINAR FLOWMETER

DISPLACEMENT FLOWMETERS

PITOT TUBE

MEASUREMENT OF TEMPERATURE THERMOCOUPLE

T1T1 T2T2 FOR A SINGLE WIRE WITH ENDS AT T 1 AND T 2 E 2 - E 1 = K ( T 2 - T 1 ) K = THE THERMO ELECTRIC SENSITIVITY

T1T1 T2T2 T3T3 T4T4 A B A

T1T1 T2T2 T3T3 T4T4 A B A 0

T1T1 T2T2 T 3 =0 T4T4 A B A MELTING ICE 0

T1T1 T2T2 T 3 =0 T4T4 A B A MELTING ICE DVDV T

RTD (RESISTANCE THERMOMETER)

R 1 =53 k W R1R1 R V ~100 W RXRX DVDV 18 v THE CURRENT IN THE ARMS OF THE WHEATSTONE BRIDGE IS ABOUT 0.5 Ma INITIALLY R v IS ADJUSTED SO THAT D V=0 AT A REFERENCE TEMPERATURE T O D V~i. D R X