Mechanical Engineering Measurements
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What is the primary function of a tachometer?

  • To convert rotational speed into an electrical signal (correct)
  • To monitor the temperature of electrical equipment
  • To regulate the speed of industrial machinery
  • To measure vibration in mechanical systems

    • Which type of tachometer is suitable for industrial machinery and automation systems?

  • Mechanical Type Tachometer
  • Stroboscope
  • Electrical Type Tachometer (correct)
  • Digital Tachometer

    • What is the principle of operation of a stroboscope?

  • It emits flashes of light at adjustable frequencies (correct)
  • It uses electronic sensors to measure rotational speed
  • It converts rotational speed into a DC voltage
  • It measures vibration using a seismic mass

    • What is the main advantage of using seismic accelerometers?

    <p>Simple construction and robustness</p> Signup and view all the answers

    What is the purpose of a strain gauge in a strain gauge accelerometer?

    <p>To detect the strain in a material caused by acceleration forces</p> Signup and view all the answers

    Which type of accelerometer is commonly used in structural health monitoring?

    <p>Seismic Accelerometer</p> Signup and view all the answers

    What is the primary application of a digital tachometer?

    <p>Modern machinery and automotive diagnostics</p> Signup and view all the answers

    What is the main disadvantage of seismic accelerometers?

    <p>Limited frequency range and temperature sensitivity</p> Signup and view all the answers

    What is the purpose of a commutator in a DC tachometer generator?

    <p>To connect the armature winding to the brushes</p> Signup and view all the answers

    What is the primary use of vibration measurement in mechanical engineering?

    <p>To detect faults and anomalies in machinery</p> Signup and view all the answers

    What is the main purpose of speed measurement in mechanical engineering applications?

    <p>To monitor and control the rotational speed of machines</p> Signup and view all the answers

    Which type of tachometer uses centrifugal force to measure rotational speed?

    <p>Centrifugal Tachometer</p> Signup and view all the answers

    What is the principle of operation of a chronometric tachometer?

    <p>It measures speed based on the time interval between successive pulses generated by a rotating element</p> Signup and view all the answers

    What is the application of a vibrating reed tachometer?

    <p>Any mechanical system with a rotating shaft</p> Signup and view all the answers

    Which of the following is not a type of tachometer?

    <p>Seismic Tachometer</p> Signup and view all the answers

    What is the component of a centrifugal tachometer that moves outward against the spring force?

    <p>Weighted arms</p> Signup and view all the answers

    What is the principle of operation of a vibrating reed tachometer?

    <p>It uses the resonance frequency of vibrating reeds to measure rotational speed</p> Signup and view all the answers

    What is measured by a chronometric tachometer?

    <p>The time interval between successive pulses generated by a rotating element</p> Signup and view all the answers

    What is the application of a centrifugal tachometer?

    <p>Older machinery</p> Signup and view all the answers

    Which type of measurement is done using seismic, strain gauge, and piezoelectric accelerometers?

    <p>Vibration measurement</p> Signup and view all the answers

    What is the primary function of the core in a Linear Variable Differential Transformer (LVDT)?

    <p>To change the inductive coupling between the primary and secondary coils</p> Signup and view all the answers

    What is the main advantage of using an LVDT over other displacement measurement methods?

    <p>High accuracy and sensitivity</p> Signup and view all the answers

    What is the operating principle of a Light Dependent Resistor (LDR)?

    <p>Measures displacement based on changes in light intensity and corresponding changes in resistance</p> Signup and view all the answers

    What is the main disadvantage of using a Capacitive Pick-up?

    <p>Sensitive to environmental changes (e.g., humidity, temperature)</p> Signup and view all the answers

    What is the primary application of Inductive Pick-ups?

    <p>Micro-electromechanical systems (MEMS)</p> Signup and view all the answers

    What is the main advantage of using an LVDT over an LDR?

    <p>Higher accuracy and sensitivity</p> Signup and view all the answers

    What is the operating principle of a Capacitive Pick-up?

    <p>Measures displacement based on changes in capacitance</p> Signup and view all the answers

    What is the main disadvantage of using an LVDT?

    <p>Sensitive to temperature variations</p> Signup and view all the answers

    What is the primary application of an LDR?

    <p>Position sensing in robotics</p> Signup and view all the answers

    What is the main advantage of using a Capacitive Pick-up over an Inductive Pick-up?

    <p>Non-contact measurement</p> Signup and view all the answers

    What is the primary function of a Wheatstone Bridge Circuit in an accelerometer?

    <p>To convert strain gauge resistance changes into an electrical signal</p> Signup and view all the answers

    What is the main advantage of piezoelectric accelerometers?

    <p>Wide frequency range and high sensitivity</p> Signup and view all the answers

    What is the primary application of seismic accelerometers?

    <p>Structural health monitoring</p> Signup and view all the answers

    What is the principle of linear variable differential transformers (LVDTs)?

    <p>Measures linear displacement using the variation in inductance</p> Signup and view all the answers

    What is the main advantage of strain gauge accelerometers?

    <p>High sensitivity and suitability for low-frequency vibrations</p> Signup and view all the answers

    What is the primary application of linear displacement resistors (LDRs)?

    <p>Precision machining</p> Signup and view all the answers

    What is the principle of angular displacement measurement?

    <p>Measures the rotation angle of an object around a reference axis</p> Signup and view all the answers

    What is the primary application of rotary encoders?

    <p>Robotics</p> Signup and view all the answers

    What is the primary disadvantage of piezoelectric accelerometers?

    <p>Requires a charge amplifier or signal conditioner</p> Signup and view all the answers

    What is the primary application of inductive pick-ups?

    <p>Machine tool alignment</p> Signup and view all the answers

    Study Notes

    Speed Measurements in Mechanical Engineering

    • Speed measurement is essential in various mechanical engineering applications to monitor and control the rotational speed of machines, engines, and other mechanical systems.
    • Different types of tachometers (mechanical and electrical) and stroboscopes are used for speed measurement.

    Mechanical Type Tachometers

    • Centrifugal Tachometer: uses centrifugal force to measure rotational speed; components: weighted arms, spring, and scale; applications: older machinery, educational demonstrations.
    • Chronometric Tachometer: measures speed based on time interval between successive pulses; components: rotating element, timing mechanism, and dial; applications: vintage vehicles, historical equipment.
    • Vibrating Reed Tachometer: uses resonance frequency of vibrating reeds to measure rotational speed; components: set of reeds, each tuned to resonate at a specific frequency; applications: portable speed measurement, industrial equipment.

    Electrical Type Tachometers

    • DC Tachometer Generator: converts rotational speed to a DC voltage; components: permanent magnet, armature winding, commutator, brushes; applications: industrial machinery, automation systems.
    • AC Tachometer Generator: converts rotational speed to an AC voltage; components: rotor, stator windings; applications: motors, generators, speed control systems.
    • Digital Tachometer: uses electronic sensors to measure rotational speed and display it digitally; components: optical or magnetic sensors, microprocessor, digital display; applications: modern machinery, automotive diagnostics, laboratory equipment.

    Stroboscope

    • Uses a flashing light to make a rotating or vibrating object appear stationary, allowing for measurement of its speed; components: light source, control unit, and viewing area; applications: rotational speed measurement, vibration analysis, machinery maintenance.

    Vibration Measurements in Mechanical Engineering

    • Vibration measurement is crucial in various mechanical engineering applications, including machinery health monitoring, structural analysis, and quality control.
    • Different types of accelerometers (seismic, strain gauge, and piezoelectric) are used to measure vibrations.

    Seismic Accelerometers

    • Measure vibration by detecting the relative motion between a mass and its housing; components: seismic mass, spring/damper system, and transducer; advantages: simple construction, robust, and reliable; disadvantages: limited frequency range, affected by temperature changes; applications: structural health monitoring, earthquake detection, low-frequency vibration measurement.

    Strain Gauge Accelerometers

    • Measure vibration by detecting the strain in a material caused by acceleration forces; components: strain gauges, flexible element, and Wheatstone bridge circuit; advantages: high sensitivity, suitable for low-frequency vibrations; disadvantages: limited dynamic range, sensitive to temperature variations; applications: structural testing, machinery health monitoring, aerospace applications.

    Piezoelectric Accelerometers

    • Measure vibration by converting mechanical stress into an electrical charge using piezoelectric materials; components: piezoelectric crystal, seismic mass, and charge amplifier; advantages: wide frequency range, high sensitivity and stability, good temperature stability; disadvantages: requires charge amplifier or signal conditioner, may be affected by base strain and thermal transients; applications: machinery condition monitoring, modal analysis, vibration testing in automotive and aerospace industries.

    Displacement Measurements in Mechanical Engineering

    • Displacement measurements are essential in various mechanical engineering applications to monitor and control the position, movement, and alignment of components.
    • These measurements can be linear or angular, and several types of sensors are used to measure displacement accurately.

    Linear Displacement Measurements

    • Rulers and Vernier Calipers: simple mechanical devices for direct measurement; applications: precision machining, material testing, structural deformation monitoring.
    • Dial Indicators: mechanical devices for precise measurement of small linear displacements; applications: precision machining, material testing.
    • Linear Variable Differential Transformers (LVDTs): sensors that provide accurate and continuous measurement; applications: precision measurement in laboratory and industrial settings, aerospace and automotive testing, material testing machines.

    Angular Displacement Measurements

    • Protractors and Angle Gauges: simple mechanical devices for direct measurement; applications: robotics, machine tool alignment, automotive steering systems.
    • Rotary Encoders: electronic devices for precise measurement; applications: robotics, machine tool alignment.
    • Inductive and Capacitive Pick-ups: sensors that provide accurate and continuous measurement; applications: robotics, machine tool alignment, automotive steering systems.

    Linear Variable Differential Transformer (LVDT)

    • Measures linear displacement using the variation in inductance; components: primary coil, secondary coils, and core; advantages: high accuracy and sensitivity, no physical contact between the core and coils, long life and reliability; disadvantages: sensitive to temperature variations, requires an AC power source; applications: precision measurement in laboratory and industrial settings, aerospace and automotive testing, material testing machines.

    Light Dependent Resistor (LDR)

    • Measures displacement based on changes in light intensity and corresponding changes in resistance; components: LDR sensor, light source, and moving object; advantages: simple and inexpensive, non-contact measurement; disadvantages: sensitive to ambient light variations, limited accuracy and resolution; applications: position sensing in robotics, light-sensitive switches, basic displacement measurements.

    Capacitive Pick-ups

    • Measure displacement by detecting changes in capacitance between two conductive plates; components: conductive plates, dielectric medium, and electronics; advantages: high sensitivity and resolution, suitable for small displacement measurements, non-contact measurement; disadvantages: sensitive to environmental changes (e.g., humidity, temperature), requires precise alignment; applications: micro-electromechanical systems (MEMS), precision positioning in semiconductor manufacturing, gap measurement in machinery.

    Inductive Pick-ups

    • Measure displacement by detecting changes in inductance; components: coil and core; applications: precision measurement, gap measurement in machinery.

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    Description

    This quiz covers various measurement techniques in mechanical engineering, including speed, vibration, and displacement measurements using different types of tachometers, accelerometers, and pick ups.

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