Displacement, velocity and acceleration sensors. There are three primary types of motion characteristics detected by vibration transducers normally referred to as accelerometers. These are • displacement, • velocity, and • acceleration. The choice between these three different types of motion transducers depends on the frequencies that have to be measured and the levels of the signal involved. (Wilcoxon Research / ND) Displacement sensors are normally used for low frequency (1 to 100 Hz) measurements and are useful for measuring very low amplitude displacements. They are employed in such applications as shaft motion and clearance measurements. Traditionally displacement transducers have employed non-contacting proximity sensors and eddy probes. Piezoelectric displacement transducers have recently been developed to overcome some of the mounting problems associated with non-contacting probes. (Wilcoxon Research / ND) Velocity sensors are used for medium to low frequency (1 to 1000 Hz) measurements. Because they filter out high frequency signals, they are less susceptible to amplifier overloads which come from white background noise and which can compromise the fidelity of low amplitude and low frequency signals. Velocity transducers are useful for monitoring and balancing operations on rotating machinery. Velocity sensors normally employ an electromagnetic sensor to pick up the velocity signal. Now piezoelectric velocity sensors are becoming more popular. (Wilcoxon Research / ND) Piezoelectric acceleration transducers are used to measure acceleration are the most commonly used motion sensors for vibration monitoring applications. They are useful over a wide band of frequencies from very low to very high frequencies (1 to 20,000... ... middle of paper ... ...ure quality products from a dimensional tolerance and surface finish quality standpoint. When the condition of a machine deteriorates, the following things will generally happen: 1. The dynamic forces generated by the machine will increase in intensity, causing an increase in machine vibration. 2. Wear, corrosion or a build-up of deposits on the rotor may increase unbalance forces. 3. Settling of the foundation may increase misalignment forces or cause distortion, piping strains, etc. 4. The physical integrity (stiffness) of the machine will be reduced, causing an increase in machine vibration. 5. Loosening or stretching of mounting bolts, a broken weld, a crack in the foundation, deterioration of the grouting, increased bearing clearance through wear or a rotor loose on its shaft will result in reduced stiffness to control even normal dynamic forces.
· Any possible obstructions or anything else that make effect the general momentum e.g. Doors opening windows being open or shut.
waves were reflected back to the transducer as they crossed interfaces of different acoustic impedance. More simply, the ultrasound bounced off the
Based on the piezoelectric effect, the transducer’s function is to emit short pulses and receive echoes of the pulse, a process repeated “over a sequence of directions to cover a 2D sectional fie...
A transducer is a mechanism that changes one form of energy to another form. A toaster is a transducer that turns electricity into heat; a loudspeaker is a transducer that changes electricity into sound. Likewise, an ultrasound transducer changes electricity voltage into ultrasound waves, and vice versa. This is possible because of the principle of piezoelectricity, which states that some materials (ceramics, quartz, and others) produce a voltage when deformed by an applied pressure. Conversely, piezoelectricity also results in production of a pressure whe...
The labs 4.1, 4.2, and 4.3 demonstrates how weight, mass, and surface area affect the amount of friction on an object. In lab 4.1, there were five different sliding surfaces that were tested. The surfaces tested were tabletop, Waxed paper, paper towel, fine sandpaper, and coarse sandpaper. Each of the surfaces had four of the same blocks that was attached to a spring scale to the blocks and drug one at a time across the surface. For 4.2, the graph showed a comparison between two surface type averages. For 4.3, the surface frictions were weighed with a spring scale.
This lab experiment was conducted in order to test the speed of sound, which is the distance traveled per unit time by a sound wave. This experiment was carried out with a certain setup, which involved materials such as a computer, a Logger Pro, a vernier microphone, two tubes, a temperature probe, a meter stick, and a dog trainer clicker. These materials were set up in a specific fashion, the Logger Pro was connected to the computer, which allowed for a temperature reading. The microphone was then connected to the lab interface and the two tubes were taped together from one end. One end of the tube was then placed against a wall, the microphone positioned near the open end of the tube as the dog clicker was pressed. Once the clicker was pressed, the speed of the sound traveling through the tube was collected by the microphone, the data then was inputted into the computer by the Logger Pro.
When this voltage level exceeds a particular value the piezoelectric structure will tends to vibrate. At particular level the resonant condition occurred in piezoelectric material.
Today’s ultrasound machines operate using the pulse-echo system. In order to produce an accurate representation of the anatomy being surveyed, the machine must determine echo’s strength and location. Ultrasound systems measure the time it takes for echoes to return and relates that to distance traveled to decipher location of reflectors using the range equation. Ultrasound equipment basically consists of four components, a beam former, receiver, processor, and display (Kaur, 2013). Figure 1 shows the pathway of the echo voltages through the ultrasound machine from first spark, through memory and display.
• For this particular experiment the gain of the output for the strain gauges are set to 1 as 0 to 8 degrees slip angle is been measured. If smaller angles are measured a larger gain may be required.
Most sensor manufacturers will rate their measuring range with a +/- sign. This means, for a +/-150 Newton sensor, it can measure 150 N in each direction.
Interference with the free fall of the drive weight by guides and/or the rope used to hoist the drive weight for successive blows.
Abstract— Rotational speed measurement with the help of wheel speed sensor is most essential task in today´s world .Wheel speed sensor in one the most important component of Anti-lock Braking System (ABS).They not only senses the rotational speed of the wheel but also helps for traction control & stability control system. Mostly used wheel speed sensors are magnetic which are under passive sensors. They develop an alternating current (AC) which increases frequency and amplitude with wheel speed. These wheel speed sensors works on different principles like Hall Effect. Magneto-resistive Effect etc. Sensors which are used to measure rotational wheel speed works well for conventional Anti-lock Braking System. For electric vehicles conventional
A Piezo-electric substance is one that produces an electric charge when a mechanical stress is applied. In a Piezo-electric accelerometer a mass is attached to a Piezo electric crystal which is in turn mounted to the case of the accelerometer. When the body of the accelerometer is subjected to vibration the mass mounted on the crystal wants to stay still in space due to inertia and so compresses and stretches the piezo electric crystal. This force causes a charge to be generated and due to Newton law (F=ma) this force is in turn proportional to acceleration. The charge output is converted to voltage output by the use of integral electronics (for example: in an IEPE accelerometer) or made available as a charge output (pc /g) in a charge output Piezo electric
Thomas, K.W., & R.H. Kilmann. (1974). Thomas-Kilmann Conflict Mode Instrument. Sterling Forest, NY: Xicom, Inc.
Experimental Mechanics involves the experimental investigations of the static and dynamic response of structures and machines, and in the development of improved techniques to obtain and analyze experimental data.