China
Africa
Explore chapters and articles related to this topic
Instrumentation for Sound and Vibration Measurement
Published in Malcolm J. Crocker, A. John Price, Noise and Noise Control, 2018
Malcolm J. Crocker, A. John Price
There are several characteristics of the piezoelectric accelerometer. As is shown in Figures 3.39 and 3.40, the piezoelectric accelerometer can be considered either as a charge or a voltage source. Hence, the sensitivity is either given in decibels re 1 mV/g or re 1pC/g*** Besides being sensitive to acceleration in the longitudinal axis due to irregularities in construction and alignment of the piezoelectric discs, the accelerometer is also slightly sensitive to vibration in the transverse axis (see Figure 3.41). Good accelerometers should have a lateral sensitivity less than 5% of the longitudinal (or main axis) sensitivity. The transverse sensitivity will vary in the base plane having maximum and minimum values in certain directions. The sensitivity of an accelerometer will be somewhat temperature dependent (one should always consult the manufacturer's instructions), however, provided the maximum (Curie point) temperature is not exceeded, the piezoelectric material will not be damaged and will retain its properties.
Sensors
Published in Bogdan M. Wilamowski, J. David Irwin, Control and Mechatronics, 2018
Tiantian Xie, Bogdan M. Wilamowski
Piezoelectric accelerometer utilizes the piezoelectric effect of materials to measure dynamic changes in mechanical variables. The structure of piezoelectric accelerometer is shown in Figure 21.11. When a physical force is exerted on the accelerometer, the seismic mass loads the piezoelectric element according to Newton’s second law of motion (F = ma). The force exerted on the piezoelectric material can be observed corresponding to the change of the voltage generated by the piezoelectric material. Therefore, the acceleration can be obtained. Single crystal, like quartz, and ceramic piezoelectric materials, such as barium titanate and lead-zirconate-lead-titanate, can be used for the purposes of accelerometer. These sensors are suitable from frequency as low as 2 Hz and up to about 5 kHz. They possess high linearity and a wide operating temperature range.
Distributed Sensor Arrays
Published in Prabhakar S. Naidu, Distributed Sensor Arrays Localization, 2017
Piezoelectric sensing of acceleration is natural, as acceleration is directly proportional to force. When certain types of crystal are compressed, charges of opposite polarity accumulate on opposite sides of the crystal. This is known as the piezoelectric effect. In a piezoelectric accelerometer, charge accumulates on the crystal and is translated and amplified into either an output current or voltage. But piezoelectric accelerometers only respond to AC phenomenon, such as vibration or shock. They have a wide dynamic range, but can be expensive depending on their quality [13]. Piezo film based accelerometers are best as they are inexpensive, and respond to other stimuli, such as temperature, sound, and pressure.
Three-objective optimization of aircraft secondary power system rotor dynamics
Published in Mechanics Based Design of Structures and Machines, 2022
Joseph Shibu K., K. Shankar, Ch. Kanna Babu, Girish K. Degaonkar
The design has evolved over the time and has culminated into the APU rotor system used in the numerical model in this study. The modified APU is manufactured by incorporating the changes discussed earlier and is tested on the test bed designed for testing the APU on ground. APU is mounted on the test bed, and critical speed and rotor response during operation are determined from testing. A piezoelectric accelerometer having sensitivity of 100 mV/g is place at the compressor end to capture vibration signature of the rotor system. A frequency range of 0–5000 Hz is available for accelerometer. A 60 channel OROS FFT analyzer is used for decoding the measured data. The features of FFT analyzer include sampling rate of 0–102.4 kHz, line resolution up to 6401 lines and display for color plot, waterfall plot, etc. The testing is carried out from 0 to 33,000 rpm. Figure 3 shows the testing arrangement.
An experimental-numerical method for the prediction of on-road comfort of city bicycles
Published in Vehicle System Dynamics, 2021
Alberto Doria, Edoardo Marconi, Luis Munoz, Alejandra Polanco, Daniel Suarez
In this research, excitation is performed by means of a hammer equipped with a force sensor (PCB 086D20, sensitivity: 0.23 mV/N). The acceleration of the vibrating table is measured by means of a uniaxial piezoelectric accelerometer (PCB 352C22, sensitivity: 1 mV/(m/s²)). The acceleration components of the sensitive points are measured by means of a triaxial piezoelectric accelerometer (PCB 356A17, sensitivity: 51 mV/(m/s2)). The FRFs are obtained from the acceleration signals by acquiring the data with an input module for sound and vibration (NI9234). For each input-output point combination, the FRF between the acceleration of the sensitive point (in or direction) and the input acceleration is calculated averaging data obtained from 20 hammer hits.
Studying seismic interaction of piles row-sandy slope under one, two and triaxial loadings: a numerical-experimental approach
Published in European Journal of Environmental and Civil Engineering, 2020
Hassan Sharafi, Yazdan Shams Maleki
Physical model instrumentation for small-scale shaking table was conducted with the help of two main instruments, including: LVDT or linear variable displacement transducer sensors and piezoelectric (P.E.) accelerometer sensors, are shown in Figure 8. A 4-pins military connector is used as shown in Figure 8(a) and (b) to connect the LVDT sensor to the 8-channels data logger connection box. Moreover, high-speed data acquisition card (National Instruments, 2017) with 14bit analogue to digital (A/D) resolution and it’s direct-current signal conditioner are shown in Figure 8(c). The uniaxial piezoelectric accelerometer sensor with a high-sensitivity of 1000mv/g and its connector is shown in Figure 8(d), and the displacement measurement sensor, it’s connections and adjustable magnet connection base are shown in Figure 8(e). Sensors with small sizes and proportional to the physical model dimensions are used due to the small sizes of the physical modelling box.