The fixed (or mounted) resonant frequency was between 16.1–30.1 kHz based on the impedance measurement. The accelerometer modules fabricated according to the optimized designs were highly reliable with a broad range of resonant frequency as well as sufficiently high values of charge sensitivity. Four kinds of optimized designs were created and fabricated into the accelerometer modules for empirical validation.
Using the metamodeling to approximate the relationship between the design variables and the performances, the constituent components were optimized so that the generated electric voltage, representing sensitivity, could be maximized at different set values of the resonant frequency (25–40 kHz). That is, the use of mechanical filters significantly reduces the mechanical load on the sensor, which makes the process of measuring vibration (especially shock) more predictable.Ī theoretical and experimental study on the design-to-performance characteristics of a compression-mode Pb(Zr,Ti)O3-based piezoelectric accelerometer is presented. The use of mechanical filters made of viscoelastic materials makes it possible to significantly reduce the amplitude of oscillations of the piezoelectric accelerometer (over -12 dB) and shift its resonant frequency towards higher frequencies. In many cases, the use of mechanical filters made of viscoelastic materials, which are placed between the object of measurement and the piezoelectric accelerometer (sensor), prevents the undesirable consequences of these shortcomings and improves the process of measuring shocks. Due to mechanical overload, under the action of high-intensity shocks, physical destruction of the sensor is also possible. This state of overload leads to the appearance of parasitic output charges, which leads to a change in the generated charge in a short period of time. When piezoelectric elements are in resonance, there may be a relative displacement of the sensing element. There is often a shift of the zero level of the output signal. The result of such modes of operation is the loss of data due to the displacement of direct current over time. This increases the electrical signal and can lead to saturation or, in many cases, damage to the signal shapers and amplifiers following the sensor. That is, the material of the sensor crystal may not have an excessive mechanical load, but generate a large amount of output charge due to the resonance of the sensor.
Thus, under broadband vibration effects, excitation in the region of mechanical resonance is observed. Therefore, piezoelectric accelerometers have become widely used in measuring shocks as more reliable and durable, but they also have a number of disadvantages. In this circuit, the accelerometer is the most vulnerable link. When conducting dynamic tests, when simulating shock effects, the measurement system - from the sensor to the data acquisition unit is subject to significant overloads.
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