A piezoelectric accelerometer measures acceleration by utilizing the principle of piezoelectricity. Piezoelectric materials are those that generate an electric charge when subjected to mechanical stress or pressure. In the case of an accelerometer, the piezoelectric element is typically made from a single crystal or ceramic material, such as quartz, tourmaline, or certain types of ceramics.
Here's a step-by-step explanation of how a piezoelectric accelerometer measures acceleration:
Structure: A typical piezoelectric accelerometer consists of a mass (also called seismic mass) attached to a piezoelectric element. The mass is connected to the structure whose acceleration needs to be measured.
Acceleration Applied: When the accelerometer experiences an acceleration, the mass attached to the piezoelectric element tends to resist that acceleration due to its inertia. This resistance leads to the deformation or stress in the piezoelectric material.
Generation of Electric Charge: The stress or deformation in the piezoelectric material causes the crystal lattice structure of the material to change, leading to the generation of an electric charge across the material. The amount of charge generated is proportional to the applied acceleration.
Electrical Signal: The generated electric charge is very small in magnitude, so the piezoelectric material is connected to a sensitive charge amplifier circuit. This circuit converts the charge into a usable voltage signal.
Signal Processing: The amplified voltage signal is then sent to signal conditioning circuits for filtering, amplification, and sometimes digital conversion.
Output: The processed signal represents the acceleration experienced by the accelerometer, which is now in a form that can be recorded, displayed, or transmitted to other systems for further analysis or control purposes.
Piezoelectric accelerometers are widely used in various applications, including vibration monitoring, aerospace, automotive, structural health monitoring, and industrial machinery analysis, due to their fast response, high sensitivity, and broad frequency range capabilities. However, it's important to note that piezoelectric accelerometers have limitations regarding DC response, temperature sensitivity, and a limited range for dynamic measurements. Different accelerometer technologies, such as capacitive and MEMS (Micro-Electro-Mechanical Systems) accelerometers, are used to address specific measurement requirements and overcome these limitations.