Meaning
Solid state electromechanical devices translate mechanical energy from vibration or shock into proportional electrical charges. A piezoelectric accelerometer relies upon the internal displacement of a seismic mass against a ceramic or crystalline material to generate this signal. The phenomenon occurs when physical force deforms the sensing element, causing a shift in dipole moments that produces a measurable voltage across opposing electrode surfaces.
Calibration ensures the sensitivity output remains linear across defined frequency ranges.
Sensor Construction
Internal assembly requires a stiff coupling between the base and the mass to preserve high frequency response. Designers house the assembly within a hermetic metallic shell to prevent environmental interference from humidity or particulate matter. A preamplifier frequently integrates into the package to convert the high impedance charge into a low impedance signal for long cable runs.
Grounding strategies prevent ground loops which otherwise introduce false noise into the measurement chain.
Operational Limits
Thermal gradients across the housing induce stress that creates erroneous outputs. Engineers compensate for base strain by utilizing symmetric sensing geometries that cancel out signals resulting from mechanical distortion of the mounting surface. Excessive shock levels fracture the sensing crystal, leading to permanent signal loss or non-linear behavior.
Periodic verification of the resonant frequency confirms the integrity of the mechanical connection to the test object.
Signal Processing
Digitization of the raw output requires an acquisition system with a high input impedance to avoid charge leakage. Systems perform double integration of the signal when displacement data is necessary for structural analysis. Digital filtering removes harmonics that interfere with the observation of primary vibration modes.
Data veracity relies on the impedance match between the sensor and the secondary instrumentation.
