A proof mass is an inertial element whose relative motion or required support force provides a measure of acceleration. In a spring-supported accelerometer, the instrument frame moves with the object being measured, while the proof mass responds through its inertia and suspension.
An ideal one-axis model is , where is displacement relative to the frame, is the proof mass, is damping and is the spring constant. At frequencies well below resonance, . A capacitive accelerometer measures this displacement electrically. The suspension determines sensitivity and bandwidth together; a more compliant spring gives greater static displacement but a lower natural frequency.[ref]
ADXL335 Data Sheet by Analog Devices. Page10, suspended mechanical sensor and differential capacitive readout; ideal oscillator model derived here
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A proof mass, often referred to in the context of mechanical systems, is a mass used to provide a known weight for testing or calibration purposes. It is commonly utilized in various applications, such as in vibration testing, sensor calibration, and structural analysis. In the context of vibration testing, for instance, a proof mass can be attached to a structure or a sensor to simulate the effects of real loads, helping engineers assess how a system behaves under different conditions.