These are available with either top or side-mounted connectors and have sensitivities in the range from 1 to 10 mV or pC per m/ s 2. Most manufacturers have a wide range of accelerometers at first sight, maybe too many to make the choice easy.Ī small group of "general purpose" types will satisfy most needs. The Compression Type where the mass exerts a compressive force on the piezoelectric element and the Shear Type where the mass exerts a shear force on the piezoelectric element.
This can be seen from the law, Force = Mass x Acceleration.įor frequencies lying well under the resonant frequency of the complete spring-mass system, the acceleration of the mass will be the same as the acceleration of the base, and the output signal magnitude will therefore be proportional to the acceleration to which the pick-up is subjected. In practical accelerometer designs, the piezoelectric element is arranged so that when the assembly is vibrated the mass applies a force to the piezoelectric element which is proportional to the vibratory acceleration. When it is mechanically stressed, either in tension, compression, or shear, it generates an electrical charge across its pole faces which is proportional to the applied force. The heart of a piezoelectric accelerometer is the slice of piezoelectric material, usually an artificially polarized ferroelectric ceramic, which exhibits the unique piezoelectric effect. They are capable of operation at extreme temperatures but are constrained by high output impedance requiring low-noise cables and charge amplifiers to condition the signal. There are no moving parts to wear out, and finally, its acceleration proportional output can be integrated to give velocity and displacement proportional signals. A piezoelectric accelerometer is self-generating so that it does not need a power supply.