Page 7 - Shock and Vibration Overview

Sensor Selection

SENSOR SELECTION

Accelerometers

Accelerometers are by far the sensor of choice for shock and vibration measurement.
Accelerometers mount directly to (or in) the vibrating structure and proportionally
converts mechanical energy to electrical when experiencing acceleration. Acceleration is
2
generally represented with the gravitational constant ‘g’ which equals 9.81 m/s . There
are three main types of accelerometers:

1) Piezoelectric Accelerometer
Piezoelectric accelerometers are the most popular and widely used for industrial
applications. They typically use lead zirconate titanate (PZT) sensing elements that
product electric charge or output under acceleration. Piezoelectric accelerometers
have very low noise and offer superior performance over capacitive MEMS or
piezoresistive accelerometers in all vibration and most shock applications.
Piezoelectric accelerometers come in many different variants: triaxial or single axis,

high sensitivity for seismic applications down to low sensitivity for shock testing, and
even have some types that can handle extreme environments including nuclear. The
major downside of piezoelectric accelerometers is that they are AC coupled so they
can’t measure the gravity vector or sustained accelerations. This also prevents the
engineer from integrating the data for velocity or displacement information because
of their intrinsic decay properties (although it can be integrated for higher frequency

7 of 69