Shock and vibration data logger

A shock data logger or vibration data logger is a measurement instrument that is capable of autonomously recording shocks or vibrations over a defined period of time. Digital data is usually in the form of acceleration and time. The shock and vibration data can be retrieved (or transmitted), viewed and evaluated after it has been recorded.

In contrast with a shock data logger, a shock detector or impact monitor is used to indicate whether or not the threshold of specified shock has occurred.

A logger comprises sensors such as accelerometers, storage media, a processor and power supply. The sensors measure and store shocks either as the entire waveform, summary data, or an indication of whether a threshold value was observed . Some devices have accelerometers built into the unit while others can use external accelerometers. The processor processes the measured data and saves it on the storage media together with the associated measurement times. This allows the measurement data to be retrieved after the measurements have been completed, either directly on the logger or via an interface to a computer. Some have an RFID interface. Software is used to present the measured data in the form of tables or graphs and provides functions for the evaluation of the measurement data. The shock and vibration data is either recorded continuously over a defined time period or on an event-driven basis where the recording of data is determined by certain criteria. Employing such an event-based measurement method allows the recording of specific shocks that exceed a critical length of time or strength. Some have wireless capability such as Bluetooth transmissions to smart phones.

Acceleration loggers usually use non-volatile storage media for recording the measurement data. These may be hard disc drives or EEPROMs for instance. Such devices will not lose the data when the device is powered down. This also means that the measured data will remain stored in the event of a power failure.

Shocks and impacts are often described by the peak acceleration expressed in g-s (sometimes called g-forces). The form of the shock pulse and particularly the pulse duration are equally important. For example, a short 1 ms 300 g shock has little damage potential and is not usually of interest but a 20 ms 300 g shock might be critical. Use of shock response spectrum analysis is also useful.

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