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Evaluation model for vibrations

SMP was commissioned by the Royal Forest Academy of Agriculture and conducted a project where a simple computational model, based on measured data, has been developed to give farmers an opportunity to estimate the magnitude of the vibration exposure he/she is exposed to during a scheduled work day. ​

Click here to download the spreadsheet "Computational basis for vibrations in agriculture". ​

Click here to download SMPs complete report "Evaluation model for vibrations, SLO-906."

Background

The Work Environment Authority has in its regulation AFS 2005:15 (ref. 15) implemented the EU directive 2002/44/EG concerning the exposure of workers to risks arising from vibration at work in Swedish legislation.

The regulation states that the employer should investigate the working conditions and assess the risks that may result from exposure to vibration at work. The risk assessment shall include an estimate of the daily vibration exposure, conducted by "qualified person". The circular indicates an input value and a limit in force daily exposure over 8 hours. Workers may not be exposed to values ​​above the limit and if the action level is exceeded, the employer shall develop and implement a program of measures designed to reduce vibration exposure.

As an alternative to measuring the vibrations magnitude may be estimated by observing the common tasks and reference to relevant information on the likely vibration acceleration of the work equipment under these conditions of use.

SMPs computational model, based on measured data, the ability to calculate the size of the daily vibration exposure.

Basic data for the spreadsheet

The calculus in the form of an Excel file was created from available and analyzed data. In the calculation, you can put an estimated exposure time for the operations it intends to perform during the working day in the tractor and get notified of the estimated vibration exposure for the current day.

For an estimate calculation of its type to be able to present statistically reliable results a much larger base in the form of practical measurements is required. Depending on the variability of available data (see above), the developed calculation calculation is not considered to present "true" values​​. Although the values ​​underlying the calculation are taken from the third quartile of the measurements, the soil conditions, tractor driving and cause the true total for the day is much higher than that indicated by calculation. However, one can assume that a smooth driving technique with a modern tractor is likely to mean that the actual value is less than the estimated.

The process for estimating vibration exposure calculation is accepted and described in a guide prepared on behalf of the European Commission and is also used in the standards for both the vibration of hand / arm that whole-body vibration.

The alternative to using a computational model is unrealistic because it would require measurements for each individual farmer's various operations, driving and ground conditions etc.

In the future, one can imagine that the tractor manufacturer supplies the tractor with some type of vibrometer that automatically measures for a few seconds and then counting time. When the action level is reached, a warning to the driver, and when the limit is reached tractor would in principle be able to be stopped. The Centre of Vibration Comfort in Umeå has developed a vibrometer that appear to be adapted to fulfill such a function. Instead of counting time, store the data continuously and can do so for several hours.