F arid Ahdad

Hydraulic excavators for mining applications are commonly used to load and unload significant volumes of gravel and all types of ore. The structural dimensioning of an excavator and its components as well as the risk assessment of the weld joints strongly depend on the frequency of the loads, the type of loads and the amount of moved matter.

The instrumentation of an excavator turned out to be necessary to determine the real loads on the field. For this purpose, strain gauges were installed on the boom of the excavator. A calibration process is performed to determine the transfer matrix linking the electric signals from the strain gauges to the efforts seen by the structure. In this way, we determine the out-of-plane loads which turn out to be the most difficult to evaluate without measurements. The state of art is presented in this work.

The data processing has been performed on a range of 1000 hours on a 600-tons excavator in an Iron ore mine in Australia. The newly determined loads provide additional information on stressed areas compared to the current validation process. That allows a better structural dimensioning. Consequently, the inputs from the field measurements will be used in our standard validation process with static calculations.

A new fatigue approach has been developed considering the field measurements. It consists in determining an equivalent damage for a specific event. It helps optimize the weld joint assessment by using FEMFAT.

The “Field Measurements” approach turns out to be necessary and brings lots of useful information for the design of Mining application structures and avoid over designing.

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