WHEEL FORCE TRANSDUCERS DATA ANALYSIS FOR DURABILITY ASSESSMENT OF AGRICULTURAL TRACTOR

Durability is the capacity of a machine to maintain its functionality during its intended service life and under recommended conditions of use, observing prescribed levels of maintenance. Durability of a designed vehicle is typically assessed through tests performed on suitable test-rigs, but its evaluation is time consuming (Mattetti, Molari, & Vertua, 2015). This procedure may be shortened by carrying out accelerated tests, where a level of damage equivalent to that of the customer usage is reached in a shortened amount of time. Such tests usually consist in reproducing repeatedly some loading events, for a number of times set by historical results based on factory experience. These loading events condense the majority of the accumulated damage during the tractor service life because the load amplitude is much higher than in any other event (Johannesson & Speckert, 2013). Axles are among the most critical components of agricultural tractors; the loads acting upon them can be measured with wheel force transducers (WFT) which are mounted between the hub and the wheel rim and measure the forces and the torques along the three axes. In this paper, a methodology to automatically identify the most damaging loading events and their frequency of occurrence during field operations is described. An agricultural tractor was equipped with WFT and a CAN-BUS based data logger, in order to acquire the load on the axles and the driver’s operation signals such as steering angle, three point hitch position, etc. Signals were acquired for three different applications. These loading events were identified through the analysis of the statistical correlation between the driver’s operation signals and the WFT signals. By using this methodology, it has been found that the most damaging events for the axles occur during the headland turn.