Machinery & Energetics

It is shown that in order to justify the extension of the life of the machine beyond the resource set by the manufacturers, it is necessary to focus on the acceptable (permissible) risks of emergency situations that can lead to accidents. At present, for mobile agricultural equipment, the operation of which relates to work of increased danger, the concept of acceptable risk is not used, it does not allow assessing the danger of staying on fields, farms and roads of machinery without technical safety equipment, with the exhaustion of the established resource. The purpose of the research is to justify the permissible risk of the operation of mobile agricultural machinery, in the array of parts and structural elements of which defects (damage) have accumulated. In this work, the kinetics of accumulation of operational defects in the array of parts of individual nodes (systems) of tractors is analyzed. The tractor MTZ-80(82) was chosen as the object of research, as one of the most common in Ukraine. To identify cracks, the developed eddy current flaw detector was used, the sensitivity of which made it possible to find cracks several millimeters in length and more without preparing the surface of the parts to be inspected. It is shown that the kinetic dependences of the accumulation of operational defects in the details of tractor units in the analyzed range of operating durations are monotonically increasing, which can be described by exponential functions with a fairly high reliability. It was noted that the obtained dependences are similar to the kinetic dependences of the accumulation of static and dynamic (fatigue) damage obtained as a result of laboratory tests of samples of structural materials, which allows us to use approaches to determine the criteria for the limiting state of laboratory samples to establish the maximum life of mobile agricultural equipment. At the same time, the kinetics of the intensity of the initiation of operational cracks in the array of tractor parts is not monotonic and has a maximum in the range of about 11-13 years of operation. This period of operation can be used as a criterion for stopping the operation of the tractor, performing flaw detection of parts and replacing defective parts. With such a duration of operation of the tractor, there is the greatest likelihood of sudden destruction of tractor units and the creation of emergency situations.

diagnostics of technical condition, operational defects, operational risk, mobile agricultural machinery, accidents