Pidgursky M. Prediction methods of the beet harvesters bearing and functional systems resource.

Analytical-experimental approaches to the estimation of the basic bearing frame systems resource of beet harvester, based on fracture mechanics and on the mathematic modeling of real processes of cracks initiation and propagation in the welded connections of the constructions profile elements are proposed in the thesis. Experimental methods and means for estimation the decision of the operating loading of mobile agricultural technique are developed. The regimes of loading of bunker combines are specified. The analysis of the disk-type digging organs effect on the stress-strain behavior of the basic bearing systems of harvesters is carried out. Dependencies of stress distributions in the statically undetermined systems while being cracked are found. Engineering approaches as to the damage standards, which take into account the stochastics of cracks initiation and propagation on the initial stage of their distribution, are developed. Mathematical models of cracks growth are built. The tasks of SIF calculation which describe the stress-strain behavior at the crack tips are solved. Tasks for the general case of crack propagation from the box-type element profile or open-type element shelf side in the fields with the heterogeneous stress-strain behavior are solved. The algorithm of rational bearing constructions synthesis of beet harvesters with the guarantied resource of operating time is developed.