The Effect of Local Wear on the Resource of Loaded Cantilever – Fixed Parts

Abstract

Among the details of the working bodies of soil-developing tools, cantilever-fixed structural elements occupy a certain place, which are operated under conditions of high-intensity abrasive wear. Known theoretical studies do not allow predicting the resource of cantilevered parts, taking into account the wear factor and the deformation ability of the material. Two tasks were theoretically solved in the work on determining the resource of a part until the moment when: 1 - the wear section becomes so thin that the transition area from the worn part to the non-worn part becomes more dangerous when bending than the cantilever fastening area; 2 - destruction will occur in the transition zone from the unworn to the worn area. Problem solving was carried out using the methods of the course "Strength of materials". The cantilever-fixed beam of variable section is taken as the design scheme. It was taken into account that the main parameter characterizing the strength of a bent beam is the magnitude of tensile strains that occur on its convex side. It was taken into account that the main parameter characterizing the strength of a bent beam is the magnitude of tensile strains that occur on its convex side. The conditions for the occurrence of the danger of destruction and the destruction itself in the section of the part, where the transition from the worn part to the non-worn part takes place, are determined by theoretical studies. The result of solving two problems was the derivation of formulas by which it is possible to predict the resource of a part in case of its local wear. A mathematical expression has been obtained that makes it possible to calculate the operating time of a locally worn cantilever-fixed part, when the width of the cross-section of the wear area decreases so much that the transition area to the unworn part becomes more dangerous than the cantilever fastening. A mathematical expression has been obtained that makes it possible to determine the resource of a structural element for the case when its destruction occurs at the point of transition from a worn area to a non-worn one.