Numerical modeling and experimental estimates of structural member fatigue characteristics

Abstract

Introduction. In the algorithm for predicting the resource of machine parts, models of external actions, fracture resistance, and temporal development of a particular type of damage to these units interact. The applied issues of the resistance of machine parts to fatigue failure are considered. The scientific research and regulatory materials are adapted to determine the characteristics of endurance to the specifics of structures and materials of the construction-and-road machinery and agricultural machinery. The work objective is to use the analysis of existing methods to develop recommendations for the calculated determination of the endurance parameters of structural members of the agricultural machines.Materials and Methods. The initial data were scientific studies on the fracture mechanics of the engineering materials and structures, as well as standards for endurance characterization methods. The need to test methods for determining fatigue characteristics to use them in the road construction machinery and agricultural machinery projects follows from the specifics of their designs, operation conditions and industry-specific range of materials. Based on the analysis of existing methods, it is required to develop recommendations for the calculation of the endurance parameters of structural parts of the agricultural machines. For this, the components of the load-bearing systems of the staged design were presented in the form of a set of plates of the corresponding thickness; and the concept of the critical radius of the stress raiser at the welding sites was also used. Numerical methods using mathematical models were applied. The calculation results were verified through comparing them to experimentally determined fatigue characteristics of the members of a combine harvester on a test bench.Results. Radius critical values of the stress raisers for various types of welds are obtained. The tables of the calculated and experimental endurance limits of the combine bearing components are well correlated and can be used under designing.Discussion and Conclusions. The theoretical foundations laid down in the study open up great opportunities for applications to the design of various machines. The considered fragment of adaptation of the theoretical approach to the agricultural engineering objects can be used in the design of load-bearing systems in the related fields of engineering.

Keywords

• endurance range
• fatigue fracture
• fatigue crack
• weld joint
• computational and experimental methods