Prediction of cyclic durability and risk analysis of inconsistencies in the supporting structures of mobile vehicles

The reliability and safety of mobile vehicles is determined by their carrier system. Achieving a low probability of failure of structures and reducing the cost of equipment is possible by changing the traditional methods of predicting reliability and applying risk analysis, as well as using risk-based design. The aim of the work is to develop methods for predicting the cyclic durability of elements, fastening prefabricated load-bearing structures and analysis to achieve acceptable risks of mobile vehicles at the stages of risk-oriented design. The methods and standards were developed in order to provide methodological support of risk-based design. Those allow designers and engineers to use new methods of design and calculation of tractor and agricultural machinery. It is proposed to introduce into the existing notation system of design and technological documentation the identifiers for parameters as the priority indicators and to achieve when designing the probability of occurrence of each potential cause of failure up to a given level of risk, taking into account priority. The tool for achieving low failure probabilities is the construction of diagrams of cause-and-effect relationships of failures is the source of cause and effect based on the method of deduction and induction. A calculation and experimental method for predicting reliability, according to the criterion of cyclic durability of load-bearing structures and fasteners was developed. The technique is based on local modeling of damage initiation zones, taking into account the influence of design and technological factors of production, simulating the load mode of a mobile vehicle, its damage zones. The following are used for the calculation: finite element method, experimental load assessment, fatigue resistance characteristics of load-bearing elements, rivets and bolts, damage accumulation hypotheses. Risk analysis is carried out using the FMEA methodology. As a result of the risk analysis in a probabilistic formulation, a conclusion is made about the possible damage to the supplier – the number of mobile vehicles that will not ensure the fulfillment of the stated requirements for a given resource and warranty mileage. Thus, data for assessing risks and making a decision on the advisability of redesigning equipment appear. The created methodological support for predicting cyclic durability and risk analysis for the implementation of risk-based design allows: to eliminate the uncompetitive level of product quality and production quality, as well as low efficiency and labor productivity; apply new design technologies, design and production preparation methods that reduce development time. The developed methods and means of the risk-based approach have been widely tested and are used in the practice of auto-tractor-agricultural machine building.