Risk Assessment and Reliability Management of Tractor Front Axles Using Experimental and Numerical Analysis

Abstract

The front axle is one of the most significant structural parts in an agricultural tractor that supports the vehicle load, provides a cushion effect when driving on uneven ground and ensures steering stability during different conditions of operation. As the front axle experiences repetitive loading, impact loads and tough weather conditions, it is prone to causing fatigue damage and structural failure. It is crucial to understand the reasons behind these failures to enhance reliability, longevity, and safety in tractor parts. This study is a complete failure analysis of a cracked front axle of a tractor that failed prematurely in the field. The investigation started with a comprehensive visual inspection and was found that there was a large crack starting at the area where the wheel is attached, and there was severe corrosion and surface deterioration. Metallurgical characterization, hardness, fractographic analysis, and finite element analysis (FEA) were used for the investigation of the root cause of failure. A numerical model was created to investigate the stresses and stress concentrations in critical areas for typical loading configurations. Next, the experimental observations were compared with the simulation results to determine the failure mechanism. Experiment results show that the crack started at the high stress concentration area and grew as cycles were repeated. Corrosion products were observed on the fracture surface, indicating that the environment degradation played a part in the crack growth, which eventually led to the loss of load carrying capacity in the axle. The maximum stresses were then seen to be concentrated near the crack initiation site so the FEA results corroborated the experimental results. The study also shows how material quality, geometric discontinuities and service loading impact the fatigue performance of the component. The results give an insight into the structural behavior and failure modes of tractor front axles and highlight and underline the need for hybrid investigations of experiments and simulations for accurate elucidation of the failure mode. The suggestions in this study, such as design optimization, material selection, and condition monitoring to be performed periodically, can greatly improve the fatigue life and reliability of any agricultural tractor's front axle. The research results will help for the design of agricultural equipment, component design, maintenance, failure prevention, and safe design of agricultural machinery which are more durable and safe.