Failure Analysis by Fracture Study of Connecting Rod Bolts in Diesel Engine for Military Tracked Vehicles

Abstract

Tracked military vehicles are operated under harsher conditions and climates than ordinary vehicles, and the components require high degrees of reliability and durability. A diesel engine is the main power generator, and when the vehicle breaks down, there is a high possibility of causing a large-scale accident. Therefore, analyzing the cause of engine failure can be important for preventing similar cases that may occur. In this study, we clarified the mechanism of engine failure according to an overhaul test, hardness measurement, and an analysis of the fracture surface. The overhaul test confirmed that a bolt was separated from the connecting rod (number 4). In addition, the hardness measurement results of the connecting rod bolt conformed to the standard, and it was found that the bolt fracture was ductile fracture through an analysis of the fracture surface. Based on the results, it was concluded that damage to a diesel engine of a tracked military vehicle was caused by separating and damage caused by loosening of the connecting rod bolts, resulting in cascading damage. The results of the study could be used as reference examples and could be useful for another study on engine failure