Failure Analysis Of A Diesel Engine Crankshaft-connecting Rod-piston System Under Variable Conditions

Diesel engine is the main power device. Improving its overall performance has a very important significance to the social development. However, with the power and speed of the engine increasing constantly, its structure also bears a greater challenge. Crankshaft-connecting rod-piston system, as the main dynamic mechanism of the engine, carries the core mission of energy conversion. It is clear that this system has a very important position in a complete machine. By analyzing crankshaft-connecting rod-piston system under variable conditions and making sure that its ability to withstand extreme conditions and possible dangerous failure point. It is very important for a new engine in development stage whose structure has been preliminarily identified.Firstly, according to the characteristics of the engine in this paper, analyze systematically a large number of failure, fault data of similar models. As the structure and working principle of an engine is similar, we can judge which part is the most prone to appear a failure phenomenon in an engine crankshaft-connecting rod-piston system and major failure forms through some similar models’conditions. After the study, select a method of the finite element combined with flexible multi-body dynamics as the analysis method of this paper. First of all, simplify the three-dimensional solid model in consideration of analysis needs in this method. Then, set up the three-dimensional solid model in Pro/E and the finite element models of the crankshaft and main bearings in ANSYS. Reduce them in the interface program, then we have some documents including freedom, geometry, mass and stiffness matrices, transformation matrix, etc, they are the base for establishing a multi-body dynamics model. On this basis, we establish a multi-body dynamics model of crankshaft-connecting rod-piston system by using a type of dedicated engine analysis software AVL-EXCITE, and make a dynamic analysis for the work condition of the crankshaft and main bearings. For the analysis results, the check by the use of allowable values and the permissible safety coefficient was carried out. Finally, make a series of variable conditions simulation analysis to determine the system’s extreme conditions.