Diesel Engine Crankshaft Fatigue Life Based On The Transient Dynamics

Crankshaft is the most important one of the moving parts of the engine, has a decisiveimpact on the structure parameters and performance parameters on the overall weight of thediesel engine, reliability and life. In the course of the actual work force crank extremelycomplex will produce tension and compression, bending, torsion alternating stress internal,resulting in premature crankshaft bending fatigue failure occurs in the main journal and rodjournal fillet more serious stress concentration, fatigue cracks prematurely in these places,causing fracture of the crankshaft. Therefore, in order to grasp the crankshaft stressdistribution in the working process of the crankshaft and the fatigue life of the transientdynamics of research is necessary. In the future, improvements to the crankshaft, optimizationalso has great significance.Would appear premature bending fatigue failure of the crankshaft for this problem, thispaper diesel engine crankshaft as the research object, the following research areas:（1）Analysis the load of crankshaft, according to the kinetic theory of finite element to thecrankshaft dynamic response analysis, and dynamic response of some of the problems werecompared.（2）Analysis of the crankshaft to withstand load, based on the kinetic theory of finiteelement basis, combined with the structural characteristics of the crankshaft and the actualworking conditions, the dynamic response analysis was carried out to determine the dynamicresponse and encountered model grid size, constraints way to determine and select the contactrelationship, select and load step method selected loading were compared. Then, focus on thestress state and characteristics of stress concentration and analysis of stress concentrationstress-time history curve, in order to understand the dynamic response of the crankshaftfeatures and fatigue analysis provides payload data.（3）Based on the research of the crankshaft on the fatigue life prediction method to predictits life. Specific studies to obtain parts SN curve and surface processing correction factor, size factor and enhanced coefficient; fatigue damage accumulation method; damage parameterselection;（4）After the dangerous parts of the crankshaft is clear, its sensitivity based on Spearman’srank correlation coefficient, by studying the results of the stress on the dangerous parts of thelargest fillet radius.