Research On Crankshaft Strength Considering The Influence Of Surface Treatment

Railroad is the main artery of national economy, with Chinese railwaydeveloping to high-speed and heavy-load, the design requirement of locomotiveare getting more and more high. Crankshaft is an important part of diesel engine.It’s processing technology level and structure parameters not only affects theoverall size and quality of diesel engine, but also influence the reliability andservice life of diesel engine to a large extent. The damage analysis showed that,bending fatigue fracture is the main part of total fracture. Thus, the strengthanalysis of crankshaft is especially important. A large number of domestic andforeign practice shows, the surface treatment of diesel engine parts is aneffective means of improving the parts’ strength. So it has importantsignificance to research the strength of the crankshaft which considered of thesurface treatment.For surface strengthening of crankshaft, due to the surface layer elasticmodulus cannot be determined, the strength calculation can’t include in theaggrandizement layer. While the existence of the surface layer of crankshaftstrength is crucial. According to Li Yuanji and Hu Yixiang’s latest proposedmethod, through the crankshaft material of test bar try bending strain test andcalculation, get the elastic modulus of surface layer, and take the16V240ZJdiesel engine crankshaft as an example, then application of finite elementanalysis technology to surface nitriding and not treatment of single crank and thewhole crankshaft, for the detailed calculation. On the basis of accurate surfacenitriding layer elastic modulus, comparison and analysis the intensity influenceof surface treatment of single turn and the overall crankshaft. In the model useshell and block units for simulation, surface layer with thin shell elementsimulation, shell side unit only1x1mm, thickness only0.2mm, very good tosimulate the surface layer.The calculation of stress distribution of single crank is fully compliancewith the law, and the biggest stress occurs in the main journal rounded, whichvalue compared with the measured error is only6.3%.The maximum axial stress amplitude of crankshaft occurred in the corners of connecting rod neck,conforming to running actual condition of the crankshaft. This shows that theanalysis is correct and reliable, and analysis method is feasible. This research isan innovation subject that provides an effective method for calculating of thesurface treatment of crankshaft strength, with strong practical significance,providing valuable reference to the theoretical research.