Research On The Boundary Conditions Of The Whole Crankshaft's Three-dimensional Analysis

The crankshaft is one of the most important parts of the diesel. The long-term use of the diesel shows that the stress concentration around the fillets of the main journals and crankpins is an important cause of the crankshaft's rupture, so the problem must be carefully analyzed, and it can be solved only by the whole crankshaft's static and dynamic analysis.On one hand, it is still a troublesome problem that how to simulate the connection between the crankshaft and the main bearing covers of the cylinder block properly when calculating the crankshaft's three-dimensional stress; on the other hand, the main journals of the crankshaft are supported on the main bearing shells via the lube film and thus supported on the main bearing covers of the cylinder block, so before calculating the dynamic response of the crankshaft, the pressure of the main bearing shells' lube film at every rotation angle should be calculated. This needs the solution of the Reynolds Equation which needs the contact forces on the surfaces of the main journals at every rotation angle. The only way to solve the problems above is to do the three-dimensional simulation of the crankshaft with contact, but the size of the contact has direct links with the calculation time and the result accuracy. So it is necessary to find out the best contact way through comparing the results of different contact models.This paper is on the basis of the mechanics and the FEM theory, using the CAD/CAE software I-DEAS and MSC.Marc to do the research on the boundary conditions of the whole 16V240ZJB crankshaft's three-dimensional analysis. The first job is to set up the initial simulation contact model without fillets under the 16 load cases at the different cylinders' explosions, then compare the results and find out the most dangerous load case. The second job is to set up 6 different complex models which have fillets with different contact ways under the most dangerous load case, then compare the results and find out the best contact way of crankshaft's transient simulation. The last job is to give out the contact force of the main journals under the most dangerous load case, this will provide great helps to the next dynamic simulation of the crankshaft.