柴油机曲轴危险工况的确定及其静强度分析

Determination on the operation condition of crankshaft of diesel engine and its static strength analysis

利用MSC.Patran&Nastran对柴油机曲轴整体进行三维实体建模、网格划分和静强度有限元分析。采用弹簧单元模拟主轴承支承,使计算模型更接近实际情况。在确定曲轴危险工况时考虑了弯扭的联合作用,以有限元结果为依据,提出了一种更准确地确定曲轴危险工况的方法,证明了曲轴最危险工况并非发生在再进气的上止点或曲柄销受气体力最大时。最后采用了等效应力法对曲轴进行了疲劳强度安全系数校核。

Utilizing MSC. Patran＆Nastran to carrying out 3D entity modeling on the entire crankshaft of the diesel engine, the division of meshes and the finite element analysis of static strength, Adopting the spring unit to simulate the support of main bearing so as to let the computation model be more close to the actual situation. The combination effect of bending and twisting has been considered while defining the dangerous operation condition of the crankshaft. Taking the finite element result as a base, a kind of method on determining more precisely the dangerous operation condition of the crankshaft was put forward. It is verified that the most dangerous operation condition of crankshaft is not happening at the upper point of gas reinlet or while the crankpin is bearing a maximum force of gas. Finally, the checking up of safety coefficient of fatigue strength was carried out on the crankshaft by means of adopting the method of equivalent stress.