基于多体动力学的曲轴应力分析

孙军¹，倪培相^1*，吕世杰¹，胡玉平^2*

1.天润工业技术股份有限公司，山东 威海  264400；2.山东大学能源与动力工程学院，山东 济南  250061

摘要：利用有限元法对某发动机锻钢曲轴进行多体动力学计算，分析曲轴在发动机实际工作过程中的应力分布，确定曲轴断裂原因。分析结果表明：正常情况下曲轴的第八曲柄臂与曲柄销过渡圆角处应力最大，为350.0 MPa；当第二主轴承螺栓松动时，第二曲柄臂与曲柄销过渡圆角处应力最大，达977.4 MPa；第二主轴承螺栓脱落时，第二曲柄臂与曲柄销过渡圆角的最大应力达995.3 MPa。在主轴承螺栓松动或脱落的情况下，曲轴曲柄销圆角的最大应力远超曲轴材料的屈服强度，曲轴容易在此处产生裂纹并断裂。

关键词：曲轴；断裂；有限元；多体动力学；应力

Stress analysis of crankshaft based on multi-body dynamics

SUN Jun¹, NI Peixiang^1*, LÜ Shijie¹, HU Yuping^2*

1.TianRun Industrial Technology Co., Ltd.，Weihai 264400, China;

2.School of Energy and Power Engineering, Shandong University, Jinan 250061, China

Abstract: The multi-body dynamic calculation of forged steel crankshaft of an engine is carried out using finite element method, the stress distribution of the crankshaft in the actual working process of the engine is analyzed, and the fracture reason of the crankshaft is determined. The results showed that under normal circumstances, the stress at the transition fillet between the eighth crank arm and the crank pin of the crankshaft is the largest, which is 350.0 MPa. When the second main bearing bolt loosens, the stress at the transition fillet of the second crank arm and crank pin is the largest, reaching 977.4 MPa. When the second main bearing bolt falls off, the maximum stress of the transition fillet between the second crank arm and crank pin reaches 995.3 MPa. In the case of loosening or falling off of the main bearing bolt, the maximum stress value of the crankshaft crankpin fillet far exceeds the yield strength of the crankshaft material, and the crankshaft is easy to crack and fracture from here.

Keywords: crankshaft; fracture; finite element; multi-body dynamics; stress