港口起重机球铰轴断裂分析及评定

Analysis and assessment of fracture in ball-socket axis in port crane

由港口起重机球铰轴的失效分析结果表明热处理残余应力是引发断裂事故的根源。通过有限元分析软件ANSYS的结构分析及热分析功能,计算得到了材料为40Cr、经正火热处理且承受128t外载荷作用的球铰轴断裂面上的弯曲应力和热处理残余应力。依据英国标准BS7910,以应力强度因子KIC作为断裂评定参量,进行含半椭圆表面裂纹和环形表面裂纹的球铰轴断裂性能的评定,得到2种缺陷形式的极限裂纹尺寸,结果表明裂纹深度是影响断裂性能的关键特征尺寸。

Failure analysis of ball - socket axis in prot crane shows that broken axis accident is caused by heat treatment residue stress. The structural analysis and heat analysis functions in ANSYS software are used to work out bend stress and heat treatment residue stress in fracture surface of the 40 Cr heat - treated ball - socket axis subjected to 128 t load. Considering BS7910 and taking stress intensity factor Kic as fracture assessment index, ball- socket axes with semi - elliptic surface crack and circumferential crack are assessed, and the limited dimensions of two kinds of crack are obtained. Analysis results show that the deepness of crack is the main cause that leads the ball - socket axis to collapse.