Abstract: Based on the experimental fact that the rate of dislocation movement and polymerization to form fatigue crack accelerates with the number of cyclic loads, it is assumed that the fatigue crack initiation rate is a monotonically increasing power function of the number of cyclic loads. The calculation model of fatigue crack initiation life is derived by integrating the power function between the fatigue crack initiation rate and the number of cyclic loads. The fatigue test results of Q460C steel notched plates show that the fatigue crack initiation life, propagation life and total fatigue life increase with the decrease of stress amplitude and nominal maximum stress, and the ratio of fatigue crack initiation life to total fatigue life ranges from 0.82 to 0.90. The calculated error of the fatigue life calculation formula recommended in China’s code ‘Standard for design of steel structures’ is -17.0%—+84.9%. Considering an ellipsoidal fracture model of structural steel originally proposed by the author as the instability propagation (fracture) criterion of fatigue crack, a set of theoretical calculation and numerical simulation were established to investigate the fatigue cracking of the notched plates. Taking a crack length of 0.05 mm at which the strain over flows at the site of fatigue crack initiation as the critical size of fatigue crack initiation, the calculated errors of the calibrated fatigue crack initiation life formula, propagation life formula and total fatigue life formula of the Q460C steel notched plates are -15.0%—-1.2%, -12.4%—+2.8% and -12.1%—-1.4%, respectively.
通讯作者:
*王万祯,宁波大学土木工程与地理环境学院教授、硕士研究生导师。1997年7月西安建筑科技大学土木工程专业本科毕业,2003年3月西安建筑科技大学结构工程专业博士毕业后到兰州理工大学工作,2009年10月到宁波大学工作至今。目前主要从事金属材料和结构的断裂与疲劳等方面的研究工作。发表论文100余篇,包括Journal of Constructional Steel Research、Fatigue & Fracture of Engineering Materials & Structures、Structures、《土木工程学报》《建筑结构学报》《固体力学学报》《工程力学》《建筑材料学报》等。wangwanzhen1975@sina.com
引用本文:
王万祯. Q460C钢缺口板的疲劳裂纹萌生寿命计算模型和总疲劳寿命计算[J]. 材料导报, 2024, 38(4): 23010056-8.
WANG Wanzhen. Calculation Model of Fatigue Crack Initiation Life and Total Fatigue Life Calculation of Q460C Steel Notched Plates. Materials Reports, 2024, 38(4): 23010056-8.
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