钢吊车梁直角式突变支座插入板端部疲劳性能研究

Research on fatigue properties of plug-plat end of crane runway girders variable section abutment with right angle end-plate

钢吊车梁直角式突变支座在工业厂房中广泛应用,工程经验表明钢吊车梁直角式突变支座插入板端部与腹板连接焊缝易出现疲劳裂纹,且通过有效的点检制度可以避免灾难性的事故发生。开展了钢吊车梁直角式突变支座缩尺模型的疲劳试验,得出该类连接的应力幅-疲劳寿命(S-N)曲线,确定了疲劳裂纹的初始位置为小圆孔下侧。通过截面参数分析得出,小圆孔处应力集中系数与插入板板厚呈正线性相关、与圆孔直径呈负线性相关。采用VCCT法和网格重划分技术,针对钢吊车梁直角式突变支座插入板端部开展了疲劳裂纹扩展模拟,明确了该类构件的疲劳裂纹扩展模式。结合S-N曲线法、概率断裂力学法,建立了适用于钢吊车梁直角式突变支座的插入板端部的概率损伤容限分析方法,分析得到在不考虑荷载、断裂韧度随机性时,其疲劳寿命不拒绝服从对数正态分布。

The crane runway girders variable section abutment(CRGVSA)with right angle end-plate is widely used in industrial plant.Engineering practice showed that the end of the weld between the web and the plug-plat of the CRGVSA with right angle end-plate is susceptible to fatigue rupture,and an effective inspection system for fatigue crack initiation location could avoid catastrophic accidents.Firstly,fatigue test of a scaled CRGVSA model with right angle end-plate was carried out.The stress amplitude-fatigue life(S-N)curve of this type of connection was obtained,and the fatigue crack initial location was determined to be the lower side of the small round hole.Subsequently,through the analysis of the cross-section parameters,it was found that the stress concentration factor at the small round hole is positively linearly related to the thickness of the plug-plat and is negatively linearly related to the small hole diameter.The fatigue crack propagation simulation was carried out at the end of the weld between web and the plug-plat of the CRGVSA with right angle end-plate by using a VCCT method and mesh re-division technology.The fatigue crack growth mode of this type of component was clarified.Finally,combined with the S-N curve method and fracture mechanics method,a probabilistic damage tolerance analysis method for the CRGVSA was established.Without considering the randomness of load and fracture toughness,the fatigue life of this type of member does not refuse to follow the lognormal distribution.