利用Abaqus的含氢鼓包缺陷液化气罐安全分析

Safety Analysis on Liquefied Tank with Defect of Hydrogen Blistering Using Abaqus

针对含氢鼓包缺陷液化气罐的安全运行问题,提出了一种基于J积分的安全分析方法.首先利用外观、磁粉和超声检测等手段确定液化气罐氢鼓包的位置和形貌;然后利用有限元法软件Abaqus对缺陷进行模拟分析,得到缺陷处的应力分布,并分别采用直接法(JA)和应力强度因子法(JK)计算裂纹尖端的J积分值;最后利用直接法得到的J积分结果对该液化气罐进行安全分析.结果表明:氢鼓包内压力为5MPa时,用JK计算的J积分值比用JA计算的大1.55倍;在氢鼓包内压力为3MPa和1MPa时,用JK计算的J积分值比用JA计算的大0.10倍.可见,如果用JK进行安全性评价,会过高估计裂纹的扩展;如果利用JA进行安全评估,当氢鼓包内压力增加到3MPa时裂纹很有可能会继续扩展,应进行监控或及时对氢鼓包缺陷进行处理.

AJ-integral based method is proposed to assess the safety of the liquefied tank with defects of hydrogen blistering.First,measuring tools,magnetic inspection powder and an ultrasonic thickness gauge are used to defect the type,position and morphology.Then Abaqus software is adopted to analyze the deformation and stress distribution,and calculate J-integral value of crack tip through definition（JA）and stress intensity factor（JK）.Finally,the Jintegrals calculated are compared with a critical value for the material to predict fracture and assess the safety.The results show that the J-integral value by JK is about 155%greater than that by JA when the pressure in hydrogen blistering is 5MPa,and about 10%greater than that by JA when the pressure in hydrogen blistering is 3MPa or 1MPa.It seems that the value calculated by JK will be overestimated for the safety assessment.The safety assessment results by JA indicate that the hydrogen blistering defect with cracks is likely to propagate when the pressure in hydrogen blistering increases to 3MPa.