SCG及含内部轴向半椭圆裂纹PE管的寿命

Slow Crack Growth( SCG) and Lifetime of PE Pipes with Internal Axial Semi-Elliptical Crack

PE管材以其良好的力学性能在工业生产中得到了广泛应用。PE管道的设计寿命一般为50年,在服役过程中,PE管材可能会发生破裂及失效,慢速裂纹增长(SCG)是造成PE管材失效、影响管道服役寿命的重要因素之一。因此,研究PE管材的裂纹扩展行为对保证PE管材的安全使用,保障工业生产的安全稳定运行至关重要。从PE100管材中制取环切圆棒试件(Cracked Round Bar,CRB),根据ISO 18489—2015在不同应力比(R=0.1、0.2、0.3)下进行疲劳实验并得到裂纹扩展规律。采用外推法将实验结果外推得到静载条件下的裂纹扩展规律。对含有内部轴向半椭圆裂纹缺陷的PE管材进行寿命计算,得到了其在50年服役寿命下的最大允许裂纹尺寸和相应的应力强度因子值。

Polythylene （PE） pipes has been widely applied in industry. The lifetime requirements for PE pipes was roughly 50 years, an investigation revealed that many PE pipes failed during survice time, and slow crack growth（SCG） was one of the most important factors that contributed to the failure of PE pipes. Therefore, it was essential to study the crack growth behavior of PE materials to ensure the safity use of PE pipes. According to ISO 18489-2015, fatigue crack growth （FCG） experiments were conducted on cracked round bar （CRB） specimens manufactured from PE100 pipes at different R-ratios. In addition, these experimental data were employed in extrapolating to the case of creep crack growth （CCG）. Afterwards, the lifetime of PE pipes with internal axial semi-elliptical was calculated, and the critical crack depth as well as corresponding stress intensity factor for pipes with an internal axial crack was determined under service time 50 years.