高应变率载荷作用下P110S管材力学性能实验研究

油管在生产服役过程中常承受射孔冲击、流体诱发振动等动载作用,引起管柱塑性弯曲、断裂等事故。为了量化动载系数和动载作用下管材屈服极限提高幅度,获得以Johnson-Cook为代表的材料动态本构模型关键参数,提高动载作用下管柱强度安全分析精度,以油田常用P110S管材为例,进行静载下的轴向拉伸实验和高应变率冲击下的力学性能实验。结果表明,静载下P110S管材屈服极限775MPa,比标称值758MPa高出2.2%;强度极限835 MPa,强屈比1.08。应变率500s-1动载作用下,管材的屈服极限比静态实测值提高了15.5%;应变率1000s-1动载作用下,管材的屈服极限比静态实测值提高了41.4%。应变率为500s-1的P110S管材动载实验对应流体诱发引起的管柱振动,其强度降低4.5%;应变率为1000s-1的P110S管材动载实验对应射孔冲击引起的管柱振动,其强度降低8.6%。本文通过实验确定了管材Johnson-Cook动态本构模型的关键参数,可为动载作用下的精确有限元仿真分析提供依据。

Experimental study on mechanical properties of P110S tubing under high strain rate loading

During production and service, tubing often suffers from dynamic loading effects such as perforating impact and fluid induced vibration, causing accidents such as plastic bending and fracture of the tubing strings. In order to quantify the dynamic load factor and the increase amplitude of pipe yield limit under dynamic loads, obtain the key parameters of the dynamic constitutive model of materials represented by the Johnson-cook, and improve the strength and safety analysis accuracy of the strings under dynamic load, this work performs axial tensile tests under static load and mechanical tests under high strain rate impact by taking the commonly used P110 S pipe in oil field as an example. The results show that the yield limit of P110 S pipe under static load is 775 MPa, which is 2.2% higher than the nominal value of 758 MPa;the strength limit is 835 MPa and the strong-flex ratio is 1.08. Under the dynamic load with a strain rate of 500 s-1, the yield limit of the pipe is increased by 15.5% compared with the static measured values. Under that of 1000 s-1, the yield limit of the pipe is 41.4% higher than the static measured values. The dynamic load of P110 S pipe with a strain rate of 500 s-1 is attributed to the fluid induced pipe vibration, and its strength is reduced by 4.5%. The dynamic load test of P110 S pipe with a strain rate of 1000 s-1 corresponds to the vibration of the pipe string due to perforation, and the intensity is reduced by 8.6%. The key parameters of the Johnson-cook dynamic constitutive model of pipe are determined by experiments, which could provide experimental evidence for the accurate finite element simulation analysis under dynamic load.