高静压下长杆中轴向应力波衰减研究

Attenuation of axial stress waves in a long rod under high hydrostatic pressure

针对用于非常规页岩油开发的可控冲击波设备负载推送杆,该文提出了一种可用于高静压环境的内置吸收杆应力波衰减结构,基于LSDYAN软件与简化Johnson-Cook本构模型,开展了推送杆中应力波衰减规律的数值模拟研究。首先,基于试验数据对材料模型参数及数值算法的可靠性进行验证,在此基础上计算了不同外部环境、不同载荷参数及不同吸收杆参数对应力波衰减效果的影响。研究结果表明:外部是否存在静压对吸收杆的应力波吸收效果无显著影响,但静压会在空腔区造成部分应力集中,在50 MPa外压力下内壁等效集中应力峰值可达100 MPa;吸收杆对应力波能量的吸收效果取决于其脱离壁面前注入其中的能量;在载荷参数适配的条件下,通过串接多个吸收杆结构可以增加对应力波的衰减效果。研究结果可为水下高静压环境下的结构抗冲击防护设计提供指导与参考。

Aiming at the load push rod of a controllable shock wave equipment used in the development of unconventional shale oil,a stress wave attenuation structure with built-in absorbing rod that can be used in high hydrostatic pressure environment was proposed.Based on the LSDYAN software and the simplified Johnson-Cook material model,the attenuation of stress wave in the push rod was numerically studied.First,the reliability of the material model parameters and the numerical algorithm was verified based on the experimental data.On this basis,the influences of different external environments,different load parameters and different absorber rod parameters on the stress wave attenuation effect were analyzed.The numerical results demonstrate that whether there is hydrostatic pressure outside or not is of no significant effect on the stress wave absorption effect of the absorbing rod.However,the hydrostatic pressure will cause partial stress concentration in the cavity area,and the peak value of the equivalent stress on the inner wall can reach 100 MPa under the external pressure of 50 MPa.The absorption effect of the absorbing rod on the stress wave energy depends on the energy injected into it before it breaks away from the push rod.When the load parameters are suitable,the attenuation effect on the stress wave can be increased by connecting multiple absorbing rod structures in series.The research results provide guidance and reference for the impact protection design of structures in underwater high hydrostatic pressure environment.