基于热老化实验的螺杆马达定子橡胶本构模型研究

随着我国油气资源勘探开发向深部地层迈进,螺杆钻具定子橡胶井下高温热老化问题日益凸显,导致螺杆钻具输出性能衰减,严重影响钻进效率,迫切需要揭示热老化对螺杆钻具定子橡胶力学性能的影响,以在设计之初提出可减小螺杆钻具输出性能衰退的综合方案。本文开展了螺杆马达定子橡胶在不同温度下的热老化实验,通过拉伸实验得出应力应变数据并拟合出Mooney-Rivlin模型常数和Yeoh模型常数;再对所得实验数据及所求得的模型常数数据进行分析;最后,使用确定了基本常数的模型开展了数值计算。计算结果表明,随着温度的上升,Mooney-Rivlin模型常数C_1增大、C_2减小,C_1和C_2呈明显相反变化的趋势,Yeoh模型常数C_(10)和C_(20)增大,C_(30)减小;通过模型计算结果与室内实验测定结果的对比,证明了Mooney-Rivlin模型较Yeoh模型更适合于螺杆马达定子橡胶的力学分析。不考虑环境温度热老化和考虑环境温度热老化,螺杆钻具定子衬套的计算结果存在很大差别,研究工作不仅证明了螺杆钻具定子橡胶热老化研究的必要性,更为螺杆钻具定子橡胶的线型设计和过盈量选取提供了参考。

Study on the constitutive model of the screw motor's stator rubber based on thermal aging experiment

With the exploration and development of the oil and gas resources to the deep formation in China,high temperature-induced thermal aging problem of the screw drill's stator rubber in the underground becomes increasingly prominent.This causes serious deterioration of the screw drill's output performance and seriously affects drilling efficiency.It is urgent to know the influence of thermal aging on the mechanical properties of the screw drill's stator rubber.We propose a comprehensive scheme that decreases the decline of the screw drill's output properties at the beginning of the design stage.This paper carried out thermal aging experiments of screw motor's stator rubber at different temperatures,derived stress-strain data for tensile tests and fitted the Mooney-Rivlin model and Yeoh model.Then the test data and the model constants are analyzed.At last numerical calculations are performed by using the models.Calculation results show that:With increasing temperature,the screw drill's stator rubber is in a state of continuous hardening,and the average hardening rate at moderate and high temperatures (90 ℃~120 ℃) is 116% higher than the average hardening rate at low temperatures (30 ℃~90 ℃);for Mooney-Rivlin model, constants C1 increases and C2 decreases.C1 and C2 have an obviously opposite trend;Yeoh model constants C10 and C20 increase,but C30 decreases.Through the comparison between calculation results of the model and the indoor experimental results,we proved that Mooney-Rivlin model is more suitable for the screw motor's stator rubber than the Yeoh model.Consideration of thermal aging at ambient temperature or omission makes a great difference in the calculation results of screw drill's stator bushing.This research work not only proves that the thermal aging research of screw drill's stator rubber not only is necessary,but also provides reference for the design of screw drill's stator rubber and the selection of interference magnitude.