Abstract
A data processing method for constitutive relation of large deformation rubber core in spherical blowout preventer is put forward in this article. Based on the Yeoh constitutive model and the large-deformation theory of rubber material, this article studied the constitutive relation of core material in blowout preventer. The constitutive relation experiments, the uniaxial tensile experiment, the uniaxial compression experiment, the plane tensile experiments, and the volume compression experiment were conducted and the corresponding experiment data were fitted, respectively, on basis of which the uniaxial compression data were selected for further study. For comparison, the data were, respectively, processed with a novel method and the method in GB/7757, and accordingly, two different constitutive relations were obtained and introduced into ABAQUS to simulate the experiment process. Research results show that the relative error of maximum axial deformation between the simulation using GB/7757 and the actual experiment is 34.7%, while that between the novel method and the actual experiment is 20.4%, having improved the accuracy by 14.3%, proving that the data processing method in this article can effectively improve the accuracy of finite element simulation for the core material and will contribute to the research on the performance of spherical blowout preventer.
Highlights
In the process of drilling, there are many uncertain factors in the well, and the potential blowout risk is more likely
The rubber core is a key part of the spherical blowout preventer (BOP) and its performance is significantly affected by the core material
The experimental data of uniaxial compression can be well-fitted with Yeoh model, which can objectively reflect the change of core material in spherical BOP, so the uniaxial compression experimental data were selected as the constitutive data for finite element analysis
Summary
In the process of drilling, there are many uncertain factors in the well, and the potential blowout risk is more likely. One of the ideal fitting curves is shown, wherein the obtained Yeoh model coefficients are that C10 = 1.15619829 MPa, C20 = 1.18908883 MPa, C30 = 0.340784687 MPa. It could be observed in Figure 7 that when the rubber compression deformation rate exceeds 40%, the error of the Yeoh model will increase, but the difference is quite small, which indicates that the overall trend of the theoretical data is basically the same as the experimental data.
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