This presentation was made at the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

Threaded connectors are widely used in oil and gas applications for drilling tools, wireline tools and fluid conveyance piping system. These connectors undergo large number of cycles of multiaxial loading which leads to localized plastic deformations close to the threads. In order to avoid potential maintenance downtimes and potential failures, optimizing the low cycle fatigue behavior for these threshed connectors becomes important. A nonlinear kinematic hardening material model (Chaboche) is chosen in the current work to allow for ratchetting and shakedown behavior typically observed in threaded connectors. The parameters for Chaboche model are calibrated with experimental uniaxial cyclic test data. Calibration of material parameters with the experimental results is performed as a least squares error norm minimization problem. Material behavior is illustrated through parametric studies on the fitted Chaboche material model. Furthermore, a threaded connector model is studied which is subjected to with combined loading to simulate the low-cycle fatigue performance during typical service load while in operation. Overall, this work provides a computational modeling framework to quantitatively understand the low-cycle fatigue behavior in threaded connectors subjected multiaxial loading which will be useful for large range of industry applications.