A Refined Methodology for Calibrating Premium Connection Make-ups

TR Number
Journal Title
Journal ISSN
Volume Title
Virginia Tech

Digital Image Correlation is used to generate high-spatial-density full-field displacement
and strain data of a connection box outer diameter for use in the calibration of finite element
make-up models. Image acquisition and data processing techniques are discussed and best
practice recommendations are made. 3D-wedge models consisting of a twenty-degree sweep of
the connection geometry are generated from manufacturer supplied profiles. Deformation
plasticity material models are developed from identified minimum strength material coupons.
Axisymmetric and 3D meshing schemes are used to capture the geometric complexity, supply
enough resolution to represent seal performance, and provide a solution in an acceptable
timeframe. Several techniques for achieving good contact resolution are presented. The
mechanics of the full 3D connection makeup are decomposed into simple idealized
representations. Finite element boundary conditions are developed to adequately represent the
360-degree make-up mechanics in a wedge section. The wedge model is loaded to achieve a
torque-rotation coupling which satisfies the experimental make-up conditions. This model
displays a much improved ability to capture box outer diameter strain and displacement fields,
and thus better represents the mechanics of a connection make-up. A 3D inspired axisymmetric
pretension loading scheme is developed which enables the 3D-wedge seal conditions to be
replicated in a computationally efficient axisymmetric form for connection performance
evaluation. Seal metrics are developed and converged to evaluate connection sealing capabilities
in the power-tight configuration. Modeling error metrics are developed, and the final 3D-wedge
model is evaluated relative to the experimental DIC data.

Oil Country Tubular Goods, Connection Make-up, Finite element method, Digital Image Correlation