FEA-enabled estimation of tightening Torque for efficient threaded Connection

Problem definition

A leading company in drilling services in Singapore wanted to estimate the optimal tightening torque to ensure an efficient threaded connection.

This estimation had to be accomplished without using any physical testing methods that could have resulted in failure of the threaded component.

As the problem was to predict behaviour of a threaded connection made of non-linear material, the FE analysis was complex in nature. No established simplified simulation methodology was available and it was important to predict accurate tightening to avoid any joint failure.

Technical approach

Performing FEA on a threaded connection is always a challenge. Based on the available literature, linear 3D FE analysis and theoretical calculation, a 2D axi-symmetric analysis methodology was developed to calculate linear stresses.

Due to simplified FE domain, the actual geometry and its response on stress distribution was captured over the entire torque range. APDL programming was done for the estimation of torque based on results and shown in a graphical format over Torque Range Vs Stresses (non-linear).

Results & Conclusions

  • A Structured approach towards this problem helped complete FE Analysis on 9 connections in record time. FE reports were approved by without any iteration.
  • This virtual testing method saved time, effort and overall cost by reducing the number of physical prototypes for accurate prediction of the optimal torque.