Abstract: 

At the 2022 UK Regional User Group Meeting in Manchester the author presented a detailed computer simulation of an M16 threaded connection which incorporated a large amount of pre-load. The aim of those simulations was to prove, or otherwise, the assertion that my father had given me: namely that a long-handled screwdriver would release a tightened screw more effectively than a short/stubby one. The simulations showed that the long screwdriver provided greater torsional flexibility and this was thought to enable the human (on the other end of it) to apply more energy to the release of the screw.

The author is in the process of extending the screwdriver work to include a further trick that could help loosen such a pre-loaded assembly. The “ehancement” will be revealed at the Gothenburg RUM and computer simulations will be used to prove the worth of this trick.

The simulations will all use finite-sliding contact, large displacements and include non-linear geometry effects. The author will also table some fears about the original work and employ mesh enhancements to support (or otherwise) those concerns. The presentation will be of interest for all those old-school users of Abaqus whose daily concerns involve contact and friction, accuracy of stress predictions and the closeness that their work mimics reality. Coupled to the above, the author will attempt to make the human connection between the human “feel” of a tool (such as the screwdrivers in question) and the simulation results which quote torque and net rotation and the like.

Presenters: 

Bob Johnson Technical Director - Realistic Engineering Analysis Limited Bob has used Abaqus since 1993 and other codes (including Boundary Element) since around 1980. Bob still works at the "coal face" making detailed consultancy models which all nowadays involve contact; friction; finite-sliding; plasticity and ultimate failure. Bob joined the SIMULIA Champion Program in 2026.