SSA Blog

Merry Christmas - Virtual Bell Simulation!

Posted by Graeme Short

Merry Christmas everyone. If you are reading this, I assume you haven’t just stumbled across it, and have been lead here either from an SSA email or some form of content feed. If that’s the case, I’m sure you’ve also seen the SSA Christmas newsletter which includes the traditional SSA festive message set against the backdrop of some virtual bells chiming.

This simulation started as an idle thought one day whilst walking through the centre of Bristol as to whether I could simulate ‘Great George’, the bell at the top of the University of Bristol’s Wills Building tower (the 4th largest swinging bell in Britain, fact-fans) using Abaqus/Explict and get anywhere close to replicating its (I have now discovered) noted low-E tone. 

With a time and budget allocation of ‘a couple of lunch hours’ this was never going to be more than a quick hack to satisfy my curiosity, but – with thanks to Google – the geometry took shape, the yoke and clapper geometries were simplified and the interactions dealt with in as simple manner as I could possibly get away with (general contact in Abaqus/Explicit was particularly useful here). Loading the system with gravity then providing an initial torque impulse to the yoke axis generated a tolerable representation of a clapper bell striking for, what turned out to be, very little effort.

With curiosity satisfied, that might well have been it for this particular model, but when ideas were canvassed for the SSA festive message, it seemed to be a good starting point. The original parts were scaled/copied to create two additional, smaller, bells and within a very short space of time the peel of bells in the animation was born.

I have yet to find another free lunchtime to perform the fast-Fourier-transform on the results of the original model bell model to find out if it does indeed match a low-E note, but for the Christmas animation, like most things at this time of year, that doesn’t really matter: it’s the thought that counts!