Ding dong wobbly and bright
By Jim Drury
Christmas bells ringing out are a popular feature of the festive season. Colorful images showing their vibration in unprecedented detail have been released by the University of Leicester's Advanced Structural Dynamics Evaluation Center (ASDEC).
Working with John Taylor & Co., a company of local bell founders, the ASDEC team scanned the structural dynamics of two large bells using a robotized 3D laser vibrometry system at approximately 4,000 measurement locations.
Their unique structural dynamic measurement can be used on its own or to correlate against finite element analysis (FEA) computer modeling - a computerized method for predicting how a product reacts to real-world forces, vibration, heat, fluid flow, and other physical effects.
According to Martin Cockrill, Technical Specialist at ASDEC, "traditional techniques at best can only provide a coarse glimpse into the murky world of structural dynamics. By utilizing ASDEC's advanced robotized laser system we were able to reveal the beauty of the bells vibration in amazing detail. A thorough, accurate measurement of any structure empowers designers to correlate their virtual models and rapidly move forward with concepts and designs that are grounded in fact."
When a bell is struck the impact causes various different vibrations or modes, whose frequency and intensity is predominantly affected by the individual profile of the bell.
Bells are one of the earliest known musical instruments, using mechanical resonance to produce a powerful harmonious sound. Bell founding - the casting of bells in a foundry - has been present in Europe since at least the fifth century. In Asia bellfounding dates back to 2000BC.
