7th November 2016

Case Study #1: NVH properties of bells?

Case Study #1: NVH properties of bells?

When a bell is struck, the impact causes a number of different vibrations or modes. The frequency and intensity of these modes is predominantly affected by the profile of the bell. For every bell manufacturer, the profile they use is unique and gives the characteristic timbre associated with them.

The quality in the design and manufacture of their bells is renowned throughout the world, perfecting their methodologies over centuries of experimentation and iterative improvement. Their bells are traditionally cast from a bronze alloy in a size appropriate for the desired pitch, and finely tuned using a lathe and calibrated tuning forks. John Taylor bells are recognised as having a colourful and rich timbre whilst retaining a pure tone. In English style change ringing, a bell is normally manufactured as part of a set, or peal, containing up to 16 bells, tuned to a diatonic major scale. Consequently, the relative pitch of the bell to the peal is more noticeable than the absolute pitch of the bell.

Mike Semken, Director, John Taylor and Co. Bell Foundry: “I am very impressed with the finished images and results and I am very pleased to see that they match my own FEA work very closely.”

Martin Cockrill, Technical Specialist at ASDEC said:

“Traditional techniques at best can only provide a coarse glimpse into the murky world of structural dynamics. By utilising ASDEC’s advanced robotised 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.”

Detail, Detail and even more Detail!

Each bell was scanned with approximately 4000 measurement locations, giving resolution that would be unimaginable with traditional instrumentation.