Engineering news
Modern robotic laser measurement technology has helped a bell foundry that can trace its roots back to the 14th century fine tune its products.
The Advanced Structural Dynamics Evaluation Centre (Asdec) consultancy at the Mira technology park, Warwickshire, employed the latest robotised 3D scanning laser vibration measurement system to scan two large bells made by Loughborough-based company John Taylor & Co.
Asdec, which is part of the University of Leicester and was set up in 2014, measures and analyses vibrations and then engineers products with reduced vibration levels, or promotes vibration levels in products where it is desired.
The structure, in this case a bell, was excited through an electrodynamic shaker over several hours. The input force was recorded and the output force measured in three dimensions at over 4,000 different points using the robotic laser. The measurements were then translated into the visual data that can be seen in the video above.
Tim Stubbs, general manager of Asdec, said: “Physical vibration testing and analysis is now at a level where it is comparable to Finite Element Analysis [FEA].
“John Taylor have a FE model and we correlated our physical test data with their simulated model to verify and then update it.”
Doppler vibrometry (LDV) uses the deflection of laser beams as they strike a vibrating object to measure vibration
FEA computer modelling is a computerised method for predicting how a product reacts to real-world forces, vibration, heat, fluid flow, and other physical effects.
Traditionally, vibration measurement is conducted with accelerometers. However, this is a slower process, does not give the same level of detail and gives skewed results because the accelerometers are stuck onto the bell, said Stubbs.
Martin Cockrill, technical specialist at Asdec, said: “Traditional techniques at best can only provide a coarse glimpse into structural dynamics.
“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.”
Asdec works in a broad range of sectors, from buildings and infrastructure to logistics, medical and aerospace, but expects its “mainstay” to be the automotive sector over the coming years, added Stubbs.
John Taylor & Co. traditionally cast their bells from a bronze alloy in a size appropriate for the desired pitch, and then finely tune using a lathe and calibrated tuning forks. John Taylor bells are recognised as having a colourful and rich timbre whilst retaining a pure tone.
Mike Semken, director of the John Taylor and Co. bell foundry, said: “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.”
The project was paid for by the government’s Regional Growth Fund and the European Regional Development Fund.