An Interview with Kevin Copleston, one of the founders of Sensor Solutions Ltd
They were the very first strain gauges, take a wire, pull it across and pluck it.
Vibes at a frequency.
If pull the ends apart and do the same thing, vibrates at a higher frequency, as the tension has gone up.
So frequency is related to tension, is related to strain.
So very early in the years gone past, say across a canal cutting they’d would stretch a wire, pluck the wire, and, … it’s not affected by electricity, or other things, there’s no spurious effects on it. So you’d pluck it this year, next year, 10 years down the line, if length hasn’t changed, so tension unchanged, frequency stays the same. So frequency is directly related to tension.
That’s the crude method years ago, when they were digging the canals.
Nowadays it’s about this big, and it looks like a Bonio.
It’s got an electronically plucked wire inside here, and electronics and everything else.
And the wire comes out…
(Me) Ah yes used for Geo applications, doesn’t vary, no drift on it etc, etc
Absolutely, stable as hell, because it’s based on plucking a wire and it’s frequency, you cannot use it dynamically, because you’ve got a carrier frequency, and interfere…
It’s for er, uh, er, uh, that’s it.
It’s not for (bang)..
And also it’s that big and so it goes into large structures, into the concrete of car parks, when your putting up the walls of a nuclear reactor, you are interested in slow structural change. Is everything settling, is it going to crack and this sort of thing.
So you can’t stick that on an aeroplane propeller.
It’s a bloody great chunky thing, it’s going to set the measurement (?), change the natural frequency, stiffen the structure locally, but in a large concrete structure, this is more a displacement transducer.
It’ll be thrown in to the concrete, what they’ll do is they wire them to the rebar pour the concrete which then fixes the ends of the Bonios, and sticks all round. But you’ll see them when their doing the wire cages you’ll see these little Bonios with a wire coming out, a little PTFE wire that’ll run back out of the concrete.
So that’s a vibrating wire gauge, they are the old type of strain gauges and they are still sold today by a company called gauge techniques.
Only used for civil engineering, static, or quasi-static applications.
