Deflection Measurement 2

[Amir.Ghafoor]

What is the latest method to record deflections during testing of material.

A bit background to the question is as follows.

I am in a firm where we are starting to test scaffolding material as per Australian codes. The head of operations has asked me to figure out all Equipements required for the purpose of testing. Now, there are so many ways to record deflection during loading and unloading. For the sake of safety, it is very crucial that my readings are as accurate as possible. So, with all the latest equipment out there, which method is the best in terms of accuracy for vertical and horizontal deflections? Most of our products are going to be aluminum.

All responses and suggestion are very welcome. Currently, I think that a theodolite can give me what I need.

 

[1503-44]

My father was a metallurgist who made titanium parts for jet engine and spacecraft components. He asked me why we didn't use titanium in making our typical skyscrapers. I thought about that for a bit and told him that Ti has a Young's modulus about half that of steel, so lateral deflections of skyscrapers might be so high, maybe they'd collide with each other at the top floor levels. Not to mention the cost.

I doubt you need to have measurement of scaffolding deflections to the nanometer. Nor will you be able to waste so much time and money taking those measurements. In fact I doubt you can even assemble scaffolding to +/- 1mm tolerance, so measurement accuracy to a nanometer makes no sense. If you really need 1mm, scaffolding is not your answer, nor should that scaffolding be made from Al.

First establish a reasonable measurement criteria that is consistent with the required accuracy and material limits needed of of your finished work. It's simply foolish to measure nm when +/-1mm would do just fine.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[SWComposites]

it is very crucial that my readings are as accurate as possible. So, with all the latest equipment out there, which method is the best in terms of accuracy for vertical and horizontal deflections? laser. do you need this, probably no. see above reply.

 

[1503-44]

Realistically, if not already overkill, you probably do not need more than this with some kind of signal processor.
Ultrasonic

https://www.walkerindustrial.com/Ba...Measuring-Sensor-with-b-p/unck-09u6914-d1.htm

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[Amir.Ghafoor]

The replies are very well appreciated. In my thread I pointed out a few details that I assumed should give a picture of the measurement criteria.

1. The material used in manufacture is going to range from t4 to t6 of 6061 aluminium alloy.

2. Aluminium is more ductile than steel, during testing I can see deflections with naked eyes. Now nanometers is going to be a huge overkill but 0.01 mm is most desirable accuracy in our case, however, 0.1 mm will still be acceptable. The manufacture tolerance is kept at 0.5 mm anyways.

3. I believe laser can be the best tool. But I have to figure out a cost effective mechanism to ensure an all in one solution if possible.

I hope the above information coupled with my original thread can clarify my goal.

The requirement is hence reiterated here:

1. What is the latest method to record deflections during testing of material?

2. Which method is the best in terms of accuracy for vertical and horizontal deflections?

I have already pointed out using a theodolite. I am open for using lasers but not sure which type of laser shall be up for the task. It can be something very simple given the measurement criteria.

 

[1503-44]

Do not do the theodolite option.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[MTNClimber]

Attach a dial gauge with a magnetic base to a tripod and have it measure the deflection of the scaffolding. We do it all the time with pile load tests, soil nail tests, and tie back testing and lock-off. Ours measure displacement with a thousandth of an inch accuracy.

 

[Amir.Ghafoor]

I agree with the dial gauge, I already have ordered two variants for the dial gauge. It is going to work with vertical deflections at easy to access levels. Now, I really don't want to proceed with the Theodolite as well but there is the case of lateral deflections and movements as well as vertical deflections at elevated levels (2 meters and above). For that reason, I am trying to device a method that will help us record measurements within the desired accuracy.

 

[dik]

A regular dial gauge... likely the easiest.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Amir.Ghafoor]

There is no fancy dial gauges anyways. Still open for further suggestions

 

[MTNClimber]

You can’t find a “fancy” dial gauge? The internet has a ton of dial gauges for sale. What constitutes a “fancy” one?

 

[Amir.Ghafoor]

What I was insinuating is that dial gauge in itself is a smart and simple tool. Hence there is nothing fancy to it without killing the inherent principle by which it shows movements to the accuracy of 0.01 mm. Hope that clears the question.

 

[dik]

If you are looking for that precision, my first question would be why. You can get it using LVDTs, but there is likely no merit. I did a cantilevered jib once for China. It was for measuring turbine 'flatness' and it had to have an accuracy of 0.003", but that was exceptional.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Amir.Ghafoor]

The answer to the question is that the final product after passing the tests will be supplied to the public to use on commercial projects at elevation and conditions that are generally quite dangerous if the equipment is not safe enough. In other words, performance and serviceability has to be measured in accordance with the industry standards for certification and safe working.

 

[dik]

You can have it safe enough without that precision. The two are generally unrelated.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik