Is FEA Sufficient for Test Certificate

Only one problem:

• An FEA calculation isn't a test.

Just to expand on PWs post.
FEA tells you nothing about the actual physical properties of the finished article or the materials used to construct it, as it may have been constructed from pasta instead of steel, or of tubing without the specified wall thickness.
Del
_{(Other inferior constructional materials are also available)}

Hello Ash-ManEng,

In my experience the Fea results are only as good as the data available for specific materials eg, for plastic we have libraries of specfic materials with all their known parameters. So we can run an FEA and it may look great. But low and behold the molder cooked the material in the dryer and then the residence time in the barrel of the molding machine finished the job for him.

None of the attributes plugged into the software are correct despite the perfect analysis carried out. I hope you get the picture. Tests are done on the actual finished product as the previous responders stated for practical reasons.

Hope this helps.

Your FEA only says that the thing should work.

The test must verify that it does work.

Can this FEA results be used to obtain a test certificate (this will be done by an external company) to comply with UK health & safety regulations or will all the calculations have to be done manually?

I would contact some of the testing companies and see what they require from you. They may not require anything but the finished product.

NO.

Ash-ManEng, my company specializes in lifting and ground support equipment for aerospace. We use FEA and hand calcs during the design phase. It's an absolute requirement to physically test lifting equipment if you expect to meet ASME standards. Static and dynamic load tests are not intended to verify the integrity of the design. It's purpose is to ensure the equipment was built correctly and functions as intended. We load test before paint then magnetic particle inspect all welded assemblies and certain critical machine parts after testing to ensure no cracks appear. This is standard procedure for most companies. Look at ASME B30.2 Below The Hook Lifting Device standards to get an understanding of the requirements. FEA and/or traditional calcs validate your design and load testing validates the manufacturing. You need both for certification.

For use in the UK the equipment must comply to the "Lifting Operations and Lifting Equipment Regulations 1998" (LOLER). This is a requirement under the Health & Safety legislation. Google LOLER for specific details of the required tests and certification.

Thanks a lot for all your replys...

What I am trying to do is to get the "lifting fixture" load tested by an external company. However, after speaking to them they have asked me to supply them with technical drawings which I already have & all calculations which I don't have cause I used the FEA to verify the design integrity & strength.

The correct material (Mild steel) and all relevant mechanical properties was used in the FEA test from the library of materials available. Therefore the FEA should refelect the correct results to certain extents. However, I would agree there might be some variations comparing to the finished lifting fixture due to materials imprefections or manufacturing inaccuracies.

This is where my original question comes, can the FEA be used instead of the calcs to get the lifting fixture load tested.

Sorry if my question wasnt very clear...

Jeez, just ask the test house!
It doesn't matter what we say, it's up to them, and I don't really see why they need any calcs at all.
If you gave them a fixture designed and built by a third party, or an old fixture for re-testing with no drawings or calcs they should be able to test it.
You are presumably paying good money to have it tested. Just tell 'em to get on with it!

Anonymous Poster#1 is right, the load testing company has no business asking you for your calcs. Their sole responsibility is to apply the loads as per your diagram/instructions and provide a certificate accordingly. We use accredited 3rd parties for testing all the time and not one of them in the past 20 years has ever asked for our calcs. Why should they? How the equipment was designed is not their problem.

I had a feeling! My cats make the "jeez" sound all the time. It must be the hairballs!