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Engineering Analysis - Tips & Tricks: 3 Steps to verify FEA results.

Before you set up an FEA, we suggest taking the following steps as checks to validate the FEA results. It may take a little bit of time, but it could help you catch out errant FEA results which could save you money and prevent disaster!

1. Draw a sketch of the expected deflections.
This may seem simple, but spend some time thinking about how the body is going to deform when the load is put on it. This is not to say that your assumptions may be wrong, but at least by putting some thought into what you expect to happen, then when you get an FEA result that is vastly different you can analyse why it's not what you expected, OR why the FEA was wrong!

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2.Draw and calculate Free Body Diagrams.
Calculate the reaction loads.  By doing this manually, when the FEA has run you can inspect the reaction loads, the global loads should be the same as your calculations unless the structure is indeterminate in which case hand calcs can vary.  Otherwise if there is a discrepency between the free body reaction forces and the FEA reaction forces there may be something wrong with your FEA load or boundary conditions?

3.Calculate stress or strain at some point in the model

Doing hand calculations of the expected stress or strain in the model, helps to check that you have applied the correct loads. Choose somewhere that is relatively easy to do a hand calculation on ie. where the geometry is nice and simple where 'I' values can be easily attained.   Once the FEA has run you can compare the results with your hand calcs. The percentage difference should be around 5% for simple parts/calculations and up to 20% for more complex situations.

Summary
These upfront verification tasks will help keep your analyses on track. Once the analysis has run the verification and validation work really begins - but that's for another tip!