I am using simscale to analyze the stress and deflection of a pressed aluminum panel under wind load. The Load is applied as a force to a face and the connections (rivets) are modelled as holes with a remote displacement boundary.
The model is non-linear and I have run it as 2 simulations;
1st Order Mesh
2nd Order Mesh
Under 1st Order Mesh Model
Deflection = 0.491mm
Stress = 20Mpa
Under 2nd Order Mesh Model
Deflection = 11mm
Stress = 241Mpa
As you can see I am having very large differences in the results and would appreciate any comments as to why this may be happening.
As far as static analysis go, second-order elements are always recommended for accuracy. For more notes, please check the following documentation page.
PS: as a good practice, make sure to run mesh sensitivity studies for your case!