ABAQUS Cantilever Beam Bending Simulation using B8 elements

[John007Smith]

I am trying to verify my finite element analysis codes written in MATLAB with commercial code ABAQUS. I am using a simple cantilever beam bending problem using B8 elements. I am pretty sure my MATLAB code is accurate but the displacements from it don't match the ones from ABAQUS. Does ABAQUS use some kind of tricks to make the B8 element better in bending? This is bugging me for a long time. Can someone help? My ABAQUS input file is attached.

 

[IceBreakerSours]

Too few elements through the thickness of the beam. Increase the mesh density. Remember that the beam "sees" both tensile, compressive and shear stress. In order for FE to model such transitions in short distance, you need to provide more than just a couple of elements.

Besides, you used "linear" hex elements, which is to say that displacement can only vary linearly in one such element => strain (spatial derivative of displacement) must be constant in one such element => stress must remain constant in one such element. Quad hex elements allow strain to vary linearly.

Use the ABAQUS documentation for details.

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[John007Smith]

Thanks! I understand what you are saying. I know that B8 is not the element of choice when it comes to bending problems. I am only using this example using B8 just to benchmark my MATLAB code. My question was more to understand what ABAQUS does in situations when the mesh is coarse B8.

 

[IceBreakerSours]

You used C3D8 elements, not beam elements.

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083