Ah OK - I found out that this has been a commonly asked question. In Abaqus the C3D8 element "is base don Hughes' selective reduced integration (SRI) method" and therefore not a really fully integrated element.
https://www.researchgate.net/post/Stiffness_matrix_of_abaqus_element_c3d8_and_by_my_8_noded_isoparametric_element_is_not_matching-can_anyone_help Sorry again for the spam, Shawn -- Yuxiang "Shawn" Wang, PhD yw...@virginia.edu +1 (434) 284-0836 On Tue, Dec 4, 2018, 22:59 Yuxiang Wang <yw...@virginia.edu wrote: > Sorry that I just realized that I wasn't clear in the boundary conditions: > > I fixed the MIN_X side of the model, and applied -Z traction on the > surface of MAX_X. The resultant displacement on the MAX_X surface is about > -3e-3 in ABAQUS, but only -2.2e-3 in the libmesh model. The other > directions and the magnitude of the displacement vector is also drastically > different. > > Shawn > > On Tue, Dec 4, 2018 at 10:53 PM Yuxiang Wang <yw...@virginia.edu> wrote: > >> Dear all, >> >> Sorry to spam again. >> >> I was playing with ABAQUS & libmesh and noticed that the single element >> result for simple linear elasticity model is different. I know that there >> could be many factors that is leading to this (e.g. ABAQUS doing tricks >> that I am not aware of), but I'd really appreciate it if anyone could help >> provide some guesses on why this is the case, even for a simple >> single-element model. Thanks! >> >> Both models are 2x2x2 cubes (from -1 to +1 so the coordinate matches the >> bi-unit domain). I added a surface traction of -0.25 in the -Z direction, >> and observe the resultant displacements in Z. The ABAQUS model is attached >> (Job-1.inp), and the modified elasticity example is also attached. The >> resultant displacement, especially at the Z direction, is totally different: >> >> >> [image: image.png] >> >> Any tips would be much appreciated! >> >> Best, >> Shawn >> -- >> Yuxiang "Shawn" Wang, PhD >> yw...@virginia.edu >> +1 (434) 284-0836 >> > > > -- > Yuxiang "Shawn" Wang, PhD > yw...@virginia.edu > +1 (434) 284-0836 > _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
