1. Meshing/elements in Abaqus
Accuracy of an Abaqus analysis strongly depends on the element type , mesh density and thickness elements.
During a study on a thin- flat plate with different loading conditions , significantly different results were obtained depending on the number of thickness elements used.
Problems : - Since reduced integration elements were used , a fine mesh in the bending direction was necessary.
- Only 2 elements were present along the thickness. - Hence Asymmetric behavior at the edges was noticed and a 12% error existed between numerical and analytic results
Fig. 1. Flat Plate under uniform loading with 2 elements through the thickness
9/17/2018
Srisharan.G.Govindarajan

2. Srisharan.G.Govindarajan
Fig. 3. Flat plate after mesh refinement along the thickness
Fig. 2. Finer mesh along the thickness
- Error reduced to less than 1% with a finer mesh along the thickness.
- It was observed that for an analysis using reduced integration elements in Abaqus , there exists an optimum value for the number of thickness elements. - To obtain a mesh independent solution , this optimum value was maintained a constant and the global seed was changed to vary the overall mesh density.
9/17/2018
Srisharan.G.Govindarajan

3. Srisharan.G.Govindarajan
Table 1. Types of Abaqus elements
Incompatible mode elements
Fully integrated linear elements
Reduced integration linear elements
Best of the linear elements
Can represent bending behavior well if they are not distorted
Element edges should be parallel and normal to the direction of bending
Eg : Cantilever beam bending analysis
They are too stiff in bending
Suffer from ‘shear -locking’ .
Should not be used if the model is to respond in bending.
Eg : Useful in simple problems , contact simulations and fully coupled thermal stress problems.
They are less stiff in bending
Suffer from ‘hourglassing’.
This can be overcome by using a really fine mesh in the bending direction.
Eg : Can be used in thin plate bending/deflection analysis , heat transfer problems .
9/17/2018
Srisharan.G.Govindarajan