See “Applying constraints to edge seeds, ” Section 17.16.5, for further information on setting seed constraints. If desired, change the default seed constraints by clicking the Constraints button in the prompt area and responding to the dialog box that appears. If you selected edges that you previously seeded using a combination of element size or number parameters, Abaqus/CAE provides an As Is option that allows you to retain the size parameters on the selected edges. When you have finished selecting edges, faces, or cells, click Done in the prompt area.įrom the Local Seeds dialog box that appears, choose the bias control ( Single or Double). For more information, see “Filtering your selection based on the type of object, ” Section 6.3.2. To select faces or cells to seed, use the Selection toolbar to change the type of object that you can select to Face, Cells, or All.
The location of your selection does not influence the seeding.īy default, Abaqus/CAE allows you to select only edges to seed. You can select only edges for single-bias seeding, and you must select each edge near the end where you expect the mesh to be denser.įor double-bias seeding, toggle off Use single-bias picking and select the edges, faces, or cells you want to seed. (For more information, see “Using the Mesh module toolbox, ” Section 17.15.)Ĭhoose the approach for picking from the viewport:įor single-bias seeding, toggle on Use single-bias picking and select the edges you want to seed.
In addition to this detailed overview, the user subroutines are added as supplementary material to this tutorial, which can be used as the ideal starting point for biomechanical engineers to implement their own material models at different levels of complexity.You can also click the tool, located with the seed tools in the Mesh module toolbox. The results show that the four implementation variations are very similar, with total relative errors between 10 − 3 and 10 − 15, number of iterations that varied by maximum one iteration, and a comparable CPU time. In these test cases, stresses, displacements, reaction forces, the required number of iterations and the total CPU time were compared.
Abaqus 6.14 edge seed bias series#
All cases are thoroughly verified by applying a series of deformations on a single cube element and by simulating an extension-inflation experiment with non-homogeneous deformations and multiple elements. In addition, three different element formulations are used: a continuum compressible, a continuum incompressible and a plane stress incompressible. The Gasser-Ogden-Holzapfel material model is used as an example, resulting in four implementation variations: the built-in implementation, a UANISOHYPER_INV formulation, a UMAT with analytical tangent stiffness formulation and a UMAT with numerical tangent stiffness formulation. This paper provides a detailed description, at the level of the biomedical engineer, of the implementation of a nonlinear hyperelastic material model using user subroutines in Abaqus®, in casu UANISOHYPER_INV and UMAT. This is a complex undertaking, requiring extensive knowledge while documentation is limited. However, since these pre-programmed models are presented to the user as a black box, without the possibility to modify the material description, many researchers turn to implementing their own material formulations.
Abaqus 6.14 edge seed bias software#
Pre-programmed material models for biological tissues are available in many finite element software packages. Using an adequate material model that describes the mechanical behavior of biological tissues is essential for a reliable outcome of the simulation. Finite element modeling is often used in biomechanical engineering to evaluate medical devices, treatments and diagnostic tools.