The parameters that you use to create a bottom-up mesh are similar to those that Abaqus/CAE uses to create a comparable top-down swept mesh. In the top-down meshing methods, Abaqus/CAE automatically selects the required geometric sides for the region. Top-down swept meshes—including extruded and revolved meshes—are discussed in “Swept meshing of three-dimensional solids,” Section 17.9.3. The parameters used in the bottom-up mesh methods are described below.
Source side
The Source side is a required parameter that defines the face or faces on which Abaqus/CAE will create a two-dimensional mesh that will be swept, extruded, or revolved to create a three-dimensional mesh. The source side may be a combination of geometric faces, element faces, and two-dimensional elements; you can also select saved surfaces instead of selecting from the viewport. For a top-down mesh Abaqus/CAE limits the angularity between multiple faces that it selects as the source side (for more information, see “Characteristics of the geometry can prevent a part from being swept meshable,” Section 17.9.5). There is no limit on the angle between the faces that you can select as the source side of a bottom-up mesh. However, increased angles between the source side faces or between the sourcewill result in decreased quality in the three-dimensional elements.
Connecting sides
Connecting sides define the direction of a swept region. Connecting sides may be a combination of geometric faces, element faces, and two-dimensional elements. Every connecting side must have only a single four-sided geometric face or be comprised of four-sided combined geometric faces, element faces, and two-dimensional elements that form a regular grid pattern.
In a top-down swept mesh Abaqus/CAE creates connecting sides along all edges of the source side. The connecting sides extend completely from the source side to the target side. In a bottom-up swept mesh connecting sides are optional for geometry, but it is recommended that you include as many connecting sides as possible. Connecting sides help to control the mesh as it is swept through the three-dimensional region and enforce associativity in the resulting mesh. Including connecting sides reduces the amount of work needed to clean up and associate the bottom-up swept mesh with the geometry. Connecting sides for a bottom-up mesh may extend completely from the source side to the target side or they may cover only part of the distance. They may also be used without a target side, in which case the end of the connecting sides defines the end of the bottom-up swept mesh. For more information, see “Defining connecting sides for a bottom-up swept mesh,” Section 17.11.7.
Target side
The Target side defines the end of a swept mesh or an extruded mesh. You cannot select a target side for revolved or offset bottom-up meshes. The target side of a swept mesh must be a single geometric face; the target side for an extruded mesh can be one or more geometric faces, a group of element faces, or a datum plane. The target side is not required for a swept mesh unless you have not included any connecting sides. However, including a target side helps you control the mesh and, if applicable, enforce associativity of the mesh to geometry. Abaqus/CAE creates a mesh for the target side by projecting the nodes from the source side if connecting sides are not used or from the last layer of nodes if connecting sides are used. The projected nodes may be positioned outside of the selected geometric target side. The target side is optional for an extruded mesh and is used only to establish the extrusion distance; selection of mesh faces for a target side will not change the extruded mesh to conform to the existing nodes and element faces.
Number of layers
The Number of layers parameter defines the number of layers of elements that Abaqus/CAE generates along the sweep, extrude, or revolve direction. If you select the bottom-up sweep method and select connecting sides, the number of element layers is driven by the mesh or seeding of the connecting sides, similar to the top-down meshing techniques. If you do not select connecting sides for the sweep method or if you choose the extrude or revolve methods, you must specify how many element layers Abaqus/CAE should generate.
Vector
The Vector parameter defines the extrusion direction and, optionally, the distance for an extruded mesh. You select an extrusion vector by picking a start point and an end point from the nodes, vertices, datum points, and interesting points in the viewport. Abaqus/CAE extrudes the mesh from the source side by the direction and, if applicable, distance of the vector regardless of where in the viewport you define the vector.
Axis
The Axis parameter defines the axis of revolution for a revolved mesh. You can define the axis of revolution by selecting two vertices, nodes, datum points, or interesting points from the viewport.
Angle
The Angle parameter defines the angle of revolution for a revolved mesh. You must specify the angle of revolution for the bottom-up revolve technique to indicate where Abaqus/CAE should end the revolved mesh.
Bias ratio
The Bias ratio parameter defines a change in the element thickness between the source side and the end of an extruded bottom-up mesh in which more than one layer is created. The bias ratio is the ratio of the thickness of the first layer of elements in the extruded mesh to the thickness of the last layer of elements. A bias ratio less than one creates thinner layers near the source side, a ratio of exactly one has equal thickness layers throughout, and a ratio greater than one creates thicker layers near the source side. Abaqus/CAE evenly distributes the bias through the number of layers in the extrusion.