17.6.1 Verifying your mesh

ABAQUS/CAE provides a set of tools in the Mesh module that allow you to verify the quality of your mesh and to obtain information about the nodes and elements in the mesh. You can use these tools to isolate regions where the mesh quality is poor and to guide you if you need to refine your mesh. To verify the quality of the mesh, choose the Object from the context bar, and select MeshVerify from the main menu bar. You can then select the part, part instances, geometric regions, or element to verify. ABAQUS/CAE allows you to choose between checking that your mesh will pass the quality tests in the analysis products and checking that your mesh passes individual quality checks, such as checking for elements with a large aspect ratio. For detailed information on using the mesh verify tools, see “Verifying element quality,” Section 17.16.1.

You can use the Analysis checks to verify that the elements in your mesh will pass the element quality checks that are included with the input file processor in ABAQUS/Standard or ABAQUS/Explicit. ABAQUS/CAE highlights any elements that fail the mesh quality tests and displays the number of elements tested along with the number of errors and warnings in the message area. The mesh quality tests in the input file processor are extensive and specific to each element type. At a minimum, the mesh quality tests issue a warning for elements that seem inappropriately distorted, and the tests issue an error if the distortion is severe. ABAQUS/CAE does not support analysis checks for shell, beam, or gasket elements.

You can use the Statistical checks to highlight elements of a selected shape that do not meet one of the following selection criteria:

Smaller face corner angle

ABAQUS/CAE highlights elements containing faces where two edges meet at an angle smaller than a specified angle.

Larger face corner angle

ABAQUS/CAE highlights elements containing faces where two edges meet at an angle larger than a specified angle.

Aspect ratio

ABAQUS/CAE highlights elements with an aspect ratio larger than a specified value. The aspect ratio is the ratio between the longest and shortest edge of an element.

Short edge

ABAQUS/CAE highlights elements with an edge shorter than a specified value.

Shape factor

ABAQUS/CAE highlights elements with a normalized shape factor smaller than a specified value. The shape factor criterion is available only for triangular and tetrahedral elements. The shape factor ranges from 0 to 1, with 1 indicating the optimal element shape and 0 indicating a degenerate element.

For triangular elements the normalized shape factor is defined as

Optimal element area is the area of an equilateral triangle with the same circumradius as the element. (The circumradius is the radius of the circle passing through the three vertices of the triangle.)

For tetrahedral elements the normalized shape factor is defined as

Optimal element volume is the volume of an equilateral tetrahedron with the same circumradius as the element. (The circumradius is the radius of the sphere passing through the four vertices of the tetrahedron.)

Table 17–2 shows the default limits for the selection criteria based on the element shape.

Table 17–2 Selection criteria limits.

Selection criterion	Quadrilateral	Triangular	Hexahedral	Tetrahedral	Wedge
Smaller face corner angle	10	5	10	5	10
Larger face corner angle	160	170	160	170	160
Aspect ratio	10	10	10	10	10
Short edge	0.01	0.01	0.01	0.01	0.01
Shape factor	N/A	0.01	N/A	0.0001	N/A

In addition, ABAQUS/CAE displays the following information in the message area for each selected part instance:

The name of the part or part instance.
The total number of elements of the selected shape in the part instance or in the selected regions.
The number of highlighted elements and the percentage of the elements being verified that these elements comprise.
The average value of the selection criterion.
The worst value found for the selection criterion.