hypermesh单元质量参数说明

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Hypermesh单元质量参数说明

Curved surfaces can be approximated by using

many short lines instead of a true curve.

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-可编辑修改- Minimum element lengths are calculated using one of two methods:

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The shortest edge of the element. This metho non-tetrahedral 3-D elements.

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The shortest distance from a corner node to it face, in the case of tetra elements); referred to node".

You can choose which method to use in the Check Element Settings window. Note that this setting also affects the calculation of Aspect Ratio.

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-可编辑修改- Height to Closest Node (HCN) is calculated differently for different element types.

For triangular elements:

For each corner node (i) HyperMesh calculates the closest (perpendicular) distance to the ray including the opposite leg of the triangle, h(i). HCN = min(hi) * 2/sqrt(3.0). The scaling factor 2/sqrt(3.0) ensures that for equilateral triangles, the HCN is the length of the minimum side.

For quadrilateral elements:

For each corner node, HM calculates the closest (perpendicular) distances to the rays

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-可编辑修改- Skew of triangular elements is calculated by finding the minimum angle between the vector from each node to the opposing

mid-side, and the vector between the two adjacent mid-sides at each node of the element.

The minimum angle found is subtracted from ninety degrees and reported as the element’s skew.

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-可编辑修改- These areas are then compared to one half of the area of the quadrilateral.

HyperMesh then finds the smallest ratio of each of these triangular areas to ? the quad element’s total area (in the diagram above, "a" is smallest). The resulting value is subtracted from 1, and the result reported as the element taper. This means that as the taper approaches 0, the shape approaches a rectangle.

Triangles are assigned a value of 0, in order to prevent HyperMesh from mistaking them for highly-tapered quadrilaterals and reporting them as "failed".

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-可编辑修改- quads. The quad is divided into two trias along its diagonal, and the angle between the trias’ normals is measured.

Warpage of up to five degrees is generally acceptable.

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-可编辑修改- The resulting minimum length/size is the minimum of all such measured distances. The height of the tetra element is measured from each of the four nodes to its opposite face, and then divided by the square root of the face’s area.

The minimum of the four resulting values (one per node) is then normalized by dividing it by 1.24. As the tetra collapses, the value approaches 0.0, while a perfect tetra has a value of 1.0. Non-tetrahedral elements are given values of 1 so that HyperMesh won’t mistake them for bad tetra elements.

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