hypermesh单元质量参数说明

弦长偏差Curved surfaces can be approximated by using many short lines instead of a true curve.

Chordal deviation is the perpendicular distance between the actual curve and the approximating line segments.

最小长度，计算使用以下两种方式：Minimum element lengths are calculated using

one of two methods:

?

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

?

The shortest distance from a corner node to its opp the case of tetra elements); referred to as "height t

You can choose which method to use in the Check Element Settings window. Note that this setting

also affects the calculation of Aspect Ratio.

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 containing the legs of the quadrilateral that do not include this node. The figure above depicts these lengths as red lines. Height to Closest Node is taken to be the minimum of all eight lines and the four edge lengths (thus, the minimum of 12 possible lengths).

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

skew.

四边形对角节点连线分割成两个三角形。锥度等于1减去最小三角形面积除以四边形一半面积的比值。

Taper ratio for the quadrilateral element is defined by first finding the area of the triangle formed at each corner grid point:

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".

Warpage

of up

to five degrees is generally acceptable.

）HyperMesh uses 2 methods to calculate the minimum element size: the shortest edge (in which the length of the shortest edge of each element is used) and the height to closest node (which is more accurate, but more complex). In the height to closest node method,

HyperMesh calculates the closest (perpendicular) distances to the planes formed by the opposite

faces for each corner node.

The resulting minimum length/size is the minimum of all such measured distances.

面的距离计算，除以面积平方根。最。网格塌陷，这个值误以为质量差的四面体单

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

其他单元都被赋体扭曲度等于四面体单元体This check applies only to tetrahedral elements; all others are assigned values of zero. Volume Skew is defined as 1-shape factor, so a skew of 0 is perfect and a skew of 1 is the worst possible value.

The shape factor for a tetrahedral element is determined by dividing the element’s volume by the volume of an ideal (equilateral) tetrahedron of the same circumradius. In the case of tetrahedral elements, the circumradius is the radius of a sphere passing through the four vertices of the tetrahedron.