A useful parameter to evaluate the quality of an element is the aspect ratio.
In simulation triangular elements are the main factor in meshing the surface of a part.
The aspect ratio can be determined in different ways.
In Moldex3D for example, the aspect ratio is calculated based on two circles.
The inside circle is touching every edge of the triangle tangential, while the outer on goes through all the edges of the element.
The aspect ratio equals twice the inner radius divided by the outer radius of the circles.
An equilateral triangle has an aspect ratio of 1, a triangle with no surface area has an aspect ratio of 0.
The higher the aspect ratio, the better the quality.
In Moldflow there are different ways to calculate an aspect ratio.
Using one strategy the aspect ratio lies between 0 and 1 similar to Moldex3D.
Another strategy leads to an aspect ratio that starts by 1,16 to infinity. Hereby the smallest value represents the best quality.