# Check or Smooth Shapes

Use the Check/Smooth function to check the element quality of shape combinations and optionally smooth the shapes to improve the element quality when applied individually or as part of a combination of shapes.

The check and smooth functionalities are intended to make shape optimization more productive. Shape optimization solvers, like Radioss, will stop iterating if the element quality falls below certain limits. The check and smooth functions help to improve the element quality when shapes are applied simultaneously as well as calculate the maximum and minimum bounds at which the shapes can be applied to ensure successful completion of an optimization run.

```
Element quality limits
Trias
Test Warning Error Invalid
Aspect ratio 50.000 500.000 10000.000
Skew 75.000 85.000 90.000
Minimum angle 15.000 3.000 0.000
Maximum angle 165.000 177.000 180.000
Warpage ------- ------- -------
Tetra collapse ------- ------- -------
Jacobian ------- ------- -------
```

The second section of the report file contains one sub-section for each combination of the selected shapes. Each sub-section will contain a list of the selected shapes and the multiplier applied to each one for the given combination. Each sub-section will also contain the value of the worst element quality for each of the following active tests: aspect ratio, skew, minimum angle, maximum angle, warpage, tetra collapse, and jacobian. The worst result for each test is measured against the element quality limits to determine whether an optimization run will give a warning or an error, and if so it will be noted in the given sub-section along with the offending element ID and the element test limits for that element type.

```
Combination 15
Shape 2 applied at 1.0000
Shape 3 applied at 1.0000
Shape 4 applied at 1.0000
Shape 5 applied at 0.0000
***** warning - poor element quality *****
Aspect ratio 4.240
Skew 60.303 Elem id 112 Limits: 60.000 75.000 90.000
Minimum angle 26.718
Maximum angle 158.141
Warpage 0.000
Tetra collapse 1.000
```

```
Optimization errors can be avoided using the following limits:
Shape 2 upper bound 0.9230 lower bound 0.0000
Shape 3 upper bound 0.8680 lower bound 0.0000
Shape 4 upper bound 0.9230 lower bound 0.0000
Shape 5 upper bound 0.8680 lower bound 0.0000
```

If you set
the upper and lower bounds on your DESVARs to these values, the optimization run
should not encounter any errors due to element quality regardless of the combination
of shapes applied.