Page 2: PTrim (Part Trim)

Purpose:

This interface can be used to trim (cut) parts with curves. The target application for this function is to trim parts after a metal stamping operation but it can be useful for other purposes as well. Note that if stresses, strains, and thicknesses are available (typically from dynain files), then upon trimming this data is updated. Adaptive constraints are also handled in the trimming process.

Only one of the following may be selected at a time: Parts, Trim Curves, or Seed element

Parts – when active, parts to trim can be selected by clicking on them in the graphics window.

Trim Curves – when active, curves that should be used for the trim/cut operation can be selected by clicking on them in the graphics window. Curves can be imported in this panel with the Load button. The curve file format has to be set prior to clicking the Load button. Available curve file formats are: VDA, IGES, and LS-PrePost XYZ.

Seed element – when active, elements in selected areas can be moved to a new part or deleted automatically after trimming. To use this function, one seed element in each area to operate on should be picked. There are 3 options for how to handle the elements that are topologically connected to the seed elements after the trimming operation is performed. If the Delete radio button is active, they will all be deleted. If the Move radio button is active, they will all be moved to a new part. If the Keep radio button is active, elements attached to the selected ones will be preserved, and the rest will be deleted.

• Parameters
• Limit: Elements further away than this distance will not be trimmed.
• Tolerance: Nodes close to the trim curve will be moved to the cutting surface if they are closer than Tolerance*element_size. This prevents very small elements from being created on the cut line.

• Trim method
• The elements can be trimmed with two different methods. Both methods cut the geometry with “cutting surfaces” which are displayed as semi-transparent.

Closest 3D proj dir. – The part(s) will be cut with cutting surfaces that are made from the curve and extruded the distance Limit in both positive and negative Vector direction. The vector direction is defined by the x, y, and z fields. The general vector creation function can be activated if the Vector button is clicked. X, Y, and Z buttons for quickly setting the vector to any of the global directions are also provided.

Vector projection – The cutting surfaces are created from the curve definition and are extended in the normal direction of the closest element. This gives a cut on the selected parts as close as possible to the curve. This method is useful when the elements to be cut would be parallel or nearly parallel to the trim vector direction with the previous method. This method can, for example, trim the rubber cut line on a tennis ball, as shown in Figure 2, where the vector projection method would fail.

• Trimming
• When the parts to be trimmed and the trim curves (and optionally any seed elements) have been selected, the trim operation is executed by clicking Trim. The result will be displayed, and the trimmed elements can be kept by clicking Accept or Done. The Done button both accepts the trim operation and exits the PTrim Interface. The trim operation can be rejected by clicking the Reject button after the trim has been made. The *CONSTRAINED_ADAPTIVITY keywords will be preserved or modified to match the new topology along the trim line. The *CONSTRAINED_ADAPTIVITY keywords for deleted elements will be deleted from the model.