Conditions for Local Shrinkage Compensation

The shrinkage evaluation according the local method are based on a large number of factors, tolerances, that can be controlled by the customer in order to tune the shrinkage compensation according to the experiences and needs of the specific yard. This is done via a large number of default parameters. Their use has partly been explained in the description of the local shrinkage method in section Local Shrinkage Compensation Method. However, in the ppanparts and platemark default files the names used there should be preceded by prefix SHRINKAGE_. A condition for proper operation is that the name of the shrinkage object has been assigned to the ip SHRINKAGE. The default parameters are:

SHRINKAGE_FLA_LIM, <fla_lim>,

Flanges in holes will not participate in shrinkage evaluation if they are smaller than <fla_lim> mm. Default value is 2000 mm.

SHRINKAGE_FLA_DIST, <fla_dist>,

Fictitious marking traces for flanges are created <fla_dist> mm from the boundary. Default value is 5 mm.

SHRINKAGE_TOL_MAXPART_IND, <tol_maxpart_ind>,

If any individual stiffener pitch exceeds <tol_maxpart_ind> mm, no longitudinal shrinkage should occur. Default value is 2000 mm.

SHRINKAGE_TOL_MAXPART_AVE, <tol_maxpart_ave>,

If the average stiffener pitch perpendicular to the shrinkage direction exceeds <tol_maxpart_ave> mm, no longitudinal shrinkage should occur. Default value is 2000 mm.

SHRINKAGE_TOL_STR, <tol_str>,

Curved contours will be approximated by a straight line if the relation between the "amplitude" of the contour and the length between the end points is less than <tol_str>. Otherwise the contour will be excluded from the shrinkage calculation. Default value is 0.25.

SHRINKAGE_TOL_ANG, <tol_ang>,

Two lines are supposed to be parallel (and in principle possible to combine) if their direction angle deviates less than <tol_ang> degrees. Default value is 5 degrees.

SHRINKAGE_TOL_DIST, <tol_dist>,

Two lines with the same direction in the sense of <tol_ang> are supposed to be able to be combined if at least one of the end points of the second line is within a perpendicular distance <tol_dist> mm from the line defined by the first line. Default value is 20 mm.

SHRINKAGE_TOL_DIR, <tol_dir>,

Two lines are considered to have the same direction if their directions deviate less than <tol_dir> degrees. This tolerance is used for internal welding traces in the evaluation of the shrinkage direction. Default value is 5 degrees.

SHRINKAGE_TOL_EDIR, <tol_edir>,

Corresponding tolerance to be used for "fictitious" marking traces, that means, for edge welding. Default value is 10 degrees.

SHRINKAGE_TOL_FACT, <tol_fact>,

The shrinkage direction is affected by both fictitious and actual traces. However, the real ones have a higher "weight" in the evaluation. <tol_fact> specifies the weight factor. Default value is 10.0.

SHRINKAGE_TOL_2ANG, <tol_2ang>,

Least allowable angle between the primary and secondary directions. Default value is 50 degrees.

SHRINKAGE_TOL_2LEN, <tol_2len>,

The accumulated length (L2) of the secondary direction must at least exceed <tol_2len>*L1 to be considered (where L1 is the accumulated length of traces in the primary direction). Default value is 0.5.

SHRINKAGE_TOL_RECT_AREA, <tol_rect_area>,

Factor for 'fullness check' of a plate part relative to min-max rectangle in the shrinkage direction. Default value is 0.65.

SHRINKAGE_TOL_TRIA_AREA, <tol_tria_area>,

Ditto for acceptance as triangular plate. Default value is 0.55.

SHRINKAGE_TOL_RECT_DIAG, <tol_rect_diag>,

Used for check of distances from corners of min-max rectangle to plate part as a factor of rectangle diagonal. Default value is 0.33.

SHRINKAGE_TOL_RECT_EDGE, <tol_rect-edge>,

Ditto for comparison with length of shortest edge of min-max rectangle. Default value is 0.85.

SHRINKAGE_TOL_K1SFT, <tol_k1sft>,

Factor for relative length of an individual marking trace to be accepted for perpendicular shrinkage. Default value is 0.2.

SHRINKAGE_TOL_K2SFT, <tol_k2sft>,

Factor for average length of marking curves for perpendicular shrinkage. Default value is 0.4.

SHRINKAGE_TOL_K1SFL, <tol_k1sfl>,

Factor for relative length of an individual marking trace to be accepted for longitudinal shrinkage. Default value is 0.4.

SHRINKAGE_TOL_K2SFL, <tol_k2sfl>,

Factor for average length of marking curves to be accepted for longitudinal shrinkage. Default value is 0.4.