Warpage due to corner effects

Warpage is a very common problem in parts that have corners.

There are two main causes for the warpage in corners:

Heat build-up.

The ability to extract heat from corner areas in the part is lower which results in asymmetric cooling and thermally induced stresses.

Differential shrinkage

Due to mold restraint, the shrinkage in the thickness direction is much greater than in-plane shrinkage in corner areas of the part, which results in further deformation.

The thermal effect is taken into account by default in all Autodesk Simulation Moldflow Insight cooling and warpage simulations. The mold-restraint induced differential shrinkage contribution is taken into account if the Consider corner effects option is turned on in the advanced options for the Warp analysis.

For further information about the differential shrinkage effect in corners, and the mathematical approach to calculate and account for this effect, please refer to the following published paper:

Ammar, A., Leo, V., and Regnier, G., "Corner deformation induced by shrinkage anisotropy of injected thermoplastics: Experimental study and numerical approach", PPS-17 (2000)