In-cavity residual stress in second principal direction result

The In-cavity residual stress in second principal direction result shows the stresses, before ejection, in the direction perpendicular to the first principal direction.

This result is generated by a Pack analysis using Midplane or Dual Domain analysis technologies, and shows the stresses, before ejection, in the direction perpendicular to the first principal direction.

Note: This result is not generated if the Residual Strain shrinkage model is selected for the material used in the analysis. View the material properties data for the specified material on the Thermoplastics material dialog (Select Material > Details > Shrinkage Properties tab).

Using this result

Residual stresses in the part can be created as a result of shear stresses generated during mold filling or packing. In addition to these flow induced stresses, residual stresses can also be created by different areas of the part cooling at differing rates due to variations in the part surface temperatures when it is ejected. To minimize these stresses, uniform cooling is required.

These residual stresses can be the cause of premature part failure in service or of part warpage and distortion.

Note: The in-cavity residual stress is calculated by the Pack analysis and represents the stresses in the part before it is ejected. It does not necessarily reflect the stresses that a part experiences after ejection. This result is best used as an input to a Warp or Stress analyses, such as Warp or Abaqus, rather than by itself.

Things to look for

Positive values on the plot indicate tension and negative values indicate compression.

• In-cavity residual stresses are almost always positive because the part is still under constraint within the mold. The mold physically prevents the material from shrinking while the part is in the cavity. The result of that is a stress that keeps the element stretched in its place. However, when the part is ejected, this stress is relieved and the part may shrink.
• Negative values indicate overpacking has occurred.

For a more accurate indication of which portions of the part are under tension and which are under compression, use the Warp stress results.