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Active Contributor
rmathan
Posts: 37
Registered: ‎02-17-2011

Corrected residual in-mold stress (CRIMS)?

406 Views, 2 Replies
10-30-2012 10:00 PM

Dear Users,

 

I am interested to know more in detail about CRIMS. How it is going to be helpful in simulation? Lot of users are saying this.

 

 

Thanks,

Mathankumar. R

 

 

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Valued Contributor
abakharev
Posts: 62
Registered: ‎08-25-2008

Re: Corrected residual in-mold stress (CRIMS)?

10-31-2012 10:16 PM in reply to: rmathan

CRIMS (corrected residual in-moldi stress) is a way to correct shrinkage and warpage predictions based on experimental shrinkage measurements for another part. This correction is only available for 2.5D analysis (midplane and surface mesh).

 

Many materials in Moldflow database are "shrinkage tested". That means that Moldflow 9or affiliated) lab measured (parallel and perpedicular) shrinkage of moldings (usually rectangular plates) molded with different parameters. They also predict shrinkages and some proprietary parameter named tau (frozen shrinkage strain) for all those regimes. After that Moldflow correlates the measured shrinkage with predicted shrinkage and tau:

 

Shrink_parallel_exp=A1*Srink_Parallel_predicted+A2*Tau+A3

Shrink_perp_exp=A4*Srink_Perp_predicted+A5*Tau+A6

 

those data (A1..A6) are provided with the material database. Every new release the correlation is repeated as the predicted shrinkages can change.

 

When the user does his analysis Moldflow calculates this TAU parameter and corrects residual stresses so that the shrinkage will be eqal to the experimental calculated by the formulas above. Yo can switch CRIMS correction OFF. There is also anther form of shrinkage correction available named "Residual Strain".

 

Usually CRIMS gives more accurate prediction although there are cases there CRIMS overcorrects things and makes predictions less accurate.

 

If you worry about accurasy of predictions then you can make simulations with and without corrections. Rarely the error of warpage calculations is more than the difference between the results with correction On and Off.

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Active Contributor
rmathan
Posts: 37
Registered: ‎02-17-2011

Re: Corrected residual in-mold stress (CRIMS)?

11-01-2012 03:08 AM in reply to: abakharev

Dear Abakharev,

 

Thank you very much for giving me a detailed information.

 

I have received a udb file from resin supplier. In which don't have any shrinkage properties. In this case how moldflow will correlates/predict warpage. How will be the results without shrinkage data?

 

 

Regards,

Mathankumar. R

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