Error!? Material properties are changed after saving

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GCS
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Error!? Material properties are changed after saving

Post by GCS »

I am working to enter new barrier materials with properties into the User Defined material database, in IP units.

I noticed when entering the thickness for small values (eg 0,04 inch), after saving the value becomes something else (eg 0,001). I don't understand how this can happen, and am concerned that the resulting permeance after multiplication with the thickness (see comment below) are not correct. I understand, the permeability value inserted in the material database is (a per one-inch-thickness-value) multiplied with the thickness of the layer as shown on the main assembly screen, is that correct?

For small values for the permeability, the values are rounded (eg 0,0035 to 0,004). Does the program analyze with the input value or the rounded values?

================ EDIT below!

After continuing to work with it, I noticed that the "permeability" value when working in the material database mode are different from the "permeability" value when working in the assembly mode.

For example I saved the permeability value for eg Henry Air-Bloc 33 as 1,45 perms and gave it a thickness of 0,1 inch or 100 mils as stated in the data sheet. After saving the new material, the thickness automatically changes from 0,1 to 0,025 inches (see comment above)!

When using this material in the assembly, the "permeability" value shows up as 14,5 which is correct for a thickness of 100 mils. Both fields for permeability in the database and the assembly mode show a unit of [perm in].

It appears the field in the assembly should be called permeance [perm] as it appears the permeability value from the database has been multiplied by the thickness. Is this correct?

I understand I am asking several questions at once in this post. Thanks for your help!! :?

PS: I use commas here instead of decimal points similar to WUFI!
--
Christoph
Manfred Kehrer
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Post by Manfred Kehrer »

Dear Christoph,

there might be some rounding errors within the DB if you use the IP unit system.

Where did you enter a "pern in" value? the Material Properties are are defined by using not-geometry-depending data and this is "perm".

Regards,
Manfred
Manfred
Wiss, Janney, Elstner Associates, Inc.
Official WUFI® Collaboration Partner for USA/Canada
Enjoy WUFI® :) .... It is easy and complex.
Michael Hurd
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Material thickness changes when saved to database

Post by Michael Hurd »

I have experienced some of the things mentioned in this post - is it necessary to save materials using SI units rather than IP perhaps? I looked through the other posts and could not fing this suggested but I seem to remember reading this somewhere?
Respectfully,

Michael Hurd
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