Flexible components and outdated mass properties

[Ralph_W]

We use the PRO_MP_MASS parameter for our weight calculation and as a value on our drawing.

To ensure everybody is executing the mass calculation the setting mass_property_calculate is set to report_outdateness_only (or check_upon_save). A warning 

For normal assemblies these settings are ok.

But in assemblies where we use flexible component (e.g. a spring or a folded flexfoil) the mass properties of the assemblies keep outdated every time the assembly is opened. 

Even a bottom up mass calculation of all parts and finally the assembly will not help. Because after closing and re-open the assembly,  the assembly shows "outdated mass properties".

How to solve, or block this?

[BenLoosli]

I'm  not sure you can prevent this due to the flexible part being 'modified' when brought into the assembly.

A hose assembly modeled as 12 inches as a standalone part, when in the assembly it is now 15 inches as it follows the flexible path, it has a new mass due to the longer length. Not sure how a sping 'stretches' as a flexible part (add coils or changes spacing) but the add coils would also change the mass.

[Ralph_W]

The strange thing is that I already brought the flexible component into the assembly and adjust the length or folding angle. I updated the mass calculation of the assembly (and this one is correct). 

But after closing and opening the assembly again (no changes made) the mass property of the assembly is outdated. 

Somehow the mass is not stored in the assembly if flexible component is in.

[kdirth]

Using flexibility does not change the part file.  It still has the unflexed mass properties.  A flexed part in an assembly loads the original part file into memory then modifies it based on the flexibility settings, changing the mass properties calculation.

[Ralph_W]

Clear, and there is not even a hidden setting to avoid this?

[Chris3]

We have the same setting and have experienced the same issue without a solution. If you make an idea for maybe people will vote it up.

[Chris3]

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@kdirth wrote:

 It still has the unflexed mass properties.  

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This is not true. The mass property parameter is not updated but if you run the mass property report (Analysis -> Mass properties) it is updated.

This is part of the reason that we don't rely on the mass properties parameter to get mass properties out.

[kdirth]

You may need to use User Defined Mass Properties for any part that you intend to flex.  Even stretching a spring by changing the spacing will change the mass calculation as the diameter of the spring is not collapsing as it would in real life.