n/a on physical iproperties

[exxon]

I modeled a screw of spheres of which I want to get the moment of inertia.

if I calculate it before the digging of the main propeller (figure 1), the program correctly calculates it.
if I calculate it after digging (figure 2), for any physical value I always get "n/a".
Is there any control over the model I can do to find out what bothers him with that propeller?
some settling that magically fix everything?

 

[Cast16]

you have to have the file to understand... but from what you said and looking online it seems that the problem is known to autodesk and "they are investigating for a future release" since 2015. Looks like the problem is connected to the extrusion coil, too complicated to calculate the properties.https://knowledge.autodesk.com/supp...to-fail-physical-properties-calculations.html

 

[exxon]

Thank you cast16.
the problem in the link you posted is exactly what happens to me too.

I take note of the thing and make the calculation of the moment of inertia in a "algebraic" way.

 

[reb_bl]

put an update of weight with a rule via triggers before saving the document, then you find everything updated.

 

[Zac69]

I modeled a screw of spheres of which I want to get the moment of inertia.

if I calculate it before the digging of the main propeller (figure 1), the program correctly calculates it.
View attachment 53912if I calculate it after digging (figure 2), for any physical value I always get "n/a".
View attachment 53913Is there any control over the model I can do to find out what bothers him with that propeller?
some settling that magically fix everything?

I answer this question to ask a question. moments of inventor inertia how do you read compared to those calculated by mechanical with calculation on a closed profile? I plan matrices and I must indicate the moments of inertia to put to catalog. If I use mechanical I have values that are correct, if I look at those of inventor I have completely different numbers. are matrices for profiles, therefore without strange processing, only an extruded profile.
Thank you.

 

[exxon]

@reb_bl I tried, but I get the same result.
Thanks anyway.
@zac69 It seems like a problem... creepy.
Have you tried a simple figure by checking with analytical calculation?

 

[Zac69]

@reb_blI tried, but I get the same result.
Thanks anyway.
@zac69It seems like a problem... creepy.
Have you tried a simple figure by checking with analytical calculation?

Yeah, I tried. what makes me think is that mechanical does the calculation without asking for the third dimension, so on the xy plane, while in inventor I have to extrude... and how much do I extrude then?

 

[reb_bl]

@exxon hai provato con questa?

thisapplication.commandmanager.controldefinitions.item("appupdatemasspropertiescmd").execute
mymass = iproperties.mass

 

[Zac69]

Yeah, I tried. what makes me think is that mechanical does the calculation without asking for the third dimension, so on the xy plane, while in inventor I have to extrude... and how much do I extrude then?

I add that mechanical as a result a value with unit measuring cm^4 which is correct, while inventor kg mm^2. Is there a conversion, or is there a reason why I have two different units of measurement?

 

[exxon]

I add that mechanical as a result a value with unit measuring cm^4 which is correct, while inventor kg mm^2. Is there a conversion, or is there a reason why I have two different units of measurement?

ugh!

you have to look for the difference between the moments of inertia of the first and second type.

the first type refers to solids (kgm^2).
the second type to the flat figures (m^4).

 

[exxon]

@reb_bl I try as soon as possible, thank you!

 

[Stan9411]

ahia.. .
in mm^4 the moment of static area or moment of the first order which is a geometric property, is used for example in the theory of the beam for the calculation of an effort associated with a flexional stress;
in kg*mm^2 measuring the moment of inertia as a dynamic property, is what is associated with the angular velocity of an object to define its resistant torque.

it is not that a result is right and a wrong one.. are two different properties

 

[Zac69]

ahia.. .
in mm^4 the moment of static area or moment of the first order which is a geometric property, is used for example in the theory of the beam for the calculation of an effort associated with a flexional stress;
in kg*mm^2 measuring the moment of inertia as a dynamic property, is what is associated with the angular velocity of an object to define its resistant torque.

it is not that a result is right and a wrong one.. are two different properties

thank you stan9411, at least I realized what is the difference and the reason. Now the question is: can I with inventor calculate inertia in mm^4? as extruded profiles is the value I need to put it to catalog.

 

[cacciatorino]

thank you stan9411, at least I realized what is the difference and the reason. Now the question is: can I with inventor calculate inertia in mm^4? as extruded profiles is the value I need to put it to catalog.

Usually there is a command like "face property", I speak in general as I do not use inventor.

 

[Stan9411]

I don't know .. theoretically should be one of the results associated with the measurement of a surface .. in creo is so

 

[Catafratto]

tab analyzes, in sketch mode, region property

 

[Zac69]

tab analyzes, in sketch mode, region property
View attachment 53927

Grazie!

 

[exxon]

@exxon hai provato con questa?

thisapplication.commandmanager.controldefinitions.item("appupdatemasspropertiescmd").execute
mymass = iproperties.mass

I finally found time to do this test.

the result is negative: you get the error"unspecified error" (exception from hresult: 0x80004005(e_fail))in the execution of educationmymass = iproperties.massdue to the fact that iproperties.mass does not exist at the time of the attempt to allot.

In practice, inventor does not calculate any of the physical parameters due to a kiss related to the "coil" feature, as already highlighted by other users.

Thank you anyway for the advice.