Polar Moment of Inertia Incorrect for Beam Sections?
Polar Moment of Inertia Incorrect for Beam Sections?
(OP)
Hello All,
I am sitting here scratching my head wondering if Mechanica's beam section polar moment of intertia (J) is incorrect.
For example, take a 2x2 inch square solid bar. According to hand calculations J = 2.667 in^4. Modeling the 2x2 solid bar in Pro/Engineer and analyzing the crossectional properties (Analysis -> Model -> XSection Mass Properties) it also comes up with 2.667 in ^4.
However, in Mechanica when you create a new beam section as square with an "a" dimension of 2 and then click "Review" the polar moment of inertia is displayed as 2.25 in^4.
Am I missing something here? This looks to be wrong. I know Mechanica has serious problems in calculating the J for custom sketched sections, but this is bizzare.
Any thoughts?
Steve
I am sitting here scratching my head wondering if Mechanica's beam section polar moment of intertia (J) is incorrect.
For example, take a 2x2 inch square solid bar. According to hand calculations J = 2.667 in^4. Modeling the 2x2 solid bar in Pro/Engineer and analyzing the crossectional properties (Analysis -> Model -> XSection Mass Properties) it also comes up with 2.667 in ^4.
However, in Mechanica when you create a new beam section as square with an "a" dimension of 2 and then click "Review" the polar moment of inertia is displayed as 2.25 in^4.
Am I missing something here? This looks to be wrong. I know Mechanica has serious problems in calculating the J for custom sketched sections, but this is bizzare.
Any thoughts?
Steve
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RE: Polar Moment of Inertia Incorrect for Beam Sections?
It would be nice to have PTC make sure that the variable name is "K" not "J" for all sketched and non-circular beam cross sections.