topic Autodesk Robot shell finite elements - theoretical background in Robot Structural Analysis Forum

Autodesk Robot shell finite elements - theoretical background

MartinTrs — Mon, 21 Nov 2022 04:52:13 GMT

Could you help me in finding theoretical background about shell finite elements used in Autodesk Robot Structural Analysis. Specifically, I am interested in:

How many and what shape functions are used for different types of shell finite elements (quads and triangles)
How is shear locking handled

Best regards,

Martin

Re: Autodesk Robot shell finite elements - theoretical background

Stephane.kapetanovic — Mon, 21 Nov 2022 06:13:18 GMT

Hi @MartinTrs

contribution on this subject before the teams answer you

https://knowledge.autodesk.com/support/robot-structural-analysis-professional/learn-explore/caas/CloudHelp/cloudhelp/2018/ENU/RSAPRO-UsersGuide/files/GUID-CA1629BB-AEFB-4BD7-AE7A-3772961C24B5-htm.html

https://knowledge.autodesk.com/support/robot-structural-analysis-professional/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/Robot/files/GUID-AE34635A-F2B5-4A62-A6B0-95066594D554-htm.html

https://knowledge.autodesk.com/support/robot-structural-analysis-professional/troubleshooting/caas/sfdcarticles/sfdcarticles/How-Qyy-shear-force-for-shell-elements-should-be-interpreted-in-Robot-Structural-Analysis.html

Best regards

Re: Autodesk Robot shell finite elements - theoretical background

MartinTrs — Mon, 21 Nov 2022 07:31:36 GMT

To clarify, I am looking for shell finite element shape functions in a similar sense as they are provided for volumetric elements in the following link. The shape functions are used to solve the underlying differential equations with FEM.

By shear locking (in the plane of finite element) I mean the error that occurs in finite elements analysis due to the linear nature of quadrilateral elements (see the following link).

Re: Autodesk Robot shell finite elements - theoretical background

MartinTrs — Mon, 21 Nov 2022 11:37:53 GMT

I was recommended to add @Krzysztof_Wasik also to this thread and clarify a bit further what I am expecting or what my doubts are.

I am trying to better understand the behaviour and limitations of ARSA. As we know, finite element methods are used to approximately solve differential equations describing a certain problem. To solve those problems a variety of approaches are available and each of them has their pros and cons (for example, in certain cases Kirchhoff theory is better suitable for plate models and in certain cases Mindlin-Reissner theory is better suitable). My goal is to better understand the theoretical background of ARSA to better evaluate the limitations of the calculations that I am performing with ARSA.

For example, here is and old thread, where additional knowledge of the calculation methods would have helped.

Best regards,

Martin

Re: Autodesk Robot shell finite elements - theoretical background

MartinTrs — Thu, 24 Nov 2022 05:59:49 GMT

Hi @Krzysztof_Wasik,

Could you help me with the subject?

Best regards

Martin

Re: Autodesk Robot shell finite elements - theoretical background

Krzysztof_Wasik — Thu, 24 Nov 2022 09:15:29 GMT

Hi @MartinTrs

Refer to this article Robot Structural Analysis finite elements

Re: Autodesk Robot shell finite elements - theoretical background

MartinTrs — Thu, 24 Nov 2022 15:40:57 GMT

@Krzysztof_Wasik

Thank you

Best regards,

Martin