×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Differences in results using SHELL EQUIVALENT SECTION

## Differences in results using SHELL EQUIVALENT SECTION

(OP)
Hello everyone, by performing the modal analysis of this wing model that has a dihedral angle of 10 °, in which I defined the thicknesses of each node of the mesh through a spatial field and then use a SHELL-EQUIVALENT SECTION property, I noticed a strong difference in the results compared to the 3D model. I had not encountered this problem in previous analyzes where the wing did not have a dihedral angle.
When I speak of diversity in the results I mean that the frequencies of the first 4 modes of vibrations go from having values of 20Hz-50Hz-80Hz (modal analysis with 3D model) to values of 180 Hz-350Hz-500Hz (modal analysis with 2D model).
I have already used this method in other analyses with wings of the same geometry (but without dihedral angle) and material, obtaining excellent results compared to 3D.
I am sure that the analysis with the 3D model is right because the values of the modal frequencies are close to those obtained previously for the same wing without dihedral angle.
The wing in question is made of Mahogany (2D orthotropic material).
Could it be that this type of method has problems when the plate does not lie on the XY plane?
In image 1: you can see the dihedral angle imposed
In image 2: you can see the plate (i.e. the wing)
In image 3: using the display shell thickness I show you the real geometry
In image 4: the settings used in the SHELL-EQUIVALENT SECTION property

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!