×
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.

# eigenvalues reactor

## eigenvalues reactor

(OP)
Hello,
I'm doing some tutorials to learn how to simulate a seismic response of a reactor. I modeled at first the reactor and did the static and modal analysis and it gives me as eigenvalues 10Hz , 14Hz, 20Hz,... 68Hz. Then Iwanted to integrate the basemat of superstructure and eigen values become 3Hz; 3,24Hz;...;4Hz. I attached a picture of the model. Can anyone please tell me why eigenvalues has changed like that , Thank you

### RE: eigenvalues reactor

Hi Anime A,
this depends on a lot of factors. It would be helpfull to have some further information like the boundary conditions of the besement, the mass of it and the stiffness in comparison to the reactor.
For example, when the stiffness is much lower than the reactor stiffness, which would make sense I think, the eigenvalues would decrease as seen.
Can you also upload some pictures of the first few eigenforms?

(OP)

(OP)

(OP)

(OP)

### RE: eigenvalues reactor

(OP)

#### 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!