Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • 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.

Students Click Here

Thermal stress in Dissimilar joint

Thermal stress in Dissimilar joint

Thermal stress in Dissimilar joint



I have a question regarding joint strength of an equipment , which is placed on a honeycomb core and backed by a doubler plate. Please see the attached picture.

The equipment sees high temperature around 102 degrees. I have analysed the joint by calculating the delta displacement from thermal expansion of two metal plates and assumed them to act as parallel spring K= K1 + K2 and found the The total force at the Joint using F= K. delta displacement.

This force is used for checking the fastener shear strength and joint bearing strength.

Is this the right approach or am i missing something??


RE: Thermal stress in Dissimilar joint

If the 2024 plates are pushing on the bolt as they expand what is restraining the bolt? A free-body diagram would help; what is pushing against what as what tries to expand? Your 'F' seems to come from the core; not possible with normal cores. Is F from the honeycomb skins? But then why would they not be subject to the same temperature? Most confusing.

RE: Thermal stress in Dissimilar joint


Thanks for the reply. I assuming the sandwich has zero TEC, therefore top and bottom doubler plates expands and restricted by the sandwich panel in bearing.

RE: Thermal stress in Dissimilar joint

When you say 'restricted by the sandwich panel in bearing' I assume you mean restricted by the sandwich panel skins, which for some reason are not subject to the temperature change or maybe are carbon with low CTE. Are the thick 2024 plates bonded to the sandwich panel skins? If their only connection to the sandwich panel is the bolt then they will just expand about that position in the sandwich panel.

RE: Thermal stress in Dissimilar joint


I have attached picture for more clarification.

The equipment (Aluminium alloy (0.125" thick base plate) attached to the sandwich mounting plate via 4 steel screws (#10) and an aluminium doubler plate and sealed/bonded at the edges.

To assess the strength due to high temperature (The equipment getting heated upto 102 deg).
I assume the metallic components expands & no expansion in sandwich panel and all the loads taken by the bolts ( no effect on bonding).

Using the above assumptions I have so far checked the bolt shear strength and doubler plate bearing strength?

RE: Thermal stress in Dissimilar joint

The carbon if woven will have a TEC of about 2e-6 / deg C if you need a little (~10%) bit of relief. Remember to add in the expansion of the Al across the panel. This is pretty rough first pass estimation. You'll need a pretty safe M.S. (I'd want at least 25%). If it's aerospace a fitting factor should be in there unless it's going to be tested.

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.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


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
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’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:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close