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.


Design of Experiment- Cyclic Loading

Design of Experiment- Cyclic Loading

G'day guys,

I need to design an experiment to investigate the behavior of steel under cyclic loading. I am particularly interested in understanding the phenomenon of Bauschinger effect after reverse loading. I noticed that one of the common way to perform the test is through cyclic tension-compression test. But the main drawback for this test is that the specimen has the tendency to buckle as it goes through compression load.

I have this idea to conduct a test using cruciform shape specimen. Since the specimen has a shape of "t", what I will do first is to apply tension on vertical arm. I will just let the horizontal arm be free. This also means that I just conduct the test on a Uniaxial test machine. Based on my FEA simulation, it looks that the region at the centre of the specimen will also experience compression because I do not constraint the horizontal arm.

In order to reverse the load, I will take out the specimen and place the horizontal arm to the fixture of the test machine. I will apply tension on this horizontal arm which means that I shall obtain tension and at the same time the previous elongated arm (vertical arm) will return back to its original position. So, it seems to me that I can conduct tension-compression test by repeating this cycle.

But, maybe I miss a few important practical aspects. Hence, I would like to hear your thoughts on this idea.


RE: Design of Experiment- Cyclic Loading

Seems like you are missing a few important practical aspects.

But it's hard to tell because your description is not very clear.

Maybe a sketch.

RE: Design of Experiment- Cyclic Loading

Here, I've attached the 1/4 a quarter of the specimen sketch. I hope this will give you a good idea on the shape of specimen that I wrote in previous post.

As you can see, if I apply tension to the vertical arm and let the horizontal arm to be free, it looks to me that the horizontal arm will be shorten. And if I'm correct, this is due to the Poisson's effect. And if I now switch to the horizontal arm to be connected to the machine fixture and I applied tension, I will be able to get compression on the initial vertical arm. So, by repeating this cycle, I can somehow conduct cyclic testing. Am I right?

If something is not clear, just let me know again. I'll try to explain it.

RE: Design of Experiment- Cyclic Loading

Quote (mhajinaw)

it looks that the region at the centre of the specimen will also experience compression because I do not constraint the horizontal arm.

I guess that the boundary conditions in your FEA simulation are not consistent with the emphasized assumption.

RE: Design of Experiment- Cyclic Loading

Well I actually apply boundary conditions that only allow the horizontal arm to move freely in horizontal direction (x-direction). That is what I meant by the previous quote. I think this is the right representation when modelling in FEA.

RE: Design of Experiment- Cyclic Loading

How do you intend to actually constrain this part in test?

Your FEA simulation is not realistic unless what you're calling the 'horizontal arm' is actually constrained so that it cannot rotate.

The force shown in your FEA plot applies a moment to the shape. Think about where that force is relative to the centroid of the cross section.

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!


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