×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

(OP)
I'm implementing stress displacement-based damage model for tension using Concrete Damaged Plasticity. So, it turns out when I select displacement-based input instead for cracking strain, ABAQUS will issue an error message if the calculated plastic strain values are negative and/or decreasing with increasing cracking strain, the tensile damage curves are incorrect. This error does not arise for when I opt for cracking strain as input.

I independently verified if my plastic strains are decreasing/negative using the formulations provided by ABAQUS and they seem very good but it turns out to be not working in the software.

ABAQUS manual says, "The implementation of this stress-displacement concept in a finite element model requires the definition of a characteristic length associated with an integration point." I do not understand where do we define the characteristic length in the software. Any assistance is appreciated.

RE: Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

Abaqus/Explicit calculates this characteristic length automatically. For first order solid elements it’s typical length of a line across an element while for second order solid elements it’s half of that. Beams, trusses, membranes and shells use different definitions. However you don’t have to specify this in Abaqus. But if you want to define it manually you can use VUCHARLENGTH user subroutine.

RE: Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

(OP)
FEA way

That's what I have read on the manual but how do you think I can implement stress-displacement based damage model in Concrete Damage Plasticity since it is showing the above mentioned error? Thanks for your time.

RE: Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

Can you share your .inp file or part of it where material is defined ? Keep in mind that in the *Concrete Tension Stiffening, Type=Displacement keyword first value of cracking displacement must be 0 while for the *Concrete Tension Damage, Type=Displacement keyword first pair of tensile damage variable and cracking displacement must be zero as well.

There are some examples with these keywords in the documentation (like the one called „Seismic analysis of a concrete gravity dam”, „Notched unreinforced concrete beam under 3-point bending” and those in Verification Guide).

RE: Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

(OP)
Hi FEA Way,

I tried reproducing the Notched unreinforced concrete beam under 3-pointing bending problem using their input file. My load-displacement output curves do not seem to be in agreement with those in the manual. Which load and displacement are used to plot the load-displacement curves. Aren't we supposed to use the RF2 and U2 at the output nodes?

RE: Stress - displacement based material input(Tension) for Concrete Damaged Plasticity

Yes, they used U2 and RF2 but they summed reaction forces for constrained nodes. That’s probably the reason why your curves are different.

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


Resources

White Paper - The Criticality of the E/E Architecture
Modern vehicles are highly sophisticated systems incorporating electrical, electronic, software and mechanical components. Mechanical systems are giving way to advanced software and electronic devices, driving automakers to innovate and differentiate their vehicles via the electric and electronic (E/E) architecture. As the pace of change accelerates, automotive companies need to evolve their development processes to deliver and maximize the value of these architectures. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
Modern cars, trucks, and other vehicles feature an ever-increasing number of sophisticated electrical and electronic features, placing a larger burden on the wiring harness that enables these new features. As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - Modeling and Optimizing Wire Harness Costs for Variation Complexity
This paper will focus on the quantification of the complexity related costs in harness variations in order to model them, allowing automated algorithms to optimize for these costs. A number of real world examples will be provided as well. Since no two businesses are alike, it is the aim of this paper to provide the foundational knowledge and methodology so the reader can assess their own business to model how variation complexity costs affect their business. 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