×
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

Plastic analysis~inelastic analysis-non-linear analysis

Plastic analysis~inelastic analysis-non-linear analysis

Plastic analysis~inelastic analysis-non-linear analysis

(OP)
I am just asking for my own learning. After crossing elastic limit, the stress and strain does not remain linear, I guess, we get more strain or even continuous increase in strain under same load. All three terms to me address same "one' issue or there is difference?

RE: Plastic analysis~inelastic analysis-non-linear analysis

Non-linear analysis can also refer to geometric non-linearity ( i.e. P-Delta effects).

RE: Plastic analysis~inelastic analysis-non-linear analysis

And "plastic" can be seen as a special case of "inelastic".
 

RE: Plastic analysis~inelastic analysis-non-linear analysis

These are distinct concepts and should not be lumped in together. Read up a little more on them to clarify the ideas in your mind.
 

RE: Plastic analysis~inelastic analysis-non-linear analysis

I found the question a little obscure.  The non-linearity of plastic analysis/design is essentially due to the formation of 'plastic' hinges that permits a redistribution of forces, increasing the load capacity as well as establishing an upper limit on the load capacity of a system.

Dik

RE: Plastic analysis~inelastic analysis-non-linear analysis

"non-linear" is just a catch-all for everything that is not, predictably, linear (and elastic).  there are two main types of non-linearity ... material and geometry.

material non-linearity is easy ... stress/strain beyond yield, the material is no longer linear elastic.

geometry non-linearity is when the structure stops responding to external load in a linear manner.  your example of plastic hinges is one case ... the beam locally yields, goes plastic, but the beam can continue to react additional load ... the analysis of the beam changes for the standard beam to one with a plastic hinge.  shear buckling of a web is another ... initially the web reacts the applied shear with in-plane shear stresses, but after it buckles, the sher is reacted by tension loads along the buckles.  there are many of examples of non-linearity.

 

RE: Plastic analysis~inelastic analysis-non-linear analysis

My statements here are not exactly textbook definitions.  But, this is how I tend to define them:

Non-Linear Analysis:
Any form of analysis in which the force displacement relationship is expected to be non-linear.  The main sub-categories of non-linear analysis would be Geometrically non-linear analysis and materially non-linear analysis.

Geometrically non-linear analysis:
An analysis where the deformation of the structure changes the stiffness properties of the structure. Normally, this is within the context of a P-Delta analysis. However, there are more complex behaviors that would also fall under this category (large deflection theory, catenary cables, fabric structures, et cetera).  

In-Elastic analysis:
A form of material non-linear analysis where material non-linearity is accounted for from within the analysis itself. The material backbone curve in this case could be elasto-plastic, or could be more complex.  

Plastic analysis:
To me this is really a sub-set of in-elastic design where the in-elastic behavior is usually associated with the plastic hinging of a moment frame....  Therefore, we're usually talking about an elasto-plastic material curve.  
 

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!


Resources