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convert load control to displacement control

Submitted by mjalilych1 on

Hello Dr. scientists

I want to study nonlinear behavior of williams toggle frame by finite element method.

I use of load control method and my results is a little different. is it reasonable that I change to displacement control. if ok please help me on useful literature in this topic. 

thanks in advance.

yawlou

Displacement control will work for the williams toggle frame.  An algorithm explaining displacement control is given in the following paper

http://people.wallawalla.edu/~louie.yaw/Co-rotational_docs/2Dcorot_trus…

Generalized displacement control or the arc length method will also solve the problem.

Using a 2D corotational beam element williams toggle frame is solved by using Generalized displacement control in the following paper:

http://people.wallawalla.edu/~louie.yaw/Co-rotational_docs/2Dcorot_beam…

Generalized displacement control is best explained in the following paper:

Y. B. Yang, L. J. Leu, and Judy P. Yang. Key considerations in tracing the postbuckling

response of structures with multi winding loops. Mechanics of Advanced Materials and

Structures, 14(3):175–189, March 2007.

Thu, 01/09/2014 - 18:21 Permalink
mjalilych1

thanks a lot

if you have the paper of Y.B. Yang I will be appreciate if send for me.(mjalilych [at] yahoo.com).

on the base of your paper 2D Corot Beam I code an cantilever with end moment by using load control algorithm. the trend of newton raphson is ok up to deltay=6(in) in figure 5(b) in your paper. after that solution is diverged. it is noted that I used this algorithm for a cantilever with end point load and results are ok.

thanks in advance.

Mon, 01/13/2014 - 08:06 Permalink
AnnaK

I read the paper and I found the explanantion about displacement control very helpful. My task is to model material non linearity.

Can you please give some explanation, how is the initial F chosen (I don't understand the need of an external force in diplsc control problem) and how does it gets updated to F(n+1)?

By ninc, do you refer to displacement increment loop?

Does delta_u_bar_q gets updated to every loop or is constant?

I am sorry, but at some moments I am not able to follow the algorithm.

Thanks in advance!

Thu, 06/29/2017 - 13:36 Permalink
yawlou

For the paper by Y.B. Yang you will need to contact your university library to get it for you.

 I do not know why the case of cantilever beam with end moment is not working for you.  At the displacement you mention the rotations are starting to become large and it might be a problem with how you implemented large rotations in your code.  Please see my paper and verify that you are calculating the angles according to the method described in my paper.  It is not easy for me to know what the problem is from what you have described.  Otherwise for the type of problem you are doing, load control should work.

 

Tue, 01/14/2014 - 18:41 Permalink
George Papazaf…

If someone is interested, in the following links one can find MATLAB source codes for implementing the arc-length method (Crisfield, 1981 and Fafard & Massicotte, 1993):

 

http://en.pudn.com/downloads599/sourcecode/math/detail2447809_en.html

http://www.mathworks.com/matlabcentral/fileexchange/44352-arc-length-method

 

_______________________________________________

George Papazafeiropoulos

First Lieutenant, Infrastructure Engineer, Hellenic Air Force

Civil Engineer, M.Sc., Ph.D. candidate, NTUA

Email: gpapazafeiropoulos [at] yahoo.gr (gpapazafeiropoulos[at]yahoo[dot]gr)

Website: http://users.ntua.gr/gpapazaf/


Thu, 01/30/2014 - 16:48 Permalink