1 Topic by Tii (edited by Tii 2013-07-23 12:45:14)

  • Tii
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  • Registered: 2013-04-15
  • Posts: 14

Topic: Checking boundary conditions

Hi,

I increase the error values for the Newton-Raphson solution method. Now I would like to check the boundary support forces of my model to see if the solution is good (the summation of the forces in the supports has to be approximate the applied load force). So I used a summation surface monitor for reactions of the nodes in the surface which is constrained by the supports.
But the value is about twice the load force. Are the error values too high (I set the resiual error to 0.05) so that there are to much residual forces?

Quote Post 1

  • dpryl
  • CC software developer
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  • Registered: 2007-07-13
  • Posts: 1,107

Re: Checking boundary conditions

Hello Tii,
what is the reason to increase the convergence tolerances? Normally, a well-defined model should converge within the default 1% tolerences, at least before reaching peak load.

I would recommend to read ATENA Treoubleshooting, sections
2.2.2 I get the message "The execution is killed due to violation of stop iteration criteria", what does it mean?,
2.2.6 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, Floating point exception: Multiple floating points traps, Zero or negative jacobian, InvertA: zero determinant, CCMaterials Extended AExc: CC5ParamYield F:project_stress_on_f_division by zero, and similar,
and
2.2.7 I get the warning "Convergence criteria (within line search) not satisfied due to eta limit, continuing super-ordinate iteration" during analysis, what does it mean?

Once you have a reasonably converging model and suspect there is somthing wrong with respect to the summation monitor, please send us the model along with an explanation what you find strange. The reaction sum definitely should correspond to the applied loads!

dpryl's Website

Quote Post 2