Topic: Number of iterations and Newton Raphson methods


I'm simulating a four-point bending test on a slab, for which I am using symmetry and only modelling half of the slab. When I use regular Newton-Raphson method (each iteration/tangent) results don't agree with the experimental conditions. Whereas, when I use modified Newton-Raphson method (each step/elastic), there is some similarity with the experimental results.

-Why is there a significant difference between these two methods?

Furthermore, I simulate results using modified N-R, but now, I varied the number of iterations in two different cases. In first case, I used 40 iterations and in second case, I used 100 iterations.

-Which of these two different iteration values should I rely on? What should be an ideal value for the number of iterations to get good results?

Re: Number of iterations and Newton Raphson methods

Dear arjun.vithalkar, please first see ATENA Troubleshooting, 2.1.19 Problems reaching convergence and understanding ATENA convergence parameters for basic related information.
We generally recommend to set the Conditional Break Criteria such that the analysis stops when the convergence errors are large at the end of a step, see ATENA Troubleshooting, 2.4.2 I get the message "The execution is killed due to violation of stop iteration criteria", what does it mean?

I guess you may also be interested in Troubleshooting, 2.2.18 My analysis results do not match the experiment/expectations. How can I improve my model?

If you still have problems/questions, please follow Troubleshooting, 2.1.1 to send us your model etc.