Hi,
In PrePoMax, is there a way to automatically increase the load by a fixed number and export the stress at a selected node? I am looking to run an analysis multiple times just increasing the load by 5-10 lbs every time.
You can use amplitude feature or multiple independent steps to vary the load during the simulation. But if you want to run many separate analyses with different load magnitudes and avoid manual changes then export the input file and change the magnitude directly in it. Optimax can automate that.
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I expect the same holds true for displacement increments right ? I would like to have multiple analysis run with progressing displacement increment, so I guess I have to manually create many steps each with slightly modified BC (or have that optimax do so). But if this is the case, I am unable to understand the field incrementation in the Static step. In fact, it seems time increment, but this is a static step. I reckon a tutorial on the use of incrementation may help a great deal. Thank you for your time.
Static analysis can be nonlinear and that’s when the incrementation matters. This concept is related to Newton-Raphson method. Best detailed description can be found in Abaqus documentation.
Check also this thread: I need some opinions on a non linear geometry problem in general - #2 by FEAnalyst
Hello @FEAnalyst. It is the first time I have seen this software here, and apparently, it is part of the PrePoMax host website. Fascinating tool, but we should discuss it more here… Automation and optimization are potent allies.
Thank you for disseminating the topic.
I am familiar with the iterative solution of nonlinear problems. However, and I checked, incrementation can be set even when NIgeom is disabled (I guess this is geometric nonlinearity) and linear elastic materials are chosen. It means that this incrementation concept can be set also for linear problems, it seems. Besides, when solving my nonlinear problem, I see only three iterations in the analysis monitor, regardless on how I set the iteration field. In fact, I don’t really understand how it works because it refers to time and there is no time in my static analysis. Perhaps time is a poorly chosen proxy of loading parameter. Where can I get some understanding of these iteration fields ?
This is also explained in Abaqus documentation. Time is physically meaningful only in dynamic and rate-dependent analyses. In static analyses, time is just a convenient measure of load incrementation.
Automatic incrementation can be controlled using initial, minimum and maximum increment sizes (plus maximum number of increments) but it’s still automatic - the solver decides what increment size to use based on convergence. You can choose fixed incrementation but it’s not recommended in most cases. Completely linear analyses (no Nlgeom, linear elastic material, no contact) are normally solved in just one increment. If you need precise control over load incrementation, there are better ways. Amplitude feature can be used for this purpose.