I have been trying understand, what does the increment column infer to, in the job monitor?
I am not referring to the stable time increment or the step time column.
I am running a Explicit, dynamic simulation (basically impact study). I have had tough time understanding the values plotted on the increment column of the job monitor. Please help me understand the same.
Thank you in advance!
Explicit simulations have a stable time increment.
I strongly recommend looking this up in the Getting Started manual.
http://194.167.201.93/English/SIMACAEGSARefMap/simagsa-c-matrunninganal.htm
Dear Samhith Shekar
An Explicit analysis in ABAQUS marches forward the kinematic state of a simulation through small time increments. This time increment is important as it will decide the accuracy of the Explicit simulation.
In fact, there is a condition that the time incrementation in Explicit analysis must be lesser than a limit called as Stability limit. Now what is this Stability limit? It is the max limit beyond which the explicit time incrementation should not exceed in order to give an accurate result.
If the time incrementation used in an ABAQUS simulation is more than the stability limit, then stability is crossed and chances of arriving at accurate results is less. So, arriving at a suitable time incrementation to be used in an Explicit analysis actually depends upon the Stability limit. Hence, the most important consideration and calculation to be done in an Explicit analysis is the Stability limit.
The stability limit is the ratio between Characteristic length of the element and the Wave speed. Hence, stability time limit can be defined as the time taken for a wave to pass through the characteristic length of the element. Since wave speed comes into play, now this is why Explicit is more suited for Wave Propagation analysis problems. The wave speed is the square root of the ratio between Young’s modulus and Density. The stability time limit depends upon wave speed of material, Young's modulus of material, smallest element length in the mesh and the mass of controlling elements.
In case of a uniform sized quadrilateral element where all the elements edges are of same length, this method is much easier. In the case of a highly distorted element where length of one edge is very small, it is the smallest edge length which will be considered. Hence, even a single badly distorted element will slow down the analysis significantly. And the length of the smallest element is used for all other elements in the analysis. Hence, if there are few elements which are badly distorted, it is better to remesh.
This time increment used in Explicit analysis, as it must be smaller than the Stable time increment is generally very small. This is the reason why an Explicit analysis requires large number of increments than an Implicit step. However, cost per increment is pretty less in an Explicit analysis.
@ Samhith Shekar
A basic concept in Abaqus is the division of the problem history into steps. A step is any convenient phase of the loading history—a thermal transient, a static, a dynamic transient, etc.
An increment is part of a step. In nonlinear analyses, the total load applied in a step is broken into smaller increments so that the nonlinear solution path can be followed.
Take a look at this article, that's what you really need!
https://caeassistant.com/blog/step-increment-iteration-abaqus/
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