Abaqus Mises Stress

[Shaquita]

Ive seen several examples on the internet of how to get the highest Von Mises stress from an instance. However, in my simulation there are 4 geometries (ie 4 instances) and my code is only evaluating the Von Mises stress in a single instance (disregarding the other three). Can anybody help me?

You are NOT accessing the mises stress for kth element. You are accessing it for some integration point of some element (However, there is way to figure it out what node and what integration point).

Now, to get the maximum mises stress for entire assembly.

You can get the maximum mises stress at integration point and centroid. let's see at the centroid.

This example illustrates how you can iterate through an output database and search for the maximum value of von Mises stress. The program opens the output database specified by the first argument on the command line and iterates through the following:Each step.

This example illustrates how you can print the content of an output database. The example opens the output database specified on the command line and calls functions that print the following:Parts

-historyCopy all history output from all available steps in the large output database. By default, history output is not copied. Warning: Copying large amounts of history data can result in the program creating a very large output database.

-debugPrint a detailed report of all the operations performed during the running of the program. By default, no debug information is generated. Warning: If you are extracting data from a large output database, the debug option can generate large amounts of information.

Run a datacheck analysis to obtain a new output database called ringshell_datacheck.odb that contains the same model data as ringshell.odb:abaqus job=ringshell_datacheck -input ringshell datacheck

The program displays the number of frames available in each step. For each step you must specify the number of increments between frames, which is the frequency at which the data will be copied to the new output database. Data for the first and last increment in each step are always copied. For example, if a step has 100 frames, and you enter a frame interval of 37, the program will copy data for frames 0, 37, 74, and 100.

The following statement will run the executable program and read data from the small output database containing only model data and the large output database created by the benchmark example:abaqus odbFilter -smallOdb ringshell_datacheck -largeOdb ringshell The program prompts you for the increment between frames:Results from ODB : ringshell.odb will be filtered & written to ODB: ringshell_datacheckBy default only the first & last increment of a step will be savedFor each step enter the increment between framesfor example : 3 => frames 0,3,6,..,lastframe will be savedSTEP Step-1 has 101 FramesEnter Increment between framesEnter 37 to define the increment between frames. The program then reads the data and displays the frames being processed:Processing frame # : 0Processing frame # : 37Processing frame # : 74Processing frame # : 100Filtering successfully completed

This example illustrates how you can use the envelope operations to compute the stress range over a number of load cases. The example program does the following:For each load case during a specified step, the program collects the S11 components of the stress tensor fields into a list of scalar fields.

Use the following command to retrieve the example program:abaqus fetch job=stressRangeThe fetch command also retrieves an input file that you can use to generate an output database that can be read by the example program.

The program reads integration point data for elbow elements from an output database to visualize one of the following:Variation of an output variable around the circumference of a given elbow element, or

You should specify the name of the output database during program execution. The program prompts for additional information, depending on the option that was chosen; this information includes the following:Your choice for storing results (ASCII file or a new output database)

Before executing the program, run an analysis that creates an output database file containing the appropriate output. This analysis includes, for example, output for the elements and the integration point coordinates of the elements. Execute the program using the following command:abaqus felbow The program prompts for other information, such as the desired postprocessing option, part name, etc. The program processes the data and produces a text file or a new output database file that contains the information required to visualize the elbow element results.

The aim of this analysis is to determine the Von- mises stress and equivalent plastic strain of the materials AA2060, C95510, and C95900. Due to energy savings in the sheet metal forming industry, demand for lightweight materials is growing. Structured sheet metal is a sturdy and lightweight material.

However, for the forming phase, the deepdrawingprocesslimitsforformedsheetmetalsshouldbe investigated. For the simulation method, ABAQUS 6.14 is used. It aids in the solution of complex computational problems. Abaqus can conduct pre-processing, post- processing, and processing stage monitoring. Deep drawingis primarily used in aerospace defense components such as closed end cases, sleeves, and other similar products. Deep drawing is also used in the manufacturing of carparts.

I number the steps simply to give you a certain framework you can use later. To be honest you can perform those steps in a different order and still be fine. I guess this will come down to personal preference!

Most likely however you will get stresses higher than yield in linear analysis. The easiest way to understand why is to take a look at the stress-strain chart of a typical ductile material (like steel):

But it can of course! This will be true i.e. in fatigue analysis where you enter low-cycle fatigue in such a case (assuming this stress higher than yield appears both in tension and compression). That is in most cases an instant-failure, even though you may be interested in designing stuff for low cycle fatigue. In such a case however I know that you fully understand what you are doing : )

Both approaches are wrong, to be honest. After all, you got the stresses so high, because of the simplified material description you used! If you would take into account a more accurate model, you would be far better off in analyzing the outcomes!

Luckily, since we are using nonlinear material, this time we can actually search for an answer! All you need to do is to check plastic strain! You can display it easily, simply because solver did calculate it for you, using nonlinear material characteristics. There are many various ones, but I think that the simplest bi-linear one is just fine:

Usually, in stability design, you will have to know stresses in your element as well. Sometimes an average value, usually the maximal value, but in some rare cases (like in EN 1993-4-1 for silos) an actual stress distribution in a given place (over support in the case of the code I just mentioned).

You can clearly see, that when the load on the top edge of that shell (vertical axis) reaches a bit over 31kN/m the model fails. This means that you know perfectly what the capacity is. Also, in such a design you and take into account imperfections, nonlinear material, and all the other things!

Such situations can really be calculated only in nonlinear FEA. There might be some interaction procedures for hand calculations but they often work only for very restricted problems, and real-life problems are often more complex than hand calculation rules allow.

Ok, I admit this has little to do with the interpretation of outcomes. If you define your model in the wrong way, use unrealistic boundary conditions, wrong meshing or any other things that may go wrong you are toasted!

This is a wrongly stated question, and there is no obvious answer! Imagine you have a steel bar under uniform tension. Is stress twice as high as yield allowable in such a case? Of course not, the bar will break under much lower load.

I have over 10 years of practical FEA experience (I'm running my own Engineering Consultancy), and I've been an academic teacher for a decade. Here, I gladly share my engineering knowledge through courses, and on the blog!

Using the software is a useful skill. It allows you to do stuff quicker. That being said, I'm 100% sure that folks that I employ use Femap better than I do... honestly I don't do that so often nowadays, and they model/mesh stuff all the time, so they simply are very good at this (and better than I am). Is this valuable for me? Of course, this gives me confidence that when the task is to be done, it will be done swiftly and without "stupid software errors" (like mesh with not connected nodes, correct load combinations, and stuff like that).

But if this is all the case, why don't I train in this? Mostly because I value the knowledge and "understanding" far more. It's the knowledge of what to do, why to do it, and how to assume boundary conditions, loads, analysis types, and how to analyze outcomes... that make you able to actually do the work. I mean, without that knowledge, you will be able to work fast... but you still won't have an idea of how to do something! So whatever you will do, will most likely be of little value (although delivered fast!). And when you know all those things, you can do stuff "correctly", and this means your work has huge value (especially if the case is complicated)... so a team of people where those two are distributed among folks is a great team to work (as with everything in life... it's hard to know everything).

I've found your writings interesting, thank you.

I'm mostly interested in reinforced concrete (RC) structures.

Would you write about the combination of "shell stresses" and "Plate stresses"? These are common in FEA applied RC slab design.

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