Running .inp files in Abaqus/CAE

What is an Abaqus input file (inp file)?

An Abaqus input file (inp file) is a text-based file containing instructions, data, and parameters required to define and run a simulation in Abaqus. In fact, the Abaqus solvers read the input file for an analysis. Here, we’ll explain what an Abaqus input file is and how to run an inp file in Abaqus.

The Abaqus input file is written in a specific format that follows a set of syntax rules. The Abaqus inp file can be created using a text editor software and by the user’s scripting capabilities or generated using Abaqus’ graphical user interface (GUI). Also, you can use Abaqus GUI to begin Python scripting and have your own modified modeling. But how and why do we need to do Python scripting? Get your answers in the Abaqus Free course Python scripting section. Now, let’s get back to inp files.

The inp file works by various keywords (commands) developed only for the Abaqus itself, each serving a specific purpose to define the simulation model, material properties, boundary conditions, analysis type, and other relevant parameters. The inp file structure can be divided into several sections.

Below, we present different sections of the inp file structure:

• Heading: The file begins with a block of comments describing the input file, including the purpose, author, date, and any other relevant information.
• Preprocessing: This section defines the model geometry, material properties, meshing parameters, etc. This section works by some predefined keywords developed only for Abaqus itself, such as “*Part”, “*Material”, “*Assembly”, “*Instance”, “*Node”, “*Element”, etc.
• Steps: The Steps section defines the analysis steps, such as loading conditions, constraints, and the type of analysis to be performed, such as Static, dynamic, thermal, etc. The keywords used for this section are “*Step”, “*Boundary”, “*Load”, “*Amplitude”, etc.
• Output: This section specifies the desired output results, such as displacements, stresses, strains, reaction forces, etc. This section uses keywords such as “*Restart”, “*Output”, “*History”, “*Element Output”, etc.
• Analysis: This part of the input file contains some commands for running the analysis, including convergence criteria, solver options, and other analysis-specific settings. It often includes keywords like *Analysis, *Solver, *Controls, etc.
• Postprocessing: This section defines any postprocessing steps or requests for additional analysis results or visualization. It includes keywords like “*Field Output”, “*Node Print”, “*Element Print”, etc.

The Abaqus input file is saved with a “.inp” extension and can be executed within Abaqus using the software’s command-line interface or submitted to a job in the Abaqus/CAE.

The structure and contents of the inp file are dependent on the simulation you’re trying to analyze. You can learn more about the commands and keywords of the input file in the Abaqus documentation.

How to run an inp file in Abaqus (Abaqus input file)?

Now, let’s see how to run the input file in the Abaqus. There are two ways to run an input file in the Abaqus: one way is the typical way by creating the model in the Abaqus GUI and creating a job, then submitting the job; in this way, the input file will be created automatically, and run. The other way is to run the input file directly; this means you already have the input file and just need to run it. Sometimes you may need to use an inp file to run an Abaqus job, instead of constructing your model through Abaqus/CAE (graphical interface of Abaqus). For example, you find a sample .inp from Abaqus documentation and want to open it in Abaqus/CAE or run it.

Running input file in Abaqus/CAE

Now, let’s say we already have an input file and need to run it. But how? Go to the Job module. Select Create Job, name the job, and then under Source pull down menu, select Input file. Browse your input file. After that, click Continue… OK, to the edit job dialog box. Now in the Job Manager window, select your newly created job. Click Submit and cross your fingers 🙂

Caution!

It is a wrong procedure to run an input file:

1. Importing .inp file in Abaqus/CAE.
2. Creating a regular job (based on the Model produced) and running it.
3. Viewing the results.

If you run the input file this way, you probably encounter an error or have wrong results, especially when you have inp files from Abaqus documentation. Why? Because some commands and keywords may not enter the Abaqus GUI correctly, or the GUI may not support the keywords! Yes, some keywords don’t have a graphical interface, and some simulations need these commands and keywords. Therefore, in these simulations, you need to create the input file and put the required keywords in the input file manually, and run the input file directly.

How to open an inp file in Abaqus?

You can also open .inp file in Abaqus to have a sense of geometry, materials, etc. See How to open the input file in Abaqus?

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