An Example for VDLoad Subroutine in Explicit Model

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Before talking about the VDload subroutine code, we need to know what the subroutine code is but let’s start with Abaqus:


Abaqus is an FEA software to analyze models with high complexity. The provided option by this software creates a great environment to study various models. Not even solid mechanics but also thermal and fluid mechanic models can be simulated in this software. It is worth to mention the fluid mechanic model was separated after Abaqus 6.16 and since version 2017 the company strat to develop an independent solver for it. In order to increase the complexity of models, engineers can use FORTRAN to develop subroutine code and Python to create a model by scripting. Here we provide a simple description to explain how these two features help you to develop a model.

Scripting by Python:

Imagine you want to create a part with holes randomly distributed inside it. You need to bring a calculator and a piece of paper to find some random number to find the center and radius of those holes. The other option is to use Matlab code or any other coding language to find those random values. However, after finding those values you still need to create those holes inside your models. You need to modify your part at least one time per hole. Fortunately, Abauqs provided Python scripting to avoid it. You can easily create your code there and use the provided function to create and modify those holes inside your part. Consequently, you don’t need to do it by clicking and modifying your part. You can develop a code in Python to do the job for you.

Subroutine for Abaqus:

Now, you created your complex part and now you are ready to define your material properties, boundary condition and loads. Now, you notice your material properties are very complex and it changes over time. Even if you didn’t have this problem, you also need to change the value of time-dependent on material properties. You look at the Abaqus feature and think there is no way you can do it. In fact, your model should change during the process. Your values are not just a simple number and you need to make them as a function of time and other variables. Here is the time you need to use subroutine to define those complex properties in your model. You need to use the proper function known as Subroutine and define your function there and run that by your model.

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Every subroutine has a special feature that makes it different from the other codes. However, it doesn’t mean if you don’t know one subroutine you need to start from scratch. You just need to use the same algorithm from the other subroutine then you become familiar with the code.

VDload Subroutine:

VDload subroutine code is one of the most simple subroutine code you can start learning. it is a subroutine in the Abaqus explicit which has many applications. One of the advantages of using Explicit Solver is its strong capability in contact analysis. In some cases, such as the movement of train wheels on a rail, which requires modelling various components or simulating the movement of a vehicle on a bridge it is beneficial to use the explicit solver. To define the complex load distribution or movement on components for explicit models the VDload subroutine is helpful. You can define complex mechanical loads for your model with minimum effort. The usage of VDload is similar to Dload and most of the variables are the same.

An example of the VDload subroutine in Abaqus is provided. In this tutorial at first, we introduce the VDload subroutine and give you some tips about it. Then, we will explain the subroutine using an example of the moving load subroutine. The plane is fixed and because of the load, you can the stress distribution during the time. In addition, in the PowerPoint file, you can find good information about the subroutine code. If you think you need more background it might be a good idea to see the other video about the subroutine (Please click here). To use subroutine we need to use the FORTRAN code and also Abaqus needs to be linked to Intel FORTRAN. The video is short so you can learn this in less than 15 minutes and you will have the output and Abaqus CAE file.

 In this video, we avoid giving too many details so you can easily use these products. Here you can find the following files:

Abaqus files: CAE, ODB, INP, FORTRAN, and JNL

PowerPoint files that contain more details.

Video files: How to create this model, PowerPoint presentation.

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1 review for An Example for VDLoad Subroutine in Explicit Model

  1. HyperLyceum Team (verified owner)

    This helps you a lot to learn Vdload subroutine and the quality of this video is good.

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