Dload subroutine for moving load on uic60 rail with thermite weld



Dload Subroutine for implicit model

Here is a tutorial to explain the Dload subroutine in Abaqus using an example of a moving load (train wheel) on a rail. We show the details of the model. The model files are provided on the website link at the end of the description. The geometry for each component is created. The material properties were assigned to each component. In the assembly section, we show how they are put together. We used the implicit step as it provides faster results for a longer process compared to the explicit step. We mesh each component based on its application. In the load and BC section we offer the necessary details as well as gravity force. We explained each part in detail so you can understand the model.

More details about Dload subroutine

Dload subroutine code is one of the most simple subroutine codes to start learning. It is developed for Abaqus standard and implicit models which cover many applications. One of the advantages of using the implicit solver is its short simulation time. However, it doesn’t necessarily mean that it can be faster than explicit models all the time. This solver is helpful in solving models which do not have large deformations but require a long step time period. In some cases, such as the movement of train wheels on a railroad track which requires modelling various components, or simulating the movement of a vehicle on the iron rail, it is beneficial to use the Abaqus implicit solver. It helps avoid simulating every component so it reduces computational time. You can use this subroutine to define complex mechanical loads for your model with minimum effort. It is worth mentioning the usage of Dload is similar to VDload and most of the variables are the same.

Dload video

To find content regarding the Dload and Vdlaod subroutine you can watch these tutorials:

An Example for Dload Subroutine

VDload Subroutine for Movement of a Train on Railroad

Dload Subroutine and Analytical Field in Abaqus

An Example for VDLoad Subroutine in Explicit Model

Please note this model requires at least 4 GB ram.

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 In this video, we avoid giving too many details so you can easily use the product. 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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More Details About Abaqus

Abaqus is an FEA software used 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 mentioning that the fluid mechanic model was separated after Abaqus 6.16 and since version 2017 the company started 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 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 numbers 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, Abaqus provided Python scripting to avoid this. 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 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. However, you notice your material properties are very complex and they change over time. Even if you didn’t have this problem, you would 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 numbers 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.

If you think you need more background it might be a good idea to see the other video about 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.

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