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(You can make good use of related content for RecurDyn, MBD for ANSYS, and NX Motion.)

It is common to run an analysis by inputting various parameters when modeling. When the results are undesirable, you may want to revert the model to its original configuration. But what if you are not sure which parameters you modified? Even if the results are desirable, you may not know which parameters you modified since you tried various parameters.

If there is a back up of the original file, you can open each file to compare with the results. But this is not an easy solution either.

In this case, you can verify changes by comparing *.rmd files.

An *.rmd file can usually be generated in the same location as result file such as *.rad or *.rplt after finishing an analysis.

Do you have any idea how to find the differences between two attached models, ValveTrain1 and ValveTrain2?

This is a relatively small-sized model consisting of 4 bodies, 5 joints, 1 spring and 1 contact. But it is quite bothersome to open each file and compare the parameters one by one. It is also even harder to know that you have found all the differences you need.

Now it is easier to verify the differences between two models by comparing the *.rmd files used for the simulation.

An *.rmd file is a text file that includes the properties of a RecurDyn model. Once you become used to it, it is much easier to wholly grasp a RecurDyn model at a glance.  

However, it is still not easy to compare two text files and figure out the differences between those two files.

In such a case, WinMerge can be a very useful utility.

WinMerge is a powerful utility that is well known for its to compare two text files to find the differences.

You can download WinMerge for free at  http://winmerge.org/ for free. (It is an open source software.)

1) Install WinMerge on your computer first. Select two different *.rmd files and right-click, and then click WinMerge to run WinMerge.

2) After running WinMerge, on the File menu, click Open and select two different *.rmd files.

Now you can compare two different files.

In WinMerge, you can verify the differences between these two text files by going through them with the arrow button in the toolbar. The highlighted lines indicate the differences between the two text files.

The differences between ValveTrain1 and ValveTrain2 are

The values of MU_DYN (Dynamic coefficient of friction in the joint coefficient of friction: 0.5 / 0.8

K of Spring1 (Spring coefficient): 100 / 200

There is no published document for the *.rmd file format.

However, in the case of MU_DYN, you can easily determine that the values in the dialog box are parameters related to Revolute2 by ‘NAME = ‘Revolute2.JointFriction’. It is also possible to determine the dynamic coefficient of friction by DYN of MU_DYN.

Even if you don't know exactly what the parameters in *.rmd file means, if you realize the difference is related to the coefficient of friction fpr Revolute2, you just need to check the coefficient of friction from the dialog box, which is saves time.  

Applications

1) If you ran a simulation with different parameters several times

The result files including the *.rmd file will be saved in a different folder after each analysis is completed. You can verify which parameters you modified on the model by comparing *.rmd files in the folder.

2) If you opened a file first and modified many parameters

When opening a file, the rdyn file is backed up automatically. You can compare the two files you want after generating an *.rmd file (Path: System-Export).

(Refer to https://support.functionbay.com/en/faq/single/60 regarding the backup file.)