Hi, I have the same problem. I could not get the .mtx file.  Did you get any update?

Thank

This is your answer. enjoy it,

https://www.sharcnet.ca/Software/Abaqus610/Documentation/docs/v6.10/books/usb/default.htm?startat=pt04ch10s03at30.html#usb-anl-amtxgenerate

Thanks, I figured it out a day after I posted the question. The only tips is that you need to define it as a separate step.

By the way, I would like to ask you that could you extract damping matrix when using Explicit dynamic step. Implicit dynamic is fine but it gives us all damping matrix element are 0. When I use in Explicit dynamic, machine always says error. Thank you very much!

May I ask what is your errors or warnings? I have not tried to printout the damping matrix because my case was implicit and I needed the stiffness matrix.

This is error message from machine. Though I simply extract mass matrix or stiffness matrix in Dynamic/explicit, this error happens. Dynamic implicit works well:

The job input file "Job-1-1.inp" has been submitted for analysis.

Error in job Job-1-1: THIS KEYWORD IS NOT AVAILABLE IN Abaqus/Explicit

Error in job Job-1-1: ANALYSIS WILL BE TERMINATED

Job Job-1-1: Analysis Input File Processor aborted due to errors.

Error in job Job-1-1: Analysis Input File Processor exited with an error.

Job Job-1-1 aborted due to errors.

Thank you very much.

Firstly, The Abaqus Explicit can not calculate the stiffness matrix. That's why you get these errors.  Abaqus/Standard must iterate to determine the solution to a nonlinear problem, however, Abaqus/Explicit determines the solution without iterating by explicitly advancing the kinematic state from the previous increment ( P-I=MU''). I also recommend you to  check sections 6.3.2 and 6.3.3 from abaqus analysis user's guide.

You are correct. Thank you very much. 

how i can read MTX file?

You can read it using matlab or any other programming language. I used matlab to read the file. The format of the mtx file is given in the link below:

http://abaqus.ethz.ch:2080/v6.14books/usb/pt04ch10s03at32.html

 I tried defining a new step to extract mass and stiffness matrix but could not get the .mtx file. I first defined a perturbation step and then defined another step to extract mass matrix. Could you please tell me what could be wrong? 

To export the matrices of stiffness, mass, ect, try abaqus from the console command: abaqus mtxasm -job name_job -oldjob name.sim -text name_out

http://130.149.89.49:2080/v6.14/books/usb/default.htm?startat=pt02ch05s01afi01.html#usb-out-fformat

What is the physical meaning of each element of the global stiffness matrix derived by ABAQUS？