Learning Forum

[HossamGhazal]

Hello

Please,I need help.I would like to ask about the below error messege which appeared to me during my simulation..... as I recived a model and I would like to reduce it to get simplifed mass and stiffnes matrices which I can use it in matlab....I used my code for small models(by using generation pass by CMS method) and it works but for the real model, I have this error which I can not understand it....any idea please 

This error messge is contradicted foe the plot list data and my input as I put all my master DOF nodes

No MASTER degrees of freedom are specified.  If the TOTAL command was used for automatic generation of MASTER degrees of freedom, it is invalid with the SPARSE solver in a substructure analysis.  Please use the M command to define at least one MASTER degree of freedom.

ALL BOUNDARY CONDITION DISPLAY KEYS SET TO  1

 

Thanks

[sk_cheah]

The error message seems to say you don't have any master DOF specified. See this doc: https://web.engr.uky.edu/~jbaker/ANSYS-Stiffness_Matrix-v8p1.pdf

[HossamGhazal]

Hello

Thanks for reply

But I had already put my master degree of freedom with same commands as you send it in your pdf and the solution options window also confirms that I select the master nodes with the total DOF as they are 6 master nodes with 36 DOF. However,I am reciving this error message as I am not selecting any master nodes.....

Model comands

then CMS commands:

/solu

antype, substr

CMSOPT, FIX, 10, , , , , TCMS

        SEOPT, CMS123, 2, 1, 0

        OUTPR,ALL,ALL

csys,0

cmsel,s,ELEMENTS_LP

nsel,s,,,Node_Load_1

nsel,a,,,Node_Load_2

nsel,a,,,Node_Load_3

nsel,a,,,Node_Load_4

nsel,a,,,Node_Load_5

nsel,a,,,Node_Load_6

        m,all,all

allsel

/output,gh

solve

/output

 

Also the solution options command :

                       S O L U T I O N   O P T I O N S

 

   PROBLEM DIMENSIONALITY. . . . . . . . . . . . .3-D                  

   DEGREES OF FREEDOM. . . . . . UX   UY   UZ   ROTX ROTY ROTZ

   ANALYSIS TYPE . . . . . . . . . . . . . . . . .SUBSTRUCTURE         

    SUPERELEMENT FILE NAME . . . . . . . . . . .CMS123

   OFFSET TEMPERATURE FROM ABSOLUTE ZERO . . . . .  273.15    

   MATRICES TO GENERATE. . . . . . . . . . . . . .K AND M       

   SUPERELEMENT PRINT OPTIONS. . . . . . . . . . .PRINT ALL         

   STRESS STIFFNESS MATRIX SPACE KEY . . . . . . .OFF

   NUMBER OF MASTER DOF. . . . . . . . . . . . . .    36

   GLOBALLY ASSEMBLED MATRIX . . . . . . . . . . .SYMMETRIC  

Then I recived this error.

 *** ERROR ***                      

 No MASTER degrees of freedom are specified.  If the TOTAL command was used for automatic generation of MASTER degrees of freedom, it is invalid with the SPARSE solver in a substructure analysis.  Please use  the M command to define at least one MASTER degree of freedom.

Any idea please as I am really confusing and I am stucked at this point

 

Thanks 

[sk_cheah]

I'm not sure what could be the cause of that. Perhaps your license doesn't allow for CMS? Sorry, I'm not much help.

[HossamGhazal]

I think I realized the problem is due to that I am selecting my master nodes for my reduced model as the same master nodes for the MPC body but I do not know how to fix this problem as when I selected other random nodes as my master nodes ....it works normaly and the reduced matrices are created.

I am trying now to fiqure out how can I select the master nodes of MPC as the same master nodes for reduced model

Thanks alot

 

[sk_cheah]

Try create MASS21 with node coincident with the MPC nodes. Join each pair nodes using COMBIN14 with keyopt(2)= 1, 2, 3 respectively and have a very high stiffness. Next, define the MASS21 nodes as master nodes. 

[KDakhili]

Hi,nDo you know how we should select master DOFs when we only want to select one of the DOFs per node, not all of them?n

[Mathilde31]

Hello, 

I have exactly the same problem with model reduction using Workbench (error: No MASTER degrees of freedom are specified.  If the TOTAL command was used for automatic generation of MASTER degrees of freedom, it is invalid with the SPARSE solver in a substructure analysis.  Please use  the M command to define at least one MASTER degree of freedom.).

Someone managed to find a solution ?