Auto Time Command Issues

[Yaakov]

Dear FEAP Team & Users,

now There are some issues in my input file. I hope, you can give me some suggestions.
The auto time commands don't work for the modified user element (no convergence after some time steps). But If I use the standard/classic method, It works well, but slowly...   
Auto, Time Commands

Code: [Select]

BATCH
  PARD
  TRANs,BACK
   DT,,dt
   AUTO, TIME, 5, 10, 6
   AUTO, DT, 0.0000001, 0.005
   LOOP INFInite
    LOOP,,500
    TIME,, 1
    LOOP,,30   
      TANG,,1
    NEXT       
    PLOT,CONT 3,,1
   NEXT
  NEXT
END
  DT = 0.0005
Classic Method

BATCH
PARD
  DT,,0.0005
  TRANs BACK
  LOOP,,2000
    TIME
    LOOP,,30
      TANG,,1   
    NEXT 
    plot cont 3,,1
  next
END

Warm Regards,
Yaakov

[FEAP_Admin]

It looks like you have two loops around your time command and AUTO is probably trying to control the wrong loop; I think it only controls one loop down.  Try removing either the LOOP INFInite and its corresponding NEXT or the LOOP 500 and its corresponding NEXT.

[Yaakov]

Dear Feap Administrator,

If I remove "LOOP INFI + NEXT" or"LOOP 500 + NEXT", the Auto Time Command can't work any more.

I'm not sure that the bugs should the auto time commands or the modified user element as it works for classic method...

Thanks very much & kind regards,
Yaakov

[Prof. R.L. Taylor]

Did you set an initial value for dt?

[Yaakov]

Dear Prof. Taylor,

my last question is not clear, I would modify this question.

There are three type of the auto time commands:

Type 1:

Code: [Select]

BATCH
  PARD
  TRANs,BACK
   DT,,dt
   AUTO, TIME, 5, 10, 6
   AUTO, DT, 0.0000001, 0.005
   LOOP INFInite
    LOOP,,500
    TIME,, 1
    LOOP,,30   
      TANG,,1
    NEXT       
    PLOT,CONT 3,,1
   NEXT
  NEXT
END
  DT = 0.0005
Type 2:

Code: [Select]

BATCH
  PARD
  TRANs,BACK
   DT,,0.000001
   AUTO, TIME, 5, 10, 6
   AUTO, DT, 0.0000001, 0.005
   LOOP INFInite
    TIME,, 1
    LOOP,,30   
      TANG,,1
    NEXT       
    PLOT,CONT 3,,1
   NEXT
END

Type 3:

Code: [Select]

BATCH
  PARD
  TRANs,BACK
   DT,,0.000001
   AUTO, TIME, 5, 10, 6
   AUTO, DT, 0.0000001, 0.005
    LOOP,,500
    TIME,, 1
    LOOP,,30   
      TANG,,1
    NEXT       
    PLOT,CONT 3,,1
  NEXT
END
 

Type 1 doesn't need the initial value of time dt, It works for many benchmarks, but not for my new modified user element (almost no convergence )... Still I am not sure, can I use type 1 for the general problem?

Warm regards,
Yaakov