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Error: TIME STEP TOO LARGE!! STOPPING!!

Open 123fgh123 opened this issue 11 months ago • 1 comments

I have encountered an error when using you CPFEM code:

              STEP     TOTAL      WALL      STABLE    CRITICAL    KINETIC      TOTAL
INCREMENT     TIME      TIME      TIME   INCREMENT     ELEMENT     ENERGY     ENERGY
        0  0.000E+00 0.000E+00  00:00:12 9.528E-04        4036  2.024E-13  2.024E-13
INSTANCE WITH CRITICAL ELEMENT: PART-1-1
Output Field Frame Number   0, with time interval 1.000E+03, at step time 0.000E+00 of 2.000E+05

***WARNING: THE ANALYSIS NEEDS AN EXTREMELY LARGE NUMBER OF INCREMENTS (MORE
            THAN 2,000,000). CHECK THE PROPERTIES OF THE MOST CRITICAL
            ELEMENTS AND THE DATA FILE FOR WARNING MESSAGES.

 TIME STEP TOO LARGE!! STOPPING!!

what does this error mean?

123fgh123 avatar Jan 02 '25 07:01 123fgh123

The VUMAT code has no intrinsic set of units. The code should be running fine if you use consistent units. See the Consistent Units table here.

From my experience, caution should be taken with these quantities: "density," "sound speed," "timestep," and "mesh size." When you change the units, the density is modified accordingly, and the timestep will be adjusted automatically to allow elastic waves to propagate.

Therefore, we use mass scaling to speed up the calculation, which implies that the "density" is usually orders of magnitude larger than the actual density. The error TIME STEP TOO LARGE!! is self-explanatory: You should decrease the "density" to lower the time step.

yzhang951 avatar Jan 03 '25 01:01 yzhang951