Hi,

Try using the previous LPF when you have seen it as positive . using the that LPF value set your coefficient of tolerance so that the when the riks method reaches this tolerance value it will stop and your LPF will remain positive.

Hi, thanks for the answer, Bala.

The only Riks step parameters I see control the maximum / minimum arc length increment. Is it possible to control the LPF increment somehow? Or could I tie the arc length increment to the LPF / LPF increment?

hi

i run the riks for a SS plate under unix com load.

but the ultimate load result  is very smaller than Pcr,

why?

It is difficult to do so in Abaqus CAE. You could use python to control the command window and read your .sta file every 60 s, and if there is a drop in the load increment, terminate the analysis by commanding 'Abaqus terminate job = jobname'. The python code below will do the job.

#########################################

command = 'abaqus job=yourjobname'

system(command)

LPFv = 10 #set an initial value for load increment

for count_time in list(numpy.arange(1.0,100,1.0)):

time.sleep(60) # at 60 s interval

filepath = 'yourjobname'

fid = open(filepath+'.sta', 'r', 0)

for line in fid:

fields = line.split()

if len(fields) > 0:

if fields[0] == '1':

LPFv = float(fields[7])

else:

break

fid.close()

if LPFv < 0.000001:

system('abaqus terminate job=yourjobname'')

break

#########################################