To date, what I have understood about the Fish User-defined model (UDM) in FLAC is that a UDM has worked on each constant strain Triangular (CST) subzone of a rectangular FLAC grid zone (i,j). A UDM gets material properties, like an initial stress tensor, and strain increments as input and provides an updated stress tensor and plastic strain tensor as an output on the current grid zone (i,j).

Now, my question is if I want to calculate a non-local or averaged plastic strain by considering the adjacent grid zones (e.g. i+1, i-1, j+1, and j-1) of the current grid zone (i,j), then how should I access the plastic strain values of adjacent grid zones (e.g. i+1, i-1, j+1, and j-1) from a FISH UDM? Because, as per my understanding, a fish UDM considers that it always works on the current grid zone (i,j), and hence, the use of indices (i.e. i and j) is restricted inside the FISH UDM.

Therefore, I will highly appreciate it if you kindly suggest me a fruitful solution to my problem of accessing plastic strain increment data of adjacent grid zones from a FISH UDM.

Please inform me if you need anything further from my end.

Thanking you in advance,

With best regards,

Dipaloke