An Efficient Heuristic Approach for Irregular Cutting Stock Problem in Ship Building Industry

Algorithm 1

The Exact Fit heuristic.

Input: Set of items sorted by decreasing area ; Set of rotations θ for items of in ; Dimensions of Stock Sheet (, ).

Output: Solution C (Cutting).

(1.1)    percentage = 0;   increment of allowed percentage

(1.2)    while    do

(1.3)      fill the stock sheet with items until the stock sheet is over 1/3 full

(1.4)      record every item that does not fit

(1.5)      call Algorithm 2

(1.6)      if  the free area up to after a item could be placed  then

(1.7)      reset and go to step (1.5)

(1.8)      call Algorithm 3

(1.9)      if  the free area up to after a combination of 2 items could be placed  then

(1.10)   reset and go to step (1.8)

(1.11)   call Algorithm 4

(1.12)   if the free area up to after a combination of 3 items could be placed  then

(1.13)   reset and go to step (1.11)

(1.14)   if  all the possible combinations of 1, 2 or 3 items could not be placed

     AND  percentage  <free area of stock sheet  then

(1.15)   percentage = percentage +

(1.16)   else  open a new stock sheet