Begin by executing program ECT.  From the CODE41 Main Menu enter Program ECT and Execute ECT. The Table of Corrugated Fiberboards shown below should appear. The results have also been saved in file ECT.PRN and files PLATEC.PRN and PLATEM.PRN have been created. Columns 1-8 on the left are program inputs. Outputs are in columns 9-12 on the right.

First examine the input and output data corresponding to board code 200C which is intended to be a nominal 42-26-42 C-flute construction. The basis weights of the single face, corrugating medium, and double back components are specified in columns 2, 3, and 4, respectively. The order used to specify materials from left to right is the same order in which materials are combined on the corrugator. The flute size is given next in column 5. Columns 6-8 are used to specify the material codes corresponding to the specified basis weights. In this case Dflt-L is used to select the default linerboard and Dflt-M is used to select the default corrugating medium.

The edgewise compressive strength determined for a short column of corrugated fiberboard is given in columns 9 and 10 corresponding to compression in the CD and MD, respectively. The bending stiffness in column 10 is an overall stiffness value equal to the square root of CD stiffness times MD stiffness. Finally, cost is given in column 12. Cost is due to the combined costs of linerboard and corrugated medium materials.

Notice that the basis weight value of the single face component of 42-26-42 C-flute construction is surrounded by brackets, i.e., [ ]. Brackets are used to identify which component triggers local buckling in the CD short column structure. If all linerboard and corrugating medium components are of equal cost, increasing the basis weight of the bracketed component will yield additional CD short column strength at the lowest cost.

Next, examine the output for board codes 200C, 200Ch, 275C, and 275Ch. The specified input for board codes 200Ch and 275Ch are identical with the input for 200C and 275C, respectively, except that a high strength linerboard with material code High has been substituted. The effect is to increase CD strength and decrease MD strength. Recall from Example 1.3 how use of material High affected box strength.

When a material code is assigned to a component the result is to fix the stress-strain properties of the component. Paper can be made to have constant stress-strain properties for small changes in basis weight. Notice that when material High is used in board 275C the basis weight is specified to be 69 lbf/1000 ft².  In Example 3.1 the default basis weight for material High is 42 lbf/1000 ft².  But in this example it is tacitly assumed that material High retains its weight-independent stress-strain properties even though the specified basis weight is different from its default.