This is for all you PHD's :>)
I using the SOLVER tool on Excel to perform iterations to find a worst case value. The value is dependent on a number of variables in the spreadsheet.
What I am asking it to do is to change the value of one cell until another reaches its maximum value. In this case, I am asking for an angle. from 0 to 180 degrees, that gives me maximum force on a group of bolts.
What the problem is, as explained to me by a PHD who sits next to me, is that the curve for the function can have several peaks and valleys. The SOLVER tool built into the program searches for a LOCAL MAXIMUM from the initial point entered in the cell.
For example, if I have a function that has 3 peaks and 4 valleys
Valley 1 = 0 degrees
Peak 1 = 35 degrees
Valley 2 = 50 degrees
Peak 2 = 80 degrees
Valley 3 = 115 degrees
Peak 3 = 125 degrees = CORRECT ANSWER
Valley 4 = 180 degrees
Assuming straight lines between peaks and valleys in the function (for simplifying my example)
Peak 3 gives me the worst case force and is the true correct answer. The solver will only select Peak 3 if my initial input value is Greater than Valley 3 and Less than Valley 4. What I want is to set the cell to zero and have it go through the entire range of values, from 0 to 180, and spit out the right number
My PhD colleague says there are more sophisticated solver modules.
My questions are ... does anyone have any hints or know of a place I could download a solver that would do what I want?
Gerard Madden, P.E.
Middlebrook + Louie, Structural Engineers
71 Stevenson Street, Suite 2100
San Francisco, CA 94105
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