1. Trip Cost Minimization Workshop 1 Introductory

2. Workshop Supplement January 30, 2001 Inventory #001450 WS1-2 1. Introductory Workshop Trip Cost Minimization Description Find the optimum speed of travel to minimize the cost of a 50-mile trip, assuming that the traveler’s time is worth $10.00/hr. The gas mileage is inversely proportional to the square of the speed (50,000/speed 2 ), and gasoline costs $1.079/gal. The trip is to take no more than an hour. Let us restate the problem as follows: Minimize the function cost = (triptime*10)+(50/mpg)*1.079 subject to the constraint triptime  1.0 given triptime = 50/speed mpg = 50000/speed**2

3. Workshop Supplement January 30, 2001 Inventory #001450 WS1-3 1. Introductory Workshop...Trip Cost Minimization Instructions 1.Using your system editor (Notepad or vi), review (or create) the file trip.dat in the directory specified by your instructor. It should contain the following parameter definitions: –speed=100 –triptime=50/speed –mpg=50000/speed**2 –tripcost=(triptime*10)+(50/mpg)*1.079 2.Enter ANSYS in the working directory specified by your instructor. 3. Change jobname to trip: –Utility Menu > File > Change Jobname… New jobname = trip [OK]

4. Workshop Supplement January 30, 2001 Inventory #001450 WS1-4 1. Introductory Workshop...Trip Cost Minimization 4.Read input from the file trip.dat: –Utility Menu > File > Read Input from… Choose trip.dat, then [OK] 5.Enter the design optimizer (OPT) and specify the analysis file: –Main Menu > Design Opt > -Analysis File- Assign... Choose trip.dat, then [OK] 6.Define speed as the design variable: –(Design Opt >) Design Variables… [Add…] –Choose SPEED, then –Min = 1 –Max = 100 –TOLER =.001 –[OK] [Close]

5. Workshop Supplement January 30, 2001 Inventory #001450 WS1-5 1. Introductory Workshop...Trip Cost Minimization 7.Define triptime as the state variable: –(Design Opt >) State Variables… [Add…] –Choose TRIPTIME, then –Max = 1 –TOLER =.001 –[OK] [Close] 8.Define tripcost as the objective function: –(Design Opt >) Objective… Choose TRIPCOST, then TOLER =.001 [OK]

6. Workshop Supplement January 30, 2001 Inventory #001450 WS1-6 1. Introductory Workshop...Trip Cost Minimization 9.Choose the optimization method: –(Design Opt >) Method/Tool… Choose Sub-Problem, then [OK] Press [OK] on the subsequent dialog 10.Run the optimization: –(Design Opt >) Run… [OK] 11.List the design sets: –(Design Opt >) -Design Sets- List… Choose Best Set, then [OK] –(Design Opt >) -Design Sets- List… Choose ALL Sets, then [OK]

7. Workshop Supplement January 30, 2001 Inventory #001450 WS1-7 1. Introductory Workshop...Trip Cost Minimization 12.Graph speed vs. tripcost: –(Design Opt >) -Design Sets- Graphs/Tables… XVAROPT = SPEED NVAR = TRIPCOST [OK]

8. Workshop Supplement January 30, 2001 Inventory #001450 WS1-8 1. Introductory Workshop...Trip Cost Minimization 13.Exit ANSYS: –Toolbar > QUIT Choose Quit - No Save!, then [OK]