1. Vehicle Problem Stephen Moore ME270 Prof. Granda October 30, 2007

2. Vehicle Problem Car impacting a wall at various speeds Car driven at 25, 40, and 55 mph

3. Parameters given Mass of the car- 1500kg Mass of the driver- 100kg Spring constants of the bumper- 300,000 N/m Resistance of the bumper- 80,000 N-s/m Spring constants of the seatbelts- 10,000 N/m Resistance of the seatbelts- 500 N-s/m Masses stay the same, the spring constants and the resistances change

4. R1 1 0 1 0 1 1 1 Cb Sf w C1 Id Rb Ic Bondgraph model

5. ElementDefinitionValue SfwSource of flow, wallSfw = 0 RbResistance of the bumperVaries CbCapacitance of the bumperVaries R1 (2 each)Resistance of the seat belt and shoulder belt Varies C1 (2 each)Capacitance of the seat belt and shoulder belt Varies IdMass of the driver100 kg IcMass of the car1500 kg

6. Design Criteria 1.Driver does not hit the windshield at 25 and 55 mph 2.Forces on driver at 25 and 55 mph 3.Critical maximum velocity 4.Traveling without a seatbelt, how long does it take to hit the windshield?

7. #1. Driver does not hit the windshield at 25 and 55 mph After running the models in Campg and running Matlab programs, the acceptable criteria are shown in table below. Design Criteria Vel. (mph) # belts k1 (N/m) R1 (N-s/m) k2 (kN/m) R2 (kN- s/m) Force on the driver (N) Displacement of the driver (m)Notes 12529000600350100128600.501 Max force w/ two belts is 13340 N 5529000600350100282001.000 Max force w/ two belts is 13340 N

8. Displacement of the driver Displacement the driver experiences at 25 mph. Displacement the driver experiences at 55 mph.

9. #2. Forces the driver experiences upon impact Design Criteria Velocity (mph) # of belts k1 (N/m) R1 (N- s/m) k2 (kN/ m) R2 (kN- s/m) Force on the driver (N) Displacement of the driver (m)Notes 2 2529000600350100128600.501 Max force w/ two belts is 13340 N 5529000600350100282001.000 Max force w/ two belts is 13340 N Max force w/ one belt is 6670 N 25 55 1111 9000 600 350 100 16640 19930 0.501 1.000 Max force w/ one belt is 6670 N

10. #2 Forces the driver experiences The figure is the force the driver experiences at 55 mph. The figure is the force the driver experiences at 25 mph.

11. #3. Critical maximum velocity Design Criteria Velocity (mph) # of belts k1 (N/m) R1 (N-s/m)k2 (kN/m) R2 (kN-s/m) Force on the driver (N) 326.042900060035010013340

12. #4. Traveling without a seat belt, how long does it take the driver to hit the windshield? Design Criteria Velocity (mph)# of belts Delta time (ms)Notes 4250 0.105 400 0.073 550 0.057