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ME 115: Dynamics of Machinery

ME 115: Dynamics of Machinery. Manuel Leija Christian Reyes. Professor Granda. Please use this power point to do the grading on. This is a new revised one, the other one was an uncorrected file. Vehicle to Vehicle Collision. Vehicle collisions cause injuries and irreparable damage

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ME 115: Dynamics of Machinery

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  1. ME 115: Dynamics of Machinery Manuel Leija Christian Reyes

  2. Professor Granda • Please use this power point to do the grading on. This is a new revised one, the other one was an uncorrected file.

  3. Vehicle to Vehicle Collision • Vehicle collisions cause injuries and irreparable damage • In order to analyze the effects of the collisions so as to reduce injuries, three dimensional dynamics and computer simulation programs are necessary

  4. Problem Statement • If a truck runs a stop sign at a constant velocity and then suddenly collides with another car also traveling at a constant velocity, what are the effects on both vehicles • What is transferred through the collision and through which dynamic principles allows this transfer to occur?

  5. Vehicle Information • Truck Data: • Weight = 2900 lb • Velocity = 45 mph (792 in/s) • Coefficient of Restitution =0 (perfectly plastic) • Car Data: • Weight = 2200 lb • Velocity = 25 mph (440 in/s) • Coefficient of Restitution = 0 (perfectly plastic)

  6. Solidworks Model of Truck

  7. Solidworks Model of Car

  8. Working Model Simulation

  9. Working Model: 2D

  10. Equations: 2D • Truck: x = xo + v*t • Solved for time to collide with Truck using xo = 0 and x = 50 ft, and constant velocity vA = 25 mph (440 in/s) • Truck can start anywhere from 990 to 1350 ft. in the y-direction of it’s starting point to ensure a collision • Car: (x – xo)B = vB*tA = (vB/vA)(x – xo)A • Solved distance that would cause collision using Car A as reference with xoB = 0 at vB = 45 mph (792 in/s) • Car can start anywhere from -33 to 170 ft. in the x-direction of it’s starting point to ensure a collision

  11. Other General Equations: 2D • Kinematics of Rigid Bodies • Position Analysis, Translation, Rotation • Kinetics of Rigid Bodies • General Plane Motion • Momentum and Impulse • Conservation of Energy

  12. Nastran 4D • Three dimensional kinematic and dynamic analysis made easy. • Similar scenario with only two vehicles. • Two different situations: • Unrealistic (frictionless surface) • Realistic (with friction)

  13. Unrealistic (No Friction)

  14. Linear Momentum Data

  15. Right Before Impact

  16. Bam!!

  17. Realistic (with Friction)

  18. Realistic (with Friction)

  19. Before Impact (With Friction)

  20. Immediately After Impact

  21. Basic Drop Test (Height = 2ft)

  22. Maximum Contact Force (at h=2ft)

  23. Learning Experience • How to use modeling programs to simulate real life situations. • Use analytical techniques from class for solving problems. • Despite what most car manufacturers say, truth be told, do not roll your car!!!!  • It’s not just the car itself that damages the vehicle, but the transferred energy from the striking vehicle as well. • It’s all about the impulse and momentum principal!!

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