me 115: dynamics of machinery manuel leija christian reyes
TRANSCRIPT
ME 115: ME 115: Dynamics of MachineryDynamics of Machinery
Manuel LeijaManuel Leija
Christian ReyesChristian Reyes
Professor GrandaProfessor Granda
Please use this power point to do the Please use this power point to do the grading on. This is a new revised one, the grading on. This is a new revised one, the other one was an uncorrected file.other one was an uncorrected file.
Vehicle to Vehicle CollisionVehicle to Vehicle Collision
Vehicle collisions cause injuries and irreparable Vehicle collisions cause injuries and irreparable damagedamage
In order to analyze the effects of the collisions In order to analyze the effects of the collisions so as to reduce injuries, three dimensional so as to reduce injuries, three dimensional dynamics and computer simulation programs are dynamics and computer simulation programs are necessarynecessary
Problem StatementProblem Statement
If a truck runs a stop sign at a constant If a truck runs a stop sign at a constant velocity and then suddenly collides with velocity and then suddenly collides with another car also traveling at a constant another car also traveling at a constant velocity, what are the effects on both velocity, what are the effects on both vehiclesvehicles
What is transferred through the collision What is transferred through the collision and through which dynamic principles and through which dynamic principles allows this transfer to occur?allows this transfer to occur?
Vehicle InformationVehicle Information
Truck Data:Truck Data:Weight = 2900 lbWeight = 2900 lbVelocity = 45 mph (792 in/s)Velocity = 45 mph (792 in/s)Coefficient of Restitution =0 (perfectly Coefficient of Restitution =0 (perfectly
plastic)plastic)Car Data: Car Data:
Weight = 2200 lbWeight = 2200 lbVelocity = 25 mph (440 in/s)Velocity = 25 mph (440 in/s)Coefficient of Restitution = 0 (perfectly Coefficient of Restitution = 0 (perfectly
plastic)plastic)
Solidworks Model of TruckSolidworks Model of Truck
Solidworks Model of CarSolidworks Model of Car
Working Model SimulationWorking Model Simulation
Working Model: 2D Working Model: 2D
Equations: 2DEquations: 2D
Truck: x = xTruck: x = xoo + + v*tv*t Solved for time to collide with Truck using xSolved for time to collide with Truck using xoo = 0 and x = 0 and x
= 50 ft, and constant velocity v= 50 ft, and constant velocity vAA = 25 mph (440 in/s) = 25 mph (440 in/s) Truck can start anywhere from 990 to 1350 ft. in the Truck can start anywhere from 990 to 1350 ft. in the
y-direction of it’s starting point to ensure a collisiony-direction of it’s starting point to ensure a collision Car: (x – xCar: (x – xoo))BB = v = vB*B*ttA A = (v= (vBB/v/vAA)(x – x)(x – xoo))AA
Solved distance that would cause collision using Car Solved distance that would cause collision using Car A as reference with xA as reference with xoBoB = 0 at v = 0 at vBB = 45 mph (792 in/s) = 45 mph (792 in/s)
Car can start anywhere from -33 to 170 ft. in the x-Car can start anywhere from -33 to 170 ft. in the x-direction of it’s starting point to ensure a collisiondirection of it’s starting point to ensure a collision
Other General Equations: 2DOther General Equations: 2D
Kinematics of Rigid BodiesKinematics of Rigid BodiesPosition Analysis, Translation, RotationPosition Analysis, Translation, RotationKinetics of Rigid BodiesKinetics of Rigid BodiesGeneral Plane MotionGeneral Plane MotionMomentum and ImpulseMomentum and ImpulseConservation of EnergyConservation of Energy
Nastran 4DNastran 4D
Three dimensional kinematic and dynamic Three dimensional kinematic and dynamic analysis made easy.analysis made easy.
Similar scenario with only two vehicles.Similar scenario with only two vehicles. Two different situations:Two different situations:
Unrealistic (frictionless surface)Unrealistic (frictionless surface) Realistic (with friction)Realistic (with friction)
Unrealistic (No Friction)Unrealistic (No Friction)
Linear Momentum DataLinear Momentum Data
Right Before ImpactRight Before Impact
Bam!!Bam!!
Realistic (with Friction)Realistic (with Friction)
Realistic (with Friction)Realistic (with Friction)
Before Impact (With Friction)Before Impact (With Friction)
Immediately After ImpactImmediately After Impact
Basic Drop Test (Height = 2ft)Basic Drop Test (Height = 2ft)
Maximum Contact Force (at h=2ft)Maximum Contact Force (at h=2ft)
Learning ExperienceLearning Experience How to use modeling programs to simulate real How to use modeling programs to simulate real
life situations. life situations. Use analytical techniques from class for solving Use analytical techniques from class for solving
problems.problems. Despite what most car manufacturers say, truth Despite what most car manufacturers say, truth
be told, do not roll your car!!!! be told, do not roll your car!!!! It’s not just the car itself that damages the It’s not just the car itself that damages the
vehicle, but the transferred energy from the vehicle, but the transferred energy from the striking vehicle as well.striking vehicle as well.
It’s all about the impulse and momentum It’s all about the impulse and momentum principal!!principal!!