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!!