COMPUTER ASSIGNMENT ME 270 BY VAMSHI KRISHNA REDDY CHADA

COMPUTER ASSIGNMENT

ME 270 BY

VAMSHI KRISHNA REDDY CHADA

PROJECT AIM

An engineering model and a bond graph model of the car,person,seat

belts,bumper needs to be created and to transform the engineering

model to of reality into a computer model for simulation using the

Computer Aided Modeling Program CAMP-G.Then to perform

interactive simulation and generate numerical and graphical output

using MATLAB and considering the design criteria.

INITIAL CONDITIONS The given initial conditions for the problem are

DATA ON INJURIES

Seat belts must be tested to 3000lbs(1.334*104 N)

Chest can sustain a force of 1500lbs

Chest area is 30 in^2

Seat belt effective area=30in^2

Shoulder strap seat belt combination=60in^2

PHYSICAL PARAMETERS

Mass of car(M)=1500kg

Mass of dummy(m)=100kg

Bumper spring constant(k1)=10000N/m

Bumper damping constant(R1)=500N-s/m

Seat belt spring constant(K2)=300000N/m

Seat belt damping constant(R2)=80000N-s/m

PROBLEM 1solution procedure

The objective of the problem is to find out weather dummy will hit the windshield or not when he travels at velocities 25mph and 55mph.In order to solve this the following steps should be followed.

1.The initial step is to draw the bond graph for given model by using CAMPG

software.

2.Then bond graph model drawn in CAMPG is to be interface with MATLAB.

3.Then by interfacing with MATLAB it will get four files namely campgequ.m,

campgmod.m,campgsym.m,campgnum.m.

4. The next step is to take campgmod.m file and required conditions for solving problem has to be initialized as follows

-First the input variables has to be initialized in that file i.e..

dummy_mass=100; (Given mass of the dummy in kilograms)

car_mass=1500; (Given mass of the car in kilograms)

mph=0.44704; (Conversion factor to convert mph to meter per seconds)

v1=25*mph; (velocity component)

v1=55*mph; (Velocity component)

- Then a for loop is to be initialized in order to find weather at given velocities

the dummy hit windshield or not. The initialization of for loop as follows.

“ For i=1:2

vel=V(1,i)”

Explanation of loop:By running for loop first 'i ' takes the value of '1' and then it takes the velocity V1 and in the next cycle ' i ' takes the value of ' 2 ' then it takes the velocity V2,then for both velocity components the pro gramme will run in the MATLAB.

-Initial conditions in the campgmod.m file has to be given.

-Then physical parameters must be declared in the campgmod.m file.

-Then external inputs i.e source of flow must be initialized as ' 0 ' because the windshield doesn't move.

-The time variables must be declared so that simulation period can be contolled within a limited period.

-Then in the next step maximum absolute displacement covered by the car and the dummy has to be taken from the graph obtained by the MATLAB program.

-Then maximum displacement obtained are compared with 100cm(i.e

displacement between car and windshield as given) by initializing 'if

statement' in campgmod.m file and the program statements has to declared

as shown in campgmod.m file which is attached to report.

5.The next step is to run the MATLAB file by clicking the debug icon.

6.Then we get the output or result as follows....

-At velocity 25mph dummy will not hit the windshield.

-At velocity 55mph dummy will hit the windshield.

7.We also get the simulation graphs for velocities 25 mph and 55 mph.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-2

-1

0

1Dummy displacement vs time at velocity=55mph

Dis

plac

emen

t

Time (seconds)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.8

-0.6

-0.4

-0.2

0 car displacemento vs time at velocity=55mph

Dis

plac

emen

t

Time (seconds)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-1

-0.5

0

0.5Dummy displacement vs time at velocity=25mph

Dis

plac

emen

t

Time (seconds)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.2

-0.15

-0.1

-0.05

0 car displacemento vs time at velocity=25mph

Dis

plac

emen

t

Time (seconds)

PROBLEM 2PART 1

SOLUTION PROCEDURE

The objective of the problem is to find out the force acting on the chest of the

dummy at 25mph and 55mph and to compare those forces with the given data and to

know weather chest injury occurs or not when he wears seat belt only. The solution is

as follows

1.The initial step is to draw the bond graph for given model by using CAMPG software.



campgmod.m,campgsym.m,campgnum.m.4. The next step is to take campgmod.m file and required conditions for solving

problem has to be initialized as follows









“ For i=1:2

vel=V(1,i)”






-Then by taking if statement we have to check weather maximum absolute

force is greater than or equal to given maximum force on the chest i.e 6700

N.

-Then we have to run the if loop by the variable ‘ i ‘ and to check weather chest

injury occur or not at 25mph and 55mph


6.The output of the MATLAB program is

-Force acting on the dummy at velocity 25mph is 9313.430429 N.

-Force acting on the dummy at velocity 55mph is 20516.798391 N .


0 0.5 1 1.5 2 2.5 3-10000

-5000

0

5000 Force Exerted on Chest of Dummy at Velocity = 25 mph

0 0.5 1 1.5 2 2.5 3-3

-2

-1

0

1x 10


PROBLEM 2PART 2

SOLUTION PROCEDURE

The objective of the problem is to find out the force acting on the chest of the dummy

at 25mph and 55mph and to compare those forces with the given data and to know

weather chest injury occurs or not when he wears seat belt and also the shoulder

strap. The solution is as follows














“ For i=1:2

vel=V(1,i)”






-Then by taking if statement we have to check weather maximum absolute force is

greater than or equal to given maximum force on the chest i.e 6700 N.

-Then we have to run the if loop by the variable ‘ i ‘ and to check weather chest injury

occur or not at 25mph and 55mph by weaing seat belt and shoulder strap



-Chest injury will occur at velocity 25mph.

-Chest injury will occur at velocity 55mph.


0 0.5 1 1.5 2 2.5 3-10000

-5000

0


0 0.5 1 1.5 2 2.5 3-20000

-15000

-10000

-5000

0


PRBLEM 3SOLUTION PROCEDURE

The objective of the problem is to find out the critical maximum velocity at which

impact occurs at which hitting the windshield, chest injury,ineternal injury,seat belt

failur,strap failure should not occur. The solution is as follows.







dummy_mass=100; (Given mass of the dummy in kilograms) car_mass=1500; (Given mass of the car in kilograms) mph=0.44704; (Conversion factor to convert mph to meter per seconds) v1=25*mph; (velocity component) v2=55*mph; (Velocity component)

- Then a for loop is to be initialized in order to find out the critical maximum

velocity .

“ For i=1:55

vel_mps=i*mph

Explanation of loop:By running for loop first 'i ' takes the value of '1' and gradually increase the ‘I’ value and checks for maximum critical velocity.




-The time variables must be declared so that simulation period can be contolled within a limited period

-Then by taking if statement we have to check weather maximum absolute force is

greater than or equal to given maximum force on the chest i.e 6700 N and

5500N.

-Then we have to run the if loop by the variable ‘ i ‘ and to find out the critical

maximum velocity



-Displacement of dummy at critical maximum velocity=0.4778meters

-Force exerted on dummy at critical maximum velocity=5777.201newtons

-Critical maximum velocity=16mph

7.We also get the simulation graphs for maximum critical velocity.

0 0.5 1 1.5 2 2.5 3-6000

-4000

-2000

0

2000 Force Exerted on the chest at Critical Maximum Velocity

PROBLEM 4SOLUTION PROCEDURE

The objective of the problem is to find out the time and force acting on dummy when he

hits the windshield at velocities 25mph,40mph and 55mph without wearing seat belt.

The solution is as follows .







dummy_mass=100; (Given mass of the dummy in kilograms) car_mass=1500; (Given mass of the car in kilograms) mph=0.44704; (Conversion factor to convert mph to meter per seconds) v1=25*mph; (velocity component) v2=40*mph; (Velocity component) v3=55mph , (velocity component)

- Then a for loop is to be initialized in order to find out the time and force acting on the

dummy at given velocities when he travels without seat belt.

“ For i=1:3

vel=V(1,i)

Explanation of loop:By running for loop first 'i ' takes the value of '1' and gradually increase the ‘I’ value and gives the time and force at which dummy hits windshield by testing if loops in prior statements in the mat lab programme.




-The time variables must be declared so that simulation period can be contolled within a limited period

-Then by taking if statement we have to obtain time by dividing distance over

corresponding velocity.

-Then we have to run the if loop by the variable ‘ i ‘ and to find out the critical

maximum velocity



-Time taken by dummy to hit windshield at 25mph= 0.089477

-Time taken by dummy to hit windshield at 40mph=0.055923

-Time taken by dummy to hit windshield at 55mph=0.044739

END OF THE REPORT

BY

CHADA,VAMSHI KRISHNA REDDY

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COMPUTER ASSIGNMENT ME 270 BY VAMSHI KRISHNA REDDY CHADA