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Brake rotor simulation - Couldn't get results

Asked by Naveen Devaraj on 30 Oct 2019
Latest activity Commented on by darova
etwa 11 Stunden ago
Hello Everyone, i'm Naveen from Texas. I have a code that simulates dynamic brake rotor temperature. I know the end result and graph. But code doesnt give me the same result. I hope its my mistake and someone can help me out.
Basically, the code simulates a car Accelerating to 60mph at 0.5G and decelerating to 30mph at 1.6G and accelerates to 60mph and repeats to 150 to 300 sec. The temperature curve has to saturate like in the picture.
I have attached the code file and the desired result file.

  6 Comments

Are those values equal?
321.PNG
Velocity curve is exactly in between [44 88]
img1.png
>> V_min = 30*(5280/3600); %minimum speed [ft/s]
>> V_max = 60*(5280/3600); %maximum speed [ft/s]
>> [V_min V_max]
ans =
44 88
The question: why it doesn't look like
1233.png
Yes, the values of Thub an d Tinfinite are equal. Thub is the initial temp of hub (75F) and Tinfinite is ambient or envirnoment temperature which is also 75F.
Oh ya 44 and 88 are ft/sec. The curve should be doing 88 to 44 to 88 to and so on for every step. it cant be between the range, it has to be excatly from 88 to 44 and 44 to 88.

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2 Answers

Answer by darova
on 31 Oct 2019
 Accepted Answer

I set up maxstep
opt = odeset('MaxStep',0.1);
[t,x] = ode45(@DerFun,Tspan,x0,opt);
And now it looks like
img1.png

  1 Comment

Hey Darova, this helped me and the code is solved. It matches the curve in paper. :)
thanks for the time and patience.

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Answer by Naveen Devaraj on 6 Dec 2019 at 1:52

Hello guys, Naveen again. I need more help with same code. Now im trying to add actual sense to the code, i have changed some input values. Now, i wanted to change the period, in other words, i want to include coasting or dwell time when the car turns and accelerates.
Old Model- Car accelerates, brakes, accelerates and repeats for 120 seconds.
New model - Car accelerates, brakes, turn, accelerates, brakes, turn and repeat.
Average acceleration takes 6 seconds and Braking takes 1.36 seconds.
I appreciate help in advance

  4 Comments

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It doesn't matter if the car turns left or right. It turns, meaning that the turning time and accelerating to the Vmax time has to be included into the code (which is 6 seconds).
Can we create a new variable as V_turn = 15*(88/60) and include this condition in If statement?
Like, car accelerates(gees = g_acc), then car decelarates (gees =g_dec), then V_turn for 4 seconds, then car accelerates, repeats.
darova
etwa 11 Stunden ago
What is the criteria of turning? What should be x(1) (speed)?

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