- #1
inamukak
- 7
- 2
Hi everyone,
So I'm working on this project where I have to determine the total force that is being applied to an assembly that is attached to a crank shaft which is in turn attached to a motor that's driving it. I looked up the equations for the acceleration and velocity of a crank shaft (or a piston at the end of it) and tried to calculate the values based on that but the numbers I'm getting are huge. I'm also dumbing it down to a very basic model ignoring friction, vibration and other factors. The following are the values that I have right now:
m = 2995 lbs
Motor rpm = 358
I converted the motor rpm to get the angular velocity of the crank, which I got as w= 37.47 rad/s
I then used this value to determine the acceleration based on a formula I looked up online:
a = -r(w^2)*(cos(theta) + ((cos (2*theta))/n)
where
n = l/r
l = 8 in
r = 0.3125 in
I'm getting an acceleration of around 450 in/s^2 (if I consider 1 as the maximum value of cosine). Now if I use F = ma here, I get a force of approximately 1.35 million lbs. Just looking at the number makes me think it's wrong. So I just wanted to check what factors I should be considering here or what I'm doing wrong and the correct way of doing this. Any help would be appreciated.
Thank you!
So I'm working on this project where I have to determine the total force that is being applied to an assembly that is attached to a crank shaft which is in turn attached to a motor that's driving it. I looked up the equations for the acceleration and velocity of a crank shaft (or a piston at the end of it) and tried to calculate the values based on that but the numbers I'm getting are huge. I'm also dumbing it down to a very basic model ignoring friction, vibration and other factors. The following are the values that I have right now:
m = 2995 lbs
Motor rpm = 358
I converted the motor rpm to get the angular velocity of the crank, which I got as w= 37.47 rad/s
I then used this value to determine the acceleration based on a formula I looked up online:
a = -r(w^2)*(cos(theta) + ((cos (2*theta))/n)
where
n = l/r
l = 8 in
r = 0.3125 in
I'm getting an acceleration of around 450 in/s^2 (if I consider 1 as the maximum value of cosine). Now if I use F = ma here, I get a force of approximately 1.35 million lbs. Just looking at the number makes me think it's wrong. So I just wanted to check what factors I should be considering here or what I'm doing wrong and the correct way of doing this. Any help would be appreciated.
Thank you!
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