eugeneh
Mechanical
- Feb 2, 2017
- 1
Hello fellow Adams/View users!
Adams gives me headaches. First of all: sorry for my grammatical errors.
The problem I seek your help with is the following: I need to simulation a fricion wheel drive. In order to keep the model simple lets say there are only two friction wheels (wheel 1 and wheel 2) and one long rigid body which has to be moved by the wheels. First B has a contact only with wheel W1. Both wheels accelerate by an implied motion, so that B is being moved to W2; there will probably be slip, which is OK.
But now there is a problem. When the moved body hits wheel 2, wheel 2 SHOULD get braked a bit because of the impact; then accelerate to its old angular velocity, but because of the motion it does not lose any speed.
The function I used to apply the motions is the Step function. I do realise that this funcion is the cause for the trouble. But how else is one supposed to accelerate the system.
I actually had the idea to calculate the braking the relationship: Δv = a *Δt together with F[sub]N[/sub] = m*a.
While F[sub]N[/sub]= value of the Impact-value and m = mass of the rigid body.
The so calculated Δv is then divided by the radius of the friction wheel in order to get Δω, wich is then subtracted from the Step-function, so I`d get :
Ang. vel = STEP (time, 0, 0, 5, 30) - IF( IMPACT: 0, 0, Impact/m_body)*dt/r
My problem at this point is to determine dt. I`m pretty sure this entire approach is a total mess, but I couldn`t figure out how else to make the ang. velocity dynamic once it has reached its end value of 30 at the time point of 5 sec.
I hope it`s comprehensible what I`m trying to say.
Thanks a lot in advance!
PS: the friction wheels are supposed to be driven by a motor, of which I do have a Torque-speed-characterisitics. But my goal is to accelerate the system in a given time, so I used a motion instead of a sforce.
Adams gives me headaches. First of all: sorry for my grammatical errors.
The problem I seek your help with is the following: I need to simulation a fricion wheel drive. In order to keep the model simple lets say there are only two friction wheels (wheel 1 and wheel 2) and one long rigid body which has to be moved by the wheels. First B has a contact only with wheel W1. Both wheels accelerate by an implied motion, so that B is being moved to W2; there will probably be slip, which is OK.
But now there is a problem. When the moved body hits wheel 2, wheel 2 SHOULD get braked a bit because of the impact; then accelerate to its old angular velocity, but because of the motion it does not lose any speed.
The function I used to apply the motions is the Step function. I do realise that this funcion is the cause for the trouble. But how else is one supposed to accelerate the system.
I actually had the idea to calculate the braking the relationship: Δv = a *Δt together with F[sub]N[/sub] = m*a.
While F[sub]N[/sub]= value of the Impact-value and m = mass of the rigid body.
The so calculated Δv is then divided by the radius of the friction wheel in order to get Δω, wich is then subtracted from the Step-function, so I`d get :
Ang. vel = STEP (time, 0, 0, 5, 30) - IF( IMPACT: 0, 0, Impact/m_body)*dt/r
My problem at this point is to determine dt. I`m pretty sure this entire approach is a total mess, but I couldn`t figure out how else to make the ang. velocity dynamic once it has reached its end value of 30 at the time point of 5 sec.
I hope it`s comprehensible what I`m trying to say.
Thanks a lot in advance!
PS: the friction wheels are supposed to be driven by a motor, of which I do have a Torque-speed-characterisitics. But my goal is to accelerate the system in a given time, so I used a motion instead of a sforce.
