- #1
infini
- 5
- 0
Hello all
I am trying to derive a quarter car model that i can use Simulink to analyse. The model is 2 DOF and consists of 1 sprung and 1 unsprung mass, suspension spring and damping co-effs, and tyre spring and damping co-effs. Positive is taken as upwards, compression is also taken as positive. There is also a road displacement input to allow for modelling bump response etc. at a later date, but this is set to 0 currently. Overall a fairly standard QCM setup.
My question is regarding gravity as one of the forces on the model. Most models I've seen don't seem to include an explicit weight force, they simply use m*a = ƩF where ƩF sums the forces acting on the unsprung and sprung masses due to the dampers and springs. On my model i have added a weight component for the sprung (Ms*g) and unsprung (Mu*g) masses which acts downwards.
Can anyone tell me if i am adding this weight component unecessarily? I seem to be getting very high frequency vibration in the model and can't tell if this is due to the added weight force. Or am i going about things correctly and simply using unrealistic values for the spring, damping co-effs etc.?
Thanks in advance for the help/advice
I am trying to derive a quarter car model that i can use Simulink to analyse. The model is 2 DOF and consists of 1 sprung and 1 unsprung mass, suspension spring and damping co-effs, and tyre spring and damping co-effs. Positive is taken as upwards, compression is also taken as positive. There is also a road displacement input to allow for modelling bump response etc. at a later date, but this is set to 0 currently. Overall a fairly standard QCM setup.
My question is regarding gravity as one of the forces on the model. Most models I've seen don't seem to include an explicit weight force, they simply use m*a = ƩF where ƩF sums the forces acting on the unsprung and sprung masses due to the dampers and springs. On my model i have added a weight component for the sprung (Ms*g) and unsprung (Mu*g) masses which acts downwards.
Can anyone tell me if i am adding this weight component unecessarily? I seem to be getting very high frequency vibration in the model and can't tell if this is due to the added weight force. Or am i going about things correctly and simply using unrealistic values for the spring, damping co-effs etc.?
Thanks in advance for the help/advice