gt6racer: we must label our quadrants differently, as I would refer to the 2nd and 4th quadrants (Force-Velocity) as the active-only regions (energy input) and the 1st and 3rd quadrants as the passive regions (energy dissipated).
These 'semi-active' systems where damper or spring...
ttx40: In addition to Greg's example you can picture a Force-Slip Angle curve. At the force peak the force sensitivity to slip angle (slope of curve) necessarily drops to zero (definition of a peak), so the tire will not respond to small changes in steer. It may or may not be sensitive to...
ttx40, nobody owes me an apology. You asked a question, probably wanting to tap into the wealth of knowledge and experience of the members on this site. I think Cibachrome's answer is fine, but I felt that the context was missing and I wanted to clarify...he/she may still disagree anyway...
Note: I'm the author of the F1-Technical post, but my normal username (GSpeedR) has registration issues.
Cibachrome: I think that you've (inadvertently) taken the post out of context, and completely ignored/missed the first sentence: "The yaw moment contribution from steer can be quite...
I think we're on the same page now. Good points, especially regarding contact patch mass. My tire models are more complicated than what we've discussed (ungrounded, more elements than just parallel-spring-damper) but certainly not an FTire model or anything. They are probably inadequate for...
Fair enough, I will stop posting. GregLocock obviously doesn't agree with me, any future readers can see what we've posted and draw their own conclusions.
I appreciate the help.
The point I have been trying to make is that F_pad = F(tire to hub).
The reason is that ideal spring and damper elements transmit force directly, so the force is unchanged from the pad up to the hub mass. I have done plenty of FBDs, I can represent this in simulation, and I have measured...
Greg, when you say "component" do you mean "masses", and therefore you are referring to a multi-DOF system? For SDOF, assuming ideal elements (mass-less springs/dampers and rigid masses), force is transmitted instantaneously through an ideal spring and an ideal damper, without change in...
I don't want to come across as dismissive of Greg's post. I feel that I did not properly describe the setup and the problem that I am attempting to solve.
Let's just simplify to a single spring-mass-damper system, with the spring/damper attached to the actuator pad. It seems as Greg is...
Thanks for the reply, Greg.
I don't know if this changes your opinion, but I am attempting to determine the energy dissipated by the damper(s).
If we simplify to a single DoF system as a tire on a pad, then the input force is transmitted directly into the tire damper/spring. My thoughts are...
Sorry for all the editing (I guess there's no way to edit posts).
To clarify the spectral calculation:
cpsd(x(t),F(t)) = E_real(w) + E_imag(w)*j
I take the real part, which is the dissipated energy, while the imaginary part is stored. Hopefully I'm not off base here.
Hello everyone,
I have been struggling to properly calculate energy ratios (energy dissipated/energy input) in servo-hydraulic test systems. Specifically, the test specimens are quarter-car (2DoF) suspensions, which include tire compliances. The rig is capable of many excitation waveforms...
The gas spring effect from reservoir pressure is in parallel to the spring rate of the traditional suspension spring, not in series. So the overall vertical rate of your SMD system is changed and thus your "rise time" would change. Imagine a huge reservoir pressure and think about the...
Good point on the failsafe, that is definitely true. I never used the Delphi controller supplies for the MRs, but I would be very surprised if Delphi were able to get unsprung mass control based on use with another controller we used (maybe you know better?). They are slightly faster than any...
It's a great concept and has the potential to see its way into a lot more OE applications and motorsport as well (until it gets banned). However, Lord (the company which holds the patent to MR fluid) charges exorbitant costs. This should have been a project to bring Delphi back from financial...
In many high speed/ high downforce style racecars with significant suspension travel (ie. more than 1" total) mechanical grip is hugely diminshed if the dampers do not have any high speed rebound force. Looking purely at the contact patch hysteresis a tire sees, using only HS compression...
