Following Cadence Design Systems’ acquisition of the Design & Engineering (D&E) business, the D&E Community Forum on the Nexus Community Center has been migrated in the Cadence Physical System Simulation Community. For more details and if you have any questions, please refer to the FAQ.

Stats

  • State Not Answered
  • Replies 2
  • Subscribers 1
  • Views 2
  • Members are here 0
More Content

Question about Lift/Squat Acceleration

jozef.bucha
Hello everyone,
 
I am trying to better understand how are outputs from suspension assemblies computed. But in help about Lift/Squat Acceleration i do not undestand to this part:
 
The suspension lift or squat during acceleration arises due to the tractive forces, weight transfer, and, in live axles, due to the differential input and output torques, as well. The longitudinal tractive forces at the tire contact patches are:
Fleft = Fright = -drive_ratio / 2.0
The vertical forces at the tire contact patch due to weight transfer are:
VWleft = VWright = - cg_height / (2 * Wheelbase)
 
What I do not understand how i can get forces on left sides of equations in newtons, when on right side drive_ration is unitless, cg_height and wheelbase is in meters
 
Thanks in advice for clarification
 
Jozef
  • 0
    Hi Jozef,
     
    I think those equal signs should be proportional intead. The idea is summarized in the documentation (with my added emphasis):
    Lift is the amount of front suspension extension (rebound) per G of vehicle acceleration. Squat is the amount of rear suspension compression (jounce) per G of vehicle acceleration. Lift and squat arise when the suspension reacts to longitudinal tractive forces, weight transfer forces, and, in dependent suspensions, to the differential input and output torques.
  • 0
    Hi Greg,
     
    I was if thinking if there is not missing (sprung_mass*Ag)
     
    Something like in Percent Anti-Dive Braking/Percent Anti-Lift Braking, where is Fleft = Fright = sprung_mass * Ag * brake_ratio / 2 and WTleft = sprung_mass * Ag * cg_height / wheelbase / 2.
     
    but in Percent Anti-Lift Acceleration/Percent Anti-Squat Acceleration sprung_mass*Ag is missing
    There is just Fleft = Fright = -drive_ratio / 2.0, VWleft = VWright = - cg_height / (2 * Wheelbase)
     
    Jozef
Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.