Post on 16-Oct-2019
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
Virtual tools for modelling and designing hydro-pneumatic suspension systems for off-road vehicles
Massimo Borghi, Barbara Zardin Laboratorio di Idraulica del Veicolo – Fluid Power Lab
DIEF Engineering Department Enzo Ferrari University of Modena and Reggio Emilia
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
OUTLINE OF THE PRESENTATION Introduction: AGT suspension
system Reference vehicle Modelling Experimental test Results Conclusion and Future works
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
SUSPENSION OF AN AG TRACTOR ROLE: to isolate the suspended part of the vehicle by dampening
vibrations in very different operating conditions (comfort & handling).
To separate the sprung mass from the unsprung one. CHARACTERISTICS: “elastic/spring” element: stores/accumulates energy “damping” element: dissipates energy
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
Design tasks Critical Issues: Big weight, position of the centre of gravity, static load changing as function of the equipment, dynamic load transferring from back to front axle, “high” vehicle speed
EVOLUTION from rigid axle to front suspended axle + cabin suspension INTERNATIONAL STANDARDS on vertical acceleration peaks amplitude and frequency (dangerous values in the 1-5 Hz range)
EXPERIMENTAL TESTING OF THESE FUNCTIONS AND TUNING
OF THE CONTROL ON DIFFERENT OPERATING CONDITIONS IS TIME
CONSUMING
SUSPENSION OF AN AG TRACTOR
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
Driveline
Front Chassis Front Axle
Case IH Puma 215 CVX
Panhard Rigid Bar
Rear Axle
VEHICLE
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
SUSPENSION OF AN AG TRACTOR
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
MODELLING FIRST APPROACH: LUMPED PARAMETER Hydraulic system + Quarter Car Model in LMS Imagine.Lab AMESim + Control Unit in Simulink
P ML
HYD CTRL
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
HYDRAULIC MODEL EHPV 3D model
Pilot Pin
Pilot Seat
Main Poppet
Contact Model
Hydraulic model details
EH
PV
FC
AM
ES
im M
odel
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
-ideal gas -heat exchange with the environment modelled using a time constant (Highsimilar to adiabatic; Lowsimilar to isothermal process)
HYDRAULIC MODEL
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
VEHICLE SETUP & TESTS
VEHICLE SETUP: • CAN Network • Accelerometer • Pressure Sensor VEHICLE DATA • Tire Pressure:
• 1,2 bar (Front) • 1,6 bar (Rear)
• Weight distribution • 42% Front – 58% Rear
• No Stabilizing Mass
SUSPENSION SETUP • SOFT • NORMAL • HARD
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
RAISING LOWERING
Raising valve [%] Lowering valve [%]
TESTING: STATIONARY
STATIC TESTS LEVELING
W/O PARK LOCK
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
SENSITIVITY ANALYSIS Load distribution Coulomb friction coefficient Stiction friction ceofficient
Friction concentrated on Panhard Bar
NUMERICAL vs EXPERIMENTAL: TUNING AND ANALYSIS
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
TESTING: DYNAMIC DYNAMIC TESTS BUMP TEST 7 / 10 kph
Valve 31 30___ SOFT 100% - 80% NORMAL 55% - 67% HARD 37% - 37%
Displacement
Pressure
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
COMMENTS AND LIMITS Qualitatively good comparison the influence of: load distribution configuration, suspension damper setup, modification and test of the Skyhook control (control logic), time responses of the damping valves. The dangerous vertical acceleration frequency values in the bump test in numerical/experimental analysis are the same (0-3 Hz), as well as the frequency correspondent to the peak of acceleration
1 Hz 1 Hz
BUT: No pitch, yaw, roll movements No modelling of the tyre-ground interface
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
FULL CAR VEHICLE MODEL: Bump Simulator Tyre Model Driveline & Chassis Panhard Bar & Rigid Bar Front Axle Hydro-Pneumatic Suspension
STEP FORWARD
Contact point trajectory
calculation
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
CONDITION Transmission in NEUTRAL
No CVT Dynamics Constant velocity (7/10 kph) Suspension in NORMAL mode
STEP FORWARD
Engineering Department Enzo Ferrari – University of Modena and Reggio Emilia
Napoli 27 Giugno 2016 – New Trends in Fluid Power, Design and Simulation Symposium
FINAL COMMENTS A tool integrating a multibody full car model of the tractor and the
detailed hydraulic model of the suspension system has been realized
Experimental tests on the vehicle have been useful both to characterized some critical aspects (friction) and to validate the model
An experimental – numerical comparison, considering the leveling test, the hysteresis test and the bump test has been performed.
A good correlation with experimental data has been found by the model analysis
We are working to optimize and improve the model, especially for: Contact between wheel and terrain Thermal effects on accumulator