Suspension Tester Specification SWG6 UPDATE AICA 14/11/2017

"Adhesion alone is not adequate for the conclusive evaluation of shock absorbers. The phase angle is a function of the damping value at different frequencies and should be used for evaluation of the damper performance. ...“ SAE Technical Paper 960735, 1996, Tsymberov A. Eusama needed improvements because of: New super light city vehicles Vehicles with Run Flat Tires Vehicles with very low profile tires Some heavy vehicles which succeded the test despite a bad working damper -> Recent developments in the vehicle industry had their influence on parameters like tire rigidity and unsprung mass -> These parameters influences the road adhesion by consequence also the Eusama value Frequency-domain response: magnitude response ("road adhesion"): indicative to vehicle safety, unreliable for dampers magnitude + phase response ("phase shift"): vehicle safety AND dampers condition

Phase shift φ The minimum phase shift φmin is the lowest value of the phase shift φ determined during the test between the sprung and unsprung mass resonant frequencies.

Phase shift φ The phase shift φ = the angular difference between the absolute “sinusoidal” position of the suspension tester platform & the “sinusoidal” vertical tire contact force between the tire + the suspension tester platform..

Test bench specifications Metal plate designed for vibrating in the range of [25 - 5] Hz with a peak to peak amplitude of 6 mm Weight measuring points per plate Sensor to detect the plate’s vertical position A drive of the frequency variation in order to have a more correct measurement by dissipating more energy in the proximity of the unsprung mass resonance frequency (min 7 sec).

Influence of the stroke of measuring plate

Influence of the Sprung Mass (car body)

Influence of the Tire Rigidity Influence of the Tire Rigidity !!!!! cases with even negative Eusama have the Minimum Phase Shift still above 35°

Influence of the main spring

Influence of the Unsprung Mass (wheel)

GOCA 2010 spec. doc CEN standard compatible format Removed references to EUSAMA and GOCA EUSAMA replaced by max force amplitude unbalance Removed details to specific implementations (e.g. Inverter). «What vs How» Deep analisys of each technical details nothing missed or misunderstood Redefined absolute and relative criterias TBD Approval procedure & Calibration procedure TBD Calibration tool & Who will certify it

Calibration tool from VIAS institute (www. vias Calibration tool from VIAS institute (www.vias.be) TBD the Egea ones, VIAS seems not interested in selling his solution

Goals Without ambiguity, everyone can make their own bench Add basic raccomandation about the system should work Convince the European commission from a nice to have to mandatory

4 key reasons to adopt it EU-wide… Single test method applicable across all European Member States for roadworthiness testing Minimum change to existing installations of suspension tester design/specification or for new installations Minimised costs due to a higher volumes of existing design and functions Existing GOCA database of test results ensures benchmarking (from 2011 ~25M vehicles tested)