Friction and Wear Analysis of Shock Absorbers Using MR Fluid-Based Bio-Lubricant with Tergitol NP-10

This study examined the friction and wear properties of organic oil-based magnetorheological (MR) fluids as bio-lubricants. Safflower Seed Oil (SSO) and Cashew Nut Shell Oil (CNSO) served as base fluids, each containing 0.3 µm iron particles and Tergitol NP-10 at 0.5–3 wt.%. Tribological performance, assessed via a four-ball machine, showed optimal results for SSO with 2.5 wt.% additives, yielding a wear scar diameter of 340 µm and a coefficient of friction of 0.0418. Real-world testing in 132 DG MR shock absorbers under varying electromagnetic fields, motion amplitudes, and frequencies revealed damping force errors of 9% (SSO, 2.5 wt.%) and 10% (CNSO, 2 wt.%), supported by finite element analysis. Molecular-level evaluation using Wavefunction Spartan 18 provided insights into tribological mechanisms. Wear progression was noted, with cylindrical wall diameters increasing by 3.36 µm after 96 hours of operation. Overall, 2.5 wt.% SSO demonstrated superior wear resistance and damping performance over other formulations, highlighting the potential of organic MR fluids as environmentally friendly alternatives for mechanical systems such as shock absorbers, combining improved performance with sustainability benefits.