Modelling and validation of shock absorption with tunable performance through liquid intrusion–extrusion cycles

In response to the global push for net-zero emissions, the automotive industry faces challenges from the environmental impact of traditional oil-based shock absorbers, as vehicle production in Europe consumes around 9000-9500 tons of hydraulic oil annually. Our research introduces an innovative shock-absorber that employs a Heterogeneous Lyophobic System (HLS) to replace hydraulic oil with a nonwetting liquid (NWL) and hydrophobic nanoporous materials (PMs). This system not only eliminates oil use but also enables the tuneability of the vehicle shock-absorber's performance. By focusing on the dynamic intrusion/extrusion process, we developed a CFD-coupled model demonstrating how the adjustment of damping characteristics can be achieved, catering to a broad spectrum of vehicular requirements. The core of this study lies in its ability to simulate the patterns of intrusion and extrusion, including complete, partial cycles, and double-step cycles, thereby demonstrating both the practical applicability and theoretical foundation of using such mechanisms in shock-absorber design. With a strong correlation between experimental and simulation data, the current study not only underpins the accuracy of the developed theoretical and CFD models but also allows for the customisation of the shock-absorber performance under assorted conditions, laying a solid groundwork for future technological advancements in this field. Overall, this work provides a practical modelling framework that can guide the industrial design of next-generation sustainable shock-absorbers and broader adaptive damping systems.