Speaker: Prof. Xufeng DONG, Dalian University of Technology, China

Chair: Dr. Weihua Li

Abstract: The vibration reduction of critical engineering structures is closely linked to their longevity, safety, and reliability. Magnetorheological (MR) fluid based intelligent vibration reduction technology offers significant advantages, including a wide range of applicable frequencies, low energy consumption, and excellent stability. Currently, the critical performance indicators of MR fluids, such as shear yield strength, sedimentation stability, and zero-field viscosity, exhibit mutual constraint effects. Achieving a balance among these key performance indicators and developing MR fluids with exceptional comprehensive performance presents a bottleneck problem that hampers the progress of intelligent vibration reduction technology in structural engineering. This study demonstrates that by incorporating homemade, high-saturation magnetization (208.0 emu·g-1) nanoparticles as a secondary component in cross-scale bidisperse MR fluids, the performance drawbacks experienced by monodisperse micron particles can effectively be mitigated, leading to a more stable equilibrium between performance factors. The main reason is that nanoparticle addition heightens chain structure density under magnetic fields, while reducing overall particle density when no magnetic field is applied. By substituting some micron particles with nanoparticles, the significant increase in zero-field viscosity caused by direct nanoparticle introduction can be circumvented. The optimal proportion of nanoparticles in MR fluids was preliminarily explored, and it was found that the Micro-Nano bidisperse MR fluids exhibit high shear yield strength (58.3 kPa at 436 kA·m-1), excellent sedimentation stability (82.6% at 7 days), suitable zero-field viscosity (1.25 Pa·s at 100 s-1), and ideal reversibility. Most notably, the method used to prepare these MR fluids is simple, bestowing considerable value for engineering applications.