Three Dispersed Magnetorheological Fluids in Dampers for Manufacturing Applications

Magnetorheological fluids (MRFs) are included in the class of “smart materials” since their viscosity can be quickly and reversibly changed upon the application of an external magnetic field. Even if MRF technology is exploited nowadays in many different fields (civil engineering, automotive, biomedical), very few manufacturing applications are on the market at the moment because of MRFs main drawback: sedimentation. This thesis aims to put the basis for the development of an innovative MRF damping device for manufacturing applications and to design an innovative MRF with improved response to the sedimentation to be employed in the damping device for manufacturing applications. The study starts from an accurate bibliographic investigation on MRF based devices, chemical features of MRFs and MRF formulations. This corpus of knowledge was organized into a model which can be used to explain the relationship between the functional requirements an MRF based device has to meet and the corresponding combination of chemical and physical properties of the fluids and the device itself (and so the MR operational mode selected); so, a rationale is provided to select the best fluid for the specific application, with particular focus on damping devices. Once the knowledge on the MRF damping functioning is gained, it can be extended to manufacturing applications. So, the designing process of a novel MRF-based damper for manufacturing applications is thus a consequence of the corpus of knowledge collected in this thesis. The experimental section of this work focuses, then, on the formulation of a novel three-dispersed MRF for damping devices with enhanced resistance to sedimentation. The experimental fluids were tested from the point of view of sedimentation and magnetization behavior. With regards to sedimentation, interesting results were reached.