The student Ainara Gomez Pedraza obtained an EXCELLENT CUM LAUDE grade with mention International Doctorate
The student Ainara Gomez Pedraza obtained an EXCELLENT CUM LAUDE grade with mention International Doctorate
The student Ainara Gomez Pedraza obtained an EXCELLENT CUM LAUDE grade with mention International Doctorate
- Thesis title: Analysis and development of new magnetoactive materials
Court:
- Presidency: Modesto T. López López (Universidad de Granada)
- Vocal: Pavel Kuzhir (University of Nice)
- Vocal: Dmitry Borin (Technische Univestät Dresden)
- Vocal: Carmen Rial Tubio (BCMaterials)
- Secretary: Ane Errarte Yarza (Mondragon Unibertsitatea)
Abstract:
The growing demand for advanced systems requiring adaptability, monitoring, and real-time response has driven the development and study of smart materials capable of adjusting their physical properties based on various external stimuli. Within this category, magnetoactive materials (MA) stand out for their ability to instantly modify their behavior in response to a magnetic field. Their rapid action, efficiency, and reversibility make them especially attractive for applications requiring precise and immediate responses. However, despite their advantages, these materials still face certain limitations that restrict their use. For this reason, this doctoral thesis has focused on developing and analyzing new MA materials and characterization systems to optimize their properties and facilitate their application. Specifically, this thesis has centered on two types of MA materials: magnetorheological fluids (MRF) and MA elastomers.
Regarding MRFs, one of the main drawbacks is their low gravitational stability. In this context, the effect of the solid phase on the magnetorheological behavior of MRFs has been analyzed, considering factors such as particles’ composition, size, and morphology. To this end, samples with different types of particles have been synthesized, and characterization has been carried out to evaluate the impact of these physical properties on MR response, the destruction mechanisms involved, and the fluid's reversibility after exposure to a magnetic field.
Additionally, a new non-invasive method based on ultrasound has been developed to measure the gravitational stability of MRFs. This development includes the design and fabrication of the measurement system, as well as procedures for data conversion and the measurement process. The method is based on the correlation between particle concentration and sound propagation speed, providing an effective solution for characterizing sedimentation in fluids composed of nano or micrometric particles.
On the other hand, concerning MA elastomers, one of the main challenges is to improve both deformability under a magnetic field and the material's ability to recover its original shape after the field is removed. This thesis addresses these challenges through the development of a new generation of MA elastomers based on magnetically soft particles, with a specific multilayer structuring that optimizes both deformability and reversibility.
To achieve precise control of the material, a 3D digitization method has been employed that correlates the material's deformation with the applied magnetic field. Additionally, to deepen the understanding of how the magnetic field affects the material's internal structure and causes deformation, an evaluation of the magneto-mechanical and magnetic properties has been conducted, complemented by microstructural analysis using micro-computed tomography.
In summary, this doctoral thesis significantly contributes to the advancement in the field of MA materials, addressing their current limitations by proposing new solutions. Thus, the results obtained not only expand knowledge about the behavior of these materials but also facilitate their implementation in advanced systems and promote the development of new technologies.