Browsing by Author "Zabala, Alaitz"

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    Bactericidal surfaces: an emerging 21st century ultra-precision manufacturing and materials puzzle
    (American Institute of Physics (AIP), 2021-04-06) Larrañaga-Altuna, Mikel; Zabala, Alaitz; Llavori, Iñigo; Pearce, Oliver; Nguyen, Dinh T.; Caro, Jaume; Mescheder, Holger; Endrino, José L.; Goel, Gaurav; Ayre, Wayne Nishio; Seenivasagam, Rajkumar Kottayasamy; Tripathy, Debendra Kumar; Armstrong, Joe; Goel, Saurav
    Progress made by materials scientists in recent years has greatly helped the field of ultra-precision manufacturing. Ranging from healthcare to electronics components, phenomena such as twinning, dislocation nucleation and high-pressure phase transformation have helped to exploit plasticity across a wide range of metallic and semiconductor materials. One current problem at the forefront of the healthcare sector that can benefit from these advances is that of bacterial infections in implanted prosthetic devices. The treatment of implant infections is often complicated by the growth of bacterial biofilms on implant surfaces, which form a barrier that effectively protects the infecting organisms from host immune defences and exogenous antibiotics. Further surgery is usually required to disrupt the biofilm, or to remove the implant altogether to permit antibiotics to clear the infection, incurring considerable cost and healthcare burdens. In this review, we focus on elucidating aspects of bactericidal surfaces inspired by the biological world to inform the design of implant surface treatments that will suppress bacterial colonization. Alongside manufacturing and materials related challenges, the review identifies the most promising natural bactericidal surfaces and provides representative models of their structure, highlighting the importance of the critical slope presented by these surfaces. The scalabl production of these complex hierarchical structures on freeform metallic implant surfaces has remained a scientific challenge to date and as identified by this review, is one of the many 21st Century puzzles to be addressed by the field of applied physics.
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    Benchmarking of several material constitutive models for tribology, wear, and other mechanical deformation simulations of Ti6Al4V
    (Elsevier, 2019-05-12) Liu, Cen; Goel, Saurav; Llavori, Iñigo; Stolf, Pietro; Giusca, Claudiu L.; Zabala, Alaitz; Kohlscheen, Joern; Paiva, Jose Mario; Endrino, José L.; Veldhuis, Stephen C.; Fox-Rabinovich, German S.
    Use of an alpha-beta (multiphase HCP-BCC) titanium alloy, Ti6Al4V, is ubiquitous in a wide range of engineering applications. The previous decade of finite element analysis research on various titanium alloys for numerous biomedical applications especially in the field of orthopedics has led to the development of more than half a dozen material constitutive models, with no comparison available between them. Part of this problem stems from the complexity of developing a vectorised user-defined material subroutine (VUMAT) and the different conditions (strain rate, temperature and composition of material) in which these models are experimentally informed. This paper examines the extant literature to review these models and provides quantitative benchmarking against the tabulated material model and a power law model of Ti6Al4V taking the test case of a uniaxial tensile and cutting simulation.
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    On the use of the theory of critical distances with mesh control for fretting fatigue lifetime assessment
    (Elsevier, 2019-10-01) Zabala, Alaitz; Infante-García, Diego; Giner, Eugenio; Goel, Saurav; Endrino, José L.; Llavori, Iñigo
    This work analyses the viability of the theory of critical distances (TCD) using mesh control for fretting fatigue lifetime assessment. More than seven hundred sets of simulations were performed by taking seventy different experimental tests reported previously in the literature. The outcome of the present study suggests that the TCD mesh control method can be extended to fretting fatigue problems by the reasonable assumption of setting the right element size proportional to critical distance. In this study, a significant computational time reduction of up to 97% was obtained. Thus, this study provides a simple method to design complex 3D industrial components subjected to fretting fatigue phenomena using finite element analysis efficiently without requiring complex remeshing techniques.
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    The possibility of performing FEA analysis of a contact loading process fed by the MD simulation data
    (Elsevier, 2018-07-17) Goel, Saurav; Llavori, Iñigo; Zabala, Alaitz; Giusca, Claudiu; Veldhuis, Stephen C.; Endrino, José L.