Ciencias Exactas y Ciencias de la Salud

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Study of the mechanical behavior and cell viability on 3D-printed Ti6Al4V surfaces: porosity optimization for intervertebral spacer design
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-12) Hidalgo Ayala, Gabriela; García López, Erika; Lopez Botello, Omar Eduardo; mtyahinojosa, emipsanchez; Vázquez Lepe, Elisa Virginia; Trujillo de Santiago, Grissel; Escuela de Ingenieria y Ciencias; Campus Monterrey
Additively manufactured porous titanium implants offer a promising strategy to reduce stress shielding and promote bone interaction in spinal fusion procedures. In this work, Ti-6Al-4V lattice structures fabricated by Electron Beam Melting (EBM) were evaluated as candidates for intervertebral spacer applications. Three pore sizes (0.8 , 0.9, and 1.0 mm) were designed and produced using an Additive Arcam SPECTRA L (GE, Gothenburg, Sweden), along with solid EBM and cast Ti-6Al-4V controls. The study combined structural, mechanical, and in vitro biological characterization to determine how pore size influences performance. Dimensional analysis using scanning electron microscopy and ImageJ confirmed good geometric fidelity between CAD models and as-built lattices, with the 0.9 mm configuration showing the smallest deviation in pore diameter and strut thickness. Under uniaxial compression (ASTM E9), increasing pore size reduced both strength and stiffness. The 0.9 mm lattice exhibited a maximum compressive stress of approximately 564 MPa and an apparent modulus of approximately 13.5 GPa, values closer to those of vertebral trabecular bone than to those of solid Ti-6Al-4V. Attempts to perform compression fatigue testing (ASTM E466) revealed limitations of standard displacement-based preload protocols for highly compliant lattices, highlighting the need for adapted fatigue methodologies. A separate rotational fatigue test on a solid EBM specimen confirmed the correct functioning of the fatigue equipment. Biological performance was assessed using C2C12 murine myoblasts cultured on Ti-6Al-4V discs representing each pore size. Fluorescence imaging (Phalloidin/DAPI) showed robust cell adhesion and organized cytoskeletal structures across all lattices, while Live/Dead assays demonstrated high viability (>97%) with no pore size dependent cytotoxicity. Integrating mechanical, structural, and cellular findings, the 0.9 mm lattice emerged as the promising design, offering favorable balance between biomechanical compatibility, structural integrity and early cell response for potential use in intervertebral spacer implants.
Structural fatigue life calculation methodology for random loading
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021-11-25) Miramontes Estrada, Jesús Orlando; Cardenas Fuentes, Diego Ernesto; puemcuervo/tolmquevedo; Delgado Gutierrez, Arturo Javier; School of Engineering and Sciences; Campus Monterrey; Probst Oleszewski, Oliver Matthias
Fatigue life calculation has become a mandatory step while designing structural components in any type of industry. Some of the loading conditions for these components have a random behavior to some extent, and even though a simplifi cation to static loads is not the most accurate way, it is one of the most used methodologies given the direct application of the fatigue theories and the knowledge and experience of the engineers. There are a couple of reported approaches to consider the randomness of the load and come up with an expected value for fatigue life, such as Steinberg, Lalanne, Tunna, Dirlik, etcetera; however, these procedures are not familiar and straightforward for most of the structural engineers in the industry. There are commercial software packages available that can help close the knowledge gap, but those are expensive and require additional training for the engineers. This thesis work defi nes a straightforward methodology and develop a cost and training free application that considers load randomness to calculate fatigue life for structural components. To achieve this, a review of the available approaches was done, and by selecting the most recommended techniques throughout literature, an application was developed in Matlab to perform all the necessary calculations, whose GUI is simple enough to be included as part of the virtual validation procedures. With this methodology and application, calculating fatigue life for random loading conditions is simpli fied, making it available for every engineer nevertheless of their fatigue experience and knowledge. This document guides the reader through a general understanding on what is a random load, the mathematical and physical concepts on the fields of mechanical vibrations and fatigue theory necessary to understand random vibration and how it connects with fatigue, a proposed methodology with a series of steps to follow to calculate random loading fatigue, and finally a demonstration of the methodology applied to a specimen and how the calculations correlate successfully with testing.

Ciencias Exactas y Ciencias de la Salud

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