Ciencias Exactas y Ciencias de la Salud

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Thermomechanical properties of architected materials
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024) Rosales Vigueras, César Alberto; Treviño Quintanilla, Cecilia Daniela; mtyahinojosa; Cuan Urquizo, Enrique; Ayala García, Ivo Neftali; Escuela de Ingeniería y Ciencias; Campus Monterrey; González Valle, Carlos Ulises
Lithium-ion batteries (LIB) in electronic vehicles (EVs) suffer a thermal hazard known as thermal runaway (TR). This phenomenon is produced when the internal temperature of the battery rises to a point where the separator between anode and cathode evaporates, initiating an unstoppable exothermic reaction culminating in fire and/or explosion of the EV. This effect is sought to be mitigated by the usage of forced convection mechanism or phase change materials. However, these cases only tackle the heat dissipation problem. In reality, in a traffic accident, a short circuit could be produced increasing the internal temperature of the battery and initiating TR. That’s why a multipurpose approach was given to this study. Porous structure offers lightweight materials with reduced properties. The focus of this study was to alter the orientation and amount of the unit cell (UC) to recover some of the properties of the base material. The rotation is focused on increasing the cross-sectional area of the structure while the amount of the UC is focused on increasing the volume fraction. With this setup, the impact of the area and volume were analyzed individually in a factorial analysis for the thermal conductivity and strain energy of the samples. After the best porous structure was obtained for its highest thermomechanical properties, composites with an onyx hybrid matrix and glass fiber reinforcement were used to manufacture a new porous structure—an architected material. The results showed that the simple cubic lattice at 45º angle and 2 UCs with a hybrid matrix (SLC4 w/ HM) produced the highest thermal conductivity while the addition of a reinforcement was not significant for the mechanical and thermomechanical analysis.
Multiscale-based computer algorithm for predicting fracture toughness enhancement in carbon fiber-reinforced epoxy due to nanoclay addition.
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2022-11-29) Rivera Santana, Juan Andrés; Guevara Morales, Andrea; puemcuervo, emipsanchez; Otero Hernández, José Antonio; Cárdenas Fuentes, Diego Ernesto; Gómez Vargas, Óscar Armando; School of Engineering and Sciences; Campus Estado de México; Figueroa López, Ulises
As global energy consumption increases at the same time humanity faces the ever-increasing threat of climate change, among other things, increasingly longer wind turbine blades are required, which translates into a need for structurally more resistant materials. To achieve this purpose, a light material capable to withstand short- and long-term loading is required. Therefore, in this work the use of nanoclays is proposed to reinforce a high-modulus and high-strength material, such as carbon fiber reinforced epoxy. The main idea behind this proposal is that nanoclays are capable of increasing the material stiffness while retarding the propagation of cracks, ultimate responsible for material failure, all this without significantly increasing the overall material weight. Now, as a first step to evaluate the effectiveness of the proposed material, a computational algorithm capable of evaluating the stiffness and fracture toughness improvement in carbon fiber reinforced epoxy materials due to nanoclay addition, is proposed in this work. For the estimation of the improvements in the material engineering constants, the unit cell homogenization technique is employed at two levels: nano- and microscopic. Subsequently, these results are used for the evaluation of fracture toughness enhancement, which also requires the individual numerical evaluation of each mechanism: debonding, plastic yielding and shear banding. Starting with the evaluation of the debonding effects on fracture toughness, an algorithm based on the bisection method is used first to find the critical debonding radius and then the corresponding mechanism. Likewise, this critical debonding radius is used to numerically evaluate plastic yielding, together with the corresponding material stress-strain curves. Subsequently, the bisection method is used once again to find the shear banding critical radius and thereby quantify the corresponding mechanism. Finally, the contributions of the three mechanisms are added to obtain the total fracture toughness enhancement. In addition, the algorithm proposed in this work proves that nanoparticles play an important role in stiffening the carbon-reinforced epoxy material, but always playing a secondary role with respect to carbon fibers. However, the most important role of nanoclays is found in the fracture toughness enhancement of CFRP. Said enhancement is generated by energy mechanisms related to the interactions between the clay and its surrounding matrix, effectively hindering the crack propagation process, which in the long run translates into increased durability for the material. For its part, the resin holds all the material together and serves as the primary transmission medium for the fracture toughness enhancement mechanisms. Finally, the results obtained by the algorithm are consistent with the experiments and analytical models available in the literature.

Ciencias Exactas y Ciencias de la Salud

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