Browsing by Autor "Fabio Arturo Rojas Mora"

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Characterising structural, mechanical and cytotoxic properties of coral-based composite material intended for bone implant applications
(National University of Colombia, 2011) Angela Samper Gaitán; Fabio Arturo Rojas Mora; Diana M. Narváez; Luis Miguel Méndez Moreno
Studies concerning the application of Porites asteroides coral for bone implant purposes have demonstrated the biological viability of its use. As a complement to previous research regarding the development of bone-powder based composite materials which are useful for such applications, this study was aimed at developing a coral powder-based composite material which would be able to satisfy the appropriate structural, mechanical and cytotoxic properties required for its use. A composite material made of coral powder, calcium sulphate powder and water was therefore developed, and its properties were tested in different compositions. The results showed how the resulting composite material had properties which were comparable to those of human cortical bone (from both a structural and mechanical point of view), as well as being non-toxic below a 0.35 mg/ml critical composite material concentration.
Characterization and Computational Validation of Multi-Layer Carbon Fiber Based Polymer Matrix Composite Material for Rocket Engine Combustion Chamber Applications
(2025) Santiago Gonzalez Buenaventura; Fabio Arturo Rojas Mora; Andrés González-Mancera
Abstract Carbon Fiber Reinforced Polymers (CFRPs) have enormous potential for weight reduction in load bearing components. This study explores their viability as an alternative material for rocket engine combustion chambers through the redesign of the hybrid rocket engine ‘Ragnar X’. Aiming to increase its Thrust/Weight ratio through the replacement of its combustion chamber steel cylinder for one developed in a CFRP-based multi-fiber composite structure. To overcome the challenge of using Carbon Reinforced Polymers for high temperature applications (2000K), an initial layer of ceramic wool was included as thermal insulation to reduce heat transfer. The mechanical properties of the CFRP were characterized according to the ASTM D3039 method [1]. This process was adapted to determine the variation of the ultimate strength with respect to the environment’s temperature. The results indicate a valid ultimate strength for the design for temperatures under 190°C. A multi-step computational validation was used to determine the thermal conditions and heat transfer the engine would be subjected to during operation. The results in conjunction with the characterization show that the engine can withstand its logistical maximum of 40 seconds of operation without failure and up to a theoretical 73 seconds of continuous operation before failure. The prototype manufactured based on the theoretical design managed to reduce the combustion chamber’s weight almost by a factor of 2 and increased the Thrust/Weight ratio from 8.58 to 15.52.
Misiones de cohetería experimental con propelente sólido: Misión séneca, cohete Ainkaa 1
(Military University Nueva Granada, 2010) José Alejandro Urrego Peña; Fabio Arturo Rojas Mora
<p>Este documento expone la metodología y los resultados obtenidos en el desarrollo de una investigación sistemática, que trata sobre a la implementación de misiones de cohetería experimental. En este proceso se obtuvieron, datos y resultados que permitieron corroborar de forma experimental, conceptos de propulsión, aerodinámica y balística propios de una aeronave tipo cohete sin elementos de control activo a bordo. Para el estudio e implementación de esta misión, se generó un método dividido en etapas por las cuales se guió el desarrollo del proyecto; primero se realizó la etapa de validación y el<br />diseño preliminar en forma teórica, se continuó con la etapa de simulación, utilizando un software especializado y culminó con la etapa del proceso constructivo y el procedimiento de disparo. La puesta en marcha de esta misión de cohetería experimental permitió alcanzar, propulsado por un combustible tipo “candy” compuesto por nitrato de potasio y sorbitol, un apogeo del cohete Ainkaa 1 de 780 m sobre la superficie de lanzamiento, con una velocidad de impacto de 526 Km/h, un tiempo de quemado de 3.2s entre otros datos, para configurar esta misión dentro de la categoría de alta potencia.</p>