Suárez, O. Marcelo

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    Tortuosity index based on dynamic mechanical properties of polyimide foam for aerospace applications
    (MDPI, 2019-06-07) Flores-Bonano, Sugeily; Vargas-Martinez, Juan C.; Suárez, O. Marcelo; Silva-Araya, Walter; College of Engineering; Department of Materials Science and Engineering
    The determination of a reliable tortuosity index is lacking in the aerospace industry. Therefore, a methodology is formulated via direct and indirect characterization methods of a fluid-filled porous media. Chemical, thermal, and mechanical characterization was performed to the PolyuMAC(TM) polyimide foam. Tortuosity was measured considering a pressure difference as the resistivity variable, rather than electrical resistivity or molecular diffusivity, as proposed on previous models. This is an empirical establishment of the tortuosity index considering the correlation among hydraulic and structural dimensionless parameters obtained through the Buckingham’s Pi theorem. The behavior of the polyimide was studied for samples of different lengths compressed at 30%, 60%, and 90% of its original length on the foaming direction. Results show that, porosity, sample length, and fluid viscosity are relevant for the insulation performance of the material. Regression analysis produced a significant statistical model fit to the data correlated from the dimensionless parameters for each dynamic compression series.
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    Fostering Students’ Graduate Education Attainment and Success in Biomedical and Aerospace Engineering and Sustainable Agriculture
    Álvarez, Jaquelina E.; Suárez, O. Marcelo; Didier M., Valdés-Díaz; Pomales-García, Cristina D.; González-Gill, Lizzette; Juan-García, Eduardo J.; Academic Affairs; General Library
    The Transformational Initiative for Graduate Education and Research (TIGER) of the University of Puerto Rico - Mayagüez upraises the institutional STEM environment, by cultivating experiential learning and field research for low-income graduate students working in biomedical and aerospace engineering, and sustainable agriculture. The project enhanced curricular activities by funding three new core research facilities: i) Center for Biomedical Engineering and Nanomedicine; ii) Center of Advanced Aerospace Engineering & Manufacturing Technologies; and iii) Thermal Processing Laboratory. TIGER also defrayed an expansion of the field research facilities of the Alzamora Educational Farm and the Graduate Research and Innovation Center (GRIC), a technology-infused, collaborative learning space. Furthermore, TIGER supports cohorts of low-income graduate students (fellows) broadening their preparation for an increasingly competitive job market. They, as key stakeholders, receive personalized guidance and tutoring through the GRIC services. In addition, UPRM students enhance their graduate training in research venues via the Extramural Research Experience Awards that funds summer investigation in renowned universities and national laboratories in the mainland. As they return, recently acquired knowledge advances research approaches in their UPRM mentors’ teams.
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    Impact of Materials Science and Engineering Clubs on student’s perceptions and aspirations towards STEM
    (Material Research Society, 2018-08-28) Pomales-García, Cristina D.; Reyes-Rivera, Zairelys; Mercado-Coon, Johana; Padovani Blanco, Agnes M.; Suárez, O. Marcelo; Alvarez, Jaquelina E.; College of Engineering; Department of Industrial Engineering
    This research evidences the impact of Materials Science and Engineering Clubs as an outreach effort to expand the education and training required for a competitive Nanotechnology workforce beyond traditional STEM areas. An engineering perception questionnaire was implemented as a pre-test/post-test to track student perceptions and goals throughout the academic year and identify trends amongst gender and school level groups. Findings (107 students) show a perceived increase in student knowledge and interest for different fields of study, based on pre/post-test responses, with differences amongst gender and school level groups (middle school and high school). Also, significant differences in students’ aspirations for higher education degree were found among school level and gender. Results show that over 20% of participants increased their aspirations to higher educational degree and their interest in pursuing STEM degrees at end of the academic year. Specific findings on engineering perceptions and perceived level of knowledge and interest in science, engineering, materials, and nanotechnology as a result of club participation and student’s educational aspirations, expectations and future study plans are discussed along with implications for future STEM education.
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    Strengthening of aluminum wires treated with A206/Alumina nanocomposites
    (MDPI, 2018-03-10) Florián-Algarín, David; Marrero, Raúl; Li, Xiaochun; Choi, Hongseok; Suárez, O. Marcelo; College of Engineering; Department of Materials Science and Engineering
    This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl2O3 nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl2O3 nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical condutivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding,