Comportamiento de un panel laminado compuesto a partir de materiales poliméricos y cerámicos ante el impacto de un proyectil metálico

En éste trabajo de investigación se exploró el comportamiento de sistemas laminados compuestos tipo sándwich, elaborados a partir de placas cerámicas y laminas de polietileno(UHWMPE) frente al impacto de un proyectil metálico; se realizó el diseño de dos grupos con diferentes arreglos, un grupo con la cara que recibe el impacto en material cerámico (SiC) con respaldo en material polimérico y un grupo con la cara que recibe el impacto en material polimérico con respaldo cerámico, las dimensiones aproximadas fueron de 200 x 200 mm de lado y espesores de 5 y 12 mm. Se realizó la prueba de impacto siguiendo los parámetros de la norma NIJ III A; se identificaron como mecanismos de disipación de energía cinética en el material cerámico a: la formación de un cráter, fracturas y delaminación; en el material polimérico se observó fibrilación, formación de geometría cónica, delaminación, torsión y fusión de fibras. Se concluyó que el grupo con mayor influencia para disipar energía fue el grupo con la cara principal que recibe el proyectil en material cerámico y contracara en material polimérico (UHWMPE), comprobado mediante un balance de energía realizado en cada uno de los arreglos, posteriormente se culminó la exploración realizando una comparación entre el arreglo que presentó mayor absorción de energía frente a un sistema adicional diseñado con un cerámico (SiC) de menor porosidad. /Abstract. In this research work has explored the behavior of composite laminate sandwich systems, made from ceramic plates and sheets of polyethylene (UHWMPE) against the impact of a metallic design was made of two groups with different arrangements, a group with the side that receives the impact of ceramic material (SiC)-backed polymeric material and a group with the side that receives the impact on polymer-backed ceramic material, the approximate dimensions were 200 x 200 mm square and thickness of 5 and 12 mm. The test was performed following the parameters of impact of the standard NIJ III A, were identified as mechanisms of dissipation of kinetic energy in the ceramic material: the formation of a crater, fracture and delamination, in the polymeric material was observed fibrillation training conical geometry, delamination, twisting, and melting fibers. It was concluded that the group's most influential energy dissipation was the group with the main side that receives the projectile in ceramic and polymeric counterface material (UHWMPE) demonstrated through an energy balance performed on each of the arrangements, later exploration culminated making a comparison between the arrangement that had higher energy absorption compared to an additional system designed with a ceramic (SiC) less porousMaestrí

Fractography on Rigid Ceramics with Ultra-High-Molecular- Weight Polyethylene Fabric after Ballistic Impacts

The impact protection systems have traditionally been developed with metallic materials and structural protection applied in the automotive sector; while personal protection systems and composite systems evolve very fast, these systems have a large increase in applications due mainly to the amplitude of the manufacturing process. In the composite system for impact protection, it exposes both functionality and the rigid systems, aimed at structural protection, and flexible systems for personal protection. Nowadays, the development of materials with ballistic applications has emphasized protection of lightweight materials, for protection against projectiles of high and low speeds, among which are the bullets from weapons, fragments of tempered steel grenade hand or aircraft fragments, or a vehicle at high speed directly against housing and human integrity. It is necessary to investigate the mechanisms of fracture of the materials usually used for protection against impact, thus, it is possible to obtain important design systems that reduce the probability of failure and protect human lives and reduce damage to infrastructure information. In this chapter, the behavior of laminate sandwich-type systems, made from handcrafted ceramic plates with sheets of polyethylene (ultra-high-molecular-weight polyethylene, UHWMPE) against the impact of a metallic projectile, has been explored. The experimental work was made of two groups with different arrangements: the first group with the side that receives the impact of ceramic material (silicon carbide, SiC)-backed polymeric material and the second group with the side that receives the impact on polymer-backed ceramic material, the plates had dimensions 200 mm2 of thickness to 5 mm for single plates and 20 mm for double plates. The experimental test was performed following the parameters of impact of NIJ III A standard. Some mechanisms (morphologies) of dissipation of kinetic energy received in the components were identified, as cited below, first in the ceramic material the formation of a crater, fracture, and delamination was observed, formed in the double and simple plates. Later, in the fabric polymeric material deformation mechanisms, such as the origination of defibrillation, conical geometry formation, delamination, twisting, and melting fibers due to the tribological contact of the metal shell impact, were observed. The exploration was culminated making a comparison between the arrangement that had higher energy absorption compared to an additional system designed with a ceramic (SiC) with less porosity, also aside to this chapter, it shows some of the deformed projectiles with a basic description of the fracture obtained after the impact, complementing the overall analysis of the systems used

Caracterización mecánica de mezclas de caucho natural y residuos de celulosa originados en la industria automotriz con enfoque en el sector del calzado

Context: This publication shows a potential use for waste from the automotive industry, namely waste originating in the manufacturing process of gaskets and seals for motorcycles, which currently do not have a final use. In addition, due to their high-performance rubber surface layer, they imply an extensive degradation process, which constitutes a harmful factor for the environment and contributes to global warming. Method: First, the crushing of the residues was carried out, then their sieving and selection via granulometry, and finally a mixture with the natural rubber through chewing in open cylinders in order to obtain the master, which was vulcanized in a shoe sole mold. The final product was mechanically characterized via the techniques, tension-elongation, wear, hardness, bending, and tearing. Results: The obtained mixture opens a window to the design of products using residues from seals and gaskets for motors. It will be possible to design other proposals for functionalized rubbers, oriented towards the development of ecological footwear applications. Conclusions: The mixture of cellulose waste from the motor seal sector and natural rubber shows promise for the reduction of the negative impact caused by these wastes and proposes a circular economy –in this case, with the development of raw material in the footwear sector.Contexto: Esta publicación muestra un potencial uso para los residuos provenientes de la industria automotriz, en este caso residuos originados en el proceso de fabricación de empaques y sellos para motocicletas, que en la actualidad no tienen un uso final. Además, debido a la capa superficial de caucho de altas prestaciones, presentan un proceso de degradación extenso, lo cual constituye un factor perjudicial para el medio ambiente y contribuye al calentamiento global. Método: Primero se realizó la trituración de los residuos, posteriormente su tamizado y selección por granulometría, y por último se realizó una mezcla con el caucho natural a través del masticado en cilindros abiertos para obtener el máster, que fue vulcanizado en un molde de suela para zapatos. El producto final fue caracterizado mecánicamente con las técnicas tensión-elongación, desgaste, dureza, flexión y rasgadura. Resultados: La mezcla obtenida abre una ventana hacia el diseño de productos utilizando residuos de sellos y empaques para motor. Será posible diseñar otras propuestas para cauchos funcionalizados, orientados al desarrollo de aplicaciones de calzado ecológico. Conclusiones: La mezcla de residuos de celulosa provenientes del sector de sellos para motor con caucho natural proyecta la reducción del impacto negativo generado por estos residuos y propone una economía circular, en este caso con el desarrollo de materia prima para el sector del calzado

Sustainable blends of LDPE/NR and sugarcane bagasse ashes with PE-g-MA thermomechanical relationships

The polymer blends obtained with residues that before were called wastes has been growing as a viablesolution, allowing improvements in the mechanical properties and as sustainable alternative. This workreports the effects of blends of low-density polyethylene (LDPE) and natural rubber (NR), with sugarcane bagasse ash (SCBA) as filler, with and without polyethylene-graft-maleic anhydride (PE-g-MA)how coupling agent. The dynamic mechanical behavior and a stress-strain analysis were studied. Thematerials were further evaluated by differential scanning calorimetry and morphological observations.The results showed that incorporation of the PE-g-MA reduced the strain and improved the stress and theYoung module of the mixtures. Moreover, the presence of SCBA increased the hardness whilemaintaining the tensile strength and the elongation behavior of the polymer. The results demonstrate thepotential use of SCBA in the elastomer and thermoplastic mixture, free of vulcanization agents.Keywords: Sustainable blends, sugarcane bagasse ashes, natural rubber, low density polyethylene,polyethylene-graft-maleic anhydride

5to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

El V Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2019, realizado del 6 al 8 de febrero de 2019 y organizado por la Universidad Politécnica Salesiana, ofreció a la comunidad académica nacional e internacional una plataforma de comunicación unificada, dirigida a cubrir los problemas teóricos y prácticos de mayor impacto en la sociedad moderna desde la ingeniería. En esta edición, dedicada a los 25 años de vida de la UPS, los ejes temáticos estuvieron relacionados con la aplicación de la ciencia, el desarrollo tecnológico y la innovación en cinco pilares fundamentales de nuestra sociedad: la industria, la movilidad, la sostenibilidad ambiental, la información y las telecomunicaciones. El comité científico estuvo conformado formado por 48 investigadores procedentes de diez países: España, Reino Unido, Italia, Bélgica, México, Venezuela, Colombia, Brasil, Estados Unidos y Ecuador. Fueron recibidas un centenar de contribuciones, de las cuales 39 fueron aprobadas en forma de ponencias y 15 en formato poster. Estas contribuciones fueron presentadas de forma oral ante toda la comunidad académica que se dio cita en el Congreso, quienes desde el aula magna, el auditorio y la sala de usos múltiples de la Universidad Politécnica Salesiana, cumplieron respetuosamente la responsabilidad de representar a toda la sociedad en la revisión, aceptación y validación del conocimiento nuevo que fue presentado en cada exposición por los investigadores. Paralelo a las sesiones técnicas, el Congreso contó con espacios de presentación de posters científicos y cinco workshops en temáticas de vanguardia que cautivaron la atención de nuestros docentes y estudiantes. También en el marco del evento se impartieron un total de ocho conferencias magistrales en temas tan actuales como la gestión del conocimiento en la universidad-ecosistema, los retos y oportunidades de la industria 4.0, los avances de la investigación básica y aplicada en mecatrónica para el estudio de robots de nueva generación, la optimización en ingeniería con técnicas multi-objetivo, el desarrollo de las redes avanzadas en Latinoamérica y los mundos, la contaminación del aire debido al tránsito vehicular, el radón y los riesgos que representa este gas radiactivo para la salud humana, entre otros

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The second-order Fourier coefficients (v(2)) characterizing the azimuthal distributions of Y(1S) and Y(2S) mesons produced in PbPb collisions at root s(NN) = 5.02 TeV are studied. The Y mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb(-1). The scalar product method is used to extract the v2 coefficients of the azimuthal distributions. Results are reported for the rapidity range vertical bar y vertical bar < 2.4, in the transverse momentum interval 0 < pT < 50 GeV/c, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/psi mesons, the measured v(2) values for the Y mesons are found to be consistent with zero. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe

Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe