Programa de Pós-Graduação em Engenharia de Infraestrutura e Desenvolvimento Energético - PPGINDE/NDAE/Tucuruí

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/9400

Navegar

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise experimental de vigas de concreto armado reforçadas à força cortante com compósitos de fibra de juta, carbono e vidro utilizando a técnica EBR
(Universidade Federal do Pará, 2022-10-18) MACIEL, Luciana Pereira; BANNA, Wassim Raja El; http://lattes.cnpq.br/2005046563115507; https://orcid.org/0000-0001-5085-4352; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
The application of FRP (Fiber Reinforced Polymer) with the EBR (Externally Bonded Reinforcement) technique for repairing and reinforcing structures stands out due to the low density of the material and ease of application. In this case, the use of synthetic fibers is common, however, these fibers are considered inaccessible and harmful to the environment. This disadvantages raised studies on the replacement of synthetic fibers by natural fibers. Therefore, this work consists of the experimental analysis of the performance of composites of jute fibers as shear reinforcement. With that aim, seven reinforced concrete beams reinforced with FRP's were molded using the EBR technique, they were dimensioned with greater flexural strength in relation to the shear force and with transverse reinforcement positioned only in a section of the span, to induce shear failure in the region without stirrups. The beams are 2 meters long and have a cross section of (15x20) cm. One beam was not reinforced, to be used as a reference, one beam was reinforced with one layer of FRP with carbon fiber, one beam with two layers of FRP with glass fiber, two with hybrid FRP of layers of glass and jute fiber with three and four layers, and finally two beams with jute fiber FRP with two and three layers. The reinforcements were applied in strips along the length of the shear span of the elements, perpendicular to the axis of the beams, U-shaped. It was observed that the reinforcement with two layers of jute fiber presented a 48% increase in shear force of the beam in relation to the reference beam, this result was similar to that observed in the beam reinforced with one layer of carbon fiber. Other positive behaviors were observed in the other reinforced beams, such as cracking control, increase in maximum shear force and containment of vertical displacement in relation to the reference beam. The experimental results were compared to theoretical results calculated according to ABNT NBR 6118 (2004), ACI 318 (2014), Eurocode 2 (2004), ACI 440.2R (2017) and fib 90 (2019). After analysis, the initial results of this research demonstrate the viability for other in-depth studies on the use of jute fibers in shear reinforcement of reinforced concrete beams.
Acesso aberto (Open Access)
Desenvolvimento de túnel de vento para avaliação de bicos de pulverização no abatimento de poeira
(Universidade Federal do Pará, 2024-12-20) SANTOS, Danilo Silva; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
Mining is extremely important economically and socially for the industry, especially iron ore, but along with its benefits, it also has environmental impacts generated in different ways, such as dust. This inconvenience has caused disruptions to mining enterprises, such as production shutdowns and heavy fines, as well as problems for people who work in the companies and surrounding communities, due to health problems associated with inhaling dust and dirt from the environments, making them unhealthy and devalued. Dust control mechanisms have been widely studied and one of these is dust control using spraying of suppressant solutions. Studying the efficiency of spray nozzles has become of great importance and bench tests act as efficient means of understanding the mechanism of dust abatement from minerals. Research has been common to use wind tunnels. Thus, a tunnel was built capable of evaluating 5 different nozzles and their efficiencies in suppressing pellet feed and sinter feed at two speeds and different water pressures. It was concluded that the tunnel is capable, through the methodology used, of evaluating and comparing the best nozzle, demonstrating that it is an important tool in consolidating this knowledge in the Fluid Dynamics and Particulates Laboratory.
Acesso aberto (Open Access)
Dispersão de energia em um cristal granular hexagonal decorado
(Universidade Federal do Pará, 2024-02-29) RAMOS, Jorde Anthonny Alves; MACHADO, Luis Paulo Silveira; http://lattes.cnpq.br/0702289670734922; https://orcid.org/0000-0003-1587-3632
The decorated hexagonal granular crystal consists of main spherical grains arranged in a two-dimensional hexagonal array, with small spherical grains filling the interstitial spaces. These additional grains barely touch the main grains, increasing the number of contacts per grain. Additionally, all grains are initially at rest, with null velocities. For comparation, we used results from a similiar arrangement without decoration (i.e., without interstitial grains). We investigated the mechanical responses of both granular arrangements to the punctual incidence of an external grain. Our analysis focused on how the mechanical energy is dispersed and mitigated after a single initial impact. The proposed model confirmed the significant role of interstitial grains in the granular crystal. The decorated arrangement demonstrated accelerated behavior of the energy wavefront, both in its mitigation and propagation. In our analysis of energy scattering orientations, we found that the decorated arrangement exhibits greater energy mitigation and reorientation of return energy compared to the undecorated arrangement. Thus, the addition of interstitial grains promoves a greater return of mechanical energy to the external medium of origin. We conclude that with proper decoration, a granular crystal could act as a barrier against strong impacts.
Acesso aberto (Open Access)
Influência da substituição de agregados naturais por reciclados de concreto na resistência à punção de lajes lisas de concreto armado com armadura de cisalhamento
(Universidade Federal do Pará, 2023-11-21) PORTILHO, Shara Katharine Melo Silva; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
This research experimentally analyzed the mechanical behavior of four reinforced concrete flat slabs with shear reinforcement, when subjected to punching shear forces. Two of these slabs were made using a concrete mixture with a total replacement of natural coarse aggregates (NGA) by recycled concrete coarse aggregates (RCCA), and two slabs served as reference (without replacement). Shear reinforcement had two types: double headed studs and individual stirrups. The specimens were octagonal in shape, with 2,500 mm between opposite faces, thickness of 210 mm, and were supported on square central columns measuring 300 mm on each side. The estimated average concrete strength was 25 MPa, and the flexural and punching shear were 1.4% and 0.34%, respectively. After the laboratory tests, a comparison was made between the experimental behavior and the theoretical predictions from ABNT NBR 6118 (2023), Eurocode 2 (2014), ACI 318 (2019), and the fib Model Code 2010 (2013) models. Regarding the use of shear reinforcement, the results showed that the slabs with double headed studs presented higher punching shear strength when compared to those with individual stirrups. It was also observed that slabs with a total replacement of natural coarse aggregates by recycled concrete aggregates presented lower punching shear strength than slabs with natural aggregates. Regarding the comparison between the estimated punching shear strength of the flat slabs with shear reinforcement using RCCA prescribed by the analyzed codes and the experimental results, it was found that almost all code predictions were very close to the experimental values, except for the Brazilian code, which indicated results against safety.
Acesso aberto (Open Access)
Projeto e fabricação de extrusora monorrosca com matriz de extrusão filamentar
(Universidade Federal do Pará, 2024-10-25) RODRIGUES, Rodimilson Coelho; EL BANNA, Wassim Raja; http://lattes.cnpq.br/2005046563115507; HTTPS://ORCID.ORG/0000-0001-5085-4352; NASCIMENTO, Walber Alexandre do; http://lattes.cnpq.br/8022410578951099; https://orcid.org/0000-0002-2699-3982
Large industrial establishments are always looking for increasingly sophisticated technologies to monitor manufacturing processes. This work aims to design and build a laboratory single-screw extruder and its extrusion die for processing polymers and polymer composites, in addition to enabling studies in the area of mechanical recycling of polymers. The first stage of the work involved choosing the type of extruder to be manufactured. The second stage consisted of dimensioning and designing the equipment using Solidworks software. In the third stage, the types of materials and mechanical and electrical components for assembling the extruder were selected. In the fourth stage, the manufacturing processes of the extruder and assembly of the mechanical and electrical components were carried out. In the fifth stage, the equipment was validated, where temperature and mass flow tests were performed, in addition to mechanical and electrical tests in the processing of a thermoplastic polymer, which, in this case, was polypropylene (PP). The last stage consisted of simulating a die with a cylindrical profile, aiming to study the characteristics of the polymer melt flow and define how the die structure should be adjusted to obtain the desired diameter. After designing the die in Solidworks software, a simulation was performed in Ansys software. In this case, the rheological behavior of the melt as it passed through the die was studied through the simulation, analyzing in which part of it the high and/or low shear rates are observed when the polymer flows through it. The drag flow and pressure flow were then extracted from the simulation parameters, which led to the calculation of the operating point and operating pressure for the die. It was also possible to calculate the mass flow rate and the velocity drop at the die wall, in addition to optimizing the die profile for the circular shape and desired diameter.

Navegar

Navegando Programa de Pós-Graduação em Engenharia de Infraestrutura e Desenvolvimento Energético - PPGINDE/NDAE/Tucuruí por Afiliação "UFPA - Universidade Federal do Pará"