This paper describes the research conducted to develop an optimal methodology to extract useful fibers from the "Ichu" grasses which can be used as reinforcement of polyester resin. Laminates were manufactured and their flexural properties were characterized as well as the optimal fiber properties. Results show that for this kind of materials, the mechanical and retting treatments are insufficient to remove lignin from the raw material state; on the other hand, alkali treatments are considerably effective. Laminates transverse strength shows an improvement (up to 30 MPa) when the alkali treatment time increases. Longitudinal strength and modulus present values around ~144 MPa and ~8.8 GPa respectively with fiber volume fraction around 0.38.
Natural fibers are a renewable resource that has become an economic alternative to replace synthetic fibers as reinforcement in composite materials. In this study, the aim was to characterize physical and thermal properties of the Andean Stipa obtusa and Jarava ichu leaves (grasses known as ichu) before and after the alkaline treatment. Energy dispersive spectrum identified external phytoliths on the surface of nontreated raw leaves. With the alkaline treatment, improvement on the thermal stability and increment in the crystalline index and size was observed. Additionally, raw leaves present a hydrophobic behavior; however, with the treatment this hydrophobicity was lost for Stipa obtusasignificantly but not for the Jarava ichu. Furthermore, low surface energy was observed for the nontreated raw leaves and increasing consistently for the treated fibers. According with these results, these grasses are quite interesting materials from which fibers can be extracted for engineering applications such as composite materials.
On any industry where the natural fibers are used, chemical composition of the fibers is an important parameter to determine, since it allows to predict the product quality. On the other hand, TAPPI standard developed a well described methodology to determine the chemical composition; however, their methodology is time and resource consuming, and furthermore it requires well trained specialist. An alternative to determine the chemical composition is to use the true density, since the density of the fiber constituents are different. In this study, we present a clear relation between the true density and the three major constituents (cellulose, lignin and extractives) with the fitting parameter R > 90%, for the Stipa obtusa base fibers.
The interaction properties between natural fiber and matrix play an important role in the mechanical performance of composite materials. The adhesion properties and the mechanical interaction between an Ichu fiber (Stipa obtusa) treated with sodium hydroxide and a cementitious matrix were studied by conducting experimental, numerical, and analytical pull-out tests. Through the experimental tests, the force–displacement curve for a fiber length embedded 5 mm deep in the cementitious matrix, maximum force, cohesive parameters, and the type of interface failure were determined. The results were used to calibrate the numerical and analytical models for different lengths of fiber (3, 5, 7, 9, and 11 mm) embedded in the cementitious matrix. The numerical model was implemented in the finite element software Abaqus CAE, and the analytical formulation considered the fiber embedded in a half-space continuous medium. From the experimental test, the force–displacement curve, interfacial shear strength of 0.124 MPa, and the softening type slip were obtained, despite obtaining the hardening-type slip in certain tests. The numerical and analytical results of the load–displacement curve closely approximate the experimental results. This study provides a numerical and analytical model to simulate the alkali-treated Ichu fiber–cementitous matrix interface.
Hydrogen permeation of AF1410 steel membranes due to cathodic polarization using the Devanathan and Starchurski double cell (DSDC) with 0.1M H2SO4 
Interface failure plays an important role in determining the mechanical properties of composites [1]. We studied the effect of matrix-fiber interfacial bonding on the transverse bending properties of glass fiber reinforced polybutylene terephthalate (G/PBT) unidirectional (UD) composites. Six types of specimens were manufactured using three different processing methods, namely reaction-based resin, prepreg and commingled yarn systems. Transverse bending properties of the UD composites were measured. Further tension failure zone after the transverse bending test was examined using scanning electron microscopy (SEM) fractography analysis. Additionally, the composites quality was evaluated using complementary microscopic techniques (optical microscopy, OM and SEM).
The goal of an engineer’s career is solving real problems for social and ecological betterment. At the University of Engineering and Technology (UTEC) in Lima, Peru, this vision is promoted from the earliest stages of a student’s engineering career to enable them to embrace their creativity while developing meaningful solutions for ecosystems in need. In this article, an educational methodology is presented that uses a project-based collaborative learning approach with the aim of evaluating, selecting and developing community-oriented engineering solutions in the Base of the Pyramid (BoP). Communication strategies and evaluation of projects based on co-design methods implemented among engineering students and isolated rural communities in the highlands of Peru are discussed. In conclusion, the process to select a community is analyzed and the most important criteria are determined. In addition, we highlight the importance of defining elements to understand the context (community and place) and to establish future objectives (group and projects) during the exploration period that will help facilitate the decision to select a community.
Fatigue crack initiation and growth process of model AA7075-T6 subjected to simulated marine environment and varying stress ratio is studied using acoustic emission technique.The results indicate a significant reduction in crack initiation and overall lifetime when specimens were tested in the presence of marine environment, while an increase in fatigue life was observed as a function of increasing stress ratio.SEM fracture surface analysis exhibited intergranular, transgranular and cleavage as modes of failure.In general terms, Cleavage fracture produce lower AE signal amplitude, whereas, transgranular tearing produces an increment of signals amplitude.However, the correlation between those modes of failure with the AE results can be cumbersome since the AE signals are highly dependent upon the loading and environmental testing conditions.
In the recent years, natural fibers are gaining an outstanding position as a reinforcement material, due to diverse advantages like high specific properties, low cost and low environmental impact. On the other hand, according to the market studies, in the next years the offer of the natural fibers will be in deficit; therefore, exploration of new natural fibers from new resources can be an alternative to fill this gap. Along the Andean region there are diverse natural resources from which cellulosic fibers can be extracted, like the Stipa obtusa grass, also commonly known as Ichu. The main purpose of this research was to determine the mechanical properties of unidirectional composite laminates made from Ichu fibers mixed with polyester resin; tensile, compressive and shear properties were evaluated. Results show that the stiffness in the principal direction (E 1 ∼ 16 GPa) and the transverse direction (E 2 ∼ 4.7 GPa) are over the average values compared to the composites made from the commercial fibers; similar behavior was observed in its shear and compression characteristics. Strength shows values around σ 1 ∼ 118 MPa, σ 2 ∼ 13 MPa, τ 12 ∼ 46 MPa and τ 21 ∼ 18 MPa, which is similar to the values reported in the literature for the commercial natural fiber composites. Based on these results, the Ichu fiber has a great potential as a reinforcement in composites materials.
Cement production consumes enormous amounts of fossil fuels, generating significant CO2 emissions, seriously impacting the environment, and tons of rice hu
Article COMPARATIVE STUDY OF HYDROGEN TRANSPORT BEHAVIORS IN ARMCO-FE AND AF1410 STEELS was published on August 1, 2007 in the journal Corrosion Reviews (volume 25, issue 3-4).
En este articulo se estudiaron los fenomenos que se producen en el sistema liquido-particula conformado por una mezcla de agua y granos de quinua, estando estos dentro de un tambor horizontal giratorio. Para tal fin se utilizo la metodologia de velocimetria por imagenes de particulas (Particle Image Velocimetry, PIV); para determinar el comportamiento de los granos durante el regimen estable de movimiento, obteniendo el campo vectorial de desplazamiento y velocidades de los granos. La velocidad angular (rpm) y la longitud de las paletas internas del tambor fueron consideradas en la evaluacion del flujo. Las pruebas experimentales mostraron una alta relacion entre la velocidad de giro del tambor y las velocidades promedio de los granos, forjando remolinos conocidos como vortices de campos cerrados (Re≤6000). Tambien se observo que el incremento de la longitud en las paletas logra aumentar la formacion de vortices elipticos, los cuales son dirigidos hacia el centro del tambor y colisionan entre si, formando los vortices hiperbolicos, lo que ocasiona que aumente la interaccion de los granos. Por otro lado, el aumento excesivo de la velocidad de rotacion inhibe la formacion de los vortices; debido al aumento de la aceleracion normal combinada con la inercia, lo cual sobrepasa el efecto la accion de la gravedad sobre los granos.
