Flexural properties and failure mechanism assessment for additive manufactured lom bars on different building orientations

Plastic Laminated Object Manufacturing has not been assessed from the flexural properties point of view. The deflection range in parts manufactured by this technique is wider than in parts fabricated by other additive manufacturing methods like SLS or FDM. This fact has increased the interest on the final application of these parts rather than restricted to Rapid Prototyping applications. In this study it will be compared the impact of building orientation and geometric features of parts over the flexural properties. Through optical observation it will be studied the failure mechanism.Postprint (published version

Obtención de sulfato de zinc (ZnS04) a partir de baterías zinc/carbón recicladas en los laboratorios de Química. UNAN-Managua. Marzo-Septiembre 2014

Una batería es una fuente de energía electroquímica portátil y autosuficiente, las cuales son utilizadas de manera indefinida por la población, para usarla en pequeños aparatos de menor demanda de energía, como lo es una linterna, controles remotos, relojes, radio, detectores de humo, juguetes de niños, etc. Así mismo existen diversos tipos de baterías, siendo la de mayor uso por la sociedad nicaragüense la batería RAYOVAC Zinc/Carbón por su bajo costo que tiene referente a otros ejemplares de baterías como las alcalinas. No hay en el país un plan sobre desechos de baterías luego de que la vida útil de estas llega a su fin, recordando que la reacción que se da en este tipo de baterías es irreversible, no encontrándose una forma de aprovecharlas y contribuyendo a la polución de nuestro planeta. Sin embargo la composición de este tipo de baterías al ser de Zinc/Carbón puede permitir el aprovechamiento luego de ser desechadas, extrayendo la lámina de zinc que recubre estas y convirtiéndola mediante una reacción química a la sal de sulfato de zinc que puede servir como un aditivo para una abono foliar proporcionándole el micro nutrimento azufre y el micro elementó zinc. Estos dos elementos son muy necesarios para la buena fertilidad de los suelos, ya que estos deben de estar presentes para el buen desarrollo y crecimiento de las plantas que se siembre en estos, además de ser muy muy influyente en los altos rendimientos de frutos de los árboles. De esta forma se pretende aliviar el problema del mal desecho de las baterías, las cuales son dejadas a la intemperie luego de que su vida útil llega a su fin y comienza su oxidación por el oxígeno presente en el ambiente quedándose en el suelo de una forma no aprovechable, además de ser persistente en este. Además se produce el aprovechamiento de la lámina de zinc que recubre la batería Zinc/Carbón, produciendo el sulfato de zinc, un aditivo para un abono foliar capaz de enriquecer de elementos a los suelos carentes de estos elementos

Ball-burnishing effect on deep residual stress on AISI 1038 and AA2017-T4

Ball-burnishing induces compressive residual stresses on treated materials by the effect of plastic deformation. The result is an increase in the fatigue life of the treated part, retarding the initiation of cracks on the surface. Compressive residual stresses have been previously measured by X-ray diffraction near the surface, revealing considerably high values at the maximum analyzed depth, in relation to other finishing processes such as shot peening. However, the maximum analyzed depth is very limited by using this technique. In this paper, the incremental hole drilling (IHD) technique is tested to measure residual stresses, being able to reach a 2-mm measuring depth. To that objective, a commercial strain gage is used and calibrated using finite element model simulations. A second Finite Element Model based on material removal rate is developed to obtain the equations to calculate the strain release through IHD. Finally, residual stresses are measured experimentally with that technique on two different materials, confirming that ball-burnishing increases the compressive residual stresses in layers up to 0.5¿mm deep for the testing conditions, which is a good response to industrial needs. The method proves to be suitable, simple and inexpensive way to measure the value of these tensions.Preprin

A hybrid numerical-experimental strategy for predicting mechanical response of components manufactured via FFF

In this paper a new methodology developed for predicting the mechanical performance of the structures additively manufactured by Fused Filament Fabrication is presented. The novelty of the approach consists in accounting for the anisotropy in the material properties induced by the printing patterns. To do so we partition the manufactured structure according to the printing patterns used in a single component. For determining the material properties of each partition, a hybrid experimental/computational characterization is proposed. The external partitions with aligned (contour) and crossed (cover) filaments are characterized through uniaxial tensile tests on General Purpose Acrylonitrile Butadiene Styrene dog-bone samples with corresponding patterns. Characterization of the inner structure (infill/lattice) is done through computational homogenization technique using Representative Volume Element. The presented methodology is validated against experimental results of square cross-section demonstrators. It is shown that the material properties depend on the geometrical relationship of the different printing patterns, exclusively. Therefore, the exhaustive experimental procedure can be avoided characterizing the printed material by a pre-defined anisotropic constitutive relationship proportional to the properties of the raw material. Moreover, the acquired geometrical relationship is validated for components made of Polylactic Acid. The given methodology may be used as design-for-manufacture tool for creating functional components."Narges Dialami is a Serra Húnter Fellow. This work has been supported by the RIS3CAT Llavor 3D Community co-financed by the Generalitat de Catalunya (ACCIÓ) through the projects TRANSPORT COMRDI16-1-0010 - 00 and PRO2 COMRDI16-1-0009-04. Financial supports from the European Union’s horizon 2020 research and innovation programme (H2020-DT-2019-1 No. 872570) under the KYKLOS 4.0 Project (An Advanced Circular and Agile Manufacturing Ecosystem based on rapid reconfigurable manufacturing process and individualized consumer preferences) and from the Ministry of Science, Innovation and Universities (MCIU) via: the PriMuS project (Printing pattern based and MultiScale enhanced performance analysis of advanced Additive Manufacturing components, ref. num. PID2020-115575RB-I00) are gratefully acknowledged. The financial support from the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centres of Excellence in R&D (CEX2018-000797-S), is gratefully acknowledged as well as from CONCYTEC R + D (Project Reference: 163-2017-FONDECYT, in association with Pontifical Catholic University of Perú and CIMNE) -” Optimización del uso de polímeros sintéticos en procesos de manufactura aditiva mediante modelos de simulación computacional y técnicas de caracterización de materiales. Caso de estudio: aplicaciones médicas - prótesis de mano.”."Peer ReviewedPostprint (published version

Efecto de los antimaláricos sobre los diferentes dominios del índice de daño SLICC en pacientes de la cohorte GLADEL

Objetivos: estimar el efecto de los antimaláricos (AM) sobre los diferentes dominios del índice de daño SLICC (SDI). Métodos: se estudiaron pacientes con diagnóstico clínico reciente (≤2 años) de lupus eritematoso sistémico (LES) de la cohorte GLADEL

Flexural properties and failure mechanism assessment for additive manufactured lom bars on different building orientations

Plastic Laminated Object Manufacturing has not been assessed from the flexural properties point of view. The deflection range in parts manufactured by this technique is wider than in parts fabricated by other additive manufacturing methods like SLS or FDM. This fact has increased the interest on the final application of these parts rather than restricted to Rapid Prototyping applications. In this study it will be compared the impact of building orientation and geometric features of parts over the flexural properties. Through optical observation it will be studied the failure mechanism

Influence of building orientation on the flexural strength of laminated object manufacturing specimens

This study aims to define the best building orientation for components produced via the Laminated object manufacturing (LOM) technique to enhance their flexural performance. Results of previous research show that components produced via LOM are capable of with-standing higher deflections than components produced through other layer manufacturing techniques. However, the relation between the building orientation and flexural strength of components has not yet been assessed. Four types of specimens have been manufactured using different building orientations for each type. The specimens have been tested in a machine with four loading points to evaluate their failure mode and identify the best building orientation toward flexural loading. The best building orientation in terms of maximum load before failure is 45°. Furthermore, a repetitive failure pattern is found for each tested condition. Building orientation is confirmed to be a relevant parameter in LOM manufacturing by influencing the mechanical properties of components.Peer ReviewedPostprint (author's final draft

Structural analysis of an automotive interior system: practical learning in the context of the new EHEA

At the IQS School of Engineering, practices has been implemented that bring students to the industrial environment through real cases. This action is in accordance with the philosophy of the European Higher Education Area (EHEA), with a strong orientation towards practical learning rather than classical education tools based on master classes. In this article, authors want to show their experience from the Area of Strength of Materials and Structures for the Bachelor's Degree in Industrial Technologies Engineering, and specifically to the subject of Mechanics of Materials. To search the preliminary information and to learn about some of the most relevant structural analysis with the Finite Element Method (FEM), such as modal analysis of vibration and elasto-plastic nonlinear analysis, and to use the Center Console assembly from a real car, make this a good active learning experience of mechanical engineering

Influence of building orientation on the flexural strength of laminated object manufacturing specimens

This study aims to define the best building orientation for components produced via the Laminated object manufacturing (LOM) technique to enhance their flexural performance. Results of previous research show that components produced via LOM are capable of with-standing higher deflections than components produced through other layer manufacturing techniques. However, the relation between the building orientation and flexural strength of components has not yet been assessed. Four types of specimens have been manufactured using different building orientations for each type. The specimens have been tested in a machine with four loading points to evaluate their failure mode and identify the best building orientation toward flexural loading. The best building orientation in terms of maximum load before failure is 45°. Furthermore, a repetitive failure pattern is found for each tested condition. Building orientation is confirmed to be a relevant parameter in LOM manufacturing by influencing the mechanical properties of components.Peer Reviewe