Development of a constitutive model for the compaction of recovered polyethylene terephthalate packages

[EN] To date, PET (polyethylene terephthalate) is the most widely used plastic in packaging and also one of the most recycled polymers worldwide. However, the high transport costs and stagnated prices of recycled PET undermine recycling process profits. Transport costs can lower through compaction, which is still not a completely wellknown process. Due to heterogeneous designs, the output density of the compaction process varies. This poses problems during equipment design, selection or operation processes as recovery costs sharply increase if the required density is not met. In this manuscript, the authors develop a constitutive model for the compaction of recovered PET packaging. This experimentally validated model, based on the elasto-plastic behaviour of PET packages, allows the output density range to be predicted according to the compression pressure during PET compaction. Unlike other generic compaction models that need more than two parameters, this model uses only one and better correlates with the experimental results. Unlike existing generic models, the model parameters have a physical meaning, which allows the influence of different factors on the compaction process to be assessed. Finally as a result of the model analysis, we provide some tips to enhance compaction equipment efficiency.Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Sanchez-Caballero, S.; Sellés, M.; Peydro, MA.; H.P. Cherukuri (2021). Development of a constitutive model for the compaction of recovered polyethylene terephthalate packages. Waste Management. 133:89-98. https://doi.org/10.1016/j.wasman.2021.07.028S899813

Synthesis of layered titanosilicate JDF-L1 for fabrication of composite polyamide 6 film

In clay polymer nanocomposite technology, nowadays there is concern about the safety and environmental effects of the nanometric materials. In this work, sheets of layered titanosilicate JDF-L1 were synthesized with a size of 5.3 µmand thickness of 115 nm and used to fabricate composite polyamide 6 (PA6) films. The JDF-L1 synthesis was scaled in one pot and the rosette-like particles obtained were disaggregated using a simple process with NaOH solution. The composite with 2 wt.% of disaggregated JDF-L1, characterized by X-ray diffraction and electron microscopy, showed parallel orientation (with respect to the film itself) and good dispersion of the sheets. The composite had a similar barrier effect as the PA6 and its mechanical properties did not deteriorate. This opens up the use of this composite as a packing material providing other properties, such as a biocidal effect and synergy effect in combination with other additives

Visual analytics for soundness verification of process models

Soundness validation of process models is a complex task for process modelers due to all the factors that must be taken into account. Although there are tools to verify this property, they do not provide users with easy information on where soundness starts breaking and under which conditions. Providing insights such as states in which problems occur, involved activities, or paths leading to those states, is crucial for process modelers to better understand why the model is not sound. In this paper we address the problem of validating the soundness property of a process model by using a novel visual approach and a new tool called PSVis (Petri net Soundness Visualization) supporting this approach. The PSVis tool aims to guide expert users through the process models in order to get insights into the problems that cause the process to be unsoun

Use of a Novel Polymer-Coated Steel as an Alternative to Traditional Can Manufacturing in the Food Industry

[EN] Metal containers (both food and beverage cans) are made from huge steel or aluminum coils that are transformed into two- or three-piece products. During the manufacturing process, the metal is sprayed on both sides and the aerosol acts as insulation, but unfortunately produces volatile organic compounds (VOCs). The present work presents a different way to manufacture these containers using a novel prelaminated two-layer polymer steel. It was experimentally possible to verify that the material survives all the involved manufacturing processes. Thus tests were carried out in an ironing simulator to measure roughness, friction coefficient and surface quality. In addition, two theoretical ironing models were developed: upper bound model and artificial neural network. These models are useful for packaging designers and manufacturers.Sellés, M.; Schmid, SR.; Sanchez-Caballero, S.; Ramezani, M.; Pérez Bernabeu, E. (2021). Use of a Novel Polymer-Coated Steel as an Alternative to Traditional Can Manufacturing in the Food Industry. Polymers. 13(2):1-15. https://doi.org/10.3390/polym13020222S11513

Influencia de la segregación de Ti4+ en la respuesta multiferroica de materiales basados en BiFeO3

Los materiales multiferroicos han cobrado un interés creciente en los últimos años dada la potencialidad de sus aplicaciones prácticas. Los materiales basados en BiFeO3 pueden considerarse los más estudiados hasta la fecha dentro de los pocos multiferroicos conocidos. No obstante, sus propiedades aún no son adecuadas para su empleo en dispositivos pues suelen presentar una elevada conductividad eléctrica y/o una respuesta antiferromagnética. La modificación de estos materiales mediante dopado con Ti4+ puede disminuir las pérdidas dieléctricas y proporcionar un comportamiento ferromagnético. Sin embargo, los cambios producidos en la estructura, microestructura y propiedades de los materiales de BiFeO3 como consecuencia del dopado con Titanio no están claros. En este trabajo se presenta una caracterización detallada de cerámicas de composición nominal BiFe0.95Ti0.05O3 con una elevada resistencia y una respuesta magnética extraordinaria. Los resultados evidencian la formación de una nanoestructura relacionada con la segregación del dopante en borde de grano que es la responsable de los cambios producidos en las propiedades magnetoeléctricas de estos materiales

Research on the Friction Properties of DP600 Stainless Steel as a Function of Bending Angle and Pin Diameter

[EN] The rapid evolution of materials and manufacturing processes, driven by global competition and new safety and environmental regulations has had an impact on automotive structures (Body In White; BIW) manufacturing. The need for lighter vehicles, with more equipment, that are safer and eco-friendly at the same time, relates to the entire life cycle of the car. Car and steelmakers agree that weight reduction is possible, and the solution involves the use of new advanced high-strength steels. Thinner and stronger materials lead to higher demands on stamping, the most used manufacturing in BIW parts. The use of advanced high-strength steels raises new challenges, especially concerning the lubrication between the die and the sheet. To study the lubrication conditions of the stamping process, a sheet metal forming a simulator was developed. The simulator consists of two cylinders that pull the strip of steel and a pin in between. The angle between the cylinders can be adjusted from 0 to 90 degrees, which allows analysis of the effect of the stamping angle. The pull force and velocity can be set and measured, and the peripheric pin velocity, the strain, and the strain velocity can be measured as well. In this work, the tribological properties of Dual-Phase 600 stainless steel using different processing conditions have been analyzed. To this end, a factorial experiments design with twelve parameters that compare the behavior of different angles and diameters was run. The results showed that the friction coefficient increases by increasing the bending angle and decreases with pin diameter.Sanchez-Caballero, S.; Sellés, M.; Pla-Ferrando, R.; Segui Llinares, VJ.; Peydro, MA. (2021). Research on the Friction Properties of DP600 Stainless Steel as a Function of Bending Angle and Pin Diameter. Materials Proceedings. 3(1):1-7. https://doi.org/10.3390/IEC2M-09248173

Revisiting the method to obtain the mechanical properties of hydrided fuel cladding in the hoop direction

The method reported in the literature to calculate the stress–strain curve of nuclear fuel cladding from ring tensile test is revisited in this paper and a new alternative is presented. In the former method, two universal curves are introduced under the assumption of small strain. In this paper it is shown that these curves are not universal, but material-dependent if geometric nonlinearity is taken into account. The new method is valid beyond small strains, takes geometric nonlinearity into consideration and does not need universal curves. The stress–strain curves in the hoop direction are determined by combining numerical calculations with experimental results in a convergent loop. To this end, ring tensile tests were performed in unirradiated hydrogen-charged samples. The agreement among the simulations and the experimental results is excellent for the range of concentrations tested (up to 2000 wppm hydrogen). The calculated stress–strain curves show that the mechanical properties do not depend strongly on the hydrogen concentration, and that no noticeable strain hardening occurs. However, ductility decreases with the hydrogen concentration, especially beyond 500 wppm hydrogen. The fractographic results indicate that as-received samples fail in a ductile fashion, whereas quasicleavage is bserved in the hydrogen-charged samples

Los problemas en ingeniería

[ES] La resolución de problemas constituye una de las facetas educativas que cualquier alumno suele relacionar con las enseñanzas técnicas. Ese reconocimiento suele también identificarse con listas interminables de problemas suministradas por el profesor o incluidas en monografías, en las que el alumno es incapaz de hallar una mínima relación con los problemas que acontecen en su quehacer diario o en la Ciencia real. Las conductas que desencadena en el profesor y en el alumno la resolución de problemas vienen a estar impregnadas de una serie de rutinas descontextualizadas, inalteradas década tras década y que promueven el aprendizaje memorístico más que la oportunidad de indagar en la comprensión del contenido científico. En este trabajo se expone cómo mejorar el proceso de resolución de problemas, y también se exponen indicaciones de como evaluar el aprendizaje.Sellés, M.; Pérez Bernabeu, E.; Sanchez-Caballero, S.; Crespo, J.; Parres, F. (2011). Los problemas en ingeniería. Instituto de Ciencias de la Educación de la Universidad de Alicante. 2317-2325. http://hdl.handle.net/10251/178197S2317232