Application of the Upper Bound Theorem to indentation processes with tilted punch by means of Modular Model

Nowadays, the indentation processes are resuming it importance due to the new deformation processes that are being developed, as the Incremental Forming Process (IFP) or the Localized-Incremental Forming Process (LIFP) [1]. In this paper, a tilt punch is considered in order to cover the largest possible number of cases in the study of the indentation,. Thus, using combinations of flat and tilt punches, it will be possible to analyze complex geometries in future studies. Present study shows the analysis of the indentation process by the Upper Bound Theorem (UBT), when it is performed with a tilt punch. A modular model is developed, compound by two modules of Triangular Rigid Zones (TRZ) each [2], which adapts to the configuration of the punch.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Use of additive manufacturing on models for sand casting process

Casting is a forming process based on material pouring in liquid state. Heat is applied to melt the material from its solid state and pour it in a mold previously constructed to obtain the desired shape after letting it cool. Molds can be permanent or expendable. In sand casting processes, the mold is manufactured from a model that usually is extracted before pouring the melted material (Figure 1). To obtain the part, the sand model needs to be destroyed. Notwithstanding, the sand can be reused several times for new molds. Several elements are needed to obtain a part by a sand casting process: permanent patterns, flasks (cope and drag), gating system (pouring cup, sprue, risers and feeding channels) and cores (only if it is needed). The aim of this work is the manufacturing of some of these elements by additive manufacturing process. The equipment will be used for the practical activities (Figure 1) that currently take place on the subjects where this topic is taught, in the different Degrees in Industrial Engineering at the University of Malaga.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fatigue test bench manufacturing by reusing a parallel lathe

Fatigue life of machined parts strongly depends on their surface condition. The rotating bar bending fatigue testing method is widely used to obtain the fatigue behavior of metallic materials due to its simplicity. In this work, the methodology for the design, manufacturing and setup of a fatigue test bench is exposed. The main novelty lies on the reuse of several elements from an old parallel lathe, currently out of order, and their use to manufacture some parts for the test bench. In this way, a double objective is achieved: high quality elements are recycled and the machine manufacturing cost is reduced.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Desarrollo de un kit de ELISA para detectar beta-lactoglobulina lácteas

La alergia a la leche, en especial de vaca, ocupa el primer lugar en importancia entre las alergias alimentarias en niños, afectando aproximadamente al 3% de la población en el primer año de vida. La complejidad creciente de los alimentos hace que sea dificil detectar la presencia de proteínas lácteas e identificarlas en el etiquetado. La b-lactoglobulina es una proteína del lactosuero de la leche de mamíferos, que no está en la leche humana, y por lo tanto actúa como alérgeno. El objetivo de este trabajo es desarrollar un sistema que permita detectar la presencia de b-lactoglobulina en diferentes matrices alimentarias y biológicas. Para ello hemos empleado una técnica inmunológica, tipo enzimoinmunoensayo (ELISA). Las razones es que es una técnica sencilla, rápida, de bajo coste y con una especificidad y sensibilidad elevada. Como anticuerpo primario se han testado anticuerpos policlonales producidos en conejo y pollo. Como anticuerpos secundarios se han empleado anticuerpos policlonales producido en conejo, a los que se les unía un sistema de detección (preferentemente HRP) para la lectura de la placa. Se probaron distintas diluciones de los anticuerpos primarios y secundarios y del alérgeno (b-lactoglobulina). Se ensayaron distintas condiciones de bloqueo y lavado, así como los tiempos de incubación mas adecuados. Esto nos permitió seleccionar como anticuerpos primarios más eficientes los anticuerpos policlonales producidos en conejo. Además, se han fijado las condiciones idóneas para desarrollar el ELISA. Finalmente, el kit de ELISA desarrollado se ha probado sobre diferentes tipos de leche (vaca, cabra, oveja, humana, fórmulas de iniciación y soja). El kit fue lo suficientemente específico, sensible y reproducible para detectar y medir la presencia de b-lactoglobulina en las leches de vaca, cabra, oveja y fórmula de iniciación. Así mismo, no detectó b-lactoglobulina en la leche humana y de soja. El kit que hemos desarrollado podrá tener varios usos según la matriz donde se quiera detectar la b-LG. Si la matriz es alimentaria, servirá para detectar la b-lactoglobulina en distintos alimentos, teniendo en este caso una utilidad para controlar el fraude alimentario. En un futuro habrá que comprobar si el kit funciona en una matriz biológica (plasma o heces). En este caso permitirá detectar la ingesta de proteínas lácteas en la dieta de los niños alérgicos a las proteínas lácteas

Influence of printing parameters and short carbon fibre reinforcement on fatigue behaviour, dimensional accuracy and macrogeometrical deviations of polylactic acid in material extrusion

This paper evaluates the potential of short carbon fibres as a reinforcement material in order to improve the fatigue resistance of PLA. The fatigue behaviour has been analysed through rotational bending fatigue tests. The influence of printing parameters, such as layer thickness, printing temperature and printing speed, on the mechanical behaviour, dimensional accuracy and macrogeometrical deviations of printed parts have also been analysed as they can too interfere with the mechanical behaviour of the parts. The results show that there is no improvement on the mechanical behaviour of the printed parts with the incorporation of short carbon fibres. On the contrary, the fatigue behaviour worsens due to the poor adhesion between the short carbon fibres and the PLA matrix. Fatigue life is reduced by 6% compared to PLA. Focusing only on the printing parameters, it is shown that at the highest temperature allowed, the fatigue behaviour improves a 12%. The Printing speed is the least influential variable, with the layer thickness having the greatest influence, increasing fatigue life by 15% comparing 0.1 mm and 0.3 mm. Therefore, the best combination would be to print with the highest temperature and the highest layer thickness, for this case study. Finally, a parametric relationship is presented in order to relate the layer thickness with the fatigue behaviour.FundiFunding for open access charge: Universidad de Málaga / CBU

Manufacture of an abrasive jet machining (AJM) equipment adapted for the treatment of rotary flexion fatigue specimens

The influence of micro-geometric irregularities on fatigue strength and, in particular, surface topography is widely accepted. The different machining processes generate surface roughness on machined parts that may significantly modify their fatigue behaviour and compromise their use in components where structural stability is required. Therefore, the study of these materials behavior under cyclic loading stresses becomes highly relevant. The aim of this work is to design and manufacture an abrasive jet machining machine, in order to improve the surface roughness in the dry turning of aluminium alloys, using similar parameters to any equivalent industrial equipment. For this purpose, several components from obsolete machines belonging to the Manufacturing Engineering Department of the University of Malaga have been reused, to reduce the final cost. Several test have been carried out with the aim of testing the manufactured equipment. The experimental data have shown results in line with those offered by others in industrial use for similar abrasives and processing material. The equipment has been built in accordance with the ISO 12100:2010 Safety of machinery - General principles for design - Risk assessment and risk reduction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Implementación del método de aprendizaje basado en Proyectos en asignaturas de Ingeniería de Fabricación de los Grados de la Universidad de Málaga

El presente trabajo de innovación educativa pretende desarrollar las capacidades y competencias de los alumnos mediante la aplicación de un Proyecto que potencia el aprendizaje cooperativo. El alumno verá enriquecido su dominio de la disciplina a través de una coherente aplicación de los conocimientos adquiridos en una primera parte teórica de la asignatura. La interacción directa con otros alumnos, la exigibilidad individual, la reflexión sobre el funcionamiento del grupo y el desarrollo de las habilidades interpersonales son la base del aprendizaje cooperativo y la implementación del presente proyecto posibilita reducir las carencias que en estos aspectos muestra el alumnado universitario. El Proyecto puede ser denominado por el siguiente titular: ¿CÓMO SE FABRICA Y CÓMO FUNCIONA? En cada curso académico el Área de Ingeniería de Procesos de Fabricación (IPF) adquirirá un conjunto mecánico de complejidad media (p. e. cortasetos) que esté compuesto de un número adecuado de piezas fabricadas con distintos materiales (metal, polímeros, cerámicos, compuestos) y mediante diferentes procesos de fabricación (fundición, mecanizado, soldadura, deformación plástica, etc.). El proyecto partirá de una inicial descomposición por explosion de la totalidad de las piezas que forman el conjunto. Un posterior análisis establecerá las relaciones funcionales de los diferentes componentes y la naturaleza del material de cada uno de ellos, así como de las posibles alternativas a emplear en su fabricación.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Dimensional Analysis in Additive Manufacturing Processes with PLA+Carbon Fiber

The rise of Additive Manufacturing (AM) processes is due to the need to reduce material and energy costs. It has the capacity to achieve specialized tools fast while offering the possibility of customize products for the end user. Unlike the majority of the traditional manufacturing processes, AM generally generates the part by depositing material in layers that fuse and create a specific geometry, like Fuse Deposition Modeling (FDM). This comparatively recent technology is still being developed and adapted to the industry and materials requirements. Thus, im-provements are needed in areas like dimensional accuracy, geometric repeatability and material defects, among others, to be able to compare and have the same relia-bility that the products obtained by conventional manufacturing processes. Present work aims to carry out a dimensional control of workpieces designed to fit (axis-hole), so that the influence of certain printing parameters and the final dimensional precision of the specimens can be stablished. The printing parameter relation is studied for a composite material with a PLA matrix, reinforced with Carbon Fibers (PLA+CF), studying the influence of the printing temperature, the layer thickness and the printing direction. This material has been selected because PLA, together with ABS, is one of the most applied materials in AM. Notwithstanding, PLA is easy to process but lacks on resistance, which can be improved introducing carbon fiber as reinforcement. The best result is obtained decreasing the thickness. Also, In comparison with the vertical printing direction,Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fatigue behaviour analysis of AISI 316-L parts obtained by machining process and additive manufacturing

Due to the great technological growth, 3D printing is becoming of great relevance within the automotive, aerospace and even medicine sectors. With this manufacturing method, parts with a complex geometry can be manufacture with considerable time and material savings compared to traditional processes such as machining. However, additive manufacturing processes still have a series of unresolved problems. Present work makes a comparison between AISI 316-L samples obtained by Selective Laser Melting technique and Dry Machining. The comparison is focus in properties mainly relevant in the industrial sectors highlighted. Macro and microgeometrical deviations, such as roughness, roundness and straightness are obtained in each case study and compared. Results show that, although for the printed samples the material deposition direction plays a fundamental role, being the horizontal samples the ones with better results due to the direction of the layers, the machining process is the one with significant better results compared to the 3D printing process. After the macro and microgeometrical deviations measurements, all samples were subjected to a rotational bending fatigue test for a mechanical behaviour study. As expected, the mechanized specimens have a better fatigue behaviour due to the better surface finish, among other aspects. Between the additive manufactured specimens, the vertical is the one that presents a better behaviour due to the transverse orientation of the deposited layersUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fatigue behavior analysis in reinforced PLA parts manufactured by FDM

Fused Material Deposition Modelling (FDM) is one of the most extensive 3D printing processes. However, its integration and application to structural parts remain limited to some extent, due to the polymeric materials that can be processed, generally PLA and ABS. FDM printing involves a large number of manufacturing parameters, which can also influence the mechanical properties of the final part. Although the static mechanical properties of FDM components are well documented, the dynamic mechanical properties are not yet fully analyzed. Similarly, in the field of composite materials, reinforced thermoplastics are increasingly used in structural load-bearing applications due to its high specific strength and ease of processing. Therefore, it is necessary to focus on the reinforcement influence on the mechanical behavior of printed parts. The fatigue response of these materials is strongly influenced by the anisotropy of the properties, due to the orientation and composition of the reinforcement. It should be noted that, despite the fact that short-fiber or particlereinforced polymers generally fail in a macroscopically brittle manner, the underlying failure mechanisms are, nevertheless, not due to crack growth. Difficulty in correctly identifying underlying failure mechanisms, during material characterization, can lead to erroneous conclusions in service life predictions. Consequently, present work focuses on the reinforcement influence analysis on the fatigue behavior with PLA-based parts manufactured by FDM, showing how the fatigue behavior life worsen with short fiber and particle reinforcement.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech