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This work presents a comprehensive study on the influence of three different processing technologies (Selective Laser Melting, Hot Pressing and conventional casting) on the microstructure, mechanical and wear behavior of an austenitic 316L Stainless Steel. A correlation between the processing technologies, the obtained microstructure and the mechanical and wear behavior was achieved. The results showed that the highest mechanical properties and tribological performance were obtained for 316L SS specimens produced by Selective Laser Melting, when compared to Hot Pressing and conventional casting. The high wear and mechanical performance of 316L Stainless Steel fabricated by Selective Laser Melting are mainly due to the finer microstructure, induced by the process. In this sense, Selective Laser Melting seems a promising method to fabricate customized 316L SS implants with improved mechanical and wear performance.

The aim of this work was to study the influence of the processing route on the microstructural constituents, hardness and tribological (wear and friction) behavior of Ti6Al4V biomedical alloy. In this sense, three different processing routes were studied: conventional casting, hot pressing and selective laser melting. A comprehensive metallurgical, mechanical and tribological characterization was performed by X-ray diffraction analysis, Vickers hardness tests and reciprocating ball-on-plate wear tests of Ti6Al4V/Al 2 O 3 sliding pairs. The results showed a great influence of the processing route on the microstructural constituents and consequent differences on hardness and wear performance. The highest hardness and wear resistance were obtained for Ti6Al4V alloy produced by selective laser melting, due to a markedly different cooling rate that leads to significantly different microstructure when compared to hot pressing and casting. This study assesses and confirms that selective laser melting is potential to produce customized Ti6Al4V implants with improved wear performance.

Selective Laser Melting (SLM) is an extremely versatile technology especially suited for the manufacturing of thin-walled parts. Micro-sized parts are highly influenced and dependent on the SLM processing parameters; thus being indispensable to assess the influence of processing parameters on SLM fabrication, as isolated parameters but also their interactions. In this study, the influence of SLM laser power and scanning speed on Ti6Al4V micro-pillars and micro-plates thickness was assessed by applying response surface methodology (RSM). These analyses resulted in four models that exhibit complex correlations of SLM process parameters, with non-linear equations, having coefficients of determination that assess the quality of the models. These developed models are accurate tools that can be used to optimize the micro manufacture of Ti6A14V thin-walled parts by SLM., This work is supported by FCT - Fundacao para a Ciencia e a Tecnologia through the grant SFRH/BPD/112111/2015 and the projects PTDC/EMS-TEC/5422/2014 and NORTE-01-0145-FEDER-000018-HAMaBICo. Additionally, this work is supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 - Programa Operational Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941.

Additive Manufacturing (AM) is a manufacturing process through which a 3D component is produced by consecutively adding material. One of the most promising AM processes is SLM. In SLM a laser completely melts metallic powder particles together forming a 3D component. SLM is known for its freedom of manufacturing constraints allowing complex geometries and high material efficiency. Topology Optimisation (TO) is an optimisation type that calculates the optimal material distribution for a given problem. The combination of SLM with TO is being developed to create lightweight components. In this work, the whole development process, from optimisation to design, production and testing is addressed. Initially, an aircraft bracket topology was optimised to be produced by means of SLM. The TO solution was interpreted and designed for AM. During the interpretation and design process, a design methodology was defined in order to facilitate and make more accurate the TO solution design and make it ready for AM. After the optimised component was produced, metrological and mechanical tests were performed in order to validate the final design and the computer analysis. The optimised component showed considerable weight reduction with an increase of the factor of safety. The experimental tests revealed a good relation to the computer analysis evidencing, however, room for improvement, both in the computer model and the experimental tests.

Additive manufacturing (AM) technologies enable the fabrication of innovative structures with complex geometries not easily manufactured by traditional processes. Regarding metallic cellular structures with tailored/customized mechanical and wear performance aiming to biomedical applications, Selective Laser Melting (SLM) is a remarkable solution for their production. Focusing on prosthesis and implants, in addition to a suitable Young's modulus it is important to assess the friction response and wear resistance of these cellular structures in a natural environment. In this sense, five cellular Ti6Al4V structures with different open-cell sizes (100–500 μm) were designed and produced by SLM. These structures were tribologicaly tested against alumina using a reciprocating sliding ball-on-plate tribometer. Samples were submerged in Phosphate Buffered Saline (PBS) fluid at 37 °C, in order to mimic in some extent the human body environment. The results showed that friction and wear performance of Ti6Al4V cellular structures is influenced by the structure open-cell size. The higher wear resistance was obtained for structures with 100 μm designed open-cell size due to the higher apparent area of contact to support tribological loading., This work was supported by FTC project PTDC/EMS-TEC/5422/ 2014, by project NORTE 01-0145_FEDER-000018 and by the grant SFRH/BPD/112111/2015. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01–0145-FEDER-006941., info:eu-repo/semantics/publishedVersion

Apple bruise damage from harvesting, handling, transporting and sorting is considered to be the major source of reduced fruit quality, resulting in loss of profits for the entire fruit industry. The three factors which can physically cause fruit bruising are vibration, compression load and impact, the latter being the most common source of bruise damage. Therefore, prediction of the level of damage, stress distribution and deformation of the fruits under external force has become a very important challenge. In this study, experimental and numerical methods were used to better understand the impact caused when an apple is dropped from different heights onto a plastic surface and a conveyor belt. Results showed that the extent of fruit damage is significantly higher for plastic surface, being dependent on the height. In order to support the development of a biomimetic electronic device for the determination of fruit damage, the mechanical properties of the apple fruit were determined using mechanical tests. Preliminary results showed different values for the Young’s modulus according to the zone of the apple tested. Along with the mechanical characterization of the apple fruit, the development of the first two prototypes is discussed and the integration of the results obtained to construct the final element model of the apple is presented. This work will help to reduce significantly the bruise damage of fruits or vegetables during the entire processing which will allow the introduction of exportation destines and consequently an increase in the economic profits in this sector., {"references":["Van Zeebroeck M, Tijskens E, Dintwa E, Kafashan J, Loodts J, De Baerdemaeker J, Ramon H, \"The discrete element method (DEM) to simulate fruit impact damage during transport and handling: Case study of vibration damage during apple bulk transport\", Postharvest Biology and Technology, Vol. 41, 2006, pp. 92-100.","Lewis, R., Yoxall, A., Canty, L.A., Romo, E.R., \"Development of engineering design tools to help reduce apple bruising\", in Journal of Food Engineering, Vol. 83, 2007, pp. 356-365.","Zdunek, A. and Umeda, M., \"Extension and Fracture of Cell Walls after Parenchyma Tissue Deformation\" in Biosystems Engineering, Vol. 93, No. 3, 2006, pp. 269-278.","Celik, H.K., Rennie, A.E.W. and Akinci, I., \"Deformation behaviour simulation of an apple under drop case by finite element method\", Journal of Food Engineering, Vol. 104, 2011, pp.293-298.","Li, Z., Yang, H., Li, P., Liu, J., Wang, J. and Xu, Y., \"Fruit biomechanics based on anatomy: a review\", International Agrophyics, Vol. 27, No. 1, 2013, pp. 97-106.","Labavitch, J. M., Greve, L. C., & Mitcham, E., \"Fruit bruising: It is more than skin deep\", Perishables Handling Quarterly, Vol. 95, 1998, pp.7–9.","García, J.L., Ruiz-Altisent, M., Barreiro, P., \"Factors Influencing Mechanical Properties and Bruise Susceptibility of Apples and Pears\", Journal Agricultural Engineering Research, Vol. 61, 1995, pp. 11-18","Vergano, P.J.; Testin, R.F.; Newal, J.R., \"W.C. Peach bruising: susceptibility to impact vibration, and compression abuse\", American Society of Agricultural Engineers, Vol. 34, No.5, 1991, pp.2110-2116.","Lin, X and Brusewitz, G.H, \"Peach bruise thresholds using the instrumented sphere\". Applied Engineering in Agriculture, Vol.10, 1994, pp. 509- 513.\n[10]\tVan Zeebroeck M, Van Linden V, Ramon H, De Baerdemaeker, \"Impact damage of apples during transport and handling\". Postharvest Biology and Technology, Vol. 45, 2007, pp.157-167. J\n[11]\tGenard, M., Bertin, N., Borel, C., Bussieres, P., Gautier, H., Habib, R., Lechaudel, M., Lecomte, A., Lescourret, F. and Lobit, P., \"Towards a virtual fruit focusing on quality: Modelling features and potential uses\", Journal of Experimental Botany, Vol. 58, 2007, pp. 917-928.\n[12]\tBain, J.M. and Robertson, R.N., \"The physiology of growth in apple fruits\", Australian Journal of Scientific research, Vol. 4, 1951, pp. 75-91.\n[13]\tCutler, D.F., Botha, T., Botha, C.E.J. and Stevenson, D.W. Plant Anatomy: An Applied Approach, (Malden, MA, USA), 2008.\n[14]\tKhan, A.A. and Vincent, J.F.V., \"Anisotropy in the fracture properties of apple flesh as investigated by crack-opening tests\", Journal of Materials Science, Vol. 28, 1993, pp. 45-51."]}

The properties of parts produced by Selective Laser Melting (SLM) are highly influenced by the processing parameters. The calculation of the energy density is not enough for justifying the mechanical and physical properties, and understand the microstructures of Ti6Al4V samples produced by SLM. In fact, samples produced with the same energy density, but with different processing parameters, present distinct properties. In this sense, it is necessary to assess the influence of processing parameters on SLM fabrication, as isolated parameters but also their interactions.This work presents a study on the influence of several SLM processing parameters (laser power, scan speed and scan spacing) on density, hardness and shear strength of Ti6Al4V samples. The influence of these processing parameters on the final properties of SLM parts was obtained by using statistical analysis. Additionality, with the drive of finding the significant main factors and their interactions, analysis of variance (ANOVA) was performed. The influence of the above mentioned processing parameters on shear strength, hardness and density resulted in three models that can be used as predictive design tools for Ti6Al4V parts produced by SLM technology. Moreover, a study on the microstructures of the Ti6Al4V samples was performed and correlated with the obtained models. (C) 2016 Elsevier B.V. All rights reserved., This work is supported by FCT through the project with the reference EXCL/EMS-TEC/0460/2012 and the grant SFRH/BPD/112111/2015. This work is also supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 Programa Operacional Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941., info:eu-repo/semantics/publishedVersion

Selective Laser Melting (SLM) processing parameters are known to greatly influence 316L stainless steel final properties. A simple energy density calculation is insufficient for explaining mechanical and physical properties as well as microstructural characteristics, which are known to significantly influence these parts performance. In fact, parts produced by using different combinations of processing parameters, even presenting similar energy density, can display different properties. Thus, it is necessary to assess their influence as isolated parameters but also their interactions. This work presents a study on the influence of several SLM processing parameters (laser power, scanning speed and scanning spacing) on density, hardness and shear strength of 316L stainless steel. The influence of these processing parameters on the abovementioned properties is assessed by using statistical analysis. In order to find the significant main factors and their interactions, analysis of variance (ANOVA) is used. Furthermore, in order to assess the effect of the part building orientation, two different building strategies were tested. The influence of these processing parameters on shear strength, hardness and density were assessed for the two building strategies, thus resulting six different models that can be used as predictive design tools. The microstructures experimentally obtained were analyzed, discussed and correlated with the obtained models., This work was supported by the Portuguese Foundation of Science and Technology through the projects EXCL/EMS-TEC/0460/2012, UID/EEA/04436/2013 and by the FCT grant SFRH/BPD/112111/2015., info:eu-repo/semantics/publishedVersion