Joining Feasibility Between Metallic- and Polymeric-Based Materials by Friction Stir Forming

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Design of custom cranial prostheses combining manufacturing and drop test finite element simulations

AbstractIn this work, impact puncture tests (drop tests) have been used to both tune numerical models and correlate the performance of customised titanium cranial prostheses to the manufacturing process. In fact, experimental drop tests were carried out either on flat disk-shaped samples or on prototypes of titanium cranial prostheses (Ti-Gr5 and Ti-Gr23 were used) fabricated via two innovative sheet metal forming processes (the super plastic forming (SPF) and the single point incremental forming (SPIF)). Results from drop tests on flat disk-shaped samples were used to define the material behaviour of the two investigated alloys in the finite element (FE) model, whereas drop tests on cranial prostheses for validation purposes. Two different approaches were applied and compared for the FE simulation of the drop test: (i) assuming a constant thickness (equal to the one of the undeformed blank) or (ii) importing the thickness distribution determined by the sheet forming processes. The FE model of the drop test was used to numerically evaluate the effect of the manufacturing process parameters on the impact performance of the prostheses: SPF simulations were run changing the strain rate and the tool configuration, whereas SPIF simulations were run changing the initial thickness of the sheet and the forming strategy. The comparison between numerical and experimental data revealed that the performance in terms of impact response of the prostheses strongly depends on its thickness distribution, being strain hardening phenomena absent due to the working conditions adopted for the SPF process or to the annealing treatment conducted after the SPIF process. The manufacturing parameters/routes, able to affect the thickness distribution, can be thus effectively related to the mechanical performance of the prosthesis determined through impact puncture tests

Job shop scheduling model for a sustainable manufacturing

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Numerical Analysis of the ISF Process on Sheet with Locally Modified Material Flow Stress

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LiSC Model: An innovative paradigm for Liquid Supply Chain

Abstract Supply chain is studied all over the world by a number of researchers who propose description models, analyze quantitatively its efficiency and, more recently, create its digital twins. In the last years, according to some unpredictable events which upset the global economy, supply chain showed the capacity to change itself according to the new constraints but, also, the new opportunities raised. Classical models developed to describe supply chain are not powerful enough to model what today I4.0 pillars allow if we use open innovation as an extraordinary amplifier. Thus, the supply chain changes shape and connections. In this perspective, the paper propose and describe a new construct of supply chain called: Liquid Supply Chain (LiSC). It takes into account also the extraordinary effects of pandemic diffusion of Covid-19 virus and its influence on the companies. A critical comparison with other existing models is proposed and discussed

incremental sheet forming of a composite made of thermoplastic matrix and glass fiber reinforcement

Abstract Incremental Sheet Forming (ISF) has been widely investigated in the last twenty years, highlighting advantages as low-cost, higher formability and greater process flexibility if compared to traditional processes. Recent works have proven the ISF feasibility for polymer processing whereas limited investigations exist on composite materials. In the proposed study, an experimental research was carried out with the aim to investigate the influence of process factors on the workability of composite parts. The attention was focused on extruded Reinforced Polyamide-6 sheets. The material is made of thermoplastic matrix and 15% of glass fibers as reinforcement. The processed material is characterized by a glass temperature higher than 50°C and, therefore, ISF was performed with the addition of an external heating source. More in detail, the experiments were carried out on a three axis CNC milling machine equipped with an additional chamber designed for the material heating. In this paper, the influence of the main process factors (i.e. wall slope angle, step depth and process temperature) on the manufactured parts and on the process feasibility was investigated

spif of tailored sheets to optimize thickness distribution along the shaped wall

Abstract Tailored blanks are widely used in industry for reducing the parts' weight without affecting stiffness. In this study, the authors proposed the use of the tailored blanks with an alternative aim. Specifically, the attention has been focused on the use of an initial blank with variable thickness for overcoming one of the main drawback of Single Point Incremental Forming process (SPIF), i.e. the material thinning. More in detail, blanks with variable thickness have been designed and experimentally tested for compensating the thinning phenomenon, which characterizes SPIF. An experimental and numerical research has been planned to consider the geometrical variables of the problem. Briefly, an artificial localised variable thickness has been imposed to the original blank with the aim to modify the overall strength of the sheet affecting its deformation. The idea has been analysed changing the depth and the position of the machined pockets on the sheet surface. The application of subtractive step, instead of forming or additive processes, was now preferred for time and cost saving. However, the outcomes of the experimentation can be easily transposed to any combination of processes. The feasibility of the proposed approach will be detailed in the paper

Performances Analysis of Titanium Prostheses Manufactured by Superplastic Forming and Incremental Forming

Abstract Titanium and its alloys are widely used in cranioplasty because they are biocompatible with excellent mechanical properties and favor the osseointegration with the bone. However, when Titanium alloys have to be worked several problems occurred from a manufacturing point of view: the standard procedure for obtaining Titanium prostheses is represented by the machining processes, which result time and cost consuming. The aim of this research consist to introduce alternative flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The research activities have already highlighted the potentiality of the investigated forming processes that can be alternatively used taking into account both the damage morphology and the need of urgency operation. In the present work, the way of manufacturing the Ti prostheses by SPF and SPIF is described. A comparative analysis has been performed, thus highlighting the peculiarities of the investigated processes and the prostheses feasibility

Environmental sustainability analysis of industrial processes

Dottorato di Ricerca in Igegneria Meccanica Ciclo XXVIII,a.a. 2015-2016Il lavoro di questa tesi si propone come introduttore e suggeritore di una serie di tecniche, strumenti e pratiche di monitoraggio e controllo degli aspetti ambientali legati al ciclo aziendale. Lo strumento attualmente in uso oggi nelle imprese, che funge da guida nella ristrutturazione in ottica ambientale delle proprie attività è l’LCA, sul quale si basa l’approccio delle 6R e le strategie di sviluppo suggerite: REDUCE, REMANUFACTURING, REUSE, RECOVER, RECYCLE, REDESIGN. L’obiettivo di fornire alle imprese strumenti utili in ottica sostenibile viene affrontato inquadrando le diverse analisi condotte nella tesi all’interno di due linee guida fondamentali: controllo dei costi e valutazione dell’impatto ambientale allo stesso tempo. Dunque, l’obiettivo è duplice e complesso: il solo traguardo morale non è sufficiente alle imprese per rimanere competitive. Dunque, costi e impatto ambientale diventano obiettivi alla pari anche se a volte apparentemente contrastantiUniversità della Calabri

Design and experimental validation of downstream manufacturin processes on polymeryc and composite materials

Dottorato di Ricerca in Igegneria Civile e Industriale. Ciclo XXXIUniversità della Calabri