https://popups.uliege.be/esaform21/index.php?id=485 Publications of Auteurs Massimo Durante fr 0 https://popups.uliege.be/esaform21/index.php?id=4131 Niobium is a ductile transition metal of growing interest for several technological applications, thanks to its intriguing characteristics, among them high melting point, moderate density, good ductility, high corrosion resistance and superconductivity. By contrast, its use is limited by some weaknesses lied to the mechanical properties, which can undermine the quality of the surfaces worked by metal forming processes. Sheets of pure Niobium can be used for the manufacture of extremely customized components and a flexible process like the incremental sheet forming fits well with this manufacturing philosophy; in fact, this technique does not require complicated tools and/or dedicated equipment and is capable to respond quickly to the market demands. The scope of this paper is to investigate the influence of the tool/sheet contact conditions on different features like the forming loads, the surface quality and the occurrence of failures, when pure Niobium rolled sheets are formed incrementally. To this aim, the simplest variant of incremental sheet forming, namely single point incremental forming, was considered by using a common fixed end forming tool with hemispherical head. The process was carried out under dry and lubricated tool/sheet contact conditions, following the indications from a preliminary campaign of wear tests conducted by a pin-on-disk apparatus. The experimental campaign highlights the strong influence of the tool/sheet contact conditions and the importance of a correct choice of them on the features investigated, in order to limit the forming forces and the risk of failure, as well as to preserve the surface quality of the components made by incremental sheet forming of Niobium. Wed, 31 Mar 2021 09:09:19 +0200 Wed, 31 Mar 2021 09:09:19 +0200 https://popups.uliege.be/esaform21/index.php?id=4131 https://popups.uliege.be/esaform21/index.php?id=4044 Gypsum is an ancient material, still widely used and suitable for many applications in the constructions due to its low cost, availability, lightweight, good thermal and sound isolating behaviour, fire resistance and low energy consumption. One of the most established application is its use as building walls and as pointed out in authors previous research works, it can be very useful and interesting to reinforce the gypsum with vegetable fibres like hemp. This aspect is in line with the current world situation where every industrial company needs to decrease the materials waste, increase recyclability and use more eco-friendly materials. Therefore, this work aims at designing, manufacturing, and testing of both commercial and recycled gypsum specimens reinforced with hemp fabrics, in order to improve impact and flexural resistance of traditional gypsum boards. The recycling process was carefully studied to detect the best grinding time, temperature and time of the heat treatment required to allow the reutilization of gypsum powders. Three point bending and impact tests at different energy levels were carried out in order to understand how the presence of the hemp fabrics within the gypsum matrix and how the recycling process affect the mechanical response of reinforced gypsum. Tue, 30 Mar 2021 10:58:08 +0200 Tue, 30 Mar 2021 10:58:08 +0200 https://popups.uliege.be/esaform21/index.php?id=4044 https://popups.uliege.be/esaform21/index.php?id=4036 Metal foams have a number of established niche market and potential applications under investigation due to their peculiarities including thermal, acoustic and mechanical properties at low weight. In order to produce structures resistant at high temperature and acting as barrier to the fire, metals with closed cells are often required, and one of the most consolidate manufacturing process for their production is the gas releasing particles decomposition in semisolids, by means of which a foam is created by a foaming agent dispersed into a precursor. In previous researches, the authors have investigated the possibility of foaming the aluminum starting by a precursor, placed between two skins consisting of steel grids, in order to obtain a sandwich structure at the same time of the foaming step. In line to continue on this topic and to improve the compression strength of the aluminum-foamed core, in this work the steel grid was used both as skins and as a corrugated skeleton inside the core. Different types of sandwich structures were manufactured, following some experimental tests executed to determine the optimal value of temperature and time to foam the precursor. Then, compression tests were carried out, in order to investigate the effectiveness of the proposed solution on the improvement of this mechanical behavior. The mechanical tests highlighted the increase of mechanical properties using this type of corrugated core. Tue, 30 Mar 2021 10:35:30 +0200 Tue, 30 Mar 2021 10:43:32 +0200 https://popups.uliege.be/esaform21/index.php?id=4036 https://popups.uliege.be/esaform21/index.php?id=2651 The use of composite hybridization using both synthetic and natural fibers, is one of the most established way to combine the advantages of each material that forms the composite system in order to obtain a composite with good in-plane and out-of-plane properties. For example, as pointed out in authors previous research works, considering carbon/hemp hybrid composites, it is possible to combine the ductile behavior and the capacity to absorb energy of hemp fibers with the higher strength and stiffness of carbon allowing the development of a hybrid system with enhanced energy absorption capability, reduced production cost and lower environmental impact respect to traditional carbon fibers composites. The aim of this work is to investigate both experimentally and numerically the mechanical behavior at impact of pure carbon, pure hemp and carbon/hemp hybrid composite laminate. Low velocity impact tests at 10 J and 20 J were carried and non-destructive analyses were performed for each impact energy to evaluate the internal damage extent. The same tests were numerically simulated with LS-DYNA software using shell elements and different material cards (i.e. MAT 54/55, MAT 24 depending on typology of fibers) and contact conditions in order to find the best configuration that matches the experimental results. Wed, 24 Mar 2021 18:37:18 +0100 Fri, 09 Apr 2021 10:38:58 +0200 https://popups.uliege.be/esaform21/index.php?id=2651 https://popups.uliege.be/esaform21/index.php?id=475 In recent years, the concepts of industry 4.0 are widely spreading in many different sectors, from agriculture to home automation, from transportation systems to manufacturing processes. One of the pillars of this concept is related to the use of robotic cells. The focus of the present work is the robotic automated layup of dry fibrous preforms to be employed in liquid composite molding (LCM) processes. In particular, the article describes a software tool developed to simulate the automated placement and layup of fiber fabrics and tissues on complex shape molds by means of a robotic system. The tool has been coded in Matlab language. An end-effector has been appositely designed for the fiber layup and it has been included in the model. The simulation provides as output the path generation and the configuration of the robotic arm and of end effector along the entire layup process. The implemented code has been compared with the commercial software RoboDK. Fri, 19 Mar 2021 22:51:39 +0100 Thu, 08 Apr 2021 22:14:49 +0200 https://popups.uliege.be/esaform21/index.php?id=475