https://popups.uliege.be/esaform21 ESAFORM is an association with the mission to stimulate applied and fundamental research in the field of material forming. Its annual conference, the International ESAFORM Conference on Material Forming, is used to achieve one of the main goals of ESAFORM: to spread scientific and technological information related to material forming within academic and industry. The next conference will be held online on 14-16 April 2021. fr https://popups.uliege.be/esaform21/index.php?id=942 Accumulative roll-bonding (ARB) is a novel plastic straining process aimed at bonding of similar and dissimilar metal combinations. Moreover, it is used recently to produce ultrafine grain materials and metal matrix reinforced composites to enhance mechanical, electrical, and corrosion resistance properties. This work presents an experimental study of roll bonding and accumulative roll bonding of similar AA3105 aluminum alloy at 300°C with a final thickness of 1.2 mm, focusing especially on bond strength evaluation and layers continuities. Tensile tests and three-points bending were performed to mechanical characterize the produced sheets in the various steps and based on the number of the cycles. The maximum strength was reached after 3 ARB cycles. After 4 cycles, the bonding interfaces have a uniform distribution through the sheet thickness, it is possible to distinguish only the interface formed in the last pass in the fracture surface, and no significant enhancement in strength was observed. Starting from 2 ARB cycles, micro-cracks were observed at the outer surface for bending angles greater than 90 deg, and at 180 deg all ARBed samples except A1 were failed. Mon, 03 May 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=942 https://popups.uliege.be/esaform21/index.php?id=2151 Auxiliary systems for sheet forming processes are widely used to improve products accuracy and increase tools life. As example, in blanking hydraulic dampers are widely used to reduce shocks and vibrations; nitrogen springs are often integrated in deep drawing tools to correct the ram tilt or to locally increase the blank-holder force, obtaining geometrical features on the stamped blank with one press pass. In this paper, a Magneto-Rheological (MR) semi-active actuator is developed for sheet forming operations and the interaction between MR fluid and electromagnetic field is investigated by Finite Element (FE) analysis. To overcome the limitations of gas springs and hydraulic actuator, the static electromagnetic circuits is reconfigured with respect of conventional MR actuators known in the state-of-the-art. The novel MR actuator has an inner bore where the electric windings are placed, while the narrow gap, in which the active MR fluid flows, is obtained between the inner bore and the cylinder internal surface. The resulting magnetic fields H and induction fields B, as well as the selection of components materials, are studied through the magneto-static FE model. The results from FE simulations show a longer activation length along the gap resulting in higher controllable forces values, without increasing the overall dimensions of the proposed prototype. Mon, 03 May 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=2151 https://popups.uliege.be/esaform21/index.php?id=2599 In this study, a data-driven deep learning model for fast and accurate prediction of temperature evolution and melting pool size of metallic additive manufacturing processes are developed. The study focuses on bulk experiments of the M4 high-speed steel material powder manufactured by Direct Energy Deposition. Under non-optimized process parameters, many deposited layers (above 30) generate large changes of microstructure through the sample depth caused by the high sensitivity of the cladding material on the thermal history. A 2D finite element analysis (FEA) of the bulk sample, validated in a previous study by experimental measurements, is able to achieve numerical data defining the temperature field evolution under different process settings. A Feed-forward neural networks (FFNN) approach is trained to reproduce the temperature fields generated from FEA. Hence, the trained FFNN is used to predict the history of the temperature fields for new process parameter sets not included in the initial dataset. Besides the input energy, nodal coordinates, and time, five additional features relating layer number, laser location, and distance from the laser to sampling point are considered to enhance prediction accuracy. The results indicate that the temperature evolution is predicted well by the FFNN with an accuracy of 99% within 12 seconds. Wed, 21 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=2599 https://popups.uliege.be/esaform21/index.php?id=4891 ESAFORM conferences would not happen without all the efforts of the Board of Directors of the association. For 24 years, without any salary, the members of the board give time and energy to launch the annual conference and new actions to fill the association objectives. We build a community and we offer networking opportunities. Friendship emerges between all these scientists who gather years after years. I thank my colleagues for the opportunity of being chairwoman of ESAFORM 2021. I organized ESAFORM in 2001 and it is a real pleasure to organize it again, in 2021. Let us be flexible even if I would have prefered to see you not on a screen and to share the progresses of Liege city in 20 years. Did you had a look at the touristic Liege visit? I thank Céline Dizier of AIM who worked hard to find solutions to organize this conference and to follow my suggestions to give not only a scientific content but also to provide some social links within this pandemic time. I had mixed feelings about giving ESAFORM money to a commercial editor as during those 23 years of proceedings, ESAFORM board could not succeed to build a long term partnership for them. Edition world is changing, authors are not happy to pay to read in classical journals and to pay again to publish in Open Access approach in the same journals or other ones sometimes far from being “fair”. Each year, the conference organizers have to fight with template problems; ghost characters to provide to the chosen editor “clea Wed, 21 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=4891 https://popups.uliege.be/esaform21/index.php?id=524 In the field of impact response of thermoplastic reinforced composites, several investigations about material behaviour in terms of delamination, indentation and fracture mechanism were conducted. Although a significant influence of the polymer temperature on the overall material impact response is expected, a limited number of studies are available in this regard. Most of the available scientific evidence concerns thermosetting composites and thermoplastic composites response only at room temperature. In particular, the purpose of this contribution is to better understand the dissipation mechanisms involved in thermoplastic reinforced composite under impact conditions for different temperatures. Starting from the few available literature data about the modelling of the problem, the aim of the present work is the development of a numerical approach able to reproduce the experimentally tested conditions. An experimental campaign on hot pressed polyamide 6 /basalt plain fabric laminates impact was selected as the benchmark for the numerical approach. The laminates impact response at increasing values of impact energy between 5J and 30J were simulated under three temperature conditions set around the polymer transition temperature (40°C, 80°C and 100°C). By validating the overall numerical model response on the room temperature experiment, considerations about the magnitude of viscous dissipation and its influence, for the different tested temperatures and in function of the adopted lamination technology, were made. Wed, 14 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=524 https://popups.uliege.be/esaform21/index.php?id=4783 EXACT Experiment and Analysis of Aluminum Cup Drawing Test The ESFORM Benchmark promotes the constitution of a network to deeply analyze a challenge present in the community of material forming processes. The earing predictions formed during the cup drawing process is an old problem (Fig.1). However here, for the first time, the organizers (see Table 1), eight well-known scientists of the ESAFORM community decide to investigate together with all the benchmark participants (Table 2) their practice in both experimental and numerical fields. The discussions and results of this work will be presented at the ESAFORM 2021 conference and gathered later within an article in the International Journal of Material Forming. The participants and the organizers together will point the impact of different choices on the results. Fig.1 Technical challenge: earing prediction for an anisotropic material Most sheet forming benchmarks include information such as: the hardening law parameters, based on limited experimental data (generally, r-values, yield stresses and ultimate strengths for 3 loading directions) extracted from uniaxial tension tests the coefficients for certain yield functions, available in the material libraries of most commercial software. The features of the ESAFORM 2021 Benchmark are : identification of constitutive models performed by participants; information concerning the experimental scatter, the “raw” data, where 3 laboratories have collaborated to duplicate some ty Tue, 13 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=4783 https://popups.uliege.be/esaform21/index.php?id=398 The growing demands of resource-saving processes and products are leading to increasing importance of lightweight construction for the automotive industry. One approach is multi-material design, which uses high-strength steels and aluminium alloys in the production of vehicle bodies. Therefore, reliable processes for joining components with different mechanical properties and geometries are necessary. As conventional joining processes reach their limits, new versatile processes and methods are required which can adapt to different process conditions and disturbance variables. A widely used joining process to join different materials is self-piercing riveting as a joining by forming method, however it is characterised as inflexible to changing process conditions due to a linear process kinematic and rigid dies. An approach to extend the process limits is the application of a tumbling kinematic for the punch. Thus, an adapted tumbling strategy can be used to influence the joining process and to achieve a controlled material flow in order to manufacture tailored joints. For the fundamental investigation of the process, numerical investigations are necessary. In order to achieve high model quality a precise material modelling is crucial. Therefore, a characterisation of the materials HCT590X+Z and EN AW-6014 as typical materials of multi-material mixes and the rivet material 38B2 is performed. Due to the different stress conditions during tumbling self-piercing riveting suitable characterisation methods are selected and carried out. Mon, 12 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=398 https://popups.uliege.be/esaform21/index.php?id=403 In recent years, recycling the powder leftover within the additive manufacturing process has been attractive for both research, development and industry production. Powder recycling can significantly enhance the sustainability of the manufacturing process, reduce the cost and avoid producing metallic waste as a potential environmental hazard. The first step in reusing the recycled powders in the 3D printing process is to characterize the microstructure and surface quality of the powder for oxidation and impurity analysis. Here, scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) have been used for the morphology and surface composition analysis of the 316L powders within the Aconity 3D printer. A new powder collection strategy has been introduced to collect powders from different locations in the powder bed: from the top most and surface of the parts and powder bed after the print terminated, from between the printed parts at different heights. The XPS measurements revealed that oxidation is a common in all the powders compared to virgin powder and more oxidation was detected from the powders collected on the very top of the leftover powder and from surface of the bed. The size of the particles does not change much but larger particles remained at the topmost surface. This finding would help in designing a protocol for collecting the recycled powder from the powder bed and it is suggested to follow a a procedure of collecting powders from the different sections of the powder bed in order to avoid mixing the most and least affected particles. Mon, 12 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=403 https://popups.uliege.be/esaform21/index.php?id=437 The current market requirements are increasingly pushing the industry towards the manufacturing of highly customized products. Tailored blanks are a class of sheet metals characterized by the local variation of properties, attributable to the presence of different materials, different thickness distribution, and thermal treatments. In the manufacturing of tailored welded blanks, welding and forming processes cover a central role. In this framework, friction stir welding demonstrated to be a suitable candidate technology for the production by joining of tailored blanks. Indeed, sheet metals welded by this solid-state welding process typically exhibit high formability when compared to the conventional welding methods. Due to the improved formability, a good deal of attention has been recently given toward the single point incremental forming (SPIF) process and its integration with FSW. Remarkable efforts have been dedicated to the numerical modeling of the SPIF of metallic alloy sheets jointed by FSW. The main criticisms in these models are related to the definition of the mechanical properties of the materials, which are affected by the structural alteration induced by the FSW. The present work aims to model the local alterations in the mechanical properties and to analyze how these local characteristics affect the formability of the blanks. With this purpose, a 20 mm wide sample collected from a FS welded blank of aluminum alloy AA6082 has been modeled using the mechanical properties variation achieved in a previous work. The influence of this local variation in properties has been assessed using a Finite Element Model Updating strategy. Mon, 12 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=437 https://popups.uliege.be/esaform21/index.php?id=759 Thermoforming is an attractive process for the low-cost high-volume manufacture of textile-reinforced composite structures with complicated geometries. Tool/ply and ply/ply frictions play critical roles during forming. The friction between the binder ring and the blank induce an in-plane tensile stress that mitigates wrinkling. Unwanted wrinkling can develop across the part if the in-plane stresses are too low but tearing of the material can occur if the applied stresses are too high. Understanding the role that friction plays during thermoforming can give insight on how to mitigate these manufacturing-induced defects in the part. In the current work, the coefficients of friction for two unidirectional cross-ply ultra-high molecular weight polyethylene (UHMWPE) materials are characterized as a function of pressure, fiber orientation, side of material, and pulling rate for [0/90/0/90] cross-ply sheets. The materials are tested at multiple fiber orientations to understand the influence that fiber direction has with respect to the coefficients of friction and on each respective side of the material to understand how surface topology influences the coefficients of friction. The results of the testing are found to correlate with modified Hersey numbers. Mon, 12 Apr 2021 00:00:00 +0200 https://popups.uliege.be/esaform21/index.php?id=759