https://popups.uliege.be/esaform21/index.php?id=84 Coordinator: Dr. Margareta Coteata Co-organisers: Dr. Hans-Peter Schulze(tbc), Prof. Massimo Durante, Prof. Loredana Santo, Prof. Laurentiu Slatineau. Description: The main topics of MS are: EDM, ECM, EME, EHE, cold spray, Friction Stir Welding and Single Point Forming for polymers, creep age forming. Historically starting from some innovative processes initially included in this MS, new symposia were created. Therefore, in order to maintain this characteristic of individuating new processes of scientific interest, the papers regarding innovative processes or forming processes of non-conventional materials (innovative materials or hybrid structures) will be considered in this MS. Mini Symposia fr Wed, 03 Mar 2021 09:35:54 +0100 Wed, 14 Apr 2021 09:55:47 +0200 https://popups.uliege.be/esaform21/index.php?id=84 0 https://popups.uliege.be/esaform21/index.php?id=1518 The quality of a forming process highly depends on the pressure applied to the workpiece. Consequently, the demand for higher workpiece qualities results in a demand for tools that can withstand high compressive stresses. Moreover, the tendency of using materials like high-strength steels as workpiece material, urges the need for tool materials that can withstand high compressive stresses and are resistant to wear. A class of materials that offer a combination of hardness or wear resistance and ductility are cemented carbides. However, these properties hamper their machining with conventional cutting technologies. Due to its electro-thermal working principle, Electrical Discharge Machining (EDM) is able to machine materials independently from their mechanical properties. On the other hand, the removal process is accompanied by thermal stresses, which can cause residual stresses and micro cracks near the machined surface. Due to their pre-existing stresses from the sintering process, cemented carbides are especially susceptible for these kind of damages. It is therefore necessary to identify the impact of EDM on the material. Different machining strategies are tested with two different types of cemented carbides and examined regarding their fracture toughness. The crack surfaces resulting from the three point bending test are microscopically inspected regarding failure initiation. Additionally pin-on-disc tests are conducted to determine the influence of the EDM strategies on the tribological properties of the machined cemented carbides. Mon, 22 Mar 2021 20:06:40 +0100 https://popups.uliege.be/esaform21/index.php?id=1518 https://popups.uliege.be/esaform21/index.php?id=2616 Literature reports several works concerning the impact response of composites reinforced with woven fibers and the mechanisms involved in impact energy dissipation. However, even if composites' structures are subjected to various environmental conditions during their service life, few papers are concerned about the impact behaviour at shallow temperatures. Very few discuss sandwich components. In this paper, sandwich composites' low-velocity impact behaviour constructed from carbon fibre reinforced face sheets surrounding a polyvinyl chloride core has been tested. Impact tests at penetration and indentation (U=5,7.5,12,10 and 15J) at room temperature and -55°C, +70 °C were carried out. After each impact test, indentation depth and ultrasound analysis measurements have been implemented to learn the damage modes of the tested samples. The results provided a useful indication on the extreme temperature's influence on both impact properties and damage evolution. Wed, 24 Mar 2021 18:31:40 +0100 https://popups.uliege.be/esaform21/index.php?id=2616 https://popups.uliege.be/esaform21/index.php?id=2681 One of the processes used to separate parts from plate-type workpiece is laser beam cutting. The evaluation of the quality of the machined surfaces can be performed by taking into account the influence exerted by some input factors in the cutting process on the width of the slot and on the roughness of the surfaces generated by the laser beam cutting process. The paper presents the results of experimental research performed on a steel plate type workpiece. The objective pursued was to reveal the influence exerted by several input factors of the laser beam cutting process on some output parameters of this process. Empirical mathematical models corresponding to the output parameters taken into account were established. It was possible to order the input factors in the process by taking into consideration their weight in the values of the output parameters. Wed, 24 Mar 2021 18:42:45 +0100 https://popups.uliege.be/esaform21/index.php?id=2681 https://popups.uliege.be/esaform21/index.php?id=2709 In principle, all non-conventional machining processes can be viewed as the sum of various sub-processes, the separate analysis of which influences the effectiveness of this machining process. The first question to answer is the criteria by which these sub-processes can analyzed. Since the non-conventional processes work exclusively based on electrical energy, voltage and current determine the character of the sub-process. The second focus is the time constant with which voltage and current influence the process, from which the measurement of the corresponding parameters result. The third group of influencing parameters is the working medium and its change due to the main removal process. In the summary, these three groups are consider with regard to a process model with which a process control (technology), a process regulation (process stability) and a safety control (limit value exceeded) are guide. Wed, 24 Mar 2021 18:48:35 +0100 https://popups.uliege.be/esaform21/index.php?id=2709 https://popups.uliege.be/esaform21/index.php?id=2798 Anisogrid lattice cylinders have been produced by means of an innovative out-of-autoclave (OOA) process by using thermoplastic prepreg. Unidirectional thermoplastic tapes with polypropylene matrix and glass fibers were wound on cylindrical mandrels at room temperature. Composite consolidation was achieved by using the compression of a heat-shrink tube during its shape recovery in oven. A cylindrical anisogrid lattice structure was manufactured and mechanically tested under vertical loading. Results from the buckling test revealed the optimal adhesion between prepreg layers after the out-of-autoclave molding. Numerical modelling of buckling has been performed to correlate the structural behavior of the anisogrid lattice cylinder with composite material properties and geometrical features. A parametric model of the lattice structure has been defined for this aim. The proposed manufacturing technology combines the advantages of thermoplastic composites (reparability, easy handling, easy storage, long prepreg life, productivity) with the designing potential of anisogrid lattice structures in terms of lightness and stiffness. Wed, 24 Mar 2021 19:03:10 +0100 https://popups.uliege.be/esaform21/index.php?id=2798 https://popups.uliege.be/esaform21/index.php?id=3831 The application of high strength aluminum sheet metal components in automotive and aviation products effectively saves material and thus weight. Material strengthening can be realized by accumulative roll bonding (ARB), which belongs to the severe plastic deformation processes. Through repeated rolling steps a multilayered sheet metal is produced, which possesses increased strength due to its ultra-fine grained microstructure. Prior to each rolling step a surface treatment via wire brushing is mandatory for removing the oxide layer and roughening the sheet surface, which enables the bonding between the unique layers during rolling. The necessary surface treatment of the sheets is not fully understood by the current state of the art. In the past, it was not possible to achieve a defined and stable surface finish, because the brushing operation was done manually. The improvement of the process stability is essential to determine the relationship between the input parameters for brushing and the resulting bond strength of multilayered ARB sheets. For this reason, a robot-controlled surface treatment is introduced. The investigated material is the precipitation-hardened aluminum AA6014 with a sheet thickness of 1 mm. A suitable brushing kinematic under constant load is implemented and its effects on the surface properties are investigated by roughness measurements. The investigation shows, that the parameter combination leads to comparable or even higher roughness values than through manual brushing. Through 16 consecutive brushing paths a homogeneous and sufficient high surface roughness is realized, which enables material bonding in the rolling step. Thus, the research results indicate, that the robot-assisted surface treatment of ARB sheet metal is a promising method for a better automation and reproducibility of the brushing and the overall ARB process. Mon, 29 Mar 2021 14:47:26 +0200 https://popups.uliege.be/esaform21/index.php?id=3831 https://popups.uliege.be/esaform21/index.php?id=4002 Bending processes have various advantages, such as less processing time, lower number of tooling parts, and cost compared to other manufacturing processes. However, one of the disadvantages of a bending process is the inevitable springback problem, which entails geometrical inaccuracy. Many researchers have made attempts to effectively measure springback in-line to control product quality and compensate for variability. While measurement tools and machines are available to measure springback, they might not be able to accommodate large products due to the size limit of measurement devices. Nevertheless, sensor-based monitoring is becoming critical to control product quality and to move towards Industry 4.0. In this paper, an in-situ springback monitoring technique for bending of large-size profiles is proposed to overcome the measurement restrictions for such profiles. A computer vision technique with the circular Hough transform was used to evaluate springback. The marked points on a profile were used to track the deformation of the workpiece. However, a weakness with image processing is to recognize the points from the complex background. Instead of employing global search for the points in an image frame, the marked points were detected by locally setting regions based on forming parameters such as a bending angle and stretching level. Springback was calculated by the change of position of those points. The results of springback monitoring were validated with the physically measured data from experiments. Based on this measurement technique, the feasibility of a computer vision-based springback monitoring in large-size profile bending is discussed in detail. Tue, 30 Mar 2021 09:56:07 +0200 https://popups.uliege.be/esaform21/index.php?id=4002 https://popups.uliege.be/esaform21/index.php?id=4032 Electrically conductive and thereby electrical discharge machinable ceramics may gain further relevance for tooling applications and in chemical industry. They combine high chemical and thermal durability with high hardness and strength. While these properties represent a significant advantage for application, they are a major challenge for conventional machining. Due to the thermophysical removal principle, wire electrical discharge machining (WEDM) is a suitable manufacturing process for hardness-independent machining and may broaden the use of ceramics especially in case of customized complex parts. Up to now, there are only a few investigations on WEDM of electrically conductive ceramics, especially with regard to the surface integrity and the influence of the EDM process on the mechanical properties. A previous study investigated the influence of different WEDM technologies on the surface integrity and the resulting load-bearing capacity of a zirconia-tungsten carbide (TZP-WC) ceramic. Based on this investigation, the heat flow in this ceramic composite was calculated with the use of a heat simulation model and compared with the analyzed rim zone, in order to predict a priori reliable process parameters. Furthermore, the wire electrical machinability and the bending strength of alumina-zirconia-tungsten carbide (ATZ-WC) composite ceramics with different fractions of the respective phases were investigated to identify the correlations and verify the simulation model. Tue, 30 Mar 2021 10:32:47 +0200 https://popups.uliege.be/esaform21/index.php?id=4032 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 https://popups.uliege.be/esaform21/index.php?id=4036 https://popups.uliege.be/esaform21/index.php?id=4040 Stretch bending is commonly used in the mass production of profile-like products in many industrial sectors due to its high dimensional accuracy and process capabilities. One of the challenges of conventional stretch bending is low flexibility, however, making it difficult to meet today’s requirements for mass customization. As a countermeasure, a novel flexible rotary stretch bending process was presented (Ma and Welo, 2021), which allows the forming of complex shapes with varying curvatures and angles. However, less knowledge is known about the most fundamental force requirements during forming, which in turn limits the design and development of product and process. In this research, an analytical model is developed for accurate and efficient prediction of real-time forming forces in flexible rotary stretch bending, aiming to enhance the understanding of applied force requirements throughout the process. In this model, the entire kinematically-controlled loading (strain) history is considered to realize real-time monitoring of force. In addition, the elastic-plastic properties of profile, the profile dimensions, the tooling geometries as well as the tool-workpiece friction are comprehensively taken into account to improve the analytical accuracy of forming force predictions. As an explicit solution can be achieved, the analytical model presents high efficiency for quick prediction, which can be used in attempts to adaptively control the process. Based on finite element simulation, the analytical model is validated in the forming of aluminium rectangular, hollow profiles, showing very high accuracy and efficiency for predicting real-time forming forces of both clamp unit and bending die for forming with different pre-stretching levels. Tue, 30 Mar 2021 10:55:06 +0200 https://popups.uliege.be/esaform21/index.php?id=4040 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 https://popups.uliege.be/esaform21/index.php?id=4044 https://popups.uliege.be/esaform21/index.php?id=4093 Multi-axis forming is a six degree of freedom forming process. This process influences actively the material flow by defining a six dimensional tool motion path and the corresponding tool velocity. Within this process, it is possible to combine a linear forming movement followed by a rolling movement and therefore tailor the induced local material properties of the work piece. The research objective of this work is to observe and quantify the interaction between tool motion and material flow for the purpose of process planning. Experiments are conducted to examine the horizontal material flow within a multi-axis forming process of a plane L-shaped work piece. Three different punches form the material: Flat, cylindrical and cone-shaped. The horizontal material flow is recorded through a transparent die by a camera to measure the material flow for different tool motions. It is shown, that a multi-axis forming process can adjust the local material flow. The resulting redirection of the material flow after the sharp inward facing edge of the L-shape is analyzed and compared. With a smaller active zone compared to a standard linear pressing, the multi-axis forming forces are reduced. In addition, the reservoir with the remaining material is more concentrated. Finally, it is possible to direct the material flow with the punch motion, which can be used to determine local part properties. Tue, 30 Mar 2021 12:39:02 +0200 https://popups.uliege.be/esaform21/index.php?id=4093 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 https://popups.uliege.be/esaform21/index.php?id=4131 https://popups.uliege.be/esaform21/index.php?id=4337 Electromagnetic embossing enables the transfer of surface structures from forming dies to metal sheets at high forming speeds. For this purpose, the contactless forming force is provided by means of a magnetic field of a tool coil which interacts with an eddy current in the workpiece. In thin sheets which are completely penetrated by the magnetic field, the resulting Lorentz forces act as body forces that accelerate the workpiece onto the forming die. In addition to the body forces, also high strain rates can support the embossing of thin sheets. This investigation deals with the embossing of pyramidal structures in the submillimeter range and an aspect ratio of about 1 into thin aluminum sheets (3.0255 / Al99,5). In order to quantify the reproduced microstructures, their extent is determined by means of a lateral analysis. From this, the replicated height is derived. Up to now it has been possible to partially reproduce microstructures with a large aspect ratio in thin sheets. In addition, the changing surface roughness of the sheets is taken into account. Before embossing, the sheets exhibit a relatively rough surface with a rolled texture, which is smoothed by the impulse forming with an optical forming die. This study reveals basic approaches for the electromagnetic embossing of optical microstructures. Thu, 01 Apr 2021 18:11:22 +0200 https://popups.uliege.be/esaform21/index.php?id=4337