https://popups.uliege.be/esaform21/index.php?id=3934 Index terms fr 0 https://popups.uliege.be/esaform21/index.php?id=3686 Liquid nitrogen cooling is widely used in the extrusion industrial practice in order to increase the production rate, to reduce the die temperature and to avoid defects on the profile exit surfaces resulting from an excessive heating. However, the efficiency of the cooling is deeply affected by position and design of the liquid nitrogen channel so that numerical modelling is gaining an increasing industrial interest in relation to the possibility offered to optimize the channel design without expensive and time-consuming experimental trials. In this work, a numerical FE model developed within COMSOL Multiphysics® is proposed and validated against experimental trials performed in industrial environment. The model combines the 3D simulation of the extrusion process with a 1D model of the cooling channel thus allowing the testing of a number of different solutions at the die design stage. The global aim of this work is the assessment of the liquid nitrogen cooling efficiency in the extrusion of an industrial aluminum profile and the proof of the potentials offered by numerical models to get an optimized channel design in terms of cooling efficiency, die thermal balancing and reduction of liquid nitrogen consumption. Mon, 29 Mar 2021 14:11:19 +0200 Mon, 26 Apr 2021 16:12:04 +0200 https://popups.uliege.be/esaform21/index.php?id=3686 https://popups.uliege.be/esaform21/index.php?id=1977 Determination of flow stress and friction in cold forging is of paramount importance. In this work, an inverse procedure is developed for predicting the Coulomb’s coefficient of friction and strain-dependent flow stress simultaneously based on the measurement of bulge and forging load. It is also established that in cold forging Coulomb’s coefficient of friction can be approximated as half the friction factor in Tresca (or constant friction) model. In the inverse procedure, forging load is estimated analytically but bulging is estimated by developing an empirical relation. The efficacy of the inverse procedure is ascertained by the data obtained from finite element method simulations. Finite element method was implemented in ABAQUS and validated with the results available in literature. In most of the cases, inverse procedure provides less than 5% error in the estimates of friction and flow stress. A sensitivity analysis is also carried out to study the effect of measurement error. It is observed that error in the estimation of friction is proportional to error in the measurement of bulge. The novelty of the method lies in the quickness and simplicity of the method. Tue, 23 Mar 2021 12:17:42 +0100 Mon, 12 Apr 2021 11:01:34 +0200 https://popups.uliege.be/esaform21/index.php?id=1977 https://popups.uliege.be/esaform21/index.php?id=3775 Energy prediction and starvation have become an essential part of process planning for the XXI century manufacturing industry due to cost-saving policies and environmental regulations. To this aim, the research presented in this paper details how machine learning-based algorithms can be an effective way to predict and minimize the energy consumptions in the widely spread radial-axial ring rolling (RARR) process. To analyze this bulk metal forming process, 380 numerical simulations have been developed using the commercial SW Simufact Forming 15 and considering three largely utilized materials, the 42CrMo4 steel, the IN 718 superalloy, and the AA6082 aluminum alloy. To create the database for both multi-variable regression and machine learning models, ring outer diameters ranging from 650 mm to 2000 mm and various process conditions including different sets of tool speeds and initial temperatures have been considered. For the case of the multi-variable regression model, to account for all the cross-influences between all the parameters, a second-order function including 26 parameters has been developed, resulting in a reasonable average accuracy (94 %) but also in an impractical huge equation. On the other hand, the machine learning model based on the Gradient Boosting (GB) approach allows obtaining a similar accuracy (96 %) but its compact form allows a more practical utilization and its training can be expanded almost indefinitely, by adding more results from both numerical simulations and experiments. The proposed approach allows to quickly and precisely predict the energy consumption in the RARR process and can be extended to other manufacturing processes. Mon, 29 Mar 2021 14:30:24 +0200 Thu, 08 Apr 2021 20:21:19 +0200 https://popups.uliege.be/esaform21/index.php?id=3775 https://popups.uliege.be/esaform21/index.php?id=574 Multi-material solutions offer benefits, as they, in contrary to conventional monolithic parts, are customised hybrid components with properties that optimally fit the application locally. Adapted components offer the possibility to use high strength material in areas where external loads require it and substitute them by lightweight material in the other areas. The presented study describes the manufacturing of a hybrid shaft along the process chain Tailored Forming, which uses serial pre-joined semi-finished products in the forming stage. Subject of this study is the numerical modelling of the heating process by induction heating of a hybrid semi-finished product and the resulting material distribution after the impact extrusion process. For this endeavour, a numerical model of an inhomogeneous induction heating process was developed. The main challenge is to determine the boundary conditions such as current intensity acting in the induction coil and the electromagnetic properties of the used material. The current intensity was measured by a Rogowski coil during experimental heating tests. The relative magnetic permeability was modelled as a function of temperature using the method of Zedler. The results show the importance of using a relative magnetic permeability as a function of temperature to guarantee a high quality of the numerical model. Subsequently, the model was applied to the heating of the hybrid semi-finished product consisting of a steel and aluminium alloy. By using inductive heating and thus a resulting inhomogeneous temperature field, good agreement of the material distribution between experiment and simulation could be achieved after the forming process. Sat, 20 Mar 2021 12:20:49 +0100 Mon, 05 Apr 2021 18:10:14 +0200 https://popups.uliege.be/esaform21/index.php?id=574 https://popups.uliege.be/esaform21/index.php?id=2502 Nowadays, virtual predictions are essential in the design and development of new engineering parts. A critical aspect for virtual predictions is the accuracy of the constitutive model to simulate the material behavior. A state-of-the-art constitutive model generally involves a large number of parameters, and according to classical procedures, this requires many mechanical experiments for its accurate identification. Fortunately, this large number of mechanical experiments can be reduced using heterogeneous mechanical tests, which provide richer mechanical information than classical homogeneous tests. However, the test’s richness is much dependent on the specimen's geometry and can be improved with the development of new specimens. Therefore, this work aims to design a uniaxial tensile load test that presents heterogeneous strain fields using a shape optimization methodology, by controlling the specimen's interior notch shape. The optimization problem is driven by a cost function composed by several indicators of the heterogeneity present in the specimen. Results show that the specimen's heterogeneity is increased with a non-circular interior notch. The achieved virtual mechanical test originates both uniaxial tension and shear strain states in the plastic region, being the uniaxial tension strain state predominant. Tue, 23 Mar 2021 20:46:27 +0100 Tue, 30 Mar 2021 17:24:34 +0200 https://popups.uliege.be/esaform21/index.php?id=2502 https://popups.uliege.be/esaform21/index.php?id=4067 Tube hydraulic bulging tests with fixed-end conditions are carried out to explore tubular material characteristics for 5049 aluminium. Tube diameter at the center of specimen and pole thickness under different internal pressures are recorded during forming process. Based on experimental data, two types of theoretical models using membrane mechanics and total strain theory are applied to determine the flow stress curve of tubular specimens. A tension specimen is cut from the same tube along longitudinal direction and strain-stress curve is fitted by a universal tensile test. In order to test their accuracy, obtained material parameters from three methods are imported into a finite element model (FEM) and its predicted results are compared with bugle height measured from experiments. The comparison shows that the flow stress curve of 5049 aluminium tube can be identified by these three methods and simulated results from total strain model has a better agreement with experimental measures compared with the other two methods. Tue, 30 Mar 2021 11:36:59 +0200 Tue, 30 Mar 2021 11:37:04 +0200 https://popups.uliege.be/esaform21/index.php?id=4067 https://popups.uliege.be/esaform21/index.php?id=919 Bulk metal components are often used in areas which are subjected to very high loads. For most technical components, a distinction between structural and functional areas can be made. These areas usually have very different loading profiles, sometimes with contradictory requirements. Nevertheless, nowadays almost only monomaterials are used for the production of bulk metal components. With increasing requirements towards more and more efficient products with lower weight, compact design and extended functionality, these materials are reaching their material-specific limits. A significant increase of product quality and economic efficiency can be expected exclusively with locally adapted properties by combining different materials within one component. In this regard, the focus of this contribution is the production of a hybrid pinion shaft made of the material combination steel (37CrS4) and aluminium (AW6082). The tool concept for extrusion of the hybrid preform, the simulation-based design of the forming process as well as the material characterisation are presented. With the help of the FE-simulation, different serially arranged semi-finished component geometries were investigated in order to minimise the occurring tensile stresses in the component during the extrusion process to prevent failure during forming. Mon, 22 Mar 2021 10:10:58 +0100 Mon, 29 Mar 2021 20:17:20 +0200 https://popups.uliege.be/esaform21/index.php?id=919 https://popups.uliege.be/esaform21/index.php?id=2340 Wire-arc welding-based additive manufacturing (WAAM) is a 3D printing technology for production of near-net-shape parts with complex geometry. This printing technology enables to build up a required shape layer by layer with a deposition of a consumable welding wire, where the welding arc is a source of heat. Welding is usually performed by CNC-controlled robotic manipulator, which provides a controlled location of material layer adding. Because the process itself involves thermo-mechanically complex phenomena, Finite Element-based virtual models are commonly employed to optimize the process parameters. This paper presents advanced computational modelling of the WAAM of a tube. A thermo-mechanical numerical model of the process is calibrated against experimental data, measured as temperature variation at the acquisition point. The virtual modelling starts with a preparation of the tube geometry in CAD software, where the geometry of the single-layer cross-section is assumed. The geometry is then exported to a G-code format data file and used to control robotic manipulator motion. On the other side, the code serves as an input to in-house developed code for automatic FEs activation in the simulation of the material layer-adding process. The time of activation of the finite elements (FEs) is directly related to the material deposition rate. The activation of the FEs is followed by a heat source, modeled with a double ellipsoidal power density distribution. The thermo-mechanical problem was solved as uncoupled to speed-up computation. Tue, 23 Mar 2021 17:02:11 +0100 Mon, 29 Mar 2021 19:26:36 +0200 https://popups.uliege.be/esaform21/index.php?id=2340