https://popups.uliege.be/esaform21/index.php?id=564 Index terms fr 0 https://popups.uliege.be/esaform21/index.php?id=1525 The accurate prediction of forming defects is fundamental for the virtual try-out of metallic sheet components. However, the constitutive model can have a strong impact on the numerical predictions, namely the cup earing, the occurrence of wrinkles and the tearing failure. The process conditions considered in this work are the ones established for the “Benchmark 2 – Cup Drawing of Anisotropic Thick Steel Sheet”, proposed under the Numisheet 2018 international conference. The axisymmetric cups are obtained from a steel sheet with 2.8 mm of thickness, resorting to different process conditions to induce different defects. The advanced yield criterion proposed by Cazacu and Barlat is used to define the anisotropic behavior of the blank. The calibration of the material parameters is carried out by fitting the following experimental data from: (i) uniaxial tensile tests performed in every 15º to the rolling direction; (ii) biaxial tension tests to evaluate the directions of the plastic strain rates in the first quadrant of the yield loci. The numerical predictions are compared with the experimental measurements, allowing to assess the accuracy of the finite element model to predict each type of forming defect. The cup earing and the strain localization are accurately predicted, while the wrinkles amplitude is clearly underestimated. Mon, 22 Mar 2021 20:07:36 +0100 Mon, 12 Apr 2021 10:56:43 +0200 https://popups.uliege.be/esaform21/index.php?id=1525 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. Fri, 19 Mar 2021 19:38:16 +0100 Mon, 12 Apr 2021 09:13:32 +0200 https://popups.uliege.be/esaform21/index.php?id=437 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=2715 The purpose of this paper is to simulate a complex forming process with parameters identified from tensile and shear tests. An elastic-plastic model is retained which combines a Hill’s 1948 anisotropic criterion and plastic potential using a non-associated flow rule. Firstly, a mechanical characterization is made with homogenous tests like tensile and shear tests [1]. On the other hand a process of micro Single Point Incremental forming is simulated [2]. It consists in deforming a clamped blank using a hemispherical punch which has a small diameter compared to the blank dimensions. From a small-size sheet of 0.2 mm thick, a square-based pyramid is obtained incrementally, with a define height path and advanced speed, by a tool instrumented to measure the forming force, which deforms locally the material. It is shown that the non-associated flow plasticity model leads to a good agreement between experimental and numerical results for the evolution of the punch force during the process. Wed, 24 Mar 2021 18:49:56 +0100 Fri, 09 Apr 2021 10:20:38 +0200 https://popups.uliege.be/esaform21/index.php?id=2715 https://popups.uliege.be/esaform21/index.php?id=1613 The increased use of polymer-based material in the manufacturing of vehicles structures makes critical the management of multi-material interfaces, and hence the issue of polymer-metal joining. It has been demonstrated in the literature that for large-scale manufacturing, self-piercing riveting (SPR) represents a reliable alternative technique to conventional resistance spot welding (RSW). However, the riveting operation induces, by nature, damages to the joint composite layer due to the steel rivet crossing it. In this study, the damage of the SMC thermoset material during SPR process has been experimentally investigated. Moreover, the influence of the riveting velocity as a major SPR process parameter on the composite layer damage has been identified. Eventually, the failure mechanisms of the polymer-metal joint resulting from failure under lap-shear and pure tension loadings were studied with the support of the numerical simulation tool. Mon, 22 Mar 2021 20:17:44 +0100 Mon, 05 Apr 2021 18:20:19 +0200 https://popups.uliege.be/esaform21/index.php?id=1613 https://popups.uliege.be/esaform21/index.php?id=929 Manufacturing high value components involves complex and non-linear thermo-mechanical processes to obtain optimum combination of microstructure and mechanical properties required for the final part. Among these, the ingot-to-billet conversion process, involving forging operations of upsetting and cogging, are critical to refine the as-cast coarse, elongated, and dendritic microstructure. In this study, the first stage of the ingot-to-billet conversion process has been investigated in type 316 austenitic stainless steel, aiming to propose a novel methodology for the characterisation of the as-cast material behaviour. Hot upsetting tests were carried out on cylindrical samples taken out from an industrial-scale ingot. The resulted microstructures were analysed, using advanced image analysis method, for the fraction and distribution of the recrystallised grains, highlighting the strong dependency of recrystallisation behaviour on the initial microstructure of the as-cast material. Using a finite element (FE) model considering the anisotropic behaviour of the material, originated from the preferential grain growth during casting, the deformation of the samples were predicted with a good accuracy. The results demonstrate the importance of considering the anisotropic plastic properties in the FE models to effectively predict the as-cast material deformation, shape and thus the thermo-mechanical characteristics applied during forging. Mon, 22 Mar 2021 10:22:17 +0100 Tue, 30 Mar 2021 10:07:33 +0200 https://popups.uliege.be/esaform21/index.php?id=929