Papers by Keyword: Finite Element Model

Abstract: Kolmogorov-Arnold networks (KANs) have emerged as a promising counterpart to multi-layer perceptrons (MLPs) which offer a more interpretable functionality for different machine learning(ML) applications. Their main difference lies in the definition of KAN layers, using learnable activa-tion functions, which has made these networks optimal for physics-based applications. In this work,we focus on analyzing the performance of KANs in capturing the physics of the hot rolling process,which is an integral part of steel manufacturing industry. Initially, we introduce non-dimensional pa-rameters to encapsulate geometrical factors in the process. We perform space-filling sampling in thespace spanned by these parameters. The sampled points yield the necessary parameters for the finite el-ement (FE) simulations, forming the ground truth (GT) data for the network. A closed-form analyticalmodel for spread is considered from previous studies in the literature, and its predictive performanceis assessed against the FE results. In defining the input space for the network, different alternatives arecompared and it was seen that input space containing the non-dimensional features and the predictionsof the analytical model reduced overfitting and better generalization. The effect of KAN hyperparam-eters are evaluated, and the network with tuned parameters demonstrate optimal performance on thetest set. Lastly, after applying symbolification for this network, a closed-form expression is obtainedthat captures the discrepancy between the analytical model and the GT results, and its performance istested against test set data.

Abstract: Skin-pass rolling is a finishing process characterized by very small thickness reductions, primarily applied to control surface texture and mechanical properties of rolled steel strips. A key outcome of this process is the transfer of surface roughness from the work roll to the strip, which is governed by local contact conditions at the roll–strip interface. In this study, roughness transfer during skin-pass rolling of DX56 steel sheets is investigated using a combined macro–micro finite element modeling approach supported by pilot-mill experiments. Rolling trials were conducted to measure thickness reduction and resulting surface roughness under different rolling forces and entry tensions. A macro-scale rolling model was first employed to estimate effective friction coefficients by reproducing the experimentally observed thickness reductions for each rolling condition. These calibrated friction coefficients were subsequently applied in a micro-scale finite element model incorporating an electro-discharge textured (EDT) roll surface to analyze local contact pressure, plastic strain accumulation, and roughness transfer mechanisms. The results show that increasing rolling force leads to higher contact pressures, longer roll bites, and enhanced asperity-scale plastic deformation, resulting in increased roughness transfer. Entry tension modifies the stress distribution within the roll bite, which facilitates localized yielding without inducing plastic deformation prior to roll entry. The simulations capture the qualitative trends of surface roughness evolution observed experimentally, demonstrating the capability of the proposed finite element framework to analyze roughness transfer mechanisms in skin-pass rolling.

Abstract: The necessity of complex-shaped components characterized by superior mechanical properties and limited weight is moving the attention to the Aluminium (Al) alloys. Deep Drawing Steel grades possess superior stamping characteristics and formability with respect to Al alloys. But the need of light-weighting pushes towards the adoption of materials with optimal strenght-to-weight ratio, like Al alloys. Todays Al alloys are certainly used in the transport sector but their formability (at room temperature) is poorer than Deep Drawing Steel grades, which still hinders their massive implementation in the forming processes and drives the research toward innovative manufacturing solutions. One of the most promising approach to overcome such a limitation and, thus, manufacture complex component using cold forming processes, is the adoption of local heat treatments to obtain a suitable distribution of material properties able to enhance the formability at room temperature.The design of cold forming using locally modified blanks needs: (i) an extensive investigation of the material behaviour at room temperature after the local heating and (ii) the adoption of a Finite Element approach. As for the former aspect, the authors proposed a fast and comprehensive methodology to investigate the hardening behaviour of an Al alloy (AA5754-H32) locally annealed by laser heat treatment. Using a similar approach, the hardening model was then enriched by considering the normal anisotropy, evaluating the correlation between the Lankford parameter and the material condition reached at the end of the local treatment. To improve the knowledge on the plastic response of the material, the present work focusses on the characterization of the plane strain behavior of the AA5754, initially in wrought condition (H32) and subsequently modified by laser heating. In particular, the study proposes a new quasi-homogeneous specimen which combines the local heating profile with an optimized geometry to produce a prevailing plane strain condition in the heat-treated zone. In such a way, data about the material response in the plane strain condition could be obtained for a large range of material conditions determined by the preliminary heat treatment.

Abstract: The definitive implementation of Aluminium alloys as the main choice for lighter structural components needs the availability of innovative manufacturing processes capable of overcoming their poor formability at room temperature. The local modifications of the material properties (by means of short-term heat treatments) have shown their effectiveness in such terms. In a previous study from the same authors, it was experimentally investigated that, if a AA6063-T6 tubular component is locally brought to the overaged condition, its strain behavior significantly changes during an expansion test with elastomer. In light of this, the equipment used for the tube expansion tests was simulated by means of a FE model created using Abaqus and properly tuned using data coming from experimental tests carried out on AA6063-T6 tubular specimens. The calibrated model could be thus used to simulate the tube expansion while considering several distributions of the material properties (obtained through different heating strategies). Numerical results confirmed the possibility to change the slope of the strain path, thus suggesting that the strain behavior of a tubular component can be tailored, according to the specific applications, by properly designing the laser heating strategy.

Abstract: The innovative sustainable technology based on natural fabric-reinforced cementitious matrix (NFRCM) is analyzed for strengthening masonry. A new frontier for composite materials is proposed as an alternative to well-known traditional technologies used to improve the seismic behavior of buildings, such as the portuguese technique ‘gaiola pombalina’, the Italian ‘baraccata house’ and the turkish ‘himis house’. Preliminary sensitivity analysis is performed on NFRCM and ‘baraccata’ numerical models. Both technologies are numerically compared. From the experimental results of in-plane incremental load test carried out by CNR-Ivalsa a numerical model is calibrated by non-linear pushover analysis to evaluate the behavior of masonry wall strengthened with natural fibers. This paper demonstrates the effectiveness of NFRCM systems for strengthening masonry as: i) a non-invasive solution without significant thickness; ii) a sustainable technology; iii) an intervention involving the whole wall surface avoiding failure local mechanisms.

Abstract: A numerical simulation model has been established to obtain the deformation, strain and stress concentration of slab narrow side. The simulated temperature profiles of slab show a agreement with the results of measured temperatures by using infrared thermal camera. Moreover, the deformation, stress and strain of the slab have been investigated systematically, especially at the slab narrow side along the thickness direction. The relationship between the reduction amount and deformation, stress and strain concentration of slab narrow face has been investigated.

Abstract: The bulge deformation of slab narrow face can cause surface defects of hot rolled steel plate. A three-dimensional bulging model, was proposed to simulate the evolution of deformation behavior of the continuous casting slab during heavy reduction (HR). The model was taken to investigate the non-uniform deformation of slab during HR process. The bulging deformation behavior of the slab was then calculated in one segment included seven pairs of rollers. To improve the edge defect on hot-rolled steel plates, the relationship between the reduction amount and bulge deformation of slab narrow face has been investigated.

Abstract: The Single point incremental sheet forming process known as a SPIF process. Which got a great attraction among other existed sheet metal forming processes because of their flexibility to manufacture complex products. The aluminum alloy material mechanical properties are adopted and integrated into the finite element (FE) code. The tool paths for the truncated cone shape are modeled in Fusion 360 software, and the coordinates are converted into 3D punch tool coordinates by the tool path generation framework tool for modeling the numerical simulation. In numerical modeling, three kinds of mesh settings are used to construct the mesh for producing consistent results. Afterward, the obtained results are tested against the experimental observations and the desired parts dimensions to verify the accuracy of the established FE model. Thickness variations in the formed parts are discussed in detail in terms of the thinning part, thinning location, and its size in percentage. A comparison of tested geometries displays that reduction in thickness tends to be uniform in the wall region and small fluctuation noticed near the tool retraction location. Overall, the statistical results of the SPIF process are well in contract with the experimental measurements. In terms of geometry dimensions and thickness reduction. In addition, the surface roughness was noticed to be increased when the step size is more extensive, and on the other hand, the machining time tends to be more if the contour step size is small in the SPIF process.

Abstract: The single-point incremental forming process has witnessed significant advantages in automobiles, aerospace, and medical applications in recent years because of its flexibility in manufacturing complex shapes. In detail, the components are produced only using the toolpath, which is guided by computer-aided manufacturing software. However, during the forming process, the parts might experience fractures, which could heavily impact the formed part's geometric accuracy. The main purpose of this study is to analyze the formability of an AA3003-H18 aluminum alloy material in the SPIF process; for this purpose, the material properties are extracted from the experimental simple tensile test in three directions corresponding to the material rolling direction. At first, a simple tensile test is modeled and estimated the material properties for conducting the numerical simulations. Second, the real-time experiments of the SPIF process in terms of predefined forming conditions are performed, and then the surface roughness was measured to check the surface quality of the formed parts. Then, the formed parts are scanned using a 3D ATOS scanner and compared against the desired computer-aided design (CAD) model. Eventually, the numerical results are discussed in comparison with the experimental outcome and displayed a significant correlation toward the expected results. This results comparison communicates that the introduced finite element (FE) model can be adopted for investigating the appearance of thinning location, thinning reduction, distributions of stress and strain. The overall results show that satisfying material formability in better surface finish and geometric dimensional accuracy can be accomplished when the forming conditions are designed appropriately.

Abstract: The purpose of this work is to increase the productivity and accuracy of processing long-length parts of the "shaft" type on CNC machines. Based on the analysis of existing methods for improving the accuracy of processing long shafts on CNC machines, a new method for controlling the spatial error of processing long shafts by changing the processing modes was proposed. The proposed method allows, by changing the processing modes, namely feed, to reduce the radial component of the cutting force and reduce the amount of deflection when machining parts on CNC machines. A technical and economic analysis and justification of scientific research was carried out. The economic effect of the proposed method.