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Comparison of Autoform’s FLD and Pam-Stamp’s FLD with the respective state of the material points in the part, at the end of the drawing operation, to the load case AC170 LC3
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There are currently several commercial Finite Element Analysis (FEA) softwares available, and it is not clear for a company the differences between them, mostly in terms of results accuracy, reliability and usability. International conferences were created to promote a world-class forum in which, simulation engineers and automakers, can exchange th...
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Advanced high strength galvanized steel sheet has been one of the dominant materials of modern automotive panels because of its outstanding mechanical properties and corrosion resistance. The zinc coating thickness of hot dip galvanized steel sheet is only about 10–20μm, which is a discarded object on the macro level. However, it is obvious to dama...
Flow stress curves of USIBOR1500 high-strength steel at high temperatures were obtained by tensile test. A constitutive model of high-temperature deformation of the material was established at 300–600 °C and 500–800 °C for one- and two-stage hot-forming processes, respectively. On the basis of the established constitutive equation, the one- and two...
Citations
... Gerlach [32,33] provided equations to calculate the three characteristic points of the FLC based on three parameters, including ultimate tensile strength, total elongation and sheet thickness. Among these empirical methods, the Keeler model, Arcelor model and Tata Steel model have been integrated into commercial finite element simulation software AutoForm R5.2 [34]. However, since these predictive models are mainly developed from cold-rolling steel sheets or aluminum alloy sheets, the FLC prediction results for hot-rolled steel sheets have a large deviation from the experimental results. ...
A phenomenological model for the prediction of the forming limit curve (FLC) based on basic mechanical properties through a uniaxial tensile test can tremendously shorten the design time of the forming process and reduce the measuring costs. In this paper, a novel phenomenological model named the IMR-Baosteel model (abbreviated as the IB model) is proposed for efficient and accurate FLC prediction of hot-rolled steel sheets featuring distinct variations in thickness and mechanical properties. With a systematic test of the plane strain forming limit (FLC0), it was found that a higher regression correlation exists between the FLC0 and the total elongation under different sheet thicknesses. For accurate assessment of the FLC0 from tensile properties, compared using experiments, the error of FLC0 calculated with the proposed model is within 10%. In the IB model, the left side of FLC can be calculated using a line with a slope of −1 while the right side of the FLC is obtained via a modified Keeler model with the exponent (p) determined as 0.45 for hot-rolled steels. Complete experimental FLCs of hot-rolled steels from measurements and the literature were used to validate the reliability of the proposed model. Resultantly, the prediction of FLCs with the proposed IB model is greatly improved, and agrees much better with the experimental FLCs than the predictions of the well-known Keeler model, Arcelor model and Tata Steel model.
... Recently, Pimentel et al. [9] proposed a comprehensive study based on the Numisheet 2008 Benchmark #2, to compare three commercial packages. The authors conclude that the accuracy of the FEA tools is roughly the same. ...
Computer simulation plays a crucial role in the designing of sheet metal stamping processes for the prediction of process output, before try-out die sets are manufactured. Different commercial software packages are available on the market for sheet forming simulation, but their accuracy can vary, depending on the selection of the pre-processing parameters and on their formulation. Software benchmarking can be used to select the most appropriate package for a given application. Calibration, i.e. the inverse determination of the correct set of pre-processing parameters, can be used for improving the prediction accuracy. The scientific literature on numerical simulations of sheet metal forming processes presents some examples of software calibration and very few examples of benchmarking. The literature generally neglects a critical and important issue: the inherent variability of real forming processes. In this work, the experimental results of two similar multi-stage deep drawing processes are presented and compared to the simulation output of two popular software packages used in the industry. Statistical methods for benchmarking and calibration are proposed. The paper demonstrates how benchmarking can be misleading if process variability is not considered.
... In addition, the material behavior during hot forming is also quite complex since the lightweight aluminum alloys exhibit strain softening and strain-rate hardening at elevated temperature as shown in [6]. Due to these process complexities, selection of accurate, reliable, and robust FE modelling and simulation methods is a cumbersome process considering that the modern FE software packages offer numerous options for modelling each and every process aspect [7]. With help of a suitable benchmark test that generally represents the important process aspects, modelling, and simulation methods can be systematically developed and experimentally validated at laboratory scale before proceeding with the simulation of a complex industrial process [8]. ...
New rapid gas-based hot sheet metal forming processes are being invented to manufacture geometrically complex automotive components from lightweight high-strength aluminum alloys. The complexity of the forming processes necessitates a computationally economic yet sufficiently accurate modelling and simulationSimulation methodology to ensure a successful simulation-aided process planning for manufacturing complex components. This includes accurate modelling of process characteristics such as large deformations, complex geometrical features, thermo-mechanical and tribological interactions. The current work aims to establish a finite element method (FEM)Finite element methodbased simulationSimulation methodology for modern gas-based hot sheet metal forming processes. For this purpose, the conventional cross-die geometry is modified with features of some typical automotive components to establish a complex benchmark geometry that covers a broader spectrum of strain states and strain paths. Moreover, a laboratory-scale hot forming test setup for forming the complex benchmark specimen is realized and the preliminary experiments are conducted. The corresponding FE simulationSimulation models are developed and experimentally validated. The applicability of the developed benchmark for establishing and validating the models for complex gas-based hot forming processes is demonstrated.
... In order to mitigate the effects of uncertainty in stamping processes, since the early 1990s, there has been a significant increase in the use of simulations by Finite Elements (FE) Methods to sheet conformation in industry (Bargmann et al., 2018;González et al., 2017;Pimental et al., 2018). For example, FE simulations are useful for reducing lead time in the design and tool development stage, as pointed out by Jadhav et al. (2018). ...
... For example, FE simulations are useful for reducing lead time in the design and tool development stage, as pointed out by Jadhav et al. (2018). Pimental et al. (2018) stated that problems involving new materials and new technologies constantly require the need to develop more robust, efficient, reliable and accurate FE analysis and simulation tools. These authors analyzed three FE software, AUTOFORM TM , PAM-STAMP TM and DD3IMP TM , and found that their accuracy were roughly the same. ...
The Response Surface Methodology (RSM), which uses a quadratic empirical function as an approximation to the original function and allows the identification of relationships between independent variables xi and dependent variables ys associated with multiple responses, stands out. The main contribution of the present study is to propose an innovative procedure for the optimization of experimental problems with multiple responses, which considers the insertion of uncertainties in the coefficients of the obtained empirical functions in order to adequately represent real situations. This new procedure, which combines RSM with the Finite Elements (FE) method and the Monte Carlo Simulation Optimization (OvMCS), was applied to a real stamping process of a Brazilian multinational automotive company. For RSM with multiple responses, were compared the results obtained using the agglutination methods: Compromise Programming, Desirability Function (DF), and the Modified Desirability Function (MDF). The functions were optimized by applying the Generalized Reduced Gradient (GRG) algorithm, which is a classic procedure widely adopted in this type of experimental problem, without the uncertainty in the coefficients of independent factors. The advantages offered by this innovative procedure are presented and discussed, as well as the statistical validation of its results. It can be highlighted, for example, that the proposed procedure reduces, and sometimes eliminates, the need for additional confirmation experiments, as well as a better adjustment of factor values and response variable values when comparing to the results of RSM with classic multiple responses. The new proposed procedure added relevant and useful information to the managers responsible for the studied stamping process. Moreover, the proposed procedure facilitates the improvement of the process, with lower associated costs.
Established formingForming processes in the automotive industry are used for series with annual production runs of more than 100,000 units. Until now, there has been a lack of formingForming technologies for the economical production of batch sizes below 100,000 units. This trend is also changing production. Swivel-bending is suitable as a flexible and low-tool process to produce variable cross-section geometries. The manufacturing technology developed for 3D-swivel-bending3D-swivel-bending significantly expands the application possibilities of the basic process by enabling the production of non-linear, three-dimensional bending edges, to manufacture cross-section variable and load-adaptedLoad adapted components. The process is designed to be scalable and thus adjustable for processing variable workpiece thicknesses, materials, and springback behavior. With additively manufactured joint structures, the effective surfaces of the tools can be adapted to individual requirements. The joint structures can also be manufactured as a print-in-place solution within a significantly shorter product development process.
Metal/polymer/metal (MPM) sandwiched composites are in the class of capable engineering materials which give outstanding strength-to-weight ratios because of their comparatively low density. These materials are vital constituents within the automobile, aerospace, marine, and civil construction industries as substitutes for sheet metals that considerably reduce weight while not compromising practicality such as load bearing capacity stiffness and flexibility. For these materials to be utilised within the aforesaid industries, they need to bear numerous forming processes. This paper investigates the formabilityFormability of metal-polymer sandwich composites made of AA-PE-AA (APA) and Galvanised Steel-PE-Galvanised Steel (GPG) considering the adhesionAdhesion strength via numerical simulation. For evaluating the formabilityFormability, the actual limit dome height (LDH)Limit dome height—bi-axial strain path—test setup is simulated using FEM. The results analysed are forming limit diagram (FLD), punch force distribution, and dome heightDome height at diverse conditions of punch velocity and friction. All the numerical simulations were performed using Altair Hyperworks with various blank sizes. The results are noted as FLD and dome heightDome height at varied conditions. A comparison is made to represent the best combinations for formabilityFormability of the sandwich composites. Maximum formabilityFormabilityand dome heightDome height are attained at low friction conditions and forming speed.
Electrically-assisted forming is a promising technology to realize the precise forming of materials with poor formability. For stamping process, the typical deformation process of sheet metal is that the sheet metal experiences bending and reverse bending when it passes through the corner of die, and the draw-bending test can well characterize this typical deformation process. Therefore, this paper studies the influence of normalized back force (0.1, 0.25), temperature (25 ℃, 65 ℃, and 150 ℃), current (0A, 830A, 1300A, and 1700A) on the springback of AA7075-T6. The results show that the springbackSpringback can be reduced by loading current during draw-bending test. Moreover, the larger the normalized back force is, the larger the reduction of springback angle is, which shows that the electroplasticityElectroplasticity becomes more obvious with the increase of normalized back force. At the same temperature, with the increase of current, the springback angle decreases. Moreover, the higher the temperature is, the larger the reduction of springback angle is, which shows that pure electroplasticityPure electroplasticity becomes more obvious with the increase of temperature.
The response surface methodology (RSM), which uses a quadratic empirical function as an approximation to the original function and allows the identification of relationships between independent variables xi and dependent variables ys associated with multiple responses, stands out. The main contribution of the present study is to propose an innovative procedure for the optimization of experimental problems with multiple responses, which considers the insertion of uncertainties in the coefficients of the obtained empirical functions in order to adequately represent real situations. This new procedure, which combines RSM with the finite element (FE) method and the Monte Carlo simulation optimization (OvMCS), was applied to a real stamping process of a Brazilian multinational automotive company. For RSM with multiple responses, were compared the results obtained using the agglutination methods: compromise programming, desirability function (DF), and the modified desirability function (MDF). The functions were optimized by applying the generalized reduced gradient (GRG) algorithm, which is a classic procedure widely adopted in this type of experimental problem, without the uncertainty in the coefficients of independent factors. The advantages offered by this innovative procedure are presented and discussed, as well as the statistical validation of its results. It can be highlighted, for example, that the proposed procedure reduces, and sometimes eliminates, the need for additional confirmation experiments, as well as a better adjustment of factor values and response variable values when comparing to the results of RSM with classic multiple responses. The new proposed procedure added relevant and useful information to the managers responsible for the studied stamping process. Moreover, the proposed procedure facilitates the improvement of the process, with lower associated costs.
In order to assure good resistance performances, automobile manufacturers are looking for high strength steel, especially for structural parts of body in white, which are formed by hot stamping process. With the aim of guaranteeing specific crash behavior, various technologies have been developed to provide tailored properties.
Typical tailored component is the B-pillar, which is studied in this work. In general, the pillar must be with greater resistance in some areas, while in others it must have greater toughness to absorb the energy of a possible impact. The tailored technology investigated in this work is the tailored tempering, in which different areas of the component experience different cooling histories leading to requested final mechanical properties.
The methodology used to investigate custom properties involves a first designing phase implemented with Finite Element (FE) commercial programs; FE simulations were performed to investigate the Press Hardening process of a 22MnB5 boron steel blank and in particular the thermo-mechanical cycles related with both the high-resistance and high-toughness regions of the pillar.
In the second phase of the proposed approach, the obtained thermo-mechanical cycles have been physically simulated, by using Gleeble 3185 system. The following consecutive steps was reproduced on home-designed specimens: (i) Blank heating for the complete austenitization (at a temperature of 930° C for 4 min). (ii) The heat loss due to the transport phase of the blank from the oven to the press. iii) The mechanical deformation of the blank due to the stamping phase. iv) The quenching phase of the part. (v) The cooling on air of the B-Pillar.
Finally, micro-hardness tests have been performed on the specimens subjected to physical simulation. FE model predictions and micro-hardness tests are in good agreement, showing that tailored tempering effectively leads to differentiation of the mechanical properties.
