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This study aims to accurately select a yield criterion by utilizing the identification coefficient method to describe anisotropic behavior using material parameters and finite element simulation. The influence of anisotropy is investigated and compared with experimental data. Three yield functions, namely von Mises, Hill'48R, and Hill'48S, are analyzed and their impact on numerical results is investigated using the Kim-Tuan stress–strain model for hardening law. The SPCC material (cold-rolled mild steel) is used for experimental validation. The main variables under study are the fracture height of cylinder cups and the evolution of simulated punch force. The deep drawing process of SPCC cylindrical cups is simulated using the finite element method (FEM) to evaluate the impact of the yield criterion on fracture height. The predicted punch force evolution remains consistent regardless of the yield criterion used, but the fracture height of cylinder cups is significantly influenced by the choice of yield criterion. The von Mises yield criterion leads to a significantly lower fracture height, while the Hill'48S yield criterion yields a fracture height that is too high. However, the results demonstrate that the Hill'48R yield criterion exhibits the most favorable agreement with experimental data for the fracture height of cylinder cups in deep drawing process. Additionally, the study investigates the influence of process parameters such as blanking holder force (FBH), nose radius of the punch (Rp), and limiting drawing ratio (Mt) on fracture height and addresses optimization problems. A highly accurate mathematical model is developed to predict fracture height based on FBH, Rp, and Mt, achieving a deviation of only 4.81% when compared to corresponding experimental values. These findings contribute significantly to the advancement of sheet metal forming technology in various industries, particularly in reducing defective product rates. [ABSTRACT FROM AUTHOR]

Determination of sheet metal formability, which is commonly evaluated through a forming limit curve (FLC), is an essential task for part designs in the automotive engineering community. This study provides a coherent comparison among four theoretical FLC criteria including Swift's instability, Hill's localized neck, Storen–Rice bifurcation analysis, and Hora's MMFC. Within these criteria, closed-form solutions for FLC are available for fast and expensiveness explicitly estimating the forming limit diagram (FLD) of sheet metals. According to their closed-form solutions, an empirical suggestion is proposed to improve the accuracy of the theoretical FLC. Quantitative comparisons are then made to evaluate the performance of these criteria for numerous aluminum alloys and steel sheets which are frequently used in automotive industries. Based on the comparisons, the advantages and limitations of each model are discussed from a physical point of view, which appears to be a useful suggestion for selecting a proper theoretical model to evaluate the FLD of sheet metals without conducting experimental tests. [ABSTRACT FROM AUTHOR]

In this study, the modified maximum force criterion was used to ensure an accurate determination of the forming limit curve (FLC) for the SUS304 sheet metal. At first, the stress–strain curves according to Voce and Swift hardening models were verified using the experimental data and the stress function deduced by Hill in 1984 to predict FLCs. The accuracy of the FLCs was evaluated by analyzing the equivalent fracture strain data at three distinct locations: Biaxial tensile strain (BT, β = 1), uniaxial tensile strain (UT, β = − 1 / 2), and plane strain (PS, β = 0), and then comparing them with the corresponding linear FLC experimental data. The accuracy of the predicted FLCs was further tested by comparing the fracture height of the samples according to the Nakazima model in the FEM simulation and the corresponding experiments. [ABSTRACT FROM AUTHOR]

This research investigates the impact of high-speed and thermal-assisted machining (HS-TAM) on tool wear and surface roughness during the milling of SKD11 steel. The goal is to identify high-speed and elevated temperature zones that can improve machining efficiency, enhance surface quality, minimize costs, and extend tool life. The study involves the high-speed milling of SKD11 steel at various temperature conditions to evaluate the effect of temperature on tool wear and surface roughness. Additionally, experiments are conducted at the highest allowable support temperature with increased high-speed cutting to examine the effect of high speed on tool wear and surface roughness. The study demonstrates the correlation between cutting-tool wear and surface roughness at various high-speed cutting conditions and TAM environments and provides recommendations for cutting speeds and heating temperatures for different quality and productivity objectives. The findings indicate that high-speed milling of SKD11 at 600 m/min and 500 °C can decrease cutting tool-wear height (wear volume) and surface roughness by 82.47% (95.74%) and 91.08%, respectively, compared to machining at room temperature. Furthermore, the higher-speed modes at 500 °C result in a slight increase in wear height and surface roughness for high-speed cutting below 800 m/min, but reduces surface roughness for high-speed cutting beyond 800 m/min, reaching a value of 0.158 µm at the high-speed cutting limit of 1000 m/min. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of Thermal-Assisted Machining (TAM) on SKD11 alloy steel using titanium-coated hard-alloy insert cutting tools. The microstructure, material hardness, chip color, cutting force, chip shrinkage coefficient, roughness, and vibration during TAM were evaluated under uniform cutting conditions. The machining process was monitored using advanced equipment. The results indicated that thermal-assisted processing up to 400 °C did not alter the microstructure and hardness of the SKD11 alloy steel. However, a significant variation in chip color was observed, indicating improved heat transfer through TAM. The cutting force, vibration amplitude of the workpiece, and surface roughness all decreased with increasing TAM. Conversely, the chip shrinkage coefficient of the machined chips tended to increase due to the high temperatures. [ABSTRACT FROM AUTHOR]

This study proposed an innovative method for improving the prediction of the cutting force (F) and chip shrinkage coefficient (K) for milling of SKD11 alloy steels using simulations and experimental results. Preliminary experimental measurements of the F and K were made for variable cutting speeds and depths, and simulations were then conducted using the Johnson–Cook model. However, significant discrepancies between the experiments and simulations were observed for the F and K. Therefore, an improved method was proposed, utilizing the relationship between simulation/experimental cutting forces and the equivalent fracture strain of simulation elements in the shear zone in the space of the stress triaxiality and equivalent strain. The progression of fracture strain paths according to the stress triaxiality until the desired cutting forces were achieved was utilized for adding new data to the fracture strain locus in the space of the stress triaxiality and equivalent strain. The new fracture strain locus was adopted again, to simulate and predict the F and K at full 2 × 3 levels of cutting speeds and cutting depths, and the results were compared with those of the corresponding experiments. Based on the highest deviations between the simulation and experimental data for the cutting force (5.29%) and chip shrinkage coefficient (5.08%), this study confirmed that the proposed method for determining the new fracture strain locus can improve the prediction of the F and K for milling of SKD11 alloy steels. [ABSTRACT FROM AUTHOR]

Thermal-assisted machining (TAM) is an effective processing solution to improve productivity and product quality made from materials with high strength and hardness. This method is widely used in nonchip machining such as forging, stamping, deep drawing, etc. For the method of heating on the molds, it is possible to control local heat or uniform heat on the workpiece. However, the calculation of heat capacity, heat transfer as well as the heating time to achieve the temperature on the workpiece is necessary to design suitable molds and heating system. This study focuses on a heating system that uses single-sided thermostatic heating rods to heat the molds, verify the effect of the heating time on the temperature of the workpieces and then control the temperature on the workpieces at various heat levels through a heating control system. Thereby, this study proposes to build a mathematical model between temperature and heating time on the workpiece. [ABSTRACT FROM AUTHOR]

We consider an Individual-Based Model for self-rotating particles interacting through local alignment and investigate its macroscopic limit. This model describes self-propelled particles moving in the plane and trying to synchronize their rotation motion with their neighbors. It combines the Kuramoto model of synchronization and the Vicsek model of swarm formation. We study the mean-field kinetic and hydrodynamic limits of this system within two different scalings. In the small angular velocity regime, the resulting model is a slight modification of the "Self-Organized Hydrodynamic" model which has been previously introduced by the first author. In the large angular velocity case, a new type of hydrodynamic model is obtained. A preliminary study of the linearized stability is proposed. [ABSTRACT FROM AUTHOR]

This paper investigates cutting force in thermal-assisted machining (TAM) by induction heating for SKD11 tool steel which is widely used in the mold industry. Experimental studies were first conducted at room and elevated temperatures to evaluate the effectiveness of the heating process on chip morphology and the cutting forces during the thermal-assisted machining and comparing with conventional machining method. The Taguchi method based on orthogonal array and analysis of variance ANOVA method was then used to design the number of experiments and evaluate the influence of cutting speed, feed rate, cutting depth, and elevated temperature on the cutting force. Study results showed a decrease in the cutting force in the TAM process. The optimal condition of parameters obtained for thermal-assisted machining were cutting speed 280 m/min, feed rate 230 mm/min, cutting depth 0.5 mm and temperature 400 °C. Finally, a proposed equation was established to determine the cutting force that was presented as a function of elevated temperatures when milling SKD11 material. A proposed cutting force model was compared, evaluated and confirmed to be in good agreement with experimental results. [ABSTRACT FROM AUTHOR]