bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robustness of macro-structured deep drawing process
Authors: Wolf A , Tulke M , Brosius A 
Published: May 2024

Abstract
Reaching robustness of forming processes is one of the main challenges in manufacturing technologies. Volatile material properties [1] and fluctuations in process parameters often result in insufficient part quality and rising production costs, especially in production chains [2]. As a common solution for this problem, numerical simulations are used to consider scattering of material parameters and define a useable process window with a specified safety margin. A new approach is the use of macro-structured tools. Result shown here indicate, in addition to the general enlargement of the useable process window [3], a high tolerance toward volatile material properties and variations of the blank. The produced parts show consistent quality with a reduction in residual stresses [4]. To examine the robustness in particular, virtual studies for steel alloy DX54 with varying alignment of the blank were performed. The resulting properties, such as the blank draw-in, thinning and springback, were examined in predefined positions on the blank to compare the experiments. The enlarged process window will be analysed and a strategy for a deeper understanding of the forming process will be generated, which will sustain the design of robust tools and processes.
Study on electric pulse-assisted plastic deformation behavior of 5182-O aluminum alloy
Authors: Shang Hongchun , Wang Songchen , Lou Yanshan 
Published: May 2024

Abstract
Plastic model-based neural networks are emerging phenomenological models with excellent calibration accuracy and interpretability of parameters, and they do not significantly increase the finite element calculation time of neural network models with a simple structure optimized by the algorithm. Because aluminum and magnesium have low ductility at room temperature, complex components made from these alloys need to be forged at high temperatures. In comparison with traditional thermoforming, advanced current-assisted processing provides energy savings, efficiency and green production. Experimental and constitutive modeling are carried out in this study to investigate the coupling effects of electrical pulse, temperature, strain rate, and strain on flow behavior and ductile fracture. It has been shown that electric pulses induce Joule heating effects and electroplastic effects, which reduce deformation resistance and improve formability. Electrical pulses suppress negative strain rate effects caused by dynamic strain aging, which is the main reason for the non-monotonic relationship between temperature and strain rate. The behavior of plasticity and fracture initiation can be described by simulations based on a neural network-based evolving plasticity model that incorporates stress states, current density, temperature, and strain rates.
Forming of large scale bipolar plates for high power fuel cell stacks
Authors: Ma Xiaolong , Zhang Xianglu , Guo Nan , Qin Li , Xiao Yao , Yang Daijun , Min Junying , Ming Pingwen , Zhang Cunman 
Published: May 2024

Abstract
Developing high-power (e.g. megawatt-scale) single fuel cell stacks is of significance to extending the application of hydrogen fuel cells in high-energy-consumption fields such as aerospace, maritime, and rail transportation. Bipolar plate is one of the core components of hydrogen fuel cell stacks. Currently, the mainstream hydrogen fuel cell stacks achieve a maximum power of about 200 kW with a bipolar plate area of approximately 600 cm2. While the megawatt-scale hydrogen fuel cell stacks requires large scale bipolar plates with an area of e.g. >2000 cm2 and higher geometric complexity of flow channel. However, the structural design and manufacturing process for such large scale bipolar plates remain unexplored. Based on the concept of “partitioned modular manufacturing”, the large scale bipolar plate is divided into multiple smaller scale bipolar plate modules in this work, and then integrated into a single component, which is then formed by applying multi-step stamping process to each module. Therefore, a so-called “partitioned multi-step stamping process” is proposed to form large scale bipolar plates with fine flow channels. Experimental validation was conducted using 0.1 mm thick titanium sheets and austenitic stainless steel sheets, demonstrating a prospective solution to manufacture large scale bipolar plates for high power hydrogen fuel cell stacks.
Inline Monitoring of the Geometry of Free-form Bent Components
Authors: Scandola Lorenzo , Maier Daniel , Meier Johannes , Volk Wolfram 
Published: May 2024

Abstract
The free-form bending process shows a high potential for the manufacturing of bent structural components. Especially in the automotive sector, the process can be employed for the production of arbitrary geometries evolving in the 3D-space, reducing tooling costs and production times. In addition, it is characterised by an outstanding flexibility, and allows the manufacturing of variants of a single component just with the adaption of the tool kinematics. Nevertheless, the reproducibility of the process is a challenging task, and a process monitoring approach is required. In this contribution, an inline-measurement strategy for evaluating the resulting geometry of free-form bent parts is developed. First, a review of the actual measurement system is given. Successively, the inline measurement of the bending radius using a laser displacement sensor, as well as of the bending angle by means of an IR-camera are presented. The obtained inline signals are then processed to retrieve the geometry of the obtained part, and the strategy is validated by comparison with the offline measurement results. The developed inline-system represents the first step towards the development and the monitoring of the free-form bending process.
Methodic Approach for the Simulation-Based, Elastic Die Surface Compensation by Creating a FE-model of the Car Body Press Predicated on Spotting Images via Neural Networks
Authors: Göltl F , Birkert A , Harst F , Stache N C 
Published: May 2024

Abstract
In recent years, the push for streamlined vehicle development and the adoption of higher-strength materials to reduce the car body weight has been prominent. However, this shift results in greater elastic deformations in press and tool components due to the elevated yield stress of these materials. The die active face is subject to the compliance of the body press and die, which influences the manufacturability and dimensional accuracy of the sheet metal part. In practice, manual die spotting is required, relying on empirical data and subjective criteria for acceptance. This paper presents a new methodological approach for the development of the car body press’s FE model in structural and forming coupled simulations. To achieve this, a series of measurements quantifies the pressure between tool and sheet metal. This information is fed into a neural network along with the die spotting images as training data. The network evaluates subsequent spotting images, assigning pressure values to distinct tool sections. Based on the die pressure distribution in the process, a virtual press model is created with the help of a newly developed objective function in topology optimization. This model aims to significantly enhance simulation-based die surface compensation, effectively reducing the die spotting process.
Experimental Measurement of the Stress Gradient in a Bent Sheet
Authors: Corral Audrie , Colllie Eric , Lu Zhaojun , Womble Grayson , Van Tyne Chester J. 
Published: May 2024

Abstract
Stress gradients were experimentally measured in a 316 stainless steel sheet after bending with a press brake. Two different tool radii and three different bend angles were used to produce plastically bent sheets. Microhardness tests were performed across the thickness of the bent sheet, and a correlation between microhardness and strength was experimentally determined and was used to obtain the stress gradient. The position of the experimentally determined neutral plane correlated well with theory. Theoretical calculations of the stress gradient were made using a power law constitutive equation along with a simple mechanics analysis of plastic bending. Four of the six bending experimental conditions had reasonable correlation with the theoretical calculations. Ideas for improving this experimental method are discussed.
New test rig for biaxial and plane strain states on uniaxial testing machines
Authors: Marker Edgar , Maier Lorenz , Gruber Maximilian , Volk Wolfram , Hartmann Christoph 
Published: May 2024

Abstract
The increasing interest in hydrogen technology and storage systems has also significant influence on material characterization. Storage solutions such as cryo-compressed hydrogen (CcH2) or compressed gaseous hydrogen (CGH2) use high pressure to improve the energy density. The pressurized hydrogen is stored in a pressure vessel. This leads to various strain states in the vessel, which are difficult to reproduce with standard testing equipment, such as a uniaxial testing machine. This contribution presents a new test rig for uniaxial testing machines that is able to generate a biaxial load on a cruciform specimen. A hinged structure converts the uniaxial load into a biaxial load. Different attachments allow both equi-biaxial and plane strain states. In addition, the test rig provides access to both sides of the specimen, extending the possibilities for testing under load, such as optical measurement, specimen cooling or permeability measurement. Finally, experiments show the functionality of the test rig and the desired strain states in the specimen.
Validation of pneumatic crack detection in hole expansion test
Authors: Leonhardt A , Haas T , Kunke A 
Published: May 2024

Abstract
According to the standard ISO 16630, the hole expansion test (HET) has to be stopped at the instant when the first through-thickness crack appears at the edge of the hole. The detection of the crack is challenging, since the maximum opening width should not exceed 0.1 mm at the inner diameter according to the newest version of the standard from 2017. A pneumatic crack detection has been introduced in which a pressure drop is used to identify the through-thickness crack. In the present paper, this method for stopping the hole expansion test is validated. It was tested for steels with different edge crack sensitivities and compared to stopping with force drop method. Therefore, the curves of pressure and force have been analysed. The influence of hole insertion method (shear cutting or abrasive water jet cutting) as well as specific hole expansion parameters (punch speed, air pressure) have been investigated. Besides the expanded diameters to evaluate the edge crack sensitivity, the opening width of the edge cracks were analysed to determine the suitability of the crack detection methods for different hole expansion ratios (HER).
The effect of elastic and plastic stresses on the electrical resistivity of conductive materials
Authors: Steinlehner F. , Ott M. , Stiegeler B. , Maier L. , Nguyen Q. , Volk W. 
Published: May 2024

Abstract
The mobility sector has been responsible for large emissions of harmful greenhouse gases worldwide for years. E-mobility can contribute to a reduction of these emissions. For a faster spread and acceptance of electric vehicles, the achievable range and thus the efficiency of the individual components in the drive and charging train is essential. In addition to the battery and the electric machine, losses in the cables and bus bars are playing an increasingly important role. The cross-sectional shape, material and manufacturing technology of these conductive materials depends on the voltage and power to be transmitted and may still change in the future, especially in the field of fast charging and increased voltage.
The aim of this work is to investigate the influence of the mechanical stress condition of copper, brass and aluminium materials on their electrical conductivity. The conductivity is measured by means of 4-wire measurements under defined tensile and compressive loads. The effects of elastic and plastic strains are taken into account. The findings can be used for an optimized manufacturing strategy for conductive components for future applications.
Reinforcement of thin hot-stamped components by fiber reinforced plastic structures with optimized fatigue strength properties
Authors: Behrens B-A , Hübner S. , Müller P. , Fünfkirchler T. , Wehmeyer J. , Dilger K. , Hartwig S. , Gundlach C. 
Published: May 2024

Abstract
Multi-material structures in the automotive industry hold great potential for lightweight design, body construction, and functionalization due to their favorable mechanical properties and reduced structural weight. The combination of metal and plastic, in particular, is commonly used to enhance the overall properties of the end product when compared to single-material structures.
This paper describes a process development with a hot-stamping and an extrusion tool. By means of this tool, a thermally assisted extrusion process can be used to join GMT (Glass Mat reinforced Thermoplastics) and 22MnB5 steel in a single process step. Through adhesion, the GMT adheres to the rough surface of the AlSi(aluminum-silicon)-coated 22MnB5. Test components were manufactured and through static tests the influence of process parameters was evaluated. Assuming that the parameters determined for the reference component are already sufficient for a design in the vehicle, the reduction of the steel thickness of the structure from 1.5 mm to 1.2 mm can be recommended on the basis of the results obtained. This is accompanied by a reduction in the mass of the test structure used while maintaining or improving its dynamic and static properties. Further weight savings appear possible through further component and process optimization.
Investigation on effect of high-efficiency solid solution and hot stamping process on microstructure evolution and mechanical properties of high-strength aluminum alloy
Authors: Wang Y.L. , Geng H.C. , Zhu B. , Zhang Y.S. , Ren X.Q. , Ren X.P. 
Published: May 2024

Abstract
Aluminum alloy has become an important lightweight material in the automotive industry due to its excellent performance. The development of hot stamping technology has effectively promoted the application of high-strength aluminum alloys in auto parts. However, aluminum alloy hot stamping requires a long time for solid solution and aging heat treatment, which hinders its mass production application in the existing mature hot stamping production line. Therefore, this paper studies the effect of a high-efficiency solid solution and hot stamping process on the microstructure and mechanical property strengthening mechanism of high-strength aluminum alloy. The contact heating and hot stamping experiment device was designed. It was found that the temperature rise rate of the sheet during the contact heating process could reach 44.51 °C/s. The experiment results show that contact heating treatment with a solution temperature of 480 °C and a solution time of 20s can achieve the high-efficient solution treatment of the sheet metal. The high-temperature deformation behavior of 7075-T6 at different temperatures (300-450 °C) and different strain rates (0.01∼1/s) under the condition of high-efficiency solid solution rapid heating was studied.
Study on preparation and properties of supported compound desulfurizer for Bayer dissolution
Authors: Huang Li , Quan Bianli , Sheng Wang , Qitao Lan , Shanlin PU 
Published: May 2024

Abstract
In view of the serious harm caused by sulfur ion to alumina production and the high cost of desulfurization in Bayer dissolution process of high sulfur bauxite leaching at high temperature and high pressure, the supported compound desulfurizer was prepared by melt infiltration method to realize simultaneous desulfurization in Bayer dissolution process. In this paper, Zn(NO3)2·6H2O and Cu(NO3)2·3H2O as the main components, kaolin, sepiolite, activated alumina as the active carrier, the supported compound desulfurizer was prepared. The active carrier was optimized and the optimum preparation parameters were determined by means of DSC, IR, TG, SEM and XRD. The results show that kaolin is more suitable as the active carrier of compound desulfurizer. The best melting temperature of the precursor is 100 °C, the best calcination temperature is 400 °C, and the best calcination time is 2 h. The supported compound desulfurizer mainly consists of ZnO, CuO, AlOOH, SiO2 and Mullite. The results provide a basis for the active preparation of the supported compound desulfurizer.
Study on the mechanism of melting oxidation of Zn-9Al-2.5Mg-Be alloy
Authors: Liu GuanChen , Shen ChengJin , Feng RuoYing 
Published: May 2024

Abstract
The oxidation resistance of Zn-9Al-2.5Mg-xBe (x = 0,0.005,0.01,0.05,0.1) alloys was investigated in this study through isothermal oxidation experiments. The alloy microstructure, morphology, and composition of the oxide film were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and x-ray diffraction (XRD). The oxidation kinetics and thermodynamics of Zn-9Al-2.5Mg were calculated, and the oxidation mechanism was discussed. The results show that the Zn-9Al-2.5Mg-0.05Be alloy exhibits a fine dendritic microstructure, with a large quantity of Zn-MgZn2 binary eutectic and Zn-Al-MgZn2/Mg2Zn11 ternary eutectic phases uniformly distributed. The Zn-9Al-2.5Mg-0.05Be alloy has the lowest oxidation rate among the tested alloys, with an oxide weight gain of 12 mg m−2, which is only 0.67 times that of the Zn-9Al-2.5Mg alloy. The oxide film on the surface of the alloy is relatively dense and maintains the appearance of the metal. The main constituents of the oxide film are Zn, Al, Mg17Al12, Mg2Zn11, and BeO, with no formation of Al2O3 or MgO. The oxidation mechanism of the Zn-9Al-2.5Mg-0.05Be alloy is attributed to the reaction of Be with oxygen, forming BeO, or the displacement reaction of Be with Al2O3 and MgO to form BeO, which inhibits the formation of Al2O3 and MgO.
Photothermally responsive graphene hybrid dry powders for diabetic wound healing
Authors: Chen Mei , Wang Fengyuan , Yan Qiao , Da Meihong , Wang Fei 
Published: May 2024

Abstract
The treatment of diabetic wounds remains a significant challenge in the medical field. In this study, we present a novel approach using photothermally responsive graphene hybrid dry powders for the treatment of diabetic wounds. These powders, derived from polyacrylic acid (PAA) and polyethyleneimine (PEI), exhibit rapid water absorption at the interface, leading to the in situ formation of physically crosslinked hydrogels due to interactions between polymers. Furthermore, by incorporating graphene into the PAA/PEI powder mixture, we establish a multifunctional platform with capabilities such as photothermal antibacterial effects and drug release. Given the outstanding performance of this hybrid material, we demonstrate its potential in wound healing by incorporating the tumor necrosis factor-alpha (TNF-α) inhibitor Etanercept into the PAA/PEI powder. This intervention resulted in a significant improvement in the wound healing process in diabetic rats, as evidenced by the downregulation of inflammatory factors, promotion of collagen deposition, and enhanced vascularization. These remarkable attributes underscore the enormous potential value of the presented hydrogel patches in the field of biomedicine.
Spin resonance spectroscopy with an electron microscope
Authors: Haslinger Philipp , Nimmrichter Stefan , Rätzel Dennis 
Published: May 2024

Abstract
Coherent spin resonance methods, such as nuclear magnetic resonance and electron spin resonance spectroscopy, have led to spectrally highly sensitive, non-invasive quantum imaging techniques. Here, we propose a pump-probe spin resonance spectroscopy approach, designed for electron microscopy, based on microwave pump fields and electron probes. We investigate how quantum spin systems couple to electron matter waves through their magnetic moments and how the resulting phase shifts can be utilized to gain information about the states and dynamics of these systems. Notably, state-of-the-art transmission electron microscopy provides the means to detect phase shifts almost as small as that due to a single electron spin. This could enable state-selective observation of spin dynamics on the nanoscale and indirect measurement of the environment of the examined spin systems, providing information, for example, on the atomic structure, local chemical composition and neighboring spins.
Design of herringbone grooved thrust bearing for locomotive turbocharger rotor
Authors: Mishra Hara Prakash , Behera Suraj Kumar 
Published: May 2024

Abstract
The herringbone texture exhibited excellent tribological performance to minimize friction and wear. However, the application of this texture in the development of grooved thrust bearings is limited. Therefore, in this study, an attempt was made to design an oil-lubricated herringbone grooved thrust bearing for high-speed locomotive turbochargers. The designed bearing accommodates the axial load generated due to the pressure difference between the turbine and compressor wheel. The bearing design starts with applying Newton’s second law to predict the thrust load acting on the locomotive turbocharger rotor. The thrust load is calculated analytically and is found to be 4.54 kN for a design rotor speed of 1,00,000 rpm. Further, the herringbone grooved thrust bearing has been modeled numerically using non-linear Reynolds equation. The modified Reynolds equation is discretized using the finite volume method (FVM) and solved by successive over-relaxation (SOR) methodology to determine the static characteristics over the bearing surface. The developed HGTB is found to have a suitable load-carrying capacity of 4.6 kN, frictional torque of 0.25 N.m, and power loss of 2.98 kW. Further, a parametric analysis has been carried out to study the influence of design parameters such as the number of grooves, helix angle, angular groove width, groove depth, and speed on load-carrying capacity, frictional torque, and power loss.
Synergistic effect of niobium carbide and titanium nanoparticles on the mechanical and microstructural properties of Al-Zn-Mg-Cu alloy hybrid composites
Authors: Vijaya D Joslin , Robinson Smart D S , K Leo Dev Wins , Dhas D S Ebenezer Jacob 
Published: May 2024

Abstract
In this study, an Al-Zn-Mg-Cu alloy matrix serves as the matrix material, with Niobium Carbide (NbC) and Titanium (Ti) nanoparticles acting as reinforcements to enhance composite strength. Incorporating nano-structured reinforcements significantly enhance both strength and toughness, surpassing micro-sized counterparts. To prevent nanoparticle agglomeration during manufacturing, we employ vigorous stirring via the stir casting technique to ensure uniform dispersion within the composite matrix. SEM analysis confirms uniform dispersion of NbC and Ti nanoparticles within the matrix. Experimentally, the composite exhibits exceptional tensile strength, with sample B achieving the highest load of 5500 N, correlated with an optimal NbC percentage of 5 wt% and Ti percentage of 2 wt%. However, increasing NbC percentage from 5 wt% to 10 wt% results in decreased ductility and tensile strength for composite C. Similar trends are observed in bending strength, with composite B exhibiting the highest load at 9023.8 N, surpassing samples C and D. Microhardness results demonstrate an increase with NbC content, peaking at 230 HV, but declining to 185 HV with reduced NbC and Ti concentrations. Charpy impact tests reveal a consistent rise in impact energy from samples B to D, attributed to the escalating proportion of NbC relative to Ti. Overall, meticulous material selection and processing optimization are essential for developing high-performance metal matrix composites with enhanced mechanical properties.