Accurate calculation of electromagnetic parameters in electromagnetic forming (EMF) process is crucial for predicting the deformation behavior of metallic workpieces. Previous theoretical and ...numerical studies for EMF process with a die have assumed that the die near the workpiece is non-conductive. However, the simplified treatment could be invalid for the cases with a conductive die since an eddy current would also be induced in the die under transient magnetic fields, thus resulting in the change of electromagnetic force acting on the workpiece. In this work, a coupled finite element method and circuit simulation approach with an improved circuit model for analyzing the workpiece deformation is presented, in which the mechanical analysis of the workpiece is done using ANSYS, while the circuit analysis is performed using an improved current filament model. Numerical simulations have been carried out for two types of EMF process, revealing the potential effects of an electrically conductive die on the electromagnetic force distribution and workpeice deformation. The coupled modeling method and simulation results could be useful for better understanding EMF process and designing EMF systems.
Electromagnetic forming using a uniform pressure actuator (UPA) has advantages for forming many components, such as car door pockets, cell phone cases, and fuel cell panels. However, how to generate ...magnetic pressures on sheet metal with enough high uniformity and high strength is a challenging issue. To improve the strength of the coil, current UPAs were machined out of a solid block of high-strength copper alloy, but its strength was still limited. In this paper, the design idea of pulsed high-field magnets has been applied to improve the coil's strength in a better way. A UPA with high strength has been designed, fabricated, and tested. A series of simulation analysis and experiments have been done; it has been found that the uniformity of the magnetic force on sheet would be increased with the decrease of the wire spacing and the wire width. In addition, the experiment results show that sheets with a thickness of 1 mm can be effectively deformed with a maximum of 14.6 mm under 2.88-kJ energy and the deformation of the sheet is in high uniformity along the direction perpendicular to the wire.
Electromagnetic forming (EMF) is a type of noncontact and high-speed forming process that offers several advantages, such as high material formability, low springback, and low die cost. In this ...study, titanium bipolar plates (BPPs) for proton exchange membrane fuel cells are fabricated by EMF using a uniform pressure actuator that provided a uniform pressure distribution and high efficiency. A three-dimensional coupled electromagnetic-mechanical simulation model is established to optimize the dynamic forming process. Simulation results show that the channel depth is proportional to the impact velocity of the titanium workpiece. A forming window is established as a design guideline. Finally, a titanium BPP with sufficient channel depth (0.4 mm), high aspect ratio (0.67), low thinning rate (not exceeding 15.89%) and high corrosion resistance is successfully fabricated at a velocity of 286 m/s, thereby demonstrating that EMF is a feasible process for fabricating titanium BPPs.
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•Fabrication of titanium bipolar plate by uniform pressure electromagnetic forming.•The impact velocity of the workpiece is almost proportional to the channel depth.•The forming velocity of the workpiece can reach about 300 m/s.•The channel depth of the TA1 bipolar plate can reach 0.4 mm (0.67 aspect ratio).•The thinning rate in the thickness of the TA1 bipolar plate is less than 15.89%.
Uniform pressure actuators (UPAs) have unique advantages for electromagnetic forming, and they have excellent prospects in specific applications. The typical structure of conventional UPAs consists ...of an internal coil and an external conductive channel; this leads to certain limitations such as poor electrical contact and low coil strength. In the present study, in order to resolve these shortcomings, a new type of UPA is proposed, in which the induced circuit consists of a conductive channel and a workpiece that is placed inside a spiral coil. Benefitting from the innovation of the special structure, the proposed UPA can improve the electrical contact by producing a squeezing force between the conductive channel and workpiece during the forming process. Moreover, it provides an open reinforced environment for increasing the coil strength without affecting the forming efficiency. Numerical and experimental studies demonstrate that forming efficiency of the proposed UPA is higher than that of the conventional UPA. Based on these advantages and the new proposed uniform-velocity method, the proposed UPA is applied to fabricate a fuel cell titanium bipolar plate in a single discharge process.
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•Inner-field uniform pressure actuator (UPA) solved arcing issues by squeezing force.•The coil strength of Inner-field UPA can be improved by open reinforcement space.•The Inner-field UPA has higher forming efficiency than the conventional UPA.•The fully coupled finite element models of two types of UPAs are first established.•The complex titanium bipolar plate was formed by the new uniform-velocity method.
A new dynamic forming method denoted as Lorentz-force-driven (LFD) sheet metal stamping was proposed in this work, which has been applied to cylindrical cup forming. A series of experiments were ...carried out to investigate the deformation behavior of workpiece based on the forming method under different conditions, and a three-dimensional coupled electromagnetic-mechanical numerical model was established to better understand the dynamic forming process. Results show that the features of discharge current waveform including current frequency and damping state have obvious effects on the forming behavior of workpiece, and an additional crowbar circuit with no resistance could be used to achieve a relatively high forming efficiency in a wide frequency range. Further, a flat-bottom cylindrical cup made of 5052-O aluminum alloy with a thickness of 0.96 mm and a drawing ratio of 2 can be achieved by only two discharges, where the total discharge energy is 32 kJ and the final cup height is about 66.4 mm. More importantly, it has been demonstrated that the thickness reduction of workpiece in the forming process could be improved by additional radial pulsed Lorentz forces, showing that the new dynamic forming method is expected to have good prospect in deep drawing of workpieces with large drawing ratios.
The uniform pressure actuator (UPA) is a specially designed coil for use in electromagnetic forming (EMF) process, which offers a uniform pressure distribution in flat sheet forming. The traditional ...coil has high strength but low forming efficiency. In this paper, in order to improve the forming efficiency, a novel coil is designed and analyzed based upon the manufacturing technique of pulsed magnets. The theoretical analysis for the forming efficiency is carried out. Both the numerical and experimental techniques are used to calculate and compare the forming efficiency of coils. After that, destructive experiment is conducted to test the coil strength. It has been found that the more turns per unit length and the smaller the skin depth of the coil can improve the forming efficiency of the coil obviously. The results show that the designed coil by the manufacturing technique of pulsed magnets has considerable strength with higher forming efficiency com-pared to the traditional ones.
Discharge current-based forming (DCF) is a forming method that directly loads a pulse current into two parallel placed metal sheets connected in series, and the mutually exclusive electromagnetic ...force between them causes the sheets to be deformed. Compared with the electromagnetic forming (EMF), this method can improve the current density for the low-conductivity sheets. However, the forming height of the sheets is extremely poor due to the weak magnetic field generated by the pulsed current. In order to solve this problem, a new DCF approach adopted a pulsed magnet for wide sheets forming is proposed, which can provide a background magnetic field (BMF) with high uniformity and strength during the forming process. The influence of magnet parameters (shape, size, wire size, number of turns, etc.) on the magnetic field uniformity and strength at the forming region is analyzed by the finite element method, and the design scheme is listed. After that, the magnet is fabricated based upon the manufacturing technique of pulsed magnets, and the DCF and EMF experiments of AA1060 and SS304 sheets with 100 mm widths are carried out. The testing results show that the magnet can provide a 2.8 T BMF with more than 93% uniformity for the forming region. The forming results show that the forming height of sheets in DCF under BMF can be increased by 300% compared with that without BMF, and DCF has a huge advantage in comparison with EMF in forming low conductivity materials.
Sterile inflammation is initiated by damage-associated molecular patterns (DAMPs) and a key contributor to acute liver injury (ALI). However, the current knowledge on those DAMPs that activate ...hepatic inflammation under ALI remains incomplete. We report here that circulating peroxiredoxin-1 (Prdx1) is a novel DAMP for ALI. Intraperitoneal injection of acetaminophen (APAP) elicited a progressive course of ALI in mice, which was developed from 12 to 24 h post injection along with liver inflammation evident by macrophage infiltration and upregulations of cytokines (IL-1β, IL-6 and TNF-α); these alterations were concurrently occurred with a robust and progressive production of serum Prdx1. Similar observations were also obtained in carbon tetrachloride (CCl4)-induced ALI in mice. Removal of the source of serum Prdx1 protected mice deficient in Prdx1 from APAP and CCl4-induced liver injury, and decreased macrophage infiltration, IL-1β, IL-6 and TNF-α production. As a result, Prdx1−/− mice were strongly protected from APAP-induced death that was likely progressed from ALI. Additionally, intravenous re-introduction of recombinant Prdx1 (rPrdx1) in Prdx1−/− mice reversed or reduced all the above events, demonstrating an important contribution of circulating Prdx1 to ALI. rPrdx1 potently induced in primary macrophages the expression of pro-IL-1β, IL-6, TNF-α, and IL-1β through the NF-κB signaling as well as the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling, evident by caspase-1 activation. Furthermore, a significant elevation of serum Prdx1 was demonstrated in patients (n = 15) with ALI; the elevation is associated with ALI severity. Collectively, we provide the first demonstration for serum Prdx1 contributing to ALI.
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•Increases in serum Prdx1 in patients and mice with acute liver injury (ALI).•Prdx1−/− mice are protected from drug-induced ALI and ALI-associated inflammation.•Intravenous injection of recombinant Prdx1 (rPrdx1) causes ALI in Prdx1−/− mice.•rPrdx1 induces IL-1β, IL-6, and TNF-α expression in primary macrophages.•Circulating Prdx1 is a novel DAMP promoting ALI.
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Acute liver failure (ALF) is a critical condition that can lead to substantial liver dysfunction. It is characterized by complex clinical manifestations and rapid progression, ...presenting significant challenges in diagnosis and treatment. We investigated the protective effect of mefunidone (MFD), a novel antifibrosis pyridone agent, on ALF in mice, and explored its potential mechanism of action. MFD pretreatment can alleviate lipopolysaccharide (LPS) and d-galactosamine (D-GalN)-induced ALF, reduce hepatocyte apoptosis, and reduce inflammation and oxidative stress. Additionally, MFD alleviated LPS/D-GalN-stimulated reactive oxygen species (ROS) production and cell death in AML12 cells. RNA sequencing enrichment analysis showed that MFD significantly affected the Mitogen-Activated Protein Kinase (MAPK) pathway. In vivo and in vitro experiments showed that MFD inhibited MKK4 and JNK phosphorylation. JNK activation caused by MKK4 and JNK activators could eliminate the therapeutic effect of MFD on AML12. In addition, MFD pretreatment alleviated ConA-induced ALF, reduced inflammation and oxidative stress in mice, and reduced mouse mortality. These results suggest that MFD can potentially protect against ALF, partially by inhibiting the MKK4-JNK pathway, and is a promising new therapeutic drug for ALF.
Abstract Idiopathic pulmonary fibrosis (IPF) is believed to be associated with a notable disruption of cellular energy metabolism. By detecting the changes of energy metabolites in the serum of ...patients with pulmonary fibrosis, we aimed to investigate the diagnostic and prognostic value of energy metabolites in IPF, and further elucidated the mechanism of their involvement in pulmonary fibrosis. Through metabolomics research, it was discovered that the TCA cycle intermediates changed dramatically in IPF patients. In another validation cohort of 55 patients with IPF compared to 19 healthy controls, it was found that succinate, an intermediate product of TCA cycle, has diagnostic and prognostic value in IPF. The cut-off levels of serum succinate were 98.36 μM for distinguishing IPF from healthy controls (sensitivity, 83.64%; specificity, 63.16%; likelihood ratio, 2.27, respectively). Moreover, a high serum succinate level was independently associated with higher rates of disease progression (OR 13.087, 95%CI (2.819–60.761)) and mortality (HR 3.418, 95% CI (1.308–8.927)). In addition, accumulation of succinate and increased expression of the succinate receptor GPR91 were found in both IPF patients and BLM mouse models of pulmonary fibrosis. Reducing succinate accumulation in BLM mice alleviated pulmonary fibrosis and 21d mortality, while exogenous administration of succinate can aggravate pulmonary fibrosis in BLM mice. Furthermore, GPR91 deficiency protected against lung fibrosis caused by BLM. In vitro, succinate promoted the activation of lung fibroblasts by activating ERK pathway through GPR91. In summary, succinate is a promising biomarker for diagnosis and prognosis of IPF. The accumulation of succinate may promote fibroblast activation through GPR91 and pulmonary fibrosis.
