Part Of Sheet Research Articles

Achieving springback-free age forming via dislocation-enhanced stress relaxation in Al alloy

Obtaining zero springback and good post-form performance simultaneously is an ultimate pursuit in metal sheet forming. The stress-relaxation ageing (SRA) behavior and mechanical properties of a commercial 2219 aluminum alloy largely pre-deformed (LPD) by 80% have been systematically investigated. The stress relaxation ratio of the LPD alloy reaches approximately 94% regardless of the initial stress (50-350 MPa) after ageing for 12 h at 140°C. This relaxation ratio is about 2.9 and 1.8 times that in the T4 tempered alloy (27.6% under 50 MPa and 31.5% under 150 MPa) and T3 tempered alloy (37.6% under 50 MPa and 51.2% under 150 MPa), respectively. The microstructures, comprised of GP zones/θ' precipitates plus dislocation tangles, and tensile properties in the stress-relaxation-aged LPD alloys remain basically invariant with different initial stresses, as is vital importance for property consistency at different locations of the formed part. Under the same SRA condition, the LPD alloy has an increase of 150-230 MPa in yield strength relative to T3/T4 tempered alloy and obtains a uniform elongation of about 8%. A simple dislocation-based constitutive model accurately describing stress relaxation enhanced by the high dislocation density is established and embedded in the finite element package through a user subroutine. Simulations and experimental verifications show the LPD alloy sheet parts exhibit a nearly zero springback (< 5%) after unloading in contrast to the springback larger than 65% in the T3/T4 alloy sheet parts under the same condition. Our findings demonstrate the high-dislocation-density-enhanced SRA response enables a high-performance springback-free age forming of Al alloy sheet.

The sedimentology and multi-stage evolution of a Pleistocene esker on soft substratum, a case from North Central Poland

Eskers are one of the meltwater landforms that enable the reconstruction of the nature of subglacial drainage systems. Therefore, they play a significant role in the study of palaeo ice sheets. While the spatial distribution of subglacial tunnels and their geometry resulting from the geomorphological features of eskers are relatively well known, the course and time of sedimentation processes taking place inside the subglacial conduits are understood only to a certain extent, especially in the case of eskers developed on soft substrata. The paper presents an example of an esker that developed on a soft substratum from Central-North Poland, which was formed in several stages. In the initial stage, meltwater drainage took place through a channel that dissected the substratum (N-channel). Its development was associated with intense flow under pressure, but the sediments filling the channel were already deposited under atmospheric pressure when the flow used only part of the available space of the conduit. The high frequency of large-scale, cross-stratified lithofacies indicates significant flow depth and sediment deposition under a lower flow regime. The succession filling the channel resembles the sediments of a low-sinuosity open river systems with varied channel morphology, however, it also contains deposits like the point bar succession. Later, the R-channel developed, dominated by deposition from supercritical flows, probably of a much smaller depth. The sediments were deposited from a traction carpet or a highly turbulent suspension. The massive structure of many lithofacies indicates that flow overload was common. The transformation of the system from N-channel to R-channel was probably related to the decrease in the slope of the ice sheet surface during ablation, which resulted in a reduction of the potential hydraulic pressure gradient. The final stage of esker sedimentation was associated with deposition in an open channel, which indicates the passive nature of the marginal part of the ice sheet.

Petrogenesis of Metamorphic Rock in the Mukito Formation at Sorawolio Region, Bau-Bau City, Buton Island, Southeast Sulawesi Province, Indonesia

The petrogenesis study of the metamorphic rocks of the Mukito Formation was carried out in the Sorawolio area, Bau-Bau City, Buton Island, Southeast Sulawesi Province, Indonesia. This research area is included in the southern part of the Buton sheet with coordinates S 5⁰23'40.8'' and E 122⁰43'44.9''. The aim of this research is to determine the petrogenesis of metamorphic rocks which includes determining the rock type, facies, type of metamorphism and protolith. The research methods used include megascopic and microscopic analysis of rocks in the form of petrographic analysis which includes identification of mineral content and rock texture and geochemical analysis in the form of XRF tests to determine the main oxide elements in metamorphic rock samples. Data obtained from the results of petrographic analysis show that the research area consists of several types of metamorphic rock, namely serpentinite, phyllite, chlorite schist, hornblende schist and amphibolite. The metamorphic rocks in the research area are included in the greenschist facies and amphibolite facies with regional metamorphism types as well as protoliths from igneous rocks in the form of basalt rock which were formed in the tholeiitic oceanic-island tectonic environment which is a convergent complex characterized by continental origin in the magma series in the form of the tholeiitic series and calc -alkaline series.

SmartFixture: Physics-guided reinforcement learning for automatic fixture layout design in manufacturing systems

Fixture layout design critically impacts the shape deformation of large-scale sheet parts and the quality of the final product in the assembly process. The existing works focus on developing Mathematical-Optimization (MO)-based methods to generate the optimal fixture layout via interacting with Finite Element Analysis (FEA)-based simulations or its surrogate models. Their limitations can be summarized as memorylessness and lack of scalability. Memorylessness indicates that the experience in designing the fixture layout for one part is usually not transferable to others. Scalability becomes an issue for MO-based methods when the design space of fixtures is large. Furthermore, the surrogate models might have limited representation capacity when modeling high-fidelity simulations. To address these limitations, we propose a learning-based framework, SmartFixture, to design the fixture layout by training a Reinforcement learning agent through direct interaction with the FEA-based simulations. The advantages of the proposed framework include: (i) it is generalizable to design fixture layouts for unseen scenarios after offline training; (ii) it is capable of finding the optimal fixture layout over a massive search space. Experiments demonstrate that the proposed framework consistently generates the best fixture layouts that receive the smallest shape deformations on the sheet parts with different initial shape variations.

Advancements in Sheet Metal and Part Modeling for Product Development

Advancements in Sheet Metal and Part Modeling for Product Development

Evaluation and Prediction of Wrapping Deformation in Sheet Part Grinding

Evaluation and Prediction of Wrapping Deformation in Sheet Part Grinding

SWOT ANALYSIS OF THE ACTIVITIES OF ADIDAS-UKRAINE DURING THE ESCALATION OF MILITARY ACTIONS IN UKRAINE

The topicality of the topic lies in determining the perspective of adaptation of enterprises to the challenges dictated by military actions, including the annexation of business territories, destruction of fixed assets, migration of workers, constant risk to life and health. The main idea of the work is to develop recommendations for the private sector to continue working in Ukraine after a full-scale invasion, in order to provide the population with jobs, high-quality goods and services, and faith in the bright future of the state. The war caused troubles and cataclysms in the domestic economy as a whole and in the market of consumer goods, in particular, because a large part of trading points, shops, pavilions was destroyed and cannot be restored. Significant minus factors of the profitable activity of the private sector are the annexation of territories led to the usurpation of the fixed assets of trade enterprises, including; decrease in the number of the workforce – personnel of organizations; decrease in demand for clothes and accessories of popular brands, due to changes in values and financial capabilities; mass migration of potential consumers of the sports goods and services market; the lack of profits causes the predominance of the expense part of the balance sheet and, accordingly, the unprofitability of the activity; withdrawal from the consumer goods market of companies with a higher level of prices and product quality. The war also necessitated the reorientation of production to military lines, and therefore goods and services for civilians are not a priority; forced closure of shops, warehouses, sales points in the aggressor country; growing consumer sensitivity to the enterprise's business policy, the level of its assistance in achieving victory; and increased the global need to help the population, even in the face of the prospect of bankruptcy and withdrawal from the country's consumer market and increased tax pressure. And, in the end, it led to a decrease in the possibilities of receiving state orders, grants, subsidies, quotas.

Real-Time Object Classification on an Enamel Paint Coating Conveyor Line Using Mask R-CNN

The rising demand to efficiently acquire live production data has added more significance to automated monitoring and reporting within the industrial manufacturing sector. Real-time parts screening requiring repetitive human intervention for data input may not be a feasible solution to meet the demands of modern industrial automation. The objective of this study is to automatically classify and report on manufactured metal sheet parts. The metal components are mechanically suspended on an enamel paint-coating conveyor line in a household appliance manufacturing plant. At any given instant, the parts may not be in the exact coordinates within the desired area of interest and the classes of objects vary based on changing production requirements. To mitigate these challenges, this study proposes the use of a trained Mask R-CNN model to detect the objects and their associated class. Images are acquired in real-time using a video camera located next to the enamel coating line which are subsequently processed using the object detection algorithm for automated entry into the plant management information system. The highest achieved average precision obtained from the model was 98.27% with an overall accuracy of 98.24% using the proposed framework. The results surpassed the acceptable standard for the average precision of 97.5% as set by the plant production quality engineers.

A VFM-based identification method for anisotropic thermal-mechanical properties of sheet metals using the digital image correlation and infrared thermography assisted heterogeneous test

The accurate characterization of the anisotropic thermal-mechanical constitutive properties of structural sheet metals at elevated temperatures and under nonuniform stress/strain states is crucial for the precise hot plastic forming and structural behavior evaluation of an engineering sheet part. Traditional thermal-mechanical testing methods rely on the assumption of states homogeneity, leading to a large number of tests required for the characterization of material anisotropy and nonlinearity at various high temperatures. In this work, a highly efficient identification method is proposed that allows the simultaneous characterization of the anisotropic yielding, strain hardening and elasto-plasticity thermal softening material properties using the minimum number of tests, releasing the limitations of traditional identification methods. This is implemented by performing a digital image correlation and infrared thermography assisted heterogeneous high temperature test and processing the full-field measurement data based on the principle of virtual work. A double-notched tensile specimen configuration combined with a center-to-periphery temperature gradient is designed first to enable the high heterogeneity of stress/temperature states. Simulations of the heterogeneous tests are then performed to supply idealized reference data that can be used to evaluate the identification sensitivity of the proposed identification algorithm. After the numerical validation of the methodology, it is then applied to the TC4 titanium alloy sheet specimen using the self-developed experimental setup. The experimental identification results verify that the multiple anisotropic thermal-mechanical elasto-plasticity constitutive parameters can be accurately identified from the heterogeneous test with high computation efficiency, significantly simplifying the testing process in comparison to applying multiple traditional homogeneous tests. The current work provides an effective and convenient alternative to high temperature identification strategies used by the material processing community.

Experimental and model investigation of spreading characteristics of the liquid sheet formed by jet impinging on a circular plane

The focus of this paper is on the spreading characteristics of the liquid sheet formed by jet impinging on a circular plane. The liquid sheet is studied in two parts: the liquid film that spreads radially on the circular plane, and the free liquid sheet after leaving the circular plane, the former determines the initial thickness and velocity of the latter. Experimental results show that, for the liquid film on the circular plane part, as the jet velocity increases, the liquid film thickness increases due to the film velocity loss caused by the inelastic collision. The liquid film thickness is positively correlated with the jet radius and negatively correlated with the circular plane radius. Liquid viscosity slows the spreading of liquid film, forms the boundary layer, and thickens the liquid film. The surface tension inhibits the velocity loss due to the inelastic collision. For the free liquid sheet part, surface tension and gravity promote the bending of the liquid sheet. The larger the initial momentum of the liquid sheet leaving the circular plane, the larger the maximum spreading range of free liquid sheet reaching the equator. As for the theoretical model, a film velocity correction coefficient reflecting collision loss is introduced to improve the radial spreading theory of the liquid film on a solid surface, and a streamline function is assumed to solve the momentum integral equation of free liquid sheet. The predicted streamline agrees well with the experimental data.

Novel Separation Processes and Their Applications

Separation processes are an integral part of any process flow sheet. Various techniques can beused to separatethe mixture depending on the raw mix. Sometimes, two or more methods must be used to get the desiredproduct. Differences in chemical and physical properties also help decide the separation technique that mustbe used. An external agent, any form of energyor matter, can act as the driving force for the separation. Someof these techniques are conventional processes like distillation, filtration, adsorption, and absorption, whichhave already been well-studied and extensively used. These days newer separation processes called novelseparation processes, such as membrane separation, gas separation, supercritical fluid extraction, use ofultrasonics, chromatographic separation, magnetic projection, and liquid- liquid extraction, among manyothers, are gaining importance in the area of research and implementation. Novel processes were firstimplemented as analytical tools in laboratories. However, they developed rapidly to become significant commercially and technically. The development in gas separation techniques has led to using Liquified Natural Gas in Air Separation Units to produce high-purity nitrogen and oxygen4. Novel separation methods also include ultrasound to enhance separation processes like extraction, demulsification, and crystallisation. Pressure-driven processes are a subset of membrane separation techniques where pressure is utilised as a driving force for separation, with asemipermeable membrane acting as a barrier. This method has various applications ranging from wastewater treatment to dairy processing. Chiral chromatography is used for enantiomeric separations by the use ofHPLC. A new magnetic separation process proposes the separation of plastics by submerging them in a paramagnetic medium and attaching a magnet. This results in moving the particles inside the medium with different trajectories, thereby separating them. This article will scrutinise and briefly describe the essential aspects and developments of novelseparation processes and their applications.

Analytical description of adjustment of rolls for manufacturing parts from elastic sheet material

The object of research is the process of bending sheet material, taking into account its springiness. When manufacturing sheet parts by bending from a completely elastic sheet, its shape is completely restored after the deformation stops, unlike an elastic sheet. Thus, when producing cylindrical parts by drawing between three rolls, the resulting radius of the cylindrical part will be larger than the calculated one. This phenomenon is evaluated by the coefficient of springing – the ratio of the calculated radius to the one obtained after partial expansion. When manufacturing conical parts, this approach cannot be applied, because the value of the radius is variable. The article applies the theory of surface bending from differential geometry. The curvature of the line on the surface has two components - normal and geodesic. When the surface is bent, the normal component changes, while the geodesic component remains unchanged. The magnitude of the normal component depends on the angle between the origin of the cone and its axis. So, for a cone with a base of radius R and an angle of 20°, the normal curvature is 0.94/R, and the geodesic curvature is 0.34/R. For cylindrical parts, the geodesic curvature of the cross-section (circle) is zero, so it is not necessary to take it into account. Usually, adjustment of rolls for the production of conical parts is carried out experimentally. The difference of the proposed approach lies in the elimination of this problem thanks to the decomposition of the curvature of the base of the cone into two components. This allows to calculate the settings of the rolls and thereby reduce their adjustment time. The parameters of the rolls and their mutual placement are calculated for the production of conical parts of the required size, taking into account their springiness. The field of application of the obtained results is the production of parts by bending flat metal sheet blanks

FIELD GEOLOGY AND PETROGRAPHY AROUND NABARDO-TORO ENVIRONS, NORTH EASTERN, NIGERIA

Background: The mapping exercise within the study ar ea on a scale of 1:25,000 was carried out to study the rocks, determine their distribution, composition, structures and assess the economic potential of the area. Objectives: The geology mapping aim to identify and understand the various geological structures present in the area to gain insights into the tectonic history and deformation processes that have shaped the area and to identify the minerals present in the rock, to understand the rock formation, composition and potential geologic processes involved. Method: Method of mapping involved road, footpath, rivers and stream traverses. Representative rock samples were collected for petrographic studies and geochemical analysis to establish the geology of the study area. Result: The study area which is part of Sheet 148, Toro SE is entirely typical of the Nigerian Basement Complex and is underlain by the following rock units: Migmatitic Gneiss, Granite gneiss, mica schist and porphyritic granite. The Migmatitic Gneiss constitutes the largest group of the rock units covering more than 45% of the mapped area and trending mainly NW/SE with few exceptions in an almost N/S to NE/SW direction. It is pertinent to know that almost E-W structures were also observed which forms relics of the older structure believed to have been affected by the eburnean (possibly) orogenic event. The granite gneiss shares boundary mainly with the migmatitic gneiss showing a weak foliation of light and dark materials. The mica schist is exposed at the western end, highly weathered with a general trend of NW/SE. The porphyritic granite intruded both the migmatite and granite gneiss occurring prominently as hilly and bouldery outcrops. However, flat lying low lying was also observed in some other localities. With respect to field observation and petrographical study the lithologies encountered were grouped into nine (9) categories- homogeneous, inhomogeneous, stromatic, banded orthogneiss, nebulitic, apo granite, pegmatite, intermediate and schist.Conclusion: Field evidence suggests that the study area has undergone an episode of metamorphism and deformations as depicted by the structural features like preferred orientation of the mineralogical and lithological units. It was also observed from the field measurements, that the main structural trend within the study area is from NNE/SSW.

Reversibility of Greenland ice sheet mass loss under artificial carbon dioxide removal scenarios

With ongoing anthropogenic CO2 emissions, the Greenland ice sheet (GIS) approaches critical thresholds of inevitable, long-term mass loss. Future technologies might be able to efficiently remove CO2 from the atmosphere and thereby cool down our planet. We explore whether and to what extent a realization of this concept could lead to a regrowth of the GIS once it has partly melted. Using the fully coupled Earth system model of intermediate complexity CLIMBER-X, emission pulses between 0 and 4000 GtC are released into the atmosphere, and after 1 kyr, 2 kyr, and 5 kyr, the atmospheric CO2 concentration is reduced back to its pre-industrial value. We find that independent of a specific trajectory, once the southern part of the GIS has partly melted with a total mass loss of more than 0.4 m sea level equivalent, regrowth is inhibited. Uncertainties preclude determination of precise thresholds, but model results indicate that cumulative industrial-era emissions approaching 1000–1500 GtC and beyond increasingly risk irreversible mass loss of the GIS. Once this threshold is passed, artificial atmospheric carbon removal would need to be utilised within the next centuries at massive scale. Beyond that, artificial atmospheric carbon removal has limited abilities to avoid long-term mass loss of the GIS. In conclusion, keeping cumulative anthropogenic emissions below 1000–1500 GtC is the only safe way to avoid irreversible mass loss of the GIS.

Geochemical Characteristics of Soils and Plants around Mining Sites in Parts of Ilorin Sheet 223

Mining is an important process that fosters economic growth by extracting valuable minerals from the earth's surface. However, this industry also poses significant environmental challenges, such as soil and water pollution and habitat destruction. This study aims to assess the impact of mining activities on heavy metal concentrations in soil and Neem plant leaves in two mining sites. The research utilized atomic absorption spectrometry (AAS) to analyze the heavy metal content in soil and plant samples. The obtained data were used to calculate various contamination indices, including the contamination factor index (CF), degree of contamination (Cd), modified degree of contamination (mCd), pollution load index (PLI), and accumulation index (Igeo) for soil samples. Additionally, the bioaccumulation coefficient (BAC) was calculated for Neem plant leaves. The X-ray diffraction (XRD) analysis was conducted to identify the mineral composition of the rock samples collected from the study area. The average values for Cu, Pb, Zn, Fe, Mn, Ni, and Co in test soil sites are higher than those in control sites, with significant differences (p-value &lt;0.05) for Cu, Zn, Fe, and Co, indicating contamination due to mining. Similarly, for Neem plant leaves, the average concentrations of Cu, Pb, Zn, and Co are higher in test sites than in control sites, indicating bioaccumulation from the mining activities. However, the calculated contamination indices suggest that the level of contamination in the study area is relatively low. The XRD analysis revealed distinct peaks corresponding to various minerals, including Orthoclase, Albite, Muscovite, Quartz, Dolomite, Anorthite, and Illite. The mineral proportions were assessed, with quartz being dominant in the igneous rocks and dolomite in the marble samples.

Identifikácia elasticko-plastickej deformácie pre rôzne stupne deformácie pri tvárnení plechu otočným ohýbaním

The thesis deal with the issue of bending. The practical part is dealing with developing of design of bending tool for bending of metal sheet parts and made technological processes for manufacturing of non standard components. The part of design is an account of bending strength, bending work, and made cutting plans. The content is also an economic assessment of the design and final evaluation.

Visualization Analysis of Wrinkle Generation Phenomenon in PP Decorative Sheets (Part 2) ―Identification of Interfacial Thermal Resistance by Measurement of Temperature Change inside Decorative PP Sheets and at Flow Front―

Visualization Analysis of Wrinkle Generation Phenomenon in PP Decorative Sheets (Part 2) ―Identification of Interfacial Thermal Resistance by Measurement of Temperature Change inside Decorative PP Sheets and at Flow Front―

Влияние режимов дуговой автоматической сварки на геометрические параметры шва стыковых соединений из низкоуглеродистой стали, выполненных с применением экспериментального флюса

Introduction. The metallurgical industry in the territory of the Russian Federation has accumulated a significant amount of slags obtained during the smelting of steels and cast iron. The presence of slag dumps adversely affects the ecology of regions with metallurgical enterprises. When reducing iron from slags, the by-product becomes an oxide agglomerate, which can be considered as a flux composition for arc welding/surfacing under a layer of flux, fillers of powder wires, coatings of welding stick electrodes. The purpose of the work is to establish the possibility of arc welding using the flux obtained by the authors and to determine the optimal welding modes with the condition of achieving the geometric parameters of the seam according to GOST 8713-79 and the quality of the welded joint (absence of internal defects). In this paper, butt welded joints of sheet steel VSt3sp with a thickness of 5 mm obtained by automatic welding under a layer of flux at direct current with forced formation of a root roller on ceramic linings using flux from recycled metallurgical slag of an electric steelmaking enterprise are investigated. Automatic welding of flat specimens was carried out on a tractor-type ADF-1250 machine with a wire with a diameter of 3 mm, at a constant welding speed of 54 cm/min with varying current and arc voltage within 400–600 A and 27–37 V. The methods of investigation: Visual measuring and radiographic control, determination of deformation of specimens by laser scanning and computer processing of 3D models were used to evaluate the quality of welded joints. Statistical modeling in the form of a two-factor experiment was also used in the work, with obtaining adequate regression equations of the influence of welding modes on the geometric parameters of the seam: the height of reinforcement and the width of the seam on the front and back of the joint. Results and discussion. The possibility of obtaining welding fluxes from metallurgical slags of an electric steelmaking enterprise and its use for creating welded joints is shown. Optimal modes of arc welding of thin-walled sheet parts made of low-carbon steel with forced formation of a root roller on ceramic linings is established, ensuring the absence of internal defects in the form of pores, cracks and lacks of penetration, a minimum of residual deformations and compliance of the weld size with the requirements of the existing standard. The nominal values of the geometric parameters of the seam according to GOST 8713-79-C4 correspond to welding mode: welding speed 54 cm/min, welding current 550 A, arc voltage 30 V. The results of the work can be applied in metallurgical electric steelmaking enterprises producing low-carbon steel in the development of technologies for the use of welding materials from slag.

Recent irreversible retreat phase of Pine Island Glacier

AbstractPine Island Glacier (PIG), a part of the West Antarctic marine ice sheet, has recently undergone substantial changes including speed up, retreat and thinning. Theoretical arguments and modelling work suggest that marine ice sheets can become unstable and undergo irreversible retreat. Here, we use an ice-flow model validated by observational data to show that a rapid PIG retreat in the 1970s from a subglacial ridge to an upstream ice plain was self-enhancing and irreversible. The results suggest that by the early 1970s, the retreat of PIG had reached a point beyond which its original position at the ridge could not be recovered, even during subsequent periods of cooler ocean conditions. The irreversible phase ended by the early 1990s after almost 40 km of retreat and 0.34 mm added to global mean sea level, making PIG the main contributor from the Antarctic ice sheet in this period.

Combined GNSS reflectometry–refractometry for automated and continuous in situ surface mass balance estimation on an Antarctic ice shelf

Abstract. Reliable in situ surface mass balance (SMB) estimates in polar regions are scarce due to limited spatial and temporal data availability. This study aims at deriving automated and continuous specific SMB time series for fast-moving parts of ice sheets and shelves (flow velocity &gt; 10 m a−1) by developing a combined global navigation satellite system (GNSS) reflectometry and refractometry (GNSS-RR) method. In situ snow density, snow water equivalent (SWE), and snow deposition or erosion are estimated simultaneously as an average over an area of several square meters and independently on weather conditions. The combined GNSS-RR method is validated and investigated regarding its applicability to a moving, high-latitude ice shelf. A combined GNSS-RR system was therefore installed in November 2021 on the Ekström ice shelf (flow velocity ≈ 150 m a−1) in Dronning Maud Land, Antarctica. The reflected and refracted GNSS observations from the site are post-processed to obtain snow accumulation (deposition and erosion), SWE, and snow density estimates with a 15 min temporal resolution. The results of the first 16 months of data show a high level of agreement with manual and automated reference observations from the same site. Snow accumulation, SWE, and density are derived with uncertainties of around 9 cm, 40 kg m−2 a−1, and 72 kg m−3, respectively. This pilot study forms the basis for extending observational networks with GNSS-RR capabilities, particularly in polar regions. Regional climate models, local snow modeling, and extensive remote sensing data products will profit from calibration and validation based on such in situ time series, especially if many such sensors will be deployed over larger regional scales.