Sheet Material Research Articles

Electrodynamic properties of a rectangular waveguide with a dielectric plate located in the center of its wide wall

A rectangular waveguide with a dielectric plate located in the E-plane is the basic element of devices for microwave heat treatment of sheet materials. In this regard, it is relevant to study the processes of propagation and transformation of electromagnetic waves in such a system. The purpose of the work is to study the influence of the transformation of the electromagnetic field in the air medium of a rectangular waveguide in the zone of propagation of the slow wave H10 on the distribution of electric field energy in the dominant wavelength range and determining the wavelength, at which its maximum value is reached. The range properties of the intrinsic electrodynamic parameters and the field structure of a rectangular waveguide with a dielectric plate located in the E-plane in the middle of its wide wall have been studied. The wavelength at which the maximum energy level of the electric field in the dielectric plate is achieved is determined. The results obtained can be used in the design of microwave heating devices for dielectric materials.

Study of Acoustic Prototypes Based on Plastic Cap Waste

This paper presents the initial prototypes of solutions designed using plastic caps, seeking acoustic applications for both airborne sound insulation and the acoustic conditioning of rooms. Plastic caps are a waste product from the packaging sector and they constitute a major waste problem, given that, if they are not attached to the packaging, they get lost during the recycling cycle and end up in landfill. Finding an application for this waste that can provide acoustic improvements is a sustainable alternative. This paper shows the results of airborne sound insulation measurements obtained in a scaled transmission chamber and sound absorption measurements obtained in a scaled reverberation chamber for different combinations of single and double plastic caps and combinations with thin sheets of sustainable materials, such as jute weaving, textile waste, hemp felt and cork board. Tests have shown that obtaining sound reduction index values of up to 20 dB is possible with plastic cap configurations, or even up to 30 dB is possible at some frequencies with combinations of caps and certain eco-materials. With regard to the sound absorption coefficient tests, close to unity absorption values have been achieved with the appropriate configuration at frequencies that can also be selected. The results indicate that these panels can be eco-solutions for airborne sound insulation as lightweight elements, or they can be used for the conditioning of rooms, tailoring the sound absorption maximums to the desired frequencies.

Development of Environmental Monitoring Sensor for Steel Corrosion in Concrete based on Micro-Electro-Mechanical Systems (MEMS)

Many bridges located near marine environments usually have high risk to lose their structural performance due to corrosion of reinforcing bars with chloride attack. While a huge amount of budget to maintain may be consumed for the structural maintenance methodologies, an efficient monitoring system for Reinforced Concrete (RC) structures in the corrosive environment is strongly demanded. Thus, structural health monitoring in real situations is significant for bridge asset management. The alternative way for preventing severe damage propagation is proactively monitoring the environmental condition containing chloride ion and its effect on the durability of concrete structures, for which numerous methods have been conventionally suggested such as dry gauze method to capture chlorides in air. In this study, Micro Energy Harvester (MEH) based on Micro-Electro-Mechanical Systems (MEMS) is technically applied to develop a sensor to identify the corrosion environment with chlorides in the exposure condition. MEMS is a rapidly evolving device, which enables to monitor the changes in natural frequency and amplitude at nodal locations of the targeting structure due to vibration-based electrostatic power generation induced by the corrosive environment. The purpose of this research is to develop a system for detecting the high corrosion-prone areas and finding the suitable metal sheet material for various chloride ion conditions, using the metal sheet as a cantilever structure for the MEMS device. 4 types of metal, aluminium, copper, iron and zinc are considered for the parametric experiments. Several scenarios are considered including chloride ion concentration, temperatures, and wet and dry conditions to compare the dominant frequency changes of each metal sheet and determine their sensitivity to corrosion environment. From the preliminary results, iron and zinc have a significant drop in frequency with the elapsed exposure period, which indicates that they are highly sensitive to the external chloride ion environment. These results offer an innovative and proactive approach to structural health monitoring for further developed applications. It enables prompt maintenance and early detection of potential issues for corrosion of steel bars in concrete, ensuring the longevity and safety of RC bridge structures.

Artificial thermal shock cracks in WRe – A proof of concept study

Thermal shock cracks are frequently observed in environments where extensive thermal cycling at high amplitudes is common. Typical cases for such are first wall materials in proposed fusion reactors and rotating anodes for computed tomography scanners. The formation of these cracks is driven by significant tensile stresses during the cooldown phase, following prior plastic deformation at elevated temperatures.This work proposes an experimental approach, where artificial thermal shock-like structures are generated via femtosecond laser ablation in WRe as a model material. Following a detailed laser parameter study in a W sheet material, patterns were introduced to WRe samples and investigated by different microscopy techniques. Their morphology as well as their response to thermo-cyclic loads was investigated and compared to conventionally induced thermal shock cracks.The introduction of artificial cracks by femtosecond laser ablation that mimic the morphology and behaviour of naturally induced thermal shock cracks is feasible within certain boundaries. Cuts, comparable to thermal shock cracks in width and depth, can be ablated. The cuts show an effect on the surrounding microstructure in line with the thermal shock cracks. Therefore, comparability could be proven concerning morphological and microstructural aspects. The conducted thermo-cyclic fatigue tests revealed an analogous effect on subsequent damage accumulation between the thermal shock cracks induced by thermal loading and artificial laser ablated cuts, proving the comparability under dynamic loading conditions. The extent of the effect is adjustable by tailoring the geometry of the lasered structures.The presented work suggests the possibility of studying the influence of thermal shock cracks on further fatigue mechanisms in exceptionally demanding applications, such as first wall materials or rotating anodes, by practical experimentation. Based on the resulting in-depth understanding of underlying interactions, the lifetime of these components might be prolonged by a deliberate introduction of crack networks or laser-ablated structures.

Unconventional Band Structure via Combined Molecular Orbital and Lattice Symmetries in a Surface-Confined Metallated Graphdiyne Sheet.

Graphyne (GY) and graphdiyne (GDY)-based monolayers represent the next generation 2D carbon-rich materials with tunable structures and properties surpassing those of graphene. However, the detection of band formation in atomically thin GY/GDY analogues has been challenging, as both long-range order and atomic precision have to be fulfilled in the system. The presentwork reports direct evidence of band formation in on-surface synthesized metallated Ag-GDY sheets with mesoscopic (≈1µm) regularity. Employing scanning tunneling and angle-resolved photoemission spectroscopies, energy-dependent transitions of real-space electronic states above the Fermi level and formation of the valence band are respectively observed. Furthermore, density functional theory (DFT) calculations corroborate the observations and reveal that doubly degenerate frontier molecular orbitals on a honeycomb lattice give rise to flat, Dirac and Kagome bands close to the Fermi level. DFT modeling also indicates an intrinsic band gap for the pristine sheet material, which is retained for a bilayer with h-BN, whereas adsorption-induced in-gap electronic states evolve at the synthesis platform with Ag-GDY decorating the (111) facet of silver. These results illustrate the tremendous potential for engineering novel band structures via molecular orbital and lattice symmetries in atomically precise 2D carbon materials.

Research on the Material Characteristics and Loss Calculation Method of Cryogenic Permanent Magnet Motor Stator for LNG Pump

This paper explores the applicability of cryogenic permanent magnet motor stator materials for LNG pumps. First, this study selected four kinds of silicon steel sheets for motor stators tested at room temperature and ultra-low temperature and obtained the magnetization characteristics and loss characteristics of the four silicon steel sheets at room temperature and ultra-low temperature. Then, through a comparative analysis of experimental data, the applicability of silicon steel sheet material in an ultra-low-temperature environment was verified. Finally, the improved methods of the basic iron loss model of silicon steel sheets and the basic iron loss model of motors were proposed, and the accuracy and feasibility of the improved models were verified.

In-situ synchrotron diffraction analysis of deformation mechanisms in an AA5083 sheet metal processed by modified equal-channel angular pressing

Severe plastic deformation (SPD) is a process to significantly improve the mechanical properties of materials by grain refinement. For forming at room temperature (RT), higher strengths can thus be achieved; for increased temperatures (HT), greater elongations can be achieved. This great potential has been chiefly applied only on laboratory scale due to a lack of industrial process design. Equal-channel angular pressing (ECAP) offers the possibility to integrate these advantages in industrial processes. This paper investigates a modified ECAP process for aluminum AA5083 sheet metal. Two passes of ECAP for sheet metal and an additional heat treatment were used. To study the material deformation on a micro-scale, in-situ synchrotron measurements at DESY (Hamburg) were performed to analyze the evolution of lattice strains and dislocation densities during tensile testing. The mechanical properties of the ECAP-processed sheet material reveal an increase in yield strength and a decrease in elongation at RT. Higher strains can be measured for the processed material at elevated test temperatures. In-situ diffraction results show a changed behavior of the ECAP sheet material compared to the reference material for both temperature regimes. These changes are based on the increased defect density in the material, which leads to increased strength at RT. At HT, dynamic recrystallization occurs during tensile testing, and the prevailing deformation mechanisms reconfigure. Electron backscatter diffraction (EBSD) and micrographs are used to interpret and supplement the observations. The findings provide the basis for the in-depth understanding of the deformation behavior of the material and help to apply the ECAP process on an industrial scale.

PENGEMBANGAN TEKNIK EXPRESSIVE WRITING DALAM BIMBINGAN KELOMPOK TERHADAP PENINGKATAN PENERIMAAN DIRI SISWA SMA DI KECAMATAN GENTENG KABUPATEN BANYUWANGI

The purpose of this research and development is to develop, determine the feasibility and test the effectiveness of expressive writing techniques in group guidance to improve self-acceptance. The research method used in this study is research and development (RD) with the ADDIE development model, which are analysis, design, development, implementation, and evaluation. The implementation of the research was carried out in five high schools in Genteng District, Banyuwangi Regency. The subjects of this study were 8 students. The data collection techniques and tools used were validation assessment sheets (material experts, media experts, and practitioners), interviews and self-acceptance instruments. The data analysis technique used is descriptive qualitative and descriptive quantitative analysis. The results of the study based on the validation of material experts obtained a percentage of feasibility of 80% (feasible), 81% (feasible) by media experts, and 86% (very feasible) by practitioners / counseling teachers. The results of the Wilcoxon test obtained a significance level of 0.012 ≤ 0.05 so that it can be stated that there are differences in pretest and posttest results in the guidance group. The results of the calculation of self-acceptance scale data in the guidance group given the expressive writing technique showed an increase of 61.17% which was included in the criteria quite effective. Thus, it means that the development of expressive writing techniques in group guidance to increase self-acceptance is feasible and effective to be implemented to the students.

Novel approach for sheet metal constitutive parameters identification based on shape index and multiple regression

To accurately predict the behavior and mechanical damage of sheet metal during hot forming process, the use of advanced thermomechanical modeling and precise identification of the constitutive parameter are required. This paper proposes a novel identification approach for constitutive parameters that relies on multiple regression and the shape index of experimental data curves. This approach is used to determine the material constants associated with the Johnson-Cook material and failure models for steel and aluminum sheets. Therefore, the obtained results approve the applicability and high accuracy of the identification procedure for the damage and the constitutive parameters of sheet metal, which allows for substantial time savings. Furthermore, to evaluate the formability of sheet metal, experimental forming tests at various temperatures were conducted. The identification process enhances the prediction of forming results, as shown by the fact that the numerical simulation of Erichsen and square die hydroforming tests using identified Johnson-Cook parameters agreed with the results of these tests carried out at different forming conditions. Moreover, the thickness measurement shows the ability of the developed model to properly predict the thickness of deformed shapes.

Tribological investigations of water-based lubricants for application in the deep drawing process

This paper describes the tribological investigation of water-based lubricants in the context of a deep drawing process. Therefore, different methods were conducted in order to determinate the suitability of these lubricants for a deep drawing process. Three lubricant manufacturers each provided their lubricants as part of this work. The sheet materials investigated are an aluminum material (AA6014) and two steel materials (DC04, DP800), each with a thickness of 1.5 mm. All sheet materials were examined in the as-delivered condition as part of this work. The hypothesis for this research proposal is that it is possible to achieve comparable tribological properties in sheet metal forming using water-based lubricants as when using mineral oil-based lubricants. The aim is to optimize a tribological system for water-based lubricants when used as additional lubrication in order to replace mineral oil-based lubricants and, as a result, to shorten the representative process chain by one process step (cleaning). In the course of this work, topographical measurements of the sheet materials were carried out in order to investigate the lubricant holding capacity of the sheet materials. Furthermore, strip drawing tests were performed to determine the friction coefficients of the different lubricant-sheet combinations. The final step was to conduct deep-drawing tests to determine the limits of use of the water-based lubricants by continuously increasing the holding-down force.

Data-Driven Approach for Minimizing Springback in Roll Forming: An Adaptive Process Parameter Control Strategy

Springback is the most common quality defect in roll forming. It is difficult to control springback efficiently because the forming process is very complex and difficult to analyze. This paper proposes a data-driven springback control method that can adaptively adjust process parameters to minimize springback. Firstly, a digital twin model was established for efficiently collecting equipment data, formed part data, and remote equipment control. Then, based on gathered springback data considering different sheet widths, materials, uphill volumes, and roll gaps, a high-precision springback prediction model was constructed using the SAPSO-SVR algorithm. Lastly, building upon the prediction model, optimization models were developed using bat algorithm, enabling the system to automatically adjust process parameters based on optimization results when forming different sheets.The experimental results show that after optimization, the springback at the two corners of the hat-shaped part is reduced by 36.8% and 14.3% respectively. Experimental findings initially demonstrate the efficacy of this approach in controlling springback across sheets of diverse materials and varying widths. The proposed adaptive springback control method significantly enhances production efficiency and forming quality, driving the intelligent advancement of sheet metal roll forming technology.

Research on Damage Evolution in Ultra-thin Sheet Material under Deep Drawing and Ironing Process

In this paper, the effect of damage induced in deep drawing and ironing processes on the subsequent service performance of deep drawn cups was investigated. To obtain the cups with different amount of deformation damage, three kinds of drawing tests including one-stage deep drawing, two-stage deep drawing, and two-stage deep drawing and ironing were conducted using a 0.3 mm interstitial-free steel sheet. With help of the DF2015 ductile fracture model, the damage evolution of the drawn cups was calculated. Moreover, ring specimens cut from the side walls of the drawn cups were tested in a specially designed tension platform. The load F max and displacement x corresponding to the maximum load point, and the difference in displacement dx from the maximum load point to the fracture initiation point of ring tensile specimens were used as indicators to evaluate the effect of accumulated damage on the subsequent service performance of the parts.

Wrinkling Determination in Sheet Metal Loaded by Shear Stresses

Lightweight concept approach in sheet metal forming requires, among others, thickness reduction and geometry complexity. This combination dramatically promotes the wrinkling occurrence, which can be considered as one of main failure mode that toolmakers must consider. The sheet metal wrinkling determination research usually considers the wrinkling in flange and conical area of a cylindrical cup. For complex geometries the loadings are more diverse than in the deep drawing of a cylindrical cup involving shear stress states. In this context, the present work proposes the application of two different wrinkling determination methodologies in an experimental sheet metal specimen loaded by shear in an aluminum alloy. One of the methodologies involves geometrical parameters to trigger the onset of wrinkling and the other methodology is physically based and considers the evolutions of the in-plane minor strain and its strain rate. The experimental formability test requires a dedicated clamping apparatus to allow its kinematics to be similar to a tensile test. Results allowed the identification of the stress state that triggered the wrinkling occurrence, and the determination of the critical strains that allow plotting the wrinkling limit curve of the sheet material.

Microstructure evolution of Incoloy 800H in industrial environment and correlation with creep mechanisms from literature

ABSTRACT The microstructures of 800 H samples affected by natural corrosion within industrial-like environmental conditions have been studied, and their potential effects on the creep response have been investigated based on literature information. Smooth cylindrical specimens of the alloy extracted from rolled sheet material have been placed into an industrial furnace, where they were exposed to high temperature thermal cycles within an air atmosphere. Samples spending 0 to 5 years inside the furnace underwent a microstructural characterisation campaign. Optical microscopy images reveal no grain coarsening. Macroscopic Vickers hardness shows a relatively wide surface hardness range (115≲HV10≲140). Compared to as-received material, micro-hardness profiles from specimens after years of high-temperature exposure exhibit a surface hardening trend within the vicinity of the edge exposed to the environment. Scanning electron microscopy analyses revealed two coexisting corrosion mechanisms: oxidation and nitridation. The latter is identified as the cause of the micro-indentation hardening trend.

A Combined simulation and experimental investigation on tool radius influence on enhancing the formability SPIF process for Al1050 sheet material

This research presents a comprehensive investigation into the pioneering domain of single point incremental forming (SPIF), focusing on elucidating the nuanced interplay between tool radius and formability. By employing a combination of rigorous simulation and experimental methodologies, the study sheds light on the pivotal influence of tool radius on forming performance. Various tool radius values spanning from 2 to 7 are systematically tested in conjunction with corresponding forming angles, revealing crucial insights into their synergistic effects. A critical threshold radius (Rt) is discerned, representing the point at which optimal formability is attained. Below this threshold, a decline in formability is observed, attributed to excessive surface cutting and metal pressing phenomena evident in tests utilizing pointed tools. Finite element (FE) analysis corroborates these findings, demonstrating that compression beneath the tool center induces unstable strain, consequently diminishing forming height as tool radius decreases. Conversely, beyond the Rt, an increase in tearing is noted due to reduced compression. This underscores the delicate balance required in selecting an appropriate tool radius to maximize shaping capacity in SPIF processes. Importantly, the research highlights the significance of achieving high compression capacity alongside an optimal tool radius, emphasizing the intricate yet essential factors influencing SPIF’s formability and shaping capabilities. Furthermore, this study contributes to the advancement of SPIF technology by uncovering novel insights into the dynamic relationship between tool geometry and formability, thereby paving the way for enhanced process optimization and design in various manufacturing applications. This research delves into the innovative realm of SPIF by exploring the intricate relationship between tool radius and formability. Through meticulous simulation and experimentation, the study unveils the pivotal role of tool radius in forming performance. The different values of tool radius, ranging from 2 to 7, are coupled with appropriate forming angles. A critical Rt is identified, where optimal formability is achieved. Conversely, below this threshold, formability declines due to excessive surface cutting and metal pressing, observed in tests employing pointed tools. FE analysis substantiates that compression below the tool center triggers unstable strain, diminishing forming height with decreasing tool radius. Notably, above the Rt, an increase in tearing is observed due to decreased compression. In this context, attaining high compression capacity alongside an appropriate tool radius emerges as the key to maximizing shaping capacity in SPIF.

PENGEMBANGAN MEDIA PEMBELAJARAN UNTUK MATA PELAJARAN KEWIRAUSAHAAN DI SMK DENGAN MENGGUNAKAN APLIKASI MACROMEDIA FLASH

Development of entrepreneurial learning media is simple, attractive, effective and efficient and whether the development of the media can improve student learning outcomes. This study aims to (1) Produce a simple media entrepreneurial learning, quality, attractive, effective and efficient form of a product (software) for vocational students of class X, (2) Examine the impact of the use of instructional media to see the difference in the value of the pre-test before using product (software) with a post-test after using the product (software). This study is a research and development by following the model of the development of Lee & Owen which consists of five phases: (1) the stage of analysis (analisys), (2) the stage of design (design), (3) the stage of development (development), (4 ) phase of implementation (implemantation), (5) the stage of evaluation (evaluation). Development focused on entrepreneurship subjects of class X SMK first semester. Before the products tested beforehand validated by experts of material and media expert. Furthermore, the product tested to students through the three stages of testing individual, small group testing, and field trials. Subject product trials are students of SMK Negeri 1 Sarolangun class X. subject of this research trial for individual testing consisted of three students, to test a small group of ten students, and for field trials consisted of 30 students. The data collected in this study is the data of expert materials, data from media experts, and student response data from the aspect of media appeal. Data collection instrument in the form of sheet material and a questionnaire to experts and media expert questionnaire sheet to subject individual testing, piloting small groups, and field trials. Analysis of data using qualitative descriptive analysis. The results showed: (1) the quality of instructional media development with Macromedia Flash applications vocational entrepreneurship subjects in terms of aspects of material including both criteria. (2) in terms of aspects of media including both criteria. (3) student responses about the appeal of media including very interesting criteria (4) an increase in the value of the average post-test of the pre-test of 23.20% of the 30 students on field trials, with 27 students (90%) have achieved mastery learning. Based on these results, it can be disimpulkn that products developed instructional media is fit for use as a source of learning for students. Keyword: Software CPB media entrepreneurial learning.

STUDY OF PHYSICAL PROPERTIES MECHANICAL PROPERTIES AND THE DEVELOPMENT OF PARTICLEBOARD FROMDURIAN PEEL USING A COMPRESSION MOLDING PROCESS

This research is the process study of producing particleboard from durian peel using the compression molding process. These studies are the physical and mechanical properties of particleboard from durian peel. The results found that the flexural test and the tensile test of furniture material sheets from durian peels at a ratio of durian pulp to glue water were 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, and 1:1.5, respectively. A specimen with dimensions of width 50 x length 200 x thickness 10 millimeters was tested with a machine. The universal testing machine of six samples in each ratio. It shows that the mechanical strength values increased when the ratio of water mixed with glue increased. The durian pulp has a better adhesion. This results are in a higher density as the ratio increases and at the ratio of 1:1.5, it has the highest strength and an average flexural strength of 5.74 MPa but it has not yet passed the criteria set by TISI 876-2004 with a flexural strength of not less than 14 MPa for plywood sheets with a thickness exceeding 6.0-13.0 millimeters. It has an average tensile strength value perpendicular to the surface of 0.49 MPa, which passes the criteria set by TISI standard, with the tensile strength value perpendicular to the surface not less MPa. than 0.40 for plywood with a thickness of more than 6.0-13.0 millimeters. For the testing of the burning rate of particleboard made from durian peels, it was found that the burning rate decreased when the ratio of water mixed with glue increased due to the increasing density of the workpiece at a ratio of 1:1.5 and it can stop the combustion by itself.

The effect of texture on the very high cycle fatigue performance and deformation mechanism of rolled AZ31B magnesium alloys

AbstractRolling can result in anisotropy in the microstructure and mechanical properties of the sheet material. This study focuses on the very high cycle fatigue (VHCF) performance of magnesium alloys in the rolling direction (RD), normal direction (ND), and the bisecting angle between the ND and RD (ND–RD). The findings reveal that RD specimens demonstrate superior fatigue performance, while the ND specimens exhibit the lowest fatigue resistance. During the crack initiation stage, the primary influential factor is the maximum shear stress. Due to c‐axis alignment with ND direction in grains, the deformation mode for ND and RD specimens primarily involves first‐order pyramidal slip, while ND–RD specimens primarily undergo basal slip and prismatic slip. In early stable crack propagation, grain size and texture cause variations in the morphology of the rough area among the three directional specimens. Notably, the RD specimens show faster crack propagation during crack initiation than early stable propagation stage.

Improved thermal properties of phase change composites reinforced by Cu nanoparticles modified anisotropic carbon rolls

The scalability of phase change materials (PCMs) for industrial applications is impeded by issues such as leakage during phase transition, suboptimal thermal conductivity, and insufficient photothermal absorption. This research introduces advanced phase change composites (PCCs) reinforced by Cu nanoparticle-enriched porous carbon rolls. These rolls are derived from cotton cloth sheets and are serviced as a scaffold to embed Cu nanoparticles, substantially enhancing interlayer thermal transport. The PCCs are synthesized through a vacuum impregnation process, utilizing paraffin wax as the PCM, yielding a composite with augmented thermal conductivity and improved structural integrity. This innovation elevates anisotropic thermal conductivity values, achieving axial and radial conductivities of 3.4 W/(m·K) and 2 W/(m·K), respectively. The PCCs exhibit advanced solar-thermal-electric energy conversion performance, positioning them as impactful materials for applications in solar energy collection, thermal energy storage, and thermal management.

Freeform Shape Fabrication by Kerfing Stiff Materials

AbstractFast, flexible, and cost efficient production of 3D models from 2D material sheets is a key component in digital fabrication and prototyping. In order to achieve high quality approximations of freeform shapes, a common set of methods aim to produce bendable 2D cutouts that are then assembled. So far bent surfaces are achieved automatically by computing developable patches of the input surface, e.g. in the context of papercraft. For stiff materials such as medium‐density fibreboard (MDF) or plywood, the 2D cutouts require the application of additional cutting patterns (“kerfing”) to make them bendable. Such kerf patterns are commonly constructed with considerable user input, e.g. in architectural design. We propose a fully automatic method that produces kerfed cutouts suitable for the assembly of freeform shapes from stiff material sheets. By exploring the degrees of freedom emerging from the choice of bending directions, the creation of box joints at the patch boundaries as well as the application of kerf cuts with adaptive density, our method is able to achieve a high quality approximation of the input.