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In recent years, hemp or flax fibers have shown a reinforcement potential that is not fully exploited, because reinforcements often come in short fibers and agro-composites are very sensitive to the quality and type of reinforcements. Associated with a polymer matrix, these reinforcements make it possible to develop agro-composites with high mechanical, thermal, phonic performance, etc. as well as good fitness. In this context, we want to master the development and characterization of high-performance agro-composites based on natural fibers by different shaping techniques (compression, injection or 3D manufacturing)., Ces dernières années, les fibres de chanvre ou du lin affichent un potentiel de renforcement qui n’est pas entièrement exploité, car les renforts se présentent souvent en fibres courtes et les agro-composites sont très sensibles à la qualité et au type de renforts. Associé à une matrice polymère, ces renforts permettent d’élaborer des agro-composites avec de hautes performances mécaniques, thermiques, phonique etc. ainsi qu’une bonne aptitude à la mise en forme. Dans ce contexte nous souhaitons maitriser l’élaboration et la caractérisation des agro-composites hautes performances à base de fibres naturelles par différentes techniques de mise en forme (compression, injection ou fabrication 3D).

A newly five-component equimolar high-entropy ceramic – (La0.2Eu0.2Gd0.2Y0.2Yb0.2)2Zr2O7 with a mixture phase of pyrochlore and fluorite structure was successfully synthesized. On this basis, a series of systematically designed and synthesized high or medium-entropy ceramics, accompanied by a large number of previous reports on multi-component rare earth zirconates, were summarized to jointly investigate the single-phase forming ability of high-entropy rare earth zirconates ceramics (HE-RE2Zr2O7 for short) in terms of entropy value and cationic radius difference ( δ ). Subsequently, the forming process and mechanism of dual-phase solid solution were analyzed. The conclusions indicated that the single-phase forming ability was more determined by the cationic radius difference rather than the entropy value，and the critical value of δ distinguishing single-phase between dual-phase zone was around 5.2%. In addition, the formation of dual-phase solid solution was essentially driven by the size disorder resulting from rattler effect of cations with significant difference in radius. This work is the first report on the single-phase forming ability of HE-RE2Zr2O7 and would pave new ways for predicting the formation of high-entropy phases.

Metal sheet forming is widely used in industrial field. Generally, the use of patchwork banks allows the manufacturing of a more uniform thickness of the formed parts. Often, they are obtained using welding techniques: in these cases, distortions and localized metallurgical transformations could have detrimental effects on the mechanical performance. Moreover, it is not possible to weld very thin patches. In this paper, an innovative approach based on bonded patches has been developed and investigated. In this manner, it is possible to adopt thinner patches, doing away with the problems arising from the welding process. Experimental tests showed the potentiality of using adhesives in forming processes to influence the thickness distribution. Moreover, the commercial code PAM-STAMP has been used for modelling the forming process. In this way, the effects of the thickness of the patch and the friction conditions on the strain state generated on the patchwork blanks have been investigated.

Uncontrolled residual stresses have significant effects on the service time and defects of the spun parts. Nowadays, X-Ray Diffraction (XRD) method has been widely used in the residual stress measurement of industry products with different forming processes. The calculated residual stress is usually obtained from the data fitting slope of strain and angle with Ordinary Least Squares (OLS) method. But this fitting method is not always suitable for the big fluctuant data. In this paper, the Weighted Least Square (WLS) method is used for the data fitting and compared with the OLS method. The nickel-based superalloy GH3030 and iron-based superalloy GH1140 are applied in the multi-pass cold spinning experiments. The residual stress distributions of normal, potential crack and wrinkle workpieces are discussed with the grain structure. The results show that WLS method has better goodness of fit compared with OLS method. The residual stress distributions have special relationship with potential crack, wrinkle workpiece and grain structure.

Recently Ukrainian scholars of ethnomusicology have increasingly turned to the theoretical understanding of the structural components of folk writings. This is, first and foremost, the study of the rhythmic forms of verse, stanza and their melodies, because, in fact, they are decisive in the genre classification and systematization of folklore, in particular ritual. The purpose of the article is to prove, on the basis of a large number of generous paradigms and their variants, which are still stored in the active and passive repertoire of older singers in the territory of West Podillya, the rhythmic form of the poem and 5+5 tunes. The most common (typical) rhythmic forms of the poem in the shchedrivkas of the Western Podillya include the tenth component of 5+5. It covers 55% of all the generous paradigms we explore and their variants. This rhythmic form is one of the oldest not only in Ukrainian folklore, but also in Eastern Slavic. It creates a genetically source base for its derivatives. The article analyzes the rhythmic form of the verse and melodies 5+5, which is characteristic of the shchedrivkas of Western Podillya and is a peculiar mode of their thinking. It is proved that this rhythmic form is most often used in the songs of this genre in the studied ethnographic region and has the widest scale of structural and syntactic creation. It is found out that the standard syntactic level is a one-line stanza 5+5 with a single-line swirling, which has nine modifications, ranging from the three folders and ending with the sixteen clusters. The structural parameters of the ten-factor construct 5+5 were determined and the evolution of its formation at the level of musical syntax was traced. The influential layers that took place in the shchedrivka genre under the influence of Christianization of songs of this genre are considered. The sapphic stanza, which is characterized by the most widespread in the field of shchedrivka “The lily grew in the lord’s garden”, was analyzed, and it was stated that it was formed under the influence of the medieval Latin versioning and thus adapted to ritual folk-verse genres. Thus, as the analysis of the 220 bounties recorded in the territory of the West Podillia shows, the rhythmic form of the poem and melodies 5+5 are dominant in them. The stanza with this rhythmic form has the broadest scale of structural and syntactic creation. This kind of construction is often a single-line with a single-line chorus, which has nine chorus modifications, ranging from a threeparter to a sixteen-parter. In analyzing this rhythmic form, we traced the evolution of its formation and development at the level of musical syntax and affinity with a similar Christmas rhythmic form., У статті проаналізовано ритмічну форму вірша і мелодії 5+5, що властива щедрівкам Західного Поділля та є своєрідним їхнім модусом мислення. Доведено, що така ритмічна форма найчастіше вживана у піснях цього жанру в досліджуваному етнографічному районі й має найширшу шкалу структурного та синтаксичного творення. З’ясовано, що типовою на синтаксичному рівні є однорядкова строфа 5+5 з однорядковим приспівом, який має дев’ять модифікацій, починаючи від трискладника й закінчуючи шістнадцятискладником. Визначено й структурні параметри строфи десятискладника 5+5 і простежено еволюцію її становлення на рівні музичного синтаксису. Розглянуто напливові нашарування, що відбулися в щедрівковому жанрі під впливом християнізації пісень цього жанру. Проаналізовано сапфічну строфу, притаманну найпоширенішій на згаданому терені щедрівці “В панськім городі росла лілія”, й констатовано, що вона сформувалася під впливом середньовічної латинської версифікації і таким чином адаптувалася в обрядові народнопісенні жанри.

In this study, the investigation of effective stresses of Titanium Grade 5 feedstock material during the continuous forming process has been carried out. The numerical simulation has been carried out through a finite element tool DEFORM-3D. The experimental plan and design have been carried out by using Response Surface Methodology (RSM) on MINTAB platform by considering extrusion wheel velocity and feedstock temperature as main extrusion parameters. Effective-stresses of Ti-6Al-4 V alloy have been investigated to understand the deformation behavior for further more applicability of feedstock material in the modern industrial sector and to keep the shoe and other components of the CONFORM machine safe. It has been found that the effective-stress of feedstock material is high in the biting - deformation region and then gradually decreases towards the flowing direction of the material. It has been observed that as the feedstock temperature increases, the value of effective stresses which occur in other region decreases to some extent. So, the result concludes that increasing extrusion wheel velocity and feedstock temperature of alloy will reduce the shear strength of feedstock material during the continuous forming process. Therefore, the load requirement for deformation can be reduced. Moreover, the wear of extrusion shoe which is one of the most important elements can also be minimized thereby enhancing the life of extrusion shoe material.

The void closure model is urgently needed for the subsequent hot forming process of additive manufacturing (AM) products. The influence of temperature, Lode parameter, and hydrostatic integration (Gm) on void closure was studied by representative volume element (RVE) simulations. The results show that Gm and the Lode parameter significantly influence void closure, and the temperature effect is related to material properties. A new model accounting for Gm and Lode parameter in evaluating void closure was developed using linear regression with an average error of 2.1% in comparison to RVE simulations. X-ray computed tomography (CT) was carried out at different high reductions for the AM cylinder's hot forging experiments. The new and stress-triaxiality-based (STB) models were integrated into the ABAQUS and compared with the CT measurements. Results indicate that the model is more precise than the STB model, suggesting that the model can be appropriately applied to forecast void closure during the hot forging process for AM products.

In the face of global warming, sustainability has become a hot topic. Sustainable manufacturing aims to analyze and improve industrial processes to mitigate their negative impact on the environment in terms of energy use and greenhouse gas emissions. In terms of sheet metal forming, and especially in incremental forming processes, it is important to study how to manipulate parameters in a way that reduces energy consumption and CO2 emissions without degrading the quality of the final product. These impacts can be controlled by the manipulation of process parameters such as: rotational speed of the tool, radial displacement, and axial advance per pass. The main objective in this study is to determine energy savings and reduce CO2 emissions caused during the forming processes. The present work shows the experimental analysis for a steel sheet (ASTM A653), subjected to a conventional forming process through a simulation that reproduces the process conditions, providing the consequent energy consumption. Additionally, the single-point incremental shaping process is experimentally developed using current- and load- sensors that record the energy consumption of the process in real-time. The results obtained clearly determine the nature of the analyzed processes in a way that reduces energy consumption and CO2 emissions, which in turn improves the process in terms of overall sustainability.

The 3D printing thixo-forming process is a method that utilizes semisolid thixotropic feedstock for layer extrusion by controlling feedstock viscosity below the complete melting temperature of metallic alloys to form a 3D structure. The process of producing metallic feedstock has a significant impact on alloy microstructure, which is critical for the material’s printability. This study aims to propose a semisolid heat treatment processing window of Pb-40% Sn alloy for use as feedstock billets for a variety of extruder nozzles (sizes 1–3 mm) during the 3D printing thixo-forming process. Firstly, Pb-40% Sn alloys were cold deformed to reduce the specimens’ diameters. Semisolid treatments for deformed specimens were performed at a variety of semisolid heating temperatures and three separate holding times (2, 5, and 10 min). The microstructure of semisolid feedstock specimens was then investigated. The temperature and time of the semisolid heating processing window of Pb- 40% Sn alloy were optimized to feedstock specimens and thixo-extruding processes with different printed output sizes. Therefore, the proposed semisolid heat treatment processing window was a promising approach to pave the way for the low-cost manufacturing of AM, which yields higher printing rates and improved scalability of printed lines. Additionally, this approach allows for a versatile manufacturing route for producing 3D metal parts with maximum density and intricate geometries as a result of the ability to tailor the microstructure.

The inverse problem of determining how to shot peen a plate such that it deforms into the desired target shape is a challenge in the peen forming industry. While peening thick plates uniformly on one side results in a spherical shape, with the same curvature in all directions, complex peening patterns are required to form other shapes, such as cylinders and saddles found on fuselages and wing skin panels. In this study, we present an optimization procedure to automatically compute shot peening patterns. This procedure relies on an idealized model of the peen forming process, where the effect of the treatment is modeled by in-plane expansion of the peened areas, and on an off-the-shelf optimization algorithm. For validation purposes, we peen formed three 305 × 305 × 4.9 mm and two 762 × 762 × 4.9 mm 2024–T3 aluminium alloy plates into cylindrical and saddle shapes using the same peening treatment. The obtained shapes qualitatively match simulations. For 305 × 305 × 4.9 mm plates, the relative differences had the same distribution and were of the same order of magnitude as initial out-of-plane deviations measured on the as-received plates.

Superplastic Forming (SPF) is the designers first choice for producing the products that have complexity as used in automobiles and aircrafts, in which the ratio of strength to weight is the major concern. SPF of sheet widely used in the manufacture of the products with more significant complexities simultaneously lighter and stronger than with any other manufacturing process. Superplastic formed products having shapes like hemispherical, conical and box results significant variation in thickness. Lowest thickness will be at the locations where the sheet contacts the die at the last. Complexity of the product, forming depth, and pressure affect the thinning. Unmitigated understanding of stress, strain rates, and strains during the forming process and the use of suitable pressures for forming can reduce this problem. In this study Lead & Tin alloy has chosen, as an exemplar material for Superplastic forming to carry out investigations. The results obtained can be applied for any other superplastic materials. The present investigation focused on studying suitable strain rates and Normalized Thickness Variation during the superplastic cone forming. Results revealed that Normalized Thickness Variation (NTV) is lower i.e., 2.27 when formed at the pressure of 3 bar, which provides an equivalent strain rate of 1.1 × 10−4 s−1. Therefore 3 bar pressure is desirable for cone forming. Results also disclosed that strain rates obtained in this investigation are in the limits of superplastic forming zone and hence no fracture happened on the conical dome due to the thinning.

Fracture constantly occurs during the plastic forming processes of thin-walled metal sheets due to the local uneven plastic deformation. During the processes, the sheets may experience different stress states, which are crucial factors related to the fracture. To predict fracture in different forming processes, various uncoupled ductile fracture criteria have been proposed due to their advantages of relatively simple expressions and less modeling parameters. Because each fracture criterion focusses on certain aspects of the deformation behavior, the ability of fracture prediction can be dramatically different. Thus, a systematical study on eight widely applied uncoupled ductile fracture criteria is carried out to evaluate their applicability under four different stress states, i.e. pure shear, dog-bone tensile, notched tensile and hydraulic bulging. Each criterion is numerically implemented and embedded into finite element models and is applied for fracture prediction of an anisotropic aluminum alloy sheet. The prediction results are compared to experimental results and the applicability of each criterion is analyzed.

Reasonable laser process parameters and heating paths are crucial in laser forming (LF) technology. Obtaining the proper laser processing parameters and the heating path is the decisive factor to determine the forming efficiency and precision of the complex 3D surfaces with double curvature. First, the 3D target surfaces with double curvature were developed in this paper to flat plates through the finite element numerical simulation tool, and the magnitude and direction of in-plane and bending strains were obtained; the direction perpendicular to the principal strain is the direction of the heating paths. Second, the database of laser process parameters and principal strains was established to determine the proper laser process parameters. Finally, combined with the above laser parameters and heating paths, the “pillow” and “spherical” surfaces were obtained, and the accuracy of this method was verified by experiments.

A pivotal development of the obsolescence of conventional methods of sheet forming has enhanced the need of augmenting an agile and novel method of fabricating the tailored components according to the requirements of customers and users. Moreover, businessmen are interested to promote their businesses by manufacturing the tailored and customized parts of intricated and complex geometries at a lower cost and with negligible waste. Single Point Incremental Forming (SPIF), also known as “negative incremental forming”, avoids the direct use of any kind of specific die-sets and produces the user-ready parts. The investigation of the surface quality of the formed specimen is important to study the suitability of this process for industrial applications. This paper explores the effects of the interactions of tool radius and forming angle on the surface roughness of parts formed by the SPIF process. A full factorial approach was taken into account as DOE. The average roughness was found to rise with the rise in forming an angle. On the other hand, the increase in tool diameter resulted in the decrease of Ra value of formed components because the increase in the tool diameter allows the decrease in the waviness on the surface of the specimen. It was observed that the Ra value of formed components was decreased by 83.87% when the experimental condition was changed from the combination of higher levels of wall angle (68°) and lower level of tool diameter (7.52 mm) to the combination of lower levels of wall angle (60°) and a higher level of tool diameter (19.50 mm).

Here, in order to develop the metallic materials with excellent relationship between strength and toughness for application, the FeCoCrNi + FeCoCrNiAl-laminated high-entropy alloys (HEAs) had been fabricated by laser melting deposition (LMD) additive manufacturing technique. The process parameter databases for FeCoCrNi and FeCoCrNiAl HEAs were built by orthogonal experiments and statistics method, which helped to select the optimised process parameters for the two HEAs. Then, the differences in the forming process, phase structure, and grain morphology of FeCoCrNi and FeCoCrNiAl HEAs were systematically investigated during the fabrication of the FeCoCrNi + FeCoCrNiAl-laminated HEAs. The results show that variations in surface tension, wettability, and other physical properties between the two HEAs led to significant differences in their LMD processes. Al not only influenced the fabrication process of both HEAs, but also promoted the phase transition from FCC (FeCoCrNi) to BCC (FeCoCrNiAl). In addition, Al also acted as a strong limiting factor to inhibit the effect of supercooling on the grain morphology, which transformed from coarse columnar grains to fine equiaxed grains. The columnar grains, with a preferred orientation in the FeCoCrNi-deposited wall, promoted the suppression of the inhibitive effects of the phase structure and strong limiting factor, led to the growth of the columnar grains in the FeCoCrNiAl-deposited wall, and helped achieve long-distance continuous growth of columnar grains across the interface in the subsequently deposited wall. The methodology used in this study could be meaningful for the exploration of process parameters of LMD, and the discoveries of grain characteristic help to understand the microstructure transition in laminated heterogeneous HEAs fabricated by laser additive manufacturing.

Yuhengtang is a representative slate-hosted Au deposit in the Jiangnan orogenic belt, South China, with a reserve of ~55 t Au and an average grade of ~3.9 g/t. Gold mineralization is characterized by veinlet and disseminated ores comprising native gold, auriferous pyrite, and arsenopyrite. Paragenesis of the Yuhengtang deposit can be divided into three stages. Pre-ore stage 1 is composed of bedding-parallel layers of pyrite in slate of the Neoproterozoic Banxi Group. Main ore stage 2 represents the Au mineralization stage, and two distinct types of mineralization can be distinguished: visible Au-arsenopyrite-pyrite in quartz veinlets and auriferous arsenopyrite-pyrite disseminated within altered slate. Post-ore stage 3 consists of quartz-pyrite-calcite-ankerite veins. In this study, we integrate electron microprobe, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and high-resolution ion microprobe (SHRIMP) analyses to document textural, isotopic, and compositional variation among texturally complex pyrite and arsenopyrite assemblages in veinlet and disseminated ores. Additionally, LA-ICP-MS sulfur isotope mapping of pyrite highlights the covariation behavior between trace elements and sulfur isotopes at the grain scale, thus allowing the factors controlling sulfur isotope fractionation in hydrothermal Au deposits to be constrained. Pyrite, of sedimentary origin (stage 1), hosts negligible Au ( All results support that multiple depositional mechanisms within a dynamic mineral system were responsible for Au concentration and define the specific textural, compositional, and sulfur isotope signatures of sulfides in coexisting vein/veinlet and disseminated mineralization. The new data highlight the ore-forming processes-based interpretation for ore genesis and underpin the importance of performing complementary in situ mineralogical analyses to elucidate the source and evolution of ore-forming fluids and enable correct interpretation of the architecture of the hydrothermal Au system.

To study the effect of the lime-soil compaction pile on the collapsible loess foundation and the influence of water-heat-force characteristics on the soil during compaction, the field test of lime-soil compaction pile treatment of collapsible loess foundation is carried out. This paper monitors the process of soil temperature, water, and soil pressure change in the process of pile forming. According to the macroprocess and micromechanism of lime-soil compaction pile treatment of collapsible loess foundation, the qualitative law of water-heat-force change in the process of pile forming is obtained. Meanwhile, the influence of soil damage is introduced in the process of compaction expansion. The model of pore expansion under linear damage conditions in the plastic zone is established. The formula of radial stress distribution under damage conditions is given. The influence of different damage factors on the expansion process is analyzed.

The single-point incremental forming process has witnessed significant advantages in automobiles, aerospace, and medical applications in recent years because of its flexibility in manufacturing complex shapes. In detail, the components are produced only using the toolpath, which is guided by computer-aided manufacturing software. However, during the forming process, the parts might experience fractures, which could heavily impact the formed part's geometric accuracy. The main purpose of this study is to analyze the formability of an AA3003-H18 aluminum alloy material in the SPIF process; for this purpose, the material properties are extracted from the experimental simple tensile test in three directions corresponding to the material rolling direction. At first, a simple tensile test is modeled and estimated the material properties for conducting the numerical simulations. Second, the real-time experiments of the SPIF process in terms of predefined forming conditions are performed, and then the surface roughness was measured to check the surface quality of the formed parts. Then, the formed parts are scanned using a 3D ATOS scanner and compared against the desired computer-aided design (CAD) model. Eventually, the numerical results are discussed in comparison with the experimental outcome and displayed a significant correlation toward the expected results. This results comparison communicates that the introduced finite element (FE) model can be adopted for investigating the appearance of thinning location, thinning reduction, distributions of stress and strain. The overall results show that satisfying material formability in better surface finish and geometric dimensional accuracy can be accomplished when the forming conditions are designed appropriately.

The effects of the curing degree of the adhesive during clinching on the forming process and the mechanical performance of the clinch-adhesive joints made of AA5754 Aluminum Alloy, Q235 steel, and ...

Cold helical rolling (CHR) is one of the most effective ways to produce small-diameter steel balls. In this study, one kind of work hardening model was established and implemented into Simufact 15.0 to investigate the work hardening phenomenon in the cold forming process. Firstly, based on the helical rolling theory, a set of finite element (FE) simulations was developed. The influence of CHR parameters, including the starting height of convex rib, forming area length, and rolling inclination angle, on the forming process was studied via simulation. Furtherly, the CHR process experiment and FE simulation were carried out; the results showed that the FE simulation was in good agreement with the experimental results and consistent with the predicted value of the theoretical calculation. Finally, the evolution of effective strain, effective stress, rolling force, work hardening, and microstructure during the cold helical rolling of Φ 5.2-mm steel balls was investigated via FE. As a result, the evolution trend of hardness was consistent with that of dislocation density, indicating that the model is credible. Besides, the microstructure of the steel ball at different positions further verified this point.

Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion forming process for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container, the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can be realized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at the forming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased with the increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated that metallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperature was 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transition layer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technical reserves for green forming of Mg/Al sheets.

The superplastic forming process has been used extensively in aerospace applications for its advantages in manufacture of complicated components. But it has been limited to the long production cycle and the non-uniform thickness distribution of the final formed part. The two-stage SPF process in opposite directions for 5083 aluminum alloy door frames was investigated. A finite element model in PAMSTAMP was used to simulate the forming process. Analyzed the effect of pre-forming die parameters on the minimum thickness of the final formed part by the Response Surface Methodology and optimized the pre-forming die parameters. Moreover, the influence of different rated pressure on the forming quality and forming time of the door frames under the same strain rate were investigated to determine the ideal pressure profile. The result was that the minimum thickness meets the requirements (thinning not exceeding 40%) while reducing the production cycle. Finally, the two-stage superplastic forming experiment in opposite directions was conducted to verify the accuracy of the numerical simulation and produce the door frames with high quality.

The wrinkling-free forming method for sheet metal forming based on the low-melting alloy (LMA) is a novel sheet forming method. The LMA as a forming pressure medium to transfer loading force is utilized to prevent bulking and wrinkling occurrence in the sheet forming process due to the its controllable fluidity by adjusting the heating temperature. In the forming process, the upper and lower surface of blank were acted by continued loading force resulting from LMA flowing. In this study, the high-temperature mechanical properties of LMA were obtained by heating tensile test for preparation of simulation. The rheological behavior of LMA during the forming process was analyzed numerically. And the effect of LMA layer thickness, forming force and mold structure on the thinning of the formed parts was studied. With obtained results, the characteristic of wall thickness distribution and the effect of rheological behavior on thinning of formed part were comprehensively revealed. Moreover, the experimental results agree with those in numerical simulation by measuring the wall thickness of the formed specimen.

The stress state of the sheet has a significant influence on the formability during the sheet metal forming process. Some research has shown that the through-thickness shear stress on the sheet can improve the formability of sheet metal. In order to provide a complete picture about the reasons and ways that the through-thickness shear stress affects the formability, this paper analyzes and summarizes the effects from three aspects: theory, numerical analyses, and experiments. Besides，the methods of generating through-thickness shear stress are discussed, and the research progresses of the M-K model considering the through-thickness shear stress are reviewed. Based on the establishment of the extended M-K model, the forming limit considering the through-thickness shear stress is predicted, and the mechanisms of through-thickness shear stress improving the formability are analyzed further. The numerical methods of analyzing through-thickness shear stress improve thickness uniformity of the sheet are also reviewed. The design of experimental setups and experimental methods for studying the influence of through-thickness shear stress based on friction and the interface tangential viscous adhesion stress on sheet formability are analyzed and compared. Finally, the future research orientation of the through-thickness shear stresses is proposed.

Due to the poor formability of zirconium alloy, crack is one of its most common failure modes when the alloy is used for strips of spacer grids of nuclear fuel assembly during the sheet forming process. In this paper, the relationships between processing parameters (including punching speed, stamping clearance and blank-holder force (BHF)) and the crack risk of sheet forming process are discussed. A continuous forecasting model is constructed by using support vector machine regression (SVR) method. The maximum thinning ratio (TMTR), which is usually used as an index to quantitatively evaluate the crack risks during sheet forming, serves as the output while the processing parameters as the input variables of the forecasting model. The performances of the SVR model are assessed by six different regression metrics and results are compared with five other machine learning models. The evaluation results demonstrate that the SVR model has the best performance (with a relative mean error of 2.76% and the value of R 2 0.939) and the capacity to accurately predict the maximum thinning ratio of the sheet forming process of zirconium alloys. The coupled and interactive effects of the processing parameters on the sheet forming are also analyzed through the results of the forecasting model.

A new technology of metal fused-coating additive manufacturing composite variable polarity tungsten inert gas (MFCAM and TIG) is adopted. Based on the analysis of the heat input during the forming process, the method for controlling morphology defects of thin-walled specimens is obtained. Considering the collapse of the starting and tail of the thin-walled samples, a new method is proposed to control the arc extinction by section attenuation. The wavy surface appearance caused by heat accumulation is solved by the combination control. The height direction stability of thin-walled specimens is improved by 8.2%. The thin-walled samples of aluminium alloy with material utilization more than 95% can be prepared, and the dimensional accuracy Wa is 0.42; thus, excellent sample would be obtained.

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.

Fresnel lenses are important compact optical components, which are comprised of multiple faceted concentric rings. These lenses are the most widely utilized diffractive optical element in the industry and has been extensively applied in various optical systems due to their distinct advantages. These include the reduction in the lens thickness, smaller occupied volume and less material required compared to their conventional spherical and aspherical counterparts. In general, the processes to manufacture Fresnel lenses can be categorized into two distinct groups: subtractive fabrication and precision forming. Precision forming processes, like molding and embossing, are usually used in mass production to replicate the optical features and profiles usually employ the use of lens molds generated by subtractive fabrication processes. Thus, the process of molding Fresnel lenses are not substantially different from that of conventional molding processes for other optical components, still relying on the accuracies of the molds utilized. Unfortunately, there is a lack of a comprehensive study to summarize and evaluate the recent advances of UPM techniques to generate these optical Fresnel lens structures. Fresnel lenses and molds differ from each other in terms of lens design, work material and tool/workpiece geometries, and such variations will then drive the development of different machining and characterization methods in terms of tool setting, tool wear, tool path generation as well as lens measurement. This paper summarizes the existing fabrication techniques to generate these lens structures, excluding molding. In addition, a discussion and analysis of the strengths and future areas of research interest of the reviewed techniques are conducted. This review is believed to be helpful and educational for the progress and further development of machining of ultra-precision Fresnel lens structures for advanced optical applications.

Considering the fact that the most of the human equipment developed by forming processes, one of the methods of producing these materials is through the metal forming process. In Industrial process, prediction of the final dimension of the part after unloading is an essential problem. Thickness distribution is the geometric change made to a part at the end of the forming process when the part has been released from the forces of the forming tool. In this study, the effects of grain size and sheet thickness on the formability of annealed copper sheets in the deep drawing process were studied. To this end, the effect of friction coefficient was evaluated for a total of 64 different cases by the finite element method (FEM). The effect of optimal parameters and grain size on the maximum deep drawing height (DDH) and thickness distribution of the square part was investigated. According to the literature review, punch and die radii uses were spotted. Based on the simulation software, the best thickness distribution was obtained in no-friction force between tools. According to the experimental results, as the grain size increased from 33 to 161 μm and from 25 to 158 μm, the thickness of wall and bottom specimens was increased, and the corner was decreased.

Due to the increased integration of functions, many components have to meet high and sometimes contradictory requirements. One way to solve this problem is Tailored Forming. Here, hybrid semi-finished products are manufactured by a joining or cladding process, which are then hot-formed and finished. For the design of hybrid components for a possible later industrial application, knowledge about properties of hybrid components is required. In this paper it is investigated how the respective process steps of the Tailored Forming process chain change the surface and subsurface properties of the applied cladding layer. For this purpose, shafts made of unalloyed steel are provided with a high-alloy austenitic steel X2CrNiMo19-12 cladding by laser hot-wire cladding. Subsequently, hot forming is carried out by cross-wedge rolling and the finishing by turning and deep rolling. After each process step, the subsurface properties of the cladding such as microstructure, hardness and residual stress state are examined. Thus, the influence of different process steps on the subsurface properties in the process chain of manufacturing hybrid shafts can be analyzed. This knowledge is necessary for the specific adjustment of defined properties for a required application behavior.

The contribution deals with the optimization of the forming process with the use of FE analysis. The impact of the planar anisotropy and friction coefficient on the drawing process was evaluated in the numerical simulation. Optimization of metal blank size and shape with the use of metal forming simulation was also performed. Studied material was galvanized drawing quality steel which is used for the production of the rain gutter end cap. Effects of planar anisotropy and friction coefficient on the quality of steel stamping were evaluated with the use of FE simulation. The effect of anisotropy was also experimentally tested. The aim of this work was to determine the correct steel blank size and shape and to evaluate the effects of planar anisotropy on the thickness variation and wall wrinkling.

In this paper, forming limit diagram (FLD) of aluminum/brass two-layer sheets through an incremental forming process (ISF) was studied numerically and experimentally. At first, the two-layer aluminum 1050/brass (65% copper) sheets were fabricated using the roll bonding process. Also, the finite element simulations of the incremental forming process with ABAQUS software were utilized to predict the FLD. For this purpose, the criterion of the second derivative of the equivalent plastic strain was used to predict fracture. Finally, the numerical simulation results were compared with the experimental results. For instance, comparing experimental and numerical FLD0 values for the formed samples with forming angle 62.5-degree showed a 7% difference. However, the difference was negligible, and numerical simulation results could be used with an appropriate reliability coefficient. The effect of sheet arrangement towards tools was then investigated. It finds out from the experimental results that the formability of the Brass/Al (brass was up layer and aluminum was bottom layer) was more than the Al/Brass (aluminum is up layer and brass is bottom layer). In the following, the ISF parameters such as forming limit angle, step-down, and thickness distribution were investigated.

To reduce the springback after sheet stamping, two forming processes which include electromagnetic forming (EMF) were designed. Compared with traditional electromagnetic-assisted stamping (EMAS), the new methods use the same mold structure and control springback without obvious plastic deformation. The ANSYS and ABAQUS software were used to analyze the influence of different discharge voltages on springback in the two forming processes. The simulation results accurately predict the deformation and springback of sheet metal after quasi-static stamping and subsequent EMF. After coil discharge, the sheet oscillates with high frequency and small amplitude and only exhibits insignificant deformation. With the increase of the discharge voltage, the sheet springback angle decreases. The springback inhibition effect of process 1, in which the sheet corners merely touch the coil surface, is greater than that of process 2, where the sheet was pressed close to the coil surface.

The fracture forming limit diagram (FFLD) is gaining special attention in high strength materials where the necking tendency rarely occurs during sheet metal forming processes. In the present work, the classical Marciniak and Kuczyński (MK) model has been modified by coupling it with different ductile damage models (Cockcroft and Latham, Brozzo, Oyane, Ko, Oh, Rice and Tracey, McClintock and Clift) and anisotropic yielding functions (Hill 1948 and Barlat 1989) to predict the fracture limits of Inconel 625 (IN625) alloy at different temperatures. Firstly, uniaxial tensile testing has been conducted for the determination of important mechanical properties. Consequently, stretch forming experiments have been performed to analyze the forming limits of a material. It has been found that the safe and fracture forming limits of the material increased by approximately 17.26% and 22.22%, respectively, on increasing the temperature from 300 to 673 K. From the comparative analysis of different combinations of ductile damage models and yielding functions, the Cockcroft and Latham (C-L) damage model in combination with the Barlat 1989 yielding function helped in best predicting the theoretical FFLD as it displayed the least average root mean square error (RMSE) of 0.033. The other ductile damage models used for predicting the theoretical fracture limits displayed large error; hence, they should not be considered while designing a critical component in the manufacturing industry using IN625 alloy.

Recently developed anisotropic yield functions can capture the material anisotropic behaviors through parameter optimization. However, sometimes the parameter optimization is not easy and does not always have a unique solution. This paper introduces an anisotropic yield function that does not require the parameter calibration process. This model simplifies the coupled quadratic and non-quadratic yield function in order to directly use the measured on-set of yielding stress and r-value data without the calibration process. The presented model is validated with five different materials for the prediction of stress and strain anisotropies. In addition, a cup drawing simulation is also presented to validate the simplified model in a practical metal forming simulation with the User-defined subroutine of ABAQUS. The results of this paper show that the simplified model can be effectively employed for the simulation of sheet metal forming processes.