bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of machine hammer peening on case-hardened 16MnCr5 gear analogue shafts
Authors: DADGAR Mohammad
Published: April 2024

Abstract. Gears are integral to many mechanical systems, including industrial machinery and automotive transmissions. Subject to significant mechanical and tribological stresses from rotational forces and torque transmission, gears often face challenges like surface wear and fatigue. Enhancing the durability and performance of gears is therefore vital, and this is where manufacturing processes such as Machine Hammer Peening (MHP) come into play. As an incremental forming process, MHP has the potential to substantially increase the mechanical and tribological load capacities of gears. The objective of this study is to assess how MHP can enhance the surface characteristics of case-hardened 16MnCr5 (1.7131) gear analogue shafts, focusing on the reduction of surface roughness and the increase in surface hardness. Such improvements contribute to improved wear resistance, which can significantly extend the lifespan of the gears, ensuring more reliable performance in demanding operational conditions.
Tool path effects on wrinkling in metal sheet incremental roll profiling
Authors: BEIGZADEH Ali
Published: April 2024

Abstract. The paper introduces an innovative Incremental Forming (IF) machine, termed "FlexRoll Bending," designed for flexible sheet forming on straight components. Unlike traditional processes, this machine employs two working rollers that can move along three directions and rotate, eliminating the need for specific dies. The study focuses on an "on-edge forming strategy" to manufacture non-uniform cross-section sheet metal parts, presenting a cost-effective alternative to conventional methods. The experimental setup utilizes a 0.8 mm DD11 steel sheet, and a novel toolpath theory is introduced for calculating the movement of the forming rollers. Numerical simulations in LS-DYNA software assess the impact of different toolpaths on the final geometry, revealing successful part manufacturing without defects using a linear toolpath and identifying wrinkling in a two-stage toolpath. The results demonstrate the potential of the FlexRoll Bending process for die-less manufacturing of complex geometry sheet metal parts with low forming forces.
Investigation of the stress state around the forming zone during the flow form process
Authors: CEBIROGLU Bugra
Published: April 2024

Abstract. Flow forming process is a cold metal forming process, which has great advantages over conventional forming techniques such as extrusion and tube drawing. Some advantages of the flow forming process are high material utilization, close dimensional tolerances and excellent surface finish. Flow forming finds extensive applications in industries such as aerospace, automotive, and manufacturing, where the demand for lightweight, durable, and intricately shaped components is crucial. Different types of geometries including thin-walled and axisymmetric cylindrical parts can be manufactured by flow form process. In flow forming process, the preform, which is clamped to a rotating mandrel, is formed by the rollers. It involves the incremental shaping of a rotating workpiece by applying axial compressive forces while simultaneously feeding it through a set of rollers. After the process, length of the preform is increased by decreasing the outer diameter. However, one of drawbacks of the process is the complex mechanical behavior around the forming zone. Understanding the material flow and stress state around the forming zone is crucial to perform a successful process. In this study, stress state around the forming zone was investigated numerically. After validating of 3-D explicit finite element model with the measured loads from experiments, a detailed examination of the stress state around the forming zone was performed numerically. Effects of different process parameters such as thickness on the stress state were emphasized. Also, differences between the stress states around the forming zone of the forward and backward flow form processes, which are two different techniques of the flow form process, were stated. It is also shown that different stress states occur at different stages of the process. Finally, the relation between stress state and failure mode was explained.
Strain rates in high velocity forming of foils
Authors: LANGSTÄDTLER Lasse
Published: April 2024

Abstract. Energy- and working media based high velocity forming processes show various advantages forming metal foils. However, due to different process characteristics, differences in workpiece response by impulse transfer for different high velocity forming processes are expected. Free forming experiments with 50 µm metallic foils were carried out to identify the process influence, using electromagnetic forming and laser shock forming. For these two forming methods the response of the workpiece was described. The description was done by in-situ measurement of the strain and the strain rate over time and determination of workpiece velocities.
Processability of aluminum-matrix composite (AMC) by ultrasonic powder atomization
Authors: JEDYNAK A.
Published: April 2024

Abstract. This research presents a comprehensive study on the production of aluminum-matrix composite (AMC) powders using ultrasonic atomization for additive manufacturing (AM). The impact of different heat sources—plasma, arc, and induction melting—was evaluated on the processability and resultant properties of the AMC powders, including morphology, size, and composite structure. Additionally, induction melting was considered in terms of process parameters such as pressure difference, nozzle size, and frequency. The analysis of AMC powder processability revealed that the efficiency of the ultrasonic process depended on the selected heat source. The highest efficiency, nearly 50%, was attained with the induction system. All produced AMC powders exhibited high sphericity, with average sizes ranging from 88.2 to 120 µm. However, the desired composite structure was not achieved under tested conditions due to the decrease in SiC particle content from 20% in the feed material to approximately 3.5% in the final AMC powder. Based on these results, the research highlights the potential and limitations of ultrasonic atomization in AMC powder production, emphasizing the need for further optimization to improve powder quality and process efficiency for broader industrial application in AM.
Numerical analysis of flanging using tailored rubber pad forming on AA7075-O sheets
Authors: BORREGO-PUCHE Marcos
Published: April 2024

Abstract. The flanging of metal sheets is extensively used in the automotive and aeronautical industries to provide rigidity or support for subsequent assembly. Flanging by rubber pad forming is one of the most common processes for small and medium batch production. Flanges with non-linear bending lines are exposed to severe conditions that significantly hinder our comprehension of the geometrical, material, and process factors associated with flange formability (i.e., flangeability). This work presents a numerical study of the flanging process by a tailored rubber pad of hollow AA7075-O parts with continuous concave and convex flanges. The flangeability limits, the geometric capabilities of the forming process, and the deformation mechanisms of stretched and shrunk flanges as well as in the transition zone between them are analysed.
Necking detection in stretch-bent materials exhibiting the Portevin-Le Chatelier effect
Authors: MARTÍNEZ-DONAIRE Andres Jesus
Published: April 2024

Abstract. In recent years, there has been increasing societal awareness of the carbon dioxide (CO2) footprint resulting from individual actions and lifestyles. One of the research actions is focused on the development of eco-friendly alloys with more recycled scrap material in order to reduce emissions, but this can also result in greater variability of material properties. In this context, accurately characterizing the formability limits of materials is of paramount importance for optimizing manufacturing processes. Although ISO 12004-2:2008 standard is commonly used for necking detection, recent years have seen time-dependent methods yield more accurate predictions. Nevertheless, in materials exhibiting the Portevin-Le Chatelier (PLC) effect, such as some common lightweight alloys used in automotive and aeronautics, necking detection introduces significant challenges, and even more so when the material is subjected to severe local stretch-bending states. In this work, various necking detection techniques were employed to analyze their capabilities in a series of stretch-bending experiments over a 2.94 mm thick AA5754H11 PLC-driven material.
Experimental testing and numerical modelling of ductile fracture of PEEK in incremental sheet forming process
Authors: GATEA Shakir
Published: April 2024

Abstract. This research investigates the use of Hooputra-based damage model to predict fracture of polyether-ether-ketone (PEEK) material and its application to single point incremental forming (SPIF) process under different conditions. Flat PEEK sheets are used to examine the influence of temperature changes on the Hooputra fracture strain-stress triaxiality damage curve and to verify the capability of the Hooputra ductile damage model in predicting fracture in uniaxial tensile tests and the SPIF process. The research showed that the formulas used to calculate stress triaxiality based on geometric dimensions are insufficient with notched samples because the radius of the notched sample is no longer circular after plastic deformation. Temperature alters the Hooputra damage curve; therefore, the Hooputra ductile damage formula should be developed to consider the effect of temperature. When the Hooputra damage curve is established according to the temperature effect, the uniaxial fracture is precisely predicted at different temperatures. Hooputra ductile damage model could be developed to capture the fracture initiation and propagation in SPIF process.
Experimental work on friction riveting process of Ti6Al4V in a CNC machine
Authors: TAN Irène
Published: April 2024

Abstract. Friction Forge Riveting (FFR) is now being considered as a good alternative for reinforcing multi-material assemblies in industrial applications with the aim of setting up a robotized assembly process. This paper investigates the feasibility of FFR through experiments using a CNC machine and force measurement instrumentation. Different combinations of parameters such as spindle speed and feed per revolution are tested to understand the forming mechanism of a Ti-6Al-4V rivet by friction. The results show that the evolution of forces in response to the load applied to the rivet by the machine is not constant. An oxide layer is observed on the surface of the rivet for a particular combination of parameters.
Influence of cold rolled surface structures with undercuts for interlocking joints on bending processes
Authors: RINGEL Aron
Published: April 2024

Abstract. Lightweight design is one of the methods to reduce CO2 emissions and optimize energy efficiency in the transportation sector. The main motivation of this study arise from weight reduction through multi-material design with the materials commonly used in the automotive industry, steel and aluminum. Metallurgical bonding of steel and aluminum carries the risk of forming brittle intermetallic phases. Hence, new joining techniques such as joining by forming or casting are promising for these multi-material components. Previously, a hybrid component method was presented using channel-like surface structures with undercuts on a steel sheet created in a modified cold rolling process. In a subsequent high-pressure die casting, the channels were filled with aluminum melt, forming an interlocking connection as it solidified. As automotive components demand increased complexity, the bending of the structured sheet before casting was investigated. This study aims to analyze how the surface structure affects the bending process. Numerical simulations and experiments were used to investigate the effect on the maximum bending force, the resulting bending angle and springback. Therefore, the parameters bending angle, bending radius, and the lateral or longitudinal orientations of the channel structure on either sides of the bend were taken into account. The results showed a strong influence of the lateral and longitudinal orientation on the maximum bending force. Furthermore, a minor effect of the bending radius on the force and springback was found.
Influence of thermal treatment on surface roughness, microstructural, and mechanical properties of 3D printed ABS
Authors: NGUYEN Khanh Q.
Published: April 2024

Abstract. Additive manufacturing (AM) has been widely used for rapid prototyping (RP) techniques due to its low cost and customizability. This technique allows for rapid and competitive price production compared to conventional manufacturing. However, pieces fabricated with the AM technique usually possess poor mechanical and surface properties compared to the injection molding technique. Based on COALIA's recent patent, a thermal treatment approach was used to improve the performance of printed parts. In this study, acrylonitrile-butadiene-styrene (ABS) was printed using fused deposition modeling (FDM) with and without heat treatment at 35 mm/s of printing speed. The physical and mechanical properties of printed ABS parts were then investigated. Tensile tests were performed to investigate the tensile strength, elastic modulus, and elongation at break. After tensile tests, X-ray microtomography was conducted to evaluate the surface morphologies. An optical profilometer analysis was also used to measure the surface roughness.
Innovative cryogenic processing for enhanced surface integrity characteristics of stainless steels
Authors: KITAY Ozhan
Published: April 2024

Abstract. In this study, the influence of the orthogonal cutting on the surface integrity characteristics of 316L austenitic stainless steel material under liquid nitrogen (LN2) condition was investigated. For this purpose, machining tests were carried out by applying LN2 to the cutting tool rake and flank face separately, and using different cutting parameters. In addition to the cutting force, the response of surface integrity characteristics such as microstructure, microhardness, and x-ray diffraction (XRD) analysis to LN2 was compared with dry cutting. The findings showed that the effect of different positioning of the LN2 nozzle on the cutting force and microhardness of the material is significant. In particular, the application of liquid nitrogen through the rake face significantly increases the microhardness of the material, while machined specimen microstructure images show that application of LN2 from the flank surface causes more grain refinement and deformation on the machined surface, especially at low cutting speed.
Investigation of temperature-dependent mechanical behaviours of polycarbonate with an innovative fractional order model
Authors: SUN Lin
Published: April 2024

Abstract. Amorphous thermoplastic polymers are considered as essential engineering materials. However, their strongly temperature-dependent elastic-viscoplastic behaviour is still not well understood. The large deformation response of these materials in the temperature range spanning the glass transition temperature is highly required. In this paper, the uniaxial compression tests are performed with large deformation on a polycarbonate amorphous polymer, within a forming temperature range from 60 °C to 180 °C. The variable order fractional constitutive model is improved to describe the evolution of mechanical behaviour of polycarbonate at different temperatures. The fractional order in the model is proposed as a function of time. The simulation results are in good agreement with the experimental data. It is concluded that the variable order fractional model is an efficient tool to predict the large deformation of amorphous polymers under different temperatures.
Effect of SiC addition on processability of AISI S2 tool steel for laser powder bed fusion
Authors: SAGGIONETTO E.
Published: April 2024

Abstract. Laser Powder Bed Fusion (LPBF) of metallic alloys allows to achieve complex shape parts with innovative properties. However, the commercial availability of powder for LPBF is still limited, thus restraining the development of new alloys. To overcome this shortcoming, mixing different powders allows to tailor the chemical composition, although affecting the LPBF process. Indeed, to achieve a fully dense and defect-free part a proper melt pool must be generated during the LPBF process, in order to ensure good overlapping between each track and layer. Melt pools can be described as conductive or key-hole like, promoting the appearance of process-induced defects such as lack of fusion or key-hole porosities. Processing a mixture of several powders by changing the amount of one constituent can affect the type of melt pool generated during the process, thus shifting the process map. In this work, AISI S2 tool steel powders are enriched with 5 and 10% (in volume) of Silicon Carbide (SiC) and processed by LPBF. The effect of SiC on the processability is discussed for different volumetric energy density (Ed). Defects within cross sections are characterized and quantified, as well as the melt pool depth and morphology.
Investigations on the production and forming of thermoplastic ceramic green tapes
Authors: Tran R.
Published: April 2024

Abstract. Technical ceramics such as alumina with its temperature stability, high mechanical stiffness, and good dielectric strength at low density, meet the requirements for highly resilient components for promising markets of high-performance electronics and the electrification of mobility. Ceramic components are usually manufactured using powder technology processes since forming of sintered ceramics is not possible due to the lack of plasticity. In this work, we use hydroforming to shape thermoplastic ceramic green tapes prior to sintering to add a third dimension to flat substrates. We developed alumina feedstocks based on a polyamide binder system that were extruded to 1 mm thick tapes, hydroformed, debinded and sintered. Depending on the binder composition, forming temperatures of 45-60 °C were sufficient, whereby precise temperature control was crucial for success. As a result, components with forming depths of up to 5 mm were produced without defects. This process offers the potential to revolutionize this market segment, not only in terms of geometric design freedom and low material waste, but also in terms of profitability of mass production.
Perforation resistance of some materials in 3D printed parts
Authors: NICOLAU Mihaela
Published: April 2024

Abstract. Sometimes, for various reasons, some parts manufactured by 3D printing need to have high perforation resistance. In such situations, it is necessary to know the perforation resistance values of the materials incorporated in the parts. In principle, conical tip penetrators are allowed to fall under their weight on the test sample material to be investigated, which allows the conical tip to penetrate and advance into the sample material. A finite element modeling allowed obtaining some information about the behavior of the material during the perforation action. Perforation resistance testing equipment has been designed to use conical tips and different heights from which the penetrator is released. Thus, it became possible to highlight the influence of some input factors in the testing process on the diameter of the hole generated by the penetrator in the thermoplastic polyurethane-type material of the test sample. As input factors, the weight of the penetrator, the drop height of the penetrator, and the thickness of the test sample were considered. The mathematical processing of the experimental results allowed the establishment of some empirical mathematical models, which highlight the influence exerted by the three input factors on the value of the considered output parameter. It was confirmed that as the penetrator weight and drop height increase, the diameter of the hole generated in the sample material increases. In contrast, the test sample thickness exerts the opposite effect.
Effect of process parameters on final geometry and quality in hot tube spinning process
Authors: GUNES Murat
Published: April 2024

Abstract. Spinning is one of the oldest metal forming processes that produce rotationally axisymmetric and seamless final products by using plates or tubes [1]. Preform can be shaped via rollers, hot or cold and it has a big advantage in terms of manufacturing complex geometries [2]. It is used in many different industries around the world. However, the wall thickness of the output (final geometry) might be uneven or the roller path might be different than expected. It is clear that all of those results have a negative impact on the quality of the process, as they make it difficult to obtain the desired final geometry. Within the context of this study, the cylindrical tube will be used in the hot spinning metal forming process. It will be investigated how the reduction ratio, the roller geometry and the initial temperature of the preform affect wall thickness of the final geometry with the help of finite element analysis software.
Effect of different auxetic cell design on the compression behavior of FDMed structures
Authors: NAPOLITANO F.
Published: April 2024

Abstract. Among the different additive manufacturing technologies for polymeric materials, Fused Deposition Modelling has obtained great visibility and, thanks to the numerous studies on the process conditions, reached high quality of workpiece production. Nevertheless, the slicers are projected to replicate standard and easy to reproduce patterns, which don’t take into account the final use of the workpiece produced. An optimization of the extruded material is represented by the design oriented to support specific loads, which are applied along specific directions. In this research work is proposed the use of auxetic geometry and two different cell types are proposed and compared with the related conventional workpieces, printed with the same volume density. The use of auxetic design allows for differentiation of the load-bearing and to obtain structures which don’t lose their original shape and that can adsorb the compressive energy reaching the compaction which improves the final resistance.
Two-step forging of polyimide powders into small-/medium-sized gears with and without carbon fiber reinforcement
Authors: AIZAWA T.
Published: April 2024

Abstract. A green polyimide cylindrical preform with short carbon fibers was prepared for two-step forging processes. Each preform was hot-forged at 623 K above the glass transition temperature of polyimide for near-net shaping of fifteen-teeth module-1.0 gear, and sinter-forged at 673 K below its melting point for densification. SEM and X-ray computer tomography were employed to make destructive and non-destructive diagnoses on the carbon fiber orientation during hot forging. Micro-hardness testing and gear-grade balancing were utilized to evaluate the engineering durability and dimensional accuracy of sinter-forged gears.
Study of surface grinding of PEEK parts
Authors: Spina R.
Published: April 2024

Abstract. The work studies the surface grinding of polyether ether ketone (PEEK) specimens, evaluating material properties and the machining process. An experimental procedure was implemented to collect data during machining to support statistical analysis. Statistical analysis was implemented, mainly based on material properties, which computes roughness achieved after machining by varying cutting speed, feed velocity, and cutting depth, giving helpful information to apply different configurations and strategies.
Investigation of the effects of gas-counter-pressure injection molding on the properties and manufacturability of post-consumer recycled polypropylene
Authors: BORTOLETTO Anna
Published: April 2024

Abstract. In contemporary times, the most effective strategy for mitigating the environmental effects of plastics and their manufacturing is recycling. However, producing high-quality items from recycled materials remains a challenge. This study addresses these challenges, specifically focusing on the injection molding process for recycled polypropylene. Key issues identified include poor surface finish of the molded items, mold contamination with oily residues, and strong odors during processing. The proposed solution involves the innovative use of gas counter pressure in conjunction with injection molding. The study explores various nitrogen pressure levels to assess their impact. Findings indicate that an optimal pressure level significantly improves the surface quality of the products and reduces the accumulation of dirt in the mold cavities. While gas counter pressure does not mitigate odor emissions, it represents a promising step forward in developing a high-quality recycled polypropylene compound. This approach could pave the way for more advanced recycling techniques, enhancing the quality of products made from recycled plastics.
Injection molding control parameter assessment by nested Taguchi design of simulation experiments: a case study
Authors: ILIOPOULOU Vasiliki
Published: April 2024

Abstract. Injection molding of a polypropylene (PP) food packaging container is studied using a dedicated simulation program. Three successive Taguchi designs of experiments (DoE) are performed to identify the influence of control factors and to adjust their levels for optimal result. These are nested, each one narrowing down the decision space of its predecessor. In the first design (L27), seven control factors were considered: polymer material in terms of MFI, melt and mold temperature, maximum injection pressure, filling time, maximum packing pressure and packing time. Part weight, clamping force and a fictitious factor related to premature solidification of the material during packing were quality factors. In the next DoE (L27 again), for fixed material, the four most important process factors determined before are examined in more detail, adding cycle time as an extra quality factor. Dependence of results on melt temperature proved to be strong, so a third DoE (L9), examined a narrower temperature range. Calculation of S/N ratios and analysis of variance (ANOVA) led to optimization of control parameters through a weighted objective function.
A combined finite element – Life cycle assessment approach for assessing the sustainability of the thermoforming process of a thermoplastic composite component
Authors: STAMOPOULOS Antonios G.
Published: April 2024

Abstract. Nowadays, thermoplastic-based composite materials are catching up in many industrial sectors due to their unique features, especially their recyclability, their lower requirements regarding their storage and the fact that may be heated-up and formed into a definitive product. To this end, the thermoforming process appears to be an appealing fabrication process. However, throughout this process, a number of defects may be introduced that can affect the morphology and structural performance of the product. Until recently, the definition of the optimal process characteristics was based on trial-and-error experimental tests that increased the resources required for its development. In addition, a significant part of the thermoplastic composite plate has to be removed/wasted after the thermoforming process. In this work, a well-established numerical methodology is applied to an industrial thermoplastic composite component. After considering an initial thermoplastic composite plate, the effect of the reduction of the overall dimensions, without compromising the product quality, on the environmental footprint is considered. To perform this task, a finite element (FE) simulation is utilized for assessing the possibility to reduce the plate dimensions without introducing defects while, in parallel, a life cycle assessment (LCA) is put into practice. Through the synergy between the 2 disciplines, useful insights are provided regarding the effectiveness of the fabrication process by defining the composite plate dimensions that contributes to the amelioration of the environmental footprint with the minimum expense on the component quality.
Investigation of the reshaping process by hydroforming using magnetorheological fluids
Authors: Piccininni A.
Published: April 2024

Abstract. The reshaping of End-of-Life (EoL) components is considered a promising approach to put in practice one of the virtuous strategies of the Circular Economy. The heterogeneity in a EoL part, the alternation of deformed/undeformed regions resulting from the manufacturing process, may hinder an effective reshaping into a brand new geometry. Therefore, the proper selection among the sheet metal forming processes to overcome such a limitation is of utmost importance. The present work, based on a full numerical approach, investigates the reshaping process of a disc-shaped EoL by hydroforming using a Magneto Rheological Fluid (MRF) as the forming medium. The basic idea is to combine the advantages coming from the flexibility of the hydroforming process with those from the MRF whose behavior (i.e. its viscosity affecting the shear stresses at the contact with the blank) can be tailored by adjusting the applied magnetic field. The reshaping approach is investigated according to two separate routes, differentiated by a different target geometry. A factorial plan of numerical simulations allowed to investigate the effect of the MRF behaviour as well as the geometry of the EoL component on the quality of the reshaped part, expressed in terms of accuracy in the final shape and thickness distribution.
Experimental and numerical study of heat transfer on an industrial FFF printer: Application to PEEK
Authors: BENARBIA A.
Published: April 2024

Abstract. The FFF process is one of the most widely used additive manufacturing processes for shaping thermoplastic polymers. The recent development of industrial printers equipped with high-temperature ovens has made it possible to print high-performance thermoplastics from the PAEK family for applications in the aerospace, medical and other industries. Numerous studies have shown that thermal history is a key factor to improve the mechanical properties of printed parts. Nevertheless, the uniformity of mechanical properties of printed parts is generally poor and highly dependent on the homogeneity of the thermal oven used, which, to our knowledge, has never been properly characterized. For semi-crystalline polymers, the thermal driven crystallization process is also a key factor in adhesion. However, the coupling between phase transformation and heat transfer is often neglected in numerical modelling and its influence has not yet been clearly demonstrated. In this work, we will carry out a preliminary characterization of the printer by measuring air velocity and temperature gradients over the whole printing zone. Secondly, the comparison between simulation and experimental measurements will show the importance of correctly predicting crystallization kinetics to obtain more accurate predictions.
Influence of deposition strategy on porosity in powder-feed directed energy deposition (DED)
Authors: DHOONOOAH Neha Devi
Published: April 2024

Abstract. Directed energy deposition (DED) is an additive manufacturing process which is increasingly being used for direct manufacturing, added function application and component repair of high-value metals and alloys that are otherwise hard to machine conventionally [1]. However, most commercially available toolpath generators are not comprehensive with regards to the deposition strategy and process parameters, emphasis usually being placed solely on the overlap of adjacent weld beads rather than including the interaction between the contour curves and infill pattern. This increases the probability of gap formation in the deposition pattern, and hence the rate of porosity in the part. This study focuses on the influence of varying bead overlap on the resulting bead geometry and surface roughness for Inconel 718 workpieces deposited using the DED process. The deposition strategy was devised using Python programming language, and the code found to be robust for both single- and multi-layer deposits.
On the scalability of strength and presumed size effects in SLM-produced 316L stainless steel
Authors: VYSOCHINSKIY Dmitry
Published: April 2024

Abstract. As additive manufacturing (AM) technology advances toward the production of structurally utilized metallic components, an accurate evaluation of mechanical properties becomes crucial. Understanding the effect of the printed cross-section size on material strength is exceptionally important since AM technology, especially laser powder bed fusion (L-PBF), enables topology optimization and favors the production of thin struts, lattice structures, and other small cross-sections, as well as thin-walled profiles. Structural designers need to know to what degree the size of the printed cross-section might affect material strength. This study focuses on the effect of printed cross-section size on the mechanical properties of L-PBF-produced 316L stainless steel. The findings reported in existing literature so far are conflicting, indicating a need for further investigation. In the presented paper, the mechanical properties of net-shape printed samples with cross-section diameters ranging from 2.5 mm to 6.0 mm are compared. Tensile tests reveal that smaller diameter net-shape samples exhibit lower strength compared to larger diameters. Machined samples display higher strength than net-shape samples. The observed size-dependent strength variations in L-PBF-produced 316L stainless steel can be explained by the surface layer being weaker than the core of the sample. Whether the effect is due to differences in microstructure between the surface and core of the sample or is simply caused by a reduction of the effective cross-sectional area due to surface roughness could be debated, but both factors are likely to contribute to the phenomenon.
Tool path strategies for single point incremental forming of fiber-reinforced thermoplastic sheets
Authors: Rath J.E.
Published: April 2024

Abstract. Continuous fiber-reinforced thermoplastics (FRTP) are gaining increasing interest as a lightweight material. However, production processes such as thermoforming rely on costly molds, making them unsuitable for individual parts or small series production. Therefore, realizing an incremental sheet forming (ISF) process for FRTP is very desirable. As direct application of ISF to FRTP is impossible, researchers placed the FRTP between two metal sheets, allowing it to slide between them during single point incremental forming (SPIF). So far, only traditional tool path strategies for metal SPIF, such as the z-level or the spiral approach, have been used, which do not consider the draping requirements of woven reinforcement fibers. To optimize the forming process and prevent the development of wrinkles or other defects in the organo sheet, we propose and test novel tool path strategies for the SPIF of an FRTP sandwiched between two metal sheets. Results show that the proposed strategies have a positive impact on part quality, as fiber orientation-based tool path approaches show less wrinkling and higher part accuracy in SPIF without support.
Characterization and modelling of grain growth in Zr-Nb alloys: Niobium concentration influence
Authors: HAHN Pauline
Published: April 2024

Abstract. Zr-Nb alloys are mainly used in the nuclear energy industry. A study was carried out with the aim of understanding the physical phenomena involved during the hot extrusion stage and modeling these phenomena with numerical simulations. However, it is first essential to determine the material parameters, including reduced mobility during pure grain growth. Experimental and numerical campaigns are therefore carried out to define this parameter, material and model dependent. Consequently, this study focuses exclusively on the influence of niobium content on the grain growth kinetics of Zr-Nb alloy.
Experimental, analytical, and numerical analysis of the copper wire multi-pass drawing process
Authors: DI DONATO S.
Published: April 2024

Abstract. In the cold wire drawing process, the stress acting on the wire depends on process parameters, as well as on the material flow stress, including the strain-hardening that occurs step by step. It is essential to ensure that the stress applied to the wire at the exit of the die remains below the material's yield stress, to prevent wire necking and fracture. Industrially, the process is carried out continuously using multi-step-multi-wires machines that deform the material to high strain at elevated strain rate values. The application of analytical models for evaluating the stresses acting on the wire assumes simplified boundary conditions, such as an average distribution of strain and strain rate within the die. Further studies are necessary, considering the entire multi-pass industrial case and involving finite element simulation, which is today the main tool for optimizing industrial processes. In this work, the drawing process applied to ETP Pure Copper (99.9% in weight) is analyzed experimentally, analytically, and numerically. The material was characterized by torsion tests and experimental drawing tests were carried out on four steps of the process. Through the analysis of the different analytical methods, it was shown that a careful evaluation of the friction coefficient values is necessary to reduce errors in estimating the drawing forces. The aim is to provide a reliable numerical model for predicting the stress acting on the wire during the multi-pass drawing process, through an appropriate characterization of the material flow stress and an evaluation of the friction model.
Behavior of volumetric core defects in friction extrusion of wire from Al-Cu alloy
Authors: RATH L.
Published: April 2024

Abstract. Friction extrusion describes the processing of metallic materials by inducing severe plastic deformation via frictional heating and shear strain. Rotational motion between die and feedstock is the key feature defining the potential of the process to generate consolidated extrudates with refined, homogenized microstructure. In this study, the effect of volumetric core defects on the material flow and properties of the extrudate is investigated, by processing from Al-Cu billets with a centric bore. Optical as well as scanning electron microscopy, X-ray microtomography and micro-hardness measurements are applied. Different material flow patterns and defect closure mechanisms are identified in correlation with the defect volume and the potential of controlling material flow via geometrical feedstock modification is discussed.
Realization of functionally graded components with an optimized hybrid additive laminated tooling method
Authors: DARDAEI JOGHAN H.
Published: April 2024

Abstract. The tool tempering method is used to manufacture the functionally graded components. In the manufactured combined tool, one side was enhanced with cooling channels to perform the press hardening process, and the other side of the tool included heating cartridges to practice warm forming. Hybrid additive laminated tooling is used to manufacture the combined tool in a short time, while conventional subtracting methods, such as milling, are costly and time-consuming. Initially, the cooling rate and the heat transfer coefficient of the laser metal deposited area by Ferro55 powder are determined. Also, functionally graded components are manufactured in which, on one side, the 22MnB5 sheets are press-hardened, whereas, on the other side, the blanks were warm formed at different elevated temperatures (150°C, 250°C, 350°C). The results show that besides the concept validation, the cooling rate on the press hardening side is higher than 27 K/s, and hardness values up to ca. 480 HV10 were achieved, while, in the wall of the formed part on the heating side, the hardness is below 300 HV10.
Perception of the prosodic features of newscaster speech
Authors: Ahn Byron , Zhou Z.L. , Gasser Emily , Napoli Donna Jo
Published: April 2024

It is frequently posited that the speech of groups with particular communicative goals constitutes cohesive prosodic genres. Here we investigate American English newscaster speech to discover whether listeners can distinguish it from non-newscaster speech based on prosody alone, and, if so, which features they use to do so and which are ignored. In a perception experiment, participants classified low-pass filtered audio clips as “newscaster” or “everyday” speech. We find that listeners were able to identify newscasters at a rate better than chance. They correctly utilized newscasters’ use of lower pitch, more intonational breaks, and little non-modal phonation, but overlooked the range of pitch accents that characterize newscaster speech. Whether this results from a coherent Newscaster genre or an interacting collection of indexical traits, our results suggest that listeners’ competence about speech registers includes sub-phonemic information about intonation, impacting the kind of data linguists must attend to when designing intonational models.
Meervoudige sluicing en de theorie van deletie
Authors: De Vries Mark
Published: April 2024

This paper investigates complex cases of sluicing in Dutch, and the consequences for possible analyses. Acceptable instances of multiple sluicing (with two or more remnants) can easily be produced, but there are some limiting factors. A hard constraint appears to be a clause-mate condition for multiple remnants. Other factors that influence acceptability are word order, D‑linking, and the presence of prepositions. These findings are corroborated by an acceptability test carried out with 20 subjects. I argue that multiple sluicing is problematic for the standard move-and-delete approach, and critically discuss possible alternatives that involve in situ deletion or selective spell-out. The final section is a brief comparison with fragment answers and right-dislocation, and points out the issue of (comma) intonation in constructions involving some iterative process.
Queen Shima as Nusantara feminist pioneer: Feminist literary study on the novels Putri Kalingga and Avatar Keadilan
Authors: Wiyatmi Wiyatmi , Sudiati Sudiati , Artanti Yeni
Published: April 2024

Up to the present time, the public is more familiar with the figures of Kartini, Dewi Sartika, and Cut Nyak Dien as icons of Indonesian women emancipation fighters. In reality, for hundreds of years before Kartini was born, in the 7th century, the Kingdom of Kalingga has been led by a woman, Queen Shima. Not much of the historical data has recorded her name and roles. In the midst of this condition, there were published two novels which enumerate the way of life of Queen Shima, entitled Putri Kalingga (Wibidharma, 2022) and Avatar Keadilan: Pesona Kebajikan Maharatu Shima dari Negeri Kalingga (Nararosa, 2010). The present study is aimed at understanding the existence of Queen Shima as a pioneer of Nusantara feminism by using the perspectives of feminist literary approach. The study was qualitative feminist research. The data sources of the study were the two novels Putri Kalingga and Avatar Keadilan: Pesona Kebajikan Maharatu Shima dari Negeri Kalingga. Data were the narratives that tell about the characteristics and way of life of Queen Shima as King of Kalingga Kingdom which contain information about her position and roles in Nusantara women history. Findings of the study show that Queen Shima, whose life story is told in the two novels Putri Kalingga and Avatar Keadilan is not only a fictitious character, but also a historical figure from the 7th century, who is hauled up as King of Kalingga Kingdom not because of inheriting the crown from her parents, but because of the intelligence, wisdom, and leardership capacities she has. In the perspectives of feminist literary criticism, Queen Shima represents Nusantara feminisim that has been practiced in the era of the Kalingga kingdom.
Language variation in the Instagram discourse of Indonesian Papuan dialect
Authors: Mawene Aleda , Handayani Tri
Published: April 2024

The language variations and substance of Papuan millennials' speech on the Instagram platform are unique. The choice of language used reflects the fact of speaking Indonesian with a distinctive Papuan dialect. This study aims to describe language variation in Papuan dialect Indonesian instragram discourse. This research is categorized as qualitative-descriptive research with a socio-pragmatic approach. The study data are words, idioms, terms, and quoted sentences as well as features of Papuan millennials' Instagram discourse. The data is sourced from the Igers' accounts which are taken purposively and representatively. The researcher acts as an observer (silent reader /host follower). The data is analyzed inductively through the process of description, interpretation, and explanation. The research findings show that the orientation of language choices made by Papuan dialectal Indonesian Instagram account owners leads to four (4) patterns of language variation, namely: (1) patterns of Papuan dialectal Indonesian (IDP); (2) patterns of Indonesian (IL); (3) patterns of code-switching of Papuan dialectal Indonesian-Foreign Language (IDP"FL); (4) patterns of code-mixing of Papuan dialectal Indonesian and foreign languages (IDP↔FL). The results of this study illustrate that there is a variety of Papuan dialectal Indonesian (IDP) among young Papuans on social media. With these findings, people can find out about the context of language use in society, especially on Instagram. The findings of this study also strengthen the view that language is a cultural product that cannot be separated from its social context.
Presenting indigenous language of Suwawa in terms of clause structure
Authors: Nawari Ahmad , Didipu Herman , Muslimin Muslimin , Hadriana Hadriana
Published: April 2024

This research is aimed to describe Suwawa language clauses (SLC) in local content subject at elementary schools. It focuses on introducing SLC and the description of types of SLC. The method used is the descriptive method. SLC Data were obtained from utterances and speech by native of Suwawa. Observation, interviews, and note-taking were used to collect the data. A distribution method on the functions of SCL was used to analyze the data. The research findings revealed that introducing Suwawa is very important since the language functions as a self-identity and a filter from global culture penetration. The language has 13 types of clauses grouped into 5 based on (1) the core elements, (2) internal structure, (3) position in the sentence, (4) the presence or absence of negation elements in the predicate, and (5) the functional category. Research shows that introducing the Suwawa language is important not only to preserve it but also to give Gorontalo, Sulawesi Indonesia's youth a sense of self and cultural identity against globalization.