bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modelling of the micro-cutting in the abrasion process with pyramidal indenter
Authors: WERCHFENI Achref
Published: April 2024

Abstract. A 3-D finite element model of abrasion process based on a CEL (Coupled Eulerian-Lagrangian) approach was developed. A scratch test on elastic-perfectly plastic materials with a pyramidal indenter was simulated. The influence of the interfacial friction coefficient f, the geometric parameters of the indenter and the cutting conditions on the overall friction coefficient μ were studied. Subsequently, the finite element simulation results were compared with an analytical model. It was found that the µ increases linearly with the friction coefficient f and the attack angle of grit β. The FE model results present a good agreement with the analytical model results.
Axial drilling investigations and the potential of orbital techniques for enhanced hole quality in orthopedics
Authors: HUSSEIN Raafat
Published: April 2024

Abstract. Precision in surgical bone drilling is essential for restoring bones mobility and function. However, the intricate nature and fiber-reinforced composite structure of bones inherently pose drilling-induced mechanical damage to the bone surface, affecting the primary stability necessary for implant anchorage and therefore leading to implant failure. The critical need for enhanced hole quality and damage reduction has spurred investigations into the optimal drilling parameters, novel drilling tools and alternative machining techniques. This study rigorously investigates the effect of the cutting speed and feed rate during axial drilling employing a center drill. It extends toward a comprehensive analysis of forces, temperature and mechanical damage, with a particular emphasis on delamination assessment. Then, the optimal parameters are established using the Tool-Material Couple (COM) optimization strategy. Subsequently, a novel approach of orbital drilling in bones is introduced for hole quality enhancement when compared to the conventional technique. This investigation serves as a foundational step for a more comprehensive study that ventures into the innovative application of orbital drilling in orthopedics.
Using the particle finite element method for predicting optimum shear cutting clearance
Authors: SANDIN Olle
Published: April 2024

Abstract. The shear cutting process, which is the most common cutting technique in the sheet forming industry, is known for introducing damage to the cut edges of high strength metal. This damage may impair the forming- or fatigue properties of the material and can cause edge-cracking during forming or in-service part failure. The edge formability of a sheared edge is strongly linked with the appearance of large notches arising due to unfavorable process parameters. By numerical modelling of the shear cutting process with the possibility to vary important process parameters, the sheared edge damage can be detected and avoided in the manufacturing process. This work present numerical modelling of shear cutting in Advanced High Strength Steel using a novel Particle Finite Element Method approach. Numerical modelling of shear cutting processes over a large range of cutting clearances were conducted and validated against laboratory experiment results. The results showed that the PFEM modelling could detect the cut edge damages with the largest negative impact on formability, thus narrowing the feasible cutting clearance range.
Preliminary assessment of material extrusion (MEX) for medical applications: The effect of hatch angle
Authors: Sala F.
Published: April 2024

Abstract. Material extrusion (MEX) is one of the most widely used Additive Manufacturing (AM) technologies owing to its simplicity and accessible cost. The technique is based on the principle of extrusion of thermoplastic material, layer-by-layer, on a building platform through multiple head nozzles. Metal filled filaments, in combination with debinding and sintering cycles, may innovate and transform the traditional functioning of the MEX technique into a cost-effective alternative for the conventional metallic AM processes. In the present document, the optimal printing conditions characterizing LPBF technology were replicated on MEX technology, with the aim of assessing the effects of the printing parameter hatch angle over the material properties and, at the same time, providing a better understanding of the production of medical metal parts via MEX. Indeed, in this particular context, the use of Powder Bed Fusion (PBF) and Directed Energy Deposition (DED) prevails, requiring MEX-based technique extensive research for its applicability. The influence of a specific AM process parameter, the hatch angle, was assessed following a single factor Design of Experiment (DOE), varying over two levels: the optimal Laser Powder Bed Fusion (LPBF) scanning strategy (67°k) and the most common MEX deposition strategy (±45°). Specimens were manufactured, using MEX technology (Ultimaker S5) and AISI 316L filament (BASF Ultrafuse 316L) and tested. Results of the defect analysis, including closed and open porosity, and mechanical properties were collected and statistically compared to determine any difference in the two-deposition strategies. Furthermore, in the analysis, LPBF key characteristics are reported as benchmark values.
Identification of friction coefficient between uncoated carbide tool and Ti-6Al-4V alloy under different lubrication conditions
Authors: FERSI Achraf
Published: April 2024

Abstract. During machining, the friction between the tool and the workpiece (cutting face and flank face) is a significant tribological phenomenon because it strongly influences the cutting operation. Indeed, higher friction leads to an increase of cutting forces, a greater heat generation, a premature tool wear and a surface degradation. This study focuses on tool (WC/Co)/workpiece (Ti-6Al-4V) friction under different cooling conditions (dry, emulsion, cryogenic). Determining the friction coefficient requires numerical simulations to separate the tribological phenomena. For this purpose, several modeling methods are compared (Lagrangian, CEL, and ALE). Experimental tests revealed that the friction coefficient depends not only on the sliding velocity but also on lubrication modes. Specifically, the lowest friction coefficient is obtained under cryogenic condition. Adhesive phenomena on the WC/Co pin are observed in the friction zone, particularly at high sliding velocities.
Tool Condition Monitoring in machining for the workpiece surface quality evaluation
Authors: DEL PRETE Antonio
Published: April 2024

Abstract. Achieving high surface quality is crucial in manufacturing, impacting product functionality and appearance. Poor quality can lead to defects, friction, and safety risks. Cutting tools endure harsh conditions and wear over time, affecting surface quality and increasing costs. Monitoring tool condition is vital for efficiency, reducing cycle times and downtime. Industries like aerospace and automotive require tight quality control for meeting standards. Historically, manual inspections and scheduled changes were used, but advanced technology now allows more efficient tool condition monitoring. The paper outlines a tool condition monitoring approach using sensors and machine learning to predict and classify tool conditions and workpiece surface quality. It integrates acoustic emission, accelerometer, and thermal infrared camera sensors into a lathe machine. Various machine learning algorithms are trained and validated to accurately predict tool and surface conditions. The most effective model is identified and presented.
Experimental analysis of burr formation during Ti6Al4V drilling
Authors: DEBARD Benoit
Published: April 2024

Abstract. To improve the assembly process of aeronautical structures by the mean of One-Way Assembly strategies (no deburring of metallic parts before the installation of final fasteners), it is mandatory to monitor the burr size of drilled holes. Indeed, burrs can have a significant effect on the fatigue life of structures. It was shown that cracks are initiated from exit burrs. This paper presents an experimental analysis of the burr geometry through cutting forces and thermal imaging measurements. The effect of the tool wear on burr geometry is also analyzed to identify phenomena occurring during burr formation.
Investigations of strain rate sensitivity under different stress triaxialities for DC04
Authors: MAIER Lorenz
Published: April 2024

Abstract. Understanding the strain rate sensitivity of materials is essential for predicting their behavior in sheet metal forming. While uniaxial tension tests are state of the art in characterizing this sensitivity, the deformation response of materials under different loading conditions can significantly deviate from uniaxial behavior. This paper presents a comprehensive study of the strain rate sensitivity of DC04 through a series of experimental investigations with different strain rates. In addition to uniaxial tension tests, the study investigates the strain rate sensitivity under shear and plane strain tests, providing a comprehensive analysis of strain rate sensitivity across different loading scenarios. The investigation aims to understand how the material responds to varying deformation rates, focusing on characterizing their deformation behavior under various loading conditions. The authors collected experimental data from the material with a DIC system. They analyzed it to derive material-specific parameters that describe their strain rate-dependent responses depending on the stress state. To explain this, the authors calibrated three models: Johnson Cook, Cowper Symonds, and Huh Kang.
The prospects of implementation of artificial intelligence for modelling of microstructural parameters in metal forming processes
Authors: TRETYAKOV Denis
Published: April 2024

Abstract. The primary trend in modern metal forming can be characterised by the increase in the complexity of the technological processes and higher demand for the quality of the products. This naturally raises the requirements for the quality of modelling prediction of various aspects of metal forming process, such as tool wear, metal flow, fracture and defects formation, microstructure evolution and mechanical properties. However, various independent benchmarking studies [1] have shown that modelling predictions can be wrong even for well-calibrated models, and all the efforts with more detailed and metrologically better experiments didn’t lead to any significant leap in the prediction quality. As an attempt to implement some alternative approach, this paper investigates the applicability of an Artificial Intelligence (AI) approach, in particular Deep Learning models. The example of a recurrent neural network model predicting recrystallisation during hot forging of Inconel 718 is presented. The model considers the entire thermo-mechanical history at every point and is trained and blind-tested using actual experimental data.
Computational thermo-mechanical process design by integrating crystal plasticity and phase field model
Authors: MIN Kyung Mun
Published: April 2024

Abstract. An integrated model, merging the crystal plasticity finite element model (CPFEM) and the phase field model (PFM), is introduced for simulating the thermo-mechanical processing of ultra-low carbon steels. CPFEM serves as the mechanical simulation tool, forecasting deformation inconsistencies such as local stress concentration, inhomogeneous dislocation distribution, and shear bands. Meanwhile, PFM is utilized for predicting microstructural evolution, particularly nucleation and growth during heat treatments. To seamlessly integrate CPFEM and PFM, which are based on the finite element and finite difference methods respectively, an optimized coupling algorithm is utilized to avoid excessive computational cost. Importantly, a generalized strain energy release maximization model is integrated into the PFM, which leverages the analytical outcomes of CPFEM to predict the recrystallization texture of steels, factoring in multiple slip activities under mechanical loading conditions. The proposed model is applied to evaluate the anisotropy and formability of the thermo-mechanically processed ultra-low carbon steel through virtual mechanical experiments.
Mechanical characterization and behavior modelling of Ti-6Al-4V alloy in hot forming conditions
Authors: D’ARCHIVIO Lucas
Published: April 2024

Abstract. Ti-6Al-4V is a widely used titanium alloy in superplastic forming process which requires high temperatures (T≈900 °C) and low strain rates (ε ˙≈〖10〗^(-3) s^(-1)). One way to reduce the costs of the process is to use a lower forming temperature and/or higher strain rate, up to 〖10〗^(-2) s^(-1). However, the behavior of Ti-6Al-4V alloy still need to be modeled at such forming conditions and for different initial microstructure. In order to characterize the mechanical behavior of Ti-6Al-4V at temperature between 400 °C and 700 °C, relaxation and tensile tests performed under small and large deformation conditions were conducted. Depending on the test, the deformations were evaluated through two kinds of measurements, respectively with an extensometer and with a digital image correlation technique (DIC). Similar experimental results were obtained, validating the use of DIC at high temperature to evaluate high strain levels. Two different microstructures of Ti-6Al-4V alloy were tested to study the impact of the initial microstructure on the mechanical behavior. For similar conditions of strain rate and temperature, representative of the forming process, a fine-grained microstructure exhibits an enhancement of mechanical behavior in comparison with the classical coarse-grained microstructure used in the current industrial process. Finally, an elasto-viscoplastic has been identified for each microstructure.
Investigations on the temperature and strain rate dependent behavior of a reinforced thermoplastic: application in hot incremental forming
Authors: FADDOULD Josephine
Published: April 2024

Abstract. This study focuses on characterizing the thermo-viscoplastic behavior of a glass fiber reinforced polypropylene through an advanced characterization technique. Based on a preliminary work addressing a mechanical characterization from conventional uniaxial tests, the proposed rheological model is calibrated using the database of in-plane equi-biaxial tensile tests on a dedicated cruciform specimen geometry from room temperature up to 140°C. The Finite Element Model Update (FEMU) method is employed for parameter calibration. A comparative analysis with the model calibrated from prior uniaxial tests is conducted through finite element simulations of a forming process. This investigation includes a parametric study to objectively assess the impact of the behavior law on forming force and final profile. This parametric study has direct implications for the simulation of an original forming process. The ability to identify the differences in forming outcomes based on different behavior laws enhances the predictive accuracy of the simulations. This ensures that the chosen behavior law aligns closely with the real behavior of the material during forming.
A strategy for minimizing the computational time of simulations involving near-surface embossing of sheet metal materials
Authors: HEINZELMANN P.
Published: April 2024

Abstract. By near-surface embossing, work hardening can be introduced into sheet metal blanks, thus increasing the material´s yield strength. Hence, this property-modifying process can be used to improve the lightweight potential of a component on the one hand and its crash performance on the other. For the early design of such embossing or forming processes and to predict the modification of the material properties, FE modelling is currently used. Here, the embossing of the near-surface structures is usually simulated first, followed by the forming process. However, existing simulation methods are time-consuming and computationally intensive, due to the simulation of the whole embossing process. For this purpose, this paper presents two approaches for improving the simulation time of embossing and forming processes. Compared to the conventional holistic embossing and forming simulation, these approaches are based on a new mapping strategy and experimental data. In the mapping variant, solid elements’ stress and strain distribution is mapped to shell elements, thus including the embossing history for the forming simulation. For the experimental-based variant, the yield curves of embossed tensile tests are determined and used to approximate the property changes in the simulation. Both concepts are compared with each other and the conventional simulation method in terms of accuracy and calculation time. This paper finally shows that simulation can be performed faster with the new approaches than with the current sequential modelled workflow.
Accurate 3D modeling of laser-matter interaction in the AFP process by a conductive-radiative FEM approach
Authors: STORTI Bruno A.
Published: April 2024

Abstract. Mainly driven by aeronautical demands, the Automated Fiber Placement (AFP) process has become pivotal in the in-situ manufacturing of intricate, high-performance composite components. AFP relies on robotic systems to meticulously lay continuous fiber-reinforced materials, employing controlled pressure and precise laser heating. Accurate thermal modeling is imperative to predict thermal effects impacting contact, adhesion, crystallinity, and residual constraints. This work introduces a novel numerical approach for efficient modeling the transient heat transfers in the AFP process using a coupled conductive-radiative finite element method (FEM) scheme. Radiative density from the laser-matter interaction is determined through an in-house parallelized FreeFEM++ code. Heat transfer at the micro-scale is assessed by using an artificial computational geometry based on fiber distributions obtained from tape micrograph. A parametric study with varying absorption coefficients of the carbon fibers is performed to accurately compute the radiative volumetric heat source. The proposed approach investigates various 2D and 3D scenarios involving different laser parameters. Results exhibit strong agreement with experimentally obtained data, showing a maximum temperature difference of 5-6°C at the end of the heating phase. Furthermore, a 3D case demonstrates the potential of this approach for modeling complex micro-scale geometries.
Numerical investigation of the effects of process parameters on forming load and failure in hot nosing process
Authors: TURSUN Huseyin
Published: April 2024

Abstract. Nosing process is generally used to reduce the diameter of the open end of the circular thin-walled tubes. Friction coefficient and workpiece temperature are two important process parameters that should be investigated to understand the process in detail. In addition, forming length and nosing ratio need to be considered to carry out a successful process. If these parameters are not determined correctly, workpiece damage like buckling is inevitable. The purpose of this study is to investigate the effects of the process parameters on the forming load and failure of the workpiece in the hot nosing process.
On the experimentation of the laser-powder bed fusion process for high-strength aluminum alloys
Authors: EL HASSANIN Andrea
Published: April 2024

Abstract. Additive Manufacturing (AM), a cutting-edge technique developed for the manufacture of prototypes that aims to produce large-scale products tailored for numerous industrial applications, has found increasing space in recent years. In this context, Laser-Powder Bed Fusion (L-PBF) technology represents one of the most intriguing ones considering the large number of processable and under-development alloys. By combining the inherent benefits of this technology, it is then possible to produce components with improved mechanical characteristics and low weight. Nevertheless, improved properties such as thermal and electrical conductivity, strength, and corrosion resistance can be achieved. In this scenario, high-performance aluminum-based alloys, tailored for the metal AM have raised increasing interest in the industrial framework. In this work, the LPBF processing of an Al-Mg-Sc-Zr was investigated. The tensile characteristics, the microhardness, the density and the microstructure of L-PBF specimens were analyzed.
Investigation of the Influences on the Indentation of tubes under lateral loads by segmented forming tools using DoE
Authors: REUTER Jonas
Published: April 2024

Abstract. Making the widely used bending processes with geometry-specific tools, such as compression bending, more flexible in terms of the part geometries that can be produced with a single tool set, is a current challenge as mass customization and small batch sizes demands on manufacturing technologies. One approach is to segment the tools and thus add degrees of freedom that allow the die to adapt to different part geometries. However, the discrete surface can cause part defects such as localized indentations and until now, there has been no design method for segmented surfaces. As a step to close this gap, this study presents a statistical, finite element (FE) simulation-based design of experiments (DoE) to investigate the main influences on the indentation depth in the lateral indentation of circular steel tubes by segmented tool surfaces, considering both tool surface parameters and tube properties. The resulting regression equation is then used to compare the prognosticated indentation depths with those obtained from FE simulations and to develop a first pre-design approach for segmented tool surfaces. The results of the simulation-based DoE show that the segment spacing, the wall thickness factor, the interaction between them, the segment radius and the interaction between the segment radius and the segment spacing are the main influencing parameters and, interestingly, the mechanical tube properties have no significant influence. Finally, it is outlined that the regression equation can be used as a pre-design tool and that refinements are necessary for its usage as a valid design tool.
Cellular automata and crystal plasticity modelling for metal additive manufacturing
Authors: KAVOUSI Majid
Published: April 2024

Abstract. This paper presents a methodology to establish a process-structure-property (PSP) relationship for the additive manufacturing (AM) of small AISI 316L parts, as might be used in coronary stent applications. The methodology includes a physically based process-structure model based on cellular automata (CA) for microstructure characterization and generation, coupled with crystal plasticity finite element (CPFE) structure-property modelling to predict the mechanical response of the AM part under tensile loading. The effect of AM process variables, such as laser power and scanning speed, are reflected in the PSP modelling through the thermal modelling of AM feeding into the CA model. The CA method is shown to be able to capture microstructure texture, which is key to anisotropic behavior of AM parts. The present study aims to (i) establish a practical link between CA and CPFE models and (ii) identify optimal process variables with respect to ductility.
One-shot drilling of unconventional thin metal hybrid stacks for aerospace applications
Authors: PANICO Martina
Published: April 2024

Abstract. The aerospace industry's relentless pursuit of lighter, stronger, and more fuel-efficient aircraft has led to the widespread use of lightweight materials, particularly aluminum alloys, in aerospace engineering. This study focuses on the challenges associated with one-shot drilling without back-up forces of thin parts, a strategy aimed at reducing cycle, avoiding part separation for cleaning after drilling, and minimizing part assembly problems. Despite its effectiveness, problems persist with defects developing at the interface due to the interlayer gap phenomenon. This gap causes metal chips to accumulate and is influenced by both process parameters and the clamping conditions and methodologies. While existing literature primarily associates process parameters with burr measurements, this study delves into the often-overlooked influence of clamping strategies on the occurrence of interface defects. Through experimental drilling on a thin stack of Al7075-T6 and Al2024-T3, various clamping schemes were analyzed to assess their impact on burr height. The results were also correlated with the drill verse, thrust force, and torque. The objective is to increase know-how about these aspects and optimize clamping strategies for effective one-shot drilling, addressing gaps in current research.
Virtual inline compensation by single point-tracking in free-form bending
Authors: SCANDOLA Lorenzo
Published: April 2024

Abstract. Free-form bending represents an attractive process for the manufacturing of structural components. Due to its kinematics-based working principle, a variety of geometries can be realised in the 3D-space featuring different radii, angles and bending planes. Nevertheless, the kinematic design of the bending head movement represents a complex task, and in order to obtain a part in the desired tolerance range a time-consuming trial and error procedure is the actual state of the art. The part is measured offline and compared to the target geometry after the bending operation, and the analysis of deviations is carried out to derive the compensated bending program. This is not only inefficient, but does not allow for compensating geometrical errors while the process runs. In this paper, a virtual inline compensation strategy based on single point-tracking is proposed. First, the process is modelled virtually and a single point on the component is tracked in space. Subsequently, the obtained tracking signals are presented and explained. Successively a kinematics adaption concept is shown and verified. On a virtual level the results show that the tracking of a single point on the geometry during the process can be used to compensate geometrical deviations in free-form bending.
Reprocessable vitrimeric composites metallized via cold spray: A preliminary study on the feasibility of novel hybrid structures
Authors: PERNA A.S.
Published: April 2024

Abstract. Due to their excellent mechanical properties and lightweight, fibre-reinforced thermoset composites are appealing materials for high-demand industries like aerospace or automotive. However, the inability to be reprocessed and the difficulty in repairing and recycling the thermoset matrices raise serious environmental issues and greatly increase the cost of materials. In fact, as a result of the irreversible chemical bonds formed during the curing process, it is not possible to reshape the material once it is set into its final form. In this context, the novel vitrimer polymers, characterised by intriguing mechanical and chemical properties as well as the ability to be reprocessed and recycled, have sparked increased attention in the literature [1]. Nevertheless, those composites are still limited by their poor surface properties strongly limiting their functionalities. In this scenario, surface metallisation has proved to be an intriguing opportunity to overcome those issues. Among the metallisation technologies, in recent years Cold Gas Dynamic Spray (CGDS) was widely investigated in the literature, owing to its capacity to produce metallic layers on thermo-sensitive materials as it does not exploit thermal energy to create the coatings. In this work, the possibility of producing hybrid fibre-reinforced vitrimer-based composites coated with metallic particles is analysed.
Investigating the effect of the addition of WC into NiTi for stent application
Authors: AGARWAL Neha
Published: April 2024

Abstract. Nitinol is used for self-expandable stents used in biomedical applications considering their excellent properties of being superelastic and biocompatible. Minimally invasive implants need to be securely positioned in the human body with the property of being visible with the help of X-rays. Limited radiopacity of nitinol implants requires additional markers on the implants to facilitate accurate placement of the implant. This study explores the path of adding different concentrations of tungsten carbide (WC) to nickel-rich nitinol powder. Tests were conducted by compacting the mixed powders with a hydraulic press and then furnace sintering the green samples, with varying pressures and temperatures, to produce the solid parts. The mechanical properties of density and hardness of the sintered samples were measured and compared. An increase in hardness from 76 HV to 150 HV indicated that better mechanical properties could be achieved. Fully dense samples without any pores were obtained. These results show potential for the introduction of WC to nitinol for additively manufactured parts.
Utilizing thermal imaging for non-destructive thermoformability assessment in vacuum-air pressure thermoforming of plastic-coated paperboards
Authors: AFSHARIANTORGHABEH Sanaz
Published: April 2024

Abstract. This study addressed the limitations of traditional post-production analyses in refining thermoforming operation by employing non-destructive, real-time thermal analysis, specifically employing thermal imaging. The focus was on assessing the thermoformability of plastic-coated paperboards, a recent area of interest in manufacturing. Three paperboards underwent vacuum and air pressure thermoforming, with continuous temperature monitoring. Findings revealed correlations between the temperature distributions, the thermal profiles, and the material shape formability. Direct analysis of the thermal images enabled accurate measurement of contact areas between the mold and material. Furthermore, temperature profiles were closely related to shape profiles, particularly concerning the depth, which might be due to exothermic response of the studied materials during the induced stretching process.
Development of novel composites of incompatible barrier polymers and their optimal processing conditions for recyclable thermoformable food packaging sheet
Authors: AKIKI Alain
Published: April 2024

Abstract. In this work, a high barrier polymer MXD6 (m-xylene diamine) has been incorporated in a PE (polyethylene) matrix to create an extensible, thermoplastic composite system. MXD6 is a high barrier and glassy polymer. However, being polar, it is incompatible with a non-polar PE. To this date, there were no significant attempts neither in compatibilizing a binary blend of PE/MXD6 nor in exploring the benefits of orientation on such a mixed system. The main value proposition in this work resides in reducing the dispersed MXD6 phase close to a submicron scale in the PE matrix by designing an adequate mixing process/compatibilizer method. Thermal characterization of the composites and the scanning electron microscopy have confirmed that the MXD6 dispersed phase in the compatibilized blends has been physically and thermally confined; its crystallization during cooling stage has been inhibited. The compatibilized blend shows a creation of an interface adhesion between phases. The dispersed phase average particle size is stabilized at around 0.5 μm enhancing the recyclability of the final product.
Laser metal deposition of NbTaTiV refractory high entropy alloy
Authors: BARTH Eric
Published: April 2024

Abstract. A mixture of Ti, V, Nb and Ta elemental powders was used to print an equimolar Refractory High Entropy Alloy NbTaTiV. Single beads and wall structures were printed on Ti-6Al-4V substrates. The samples were then cut to analyze their cross-section and composition. The samples present a large proportion of non-melted Ta particles, due to the low max power of the used laser (500W) and of the high melting-point of Ta. It was found that using a two-step deposition process (deposition, followed by a powder-less re-melting pass) could allow to homogenize the samples and melt said Ta particles. Moreover, the authors report difficulty to control the composition of the samples due to the very different physical properties of the different elements composing the alloy, with a preferential deposition of Ta.
Identification of the thermal conductivity of polymer materials during their crystallization
Authors: MOUSSALLEM Rita
Published: April 2024

Abstract. Controlling the quality of industrial products requires an accurate comprehension of the material’s behavior during the several transformation phases. An accurate estimation of the heat transfers taking place throughout the production phases necessitates the exact knowledge of the thermophysical properties. These properties are well known in the solid state, however they are less mastered in the liquid state and during transformation. The main objective of this research project is to estimate the evolution of the thermal conductivity during transformation by solving an inverse heat conduction problem. The calculation outputs ought to describe the evolution of the thermal conductivity function of two coupled fields: the temperature and the transformation degree. The inverse method relies on a finite difference numerical model and a hybrid optimization algorithm, combining a stochastic method with a deterministic method. The temperature evolution within a thermoplastic undergoing transformation is measured with the help of an instrumented mold. The thermal conductivity values are identified by minimizing the discrepancy between the experimentally measured temperature profile and the one numerically simulated. The acquired results are compared with the mixing law, classically used to take into account the phase change of a material. It is observed that the values acquired by the established inverse method reproduce the measured temperature profiles more accurately than the mixing law.
Finite element modeling (FEM) as a design tool to produce thin wall structures in laser powder bed fusion (L-PBF)
Authors: Pollara G.
Published: April 2024

Abstract. Laser Powder Bed Fusion (LPBF) has been widely adopted in many industrial sectors such as biomedical, automotive, and aerospace thanks to the possibility to produce objects with complex shapes and meet customers' needs. Despite all the advantages that LPBF can offer, the rise of residual stress due to the high thermal gradients generated during the process can limit its application. This is the case with thin-wall structures where the build-up of residual stress can compromise the success of the printing process. Being able to print this structure can be useful in fuel cell applications where the implementation of cooling channels in bipolar plates can improve their performance. This paper aims to provide guidelines for designing thin-wall structures produced by LPBF processes through numerical simulations by understanding the effect of residual stress on part distortion.
Influence of the use of mechanically recycled pet in injection stretch blow moulding process (ISBM)
Authors: VIORA Laurianne
Published: April 2024

Abstract. Different mechanically recycled PET issuing from different countries of origin have been studied and compared to a neat one, as a reference. Strech ability above glass transition temperature was explored towards uni-axial tensile experiments or injection stretch blow moulding (ISBM) tests. It has been shown in that study that rPETs and virgin do present global mechanical behaviours. This similar trend is obvious either in low or large deformations domains. Master curves built for the 5 grades indicated equivalent behaviour between the grades from the glassy to the rubbery state. A controlled stretching campaign confirmed that all grades present visco-hyperelastic behaviours that are similar until the deformation for which the materials start to strain-harden. Uni-axial tensile tests were proved to be efficient to discriminate all grades especially regarding the Natural Draw Ratio (NDR) onset of all grades. The virgin PET does present a lower NDR that comforts the fact that strain-induced crystallization can be easier in the virgin case. This test campaign analysis is confirmed by the injected preforms blowing process where the virgin case grade develops lower blowing volumes because of a sooner NDR. It highlights the fact that forming behaviours of rPET must be slightly adapted compared to virgin PET. For rPET, the effects of loss of molar mass combined with the presence of contaminants could be at the origin of these discrepancies.
Influence of surface treatments on the fatigue strength of cross bores in shafts from EN-GJS700-2
Authors: UHLMANN Lars
Published: April 2024

Abstract. The European Union's Federal Climate Protection Act mandates a 55 % reduction in greenhouse gas emissions from 1990 levels by 2030, aiming for climate neutrality by 2050. Achieving these goals requires emission cuts across sectors, including energy, industry, and transportation. Lightweight design in transportation, achieved through alternative materials, geometry optimization, or enhanced fatigue strength, is vital. Highly stressed components like shafts are prone to failure due to notch locations which reduces the fatigue strength significantly. Inducing compressive residual stresses through methods like deep rolling and shot peening may improve the fatigue strength by reducing critical tensile load stresses. This study compares the fatigue strength of shaft cross bores treated with induction hardening, deep rolling, shot peening, and the combination of induction hardening and deep rolling. The research aims to establish a cause-effect relationship between surface layer properties and fatigue strength, considering the redistribution of residual stresses during testing.
Friction stir-assisted cladding: Solid-state recycling of machine shop scrap for sustainable metal production
Authors: KAUSHIK Pankaj
Published: April 2024

Abstract. The manufacturing industry, a cornerstone of modern economies, generates a substantial amount of waste in the form of manufacturing chips, which often end up as discarded byproducts. This waste not only poses environmental hazards but also represents a missed opportunity for resource efficiency and cost savings. This article explores the innovative use of friction stir-assisted cladding (FS-AC) as a sustainable and cost-effective solution for repurposing aluminum chips on a steel substrate without melting the material. The study investigates the mechanism of the FS-AC process, highlighting the conversion of metallic swarf into a feedstock material for cladding without entailing costly clad materials. Metallographic analysis demonstrates a uniformly clad layer with an average thickness of 0.95 mm. The study addresses challenges related to bonding at the clad layer-substrate interface and proposes further advanced characterization studies for diffusion analysis and coating-substrate bond strength. In conclusion, the FS-AC process presents a valuable method for recycling machine shop floor scrap, transforming it into useful feedstock material for cladding purposes, and that too in an energy-efficient manner. This proposed approach has promising potential for processing different material combinations for additive manufacturing and exploring functionally graded material development using metallic swarf.
Machine learning application for optimization of laser directed energy deposition process for aerospace component rapid prototyping in additive manufacturing
Authors: ERTUGRUL G.
Published: April 2024

Abstract. The paper proposes a methodology for determining the optimal L-DED parameters based on the minimum number planned of L-DED trials. A dataset compiled from planned L-DED experiments was used to train a machine learning model. The algorithm demonstrated a robust ability to predict the output metrics with notable accuracy and proposed a theoretical framework that modeled the complex relationships between the input variables and the resulting critical welding properties for AM. The application of the developed model and its comparison with conventional methods thus offers a methodical approach to determining the optimum process parameters in advance. This is a step towards the development and production of additively manufactured components for future digital twin application in the aerospace industry.
Assessing single and multi-step friction stir consolidated recycled billets through uniaxial upsetting test
Authors: Latif A.
Published: April 2024

Abstract. Friction stir consolidation (FSC) represents a solid-state recycling technique that directly transforms machining waste into billets by the stirring action and friction heat of the rotating tool. This technology has demonstrated superior energy efficiency compared to remelting-based traditional recycling methods. Concerning the FSC process mechanics, they impart temperature, strain and strain rate gradients across the billet sections leading to variations in mechanical properties such as hardness values and grain size distribution. Therefore, multi-step FSC variants were introduced to eliminate this inherent inhomogeneity inside the billets of the single-step FSC approach. However, the billets manufactured by multi-step methods showed better mechanical properties, and gradation across the billet section still persisted. This property led to the evolution of friction stir consolidation as a new manufacturing method for developing functionally graded materials. Previously, the gradation was highlighted by the Vickers hardness test and grain size distribution. Therefore, in the ongoing study, an advanced characterization technique was adopted by extracting miniaturized samples from the section of FSC billets and subjected them to the upsetting test. Employing advanced characterization techniques to get insights into the gradation and quality of billets manufactured through various process variants and will allow to draw a better conclusion regarding adoption of a more suitable FSC process variant.
Life cycle assessment (LCA) of a novel solid-state recycling process for aluminum alloy AA6063 chips via direct hot rolling
Authors: CARTA Mauro
Published: April 2024

Abstract. Aluminum utilization has been growing in the last decades thanks to its high strength to weight ratio, corrosion resistance, excellent plasticity, and good weldability. Recently, unconventional processes have been developed for aluminum recycling, called Solid-State Recycling (SSR), by avoiding melting process, allow to save up to 85% of energy needed for secondary aluminum production. The aim of this study is to assess the environmental advantages of a novel recycling technique namely Direct Hot Rolling process. This innovative solid state recycling process will be evaluated for its eco-friendliness. The Life Cycle Assessment (LCA) analysis follows a gate-to-gate approach: collected chips coming from prior cutting process are cold pressed and subsequently hot and cold rolled to obtain the functional unit, defined as the sheet produced through Direct Rolling of 35g of AA6063 chips. Primary data come from direct measurements provided by an industry plant operating in aluminum production field and direct measurements taken during the experimental activity in laboratory. Secondary data were provided by studies available in literature and SimaPro® databases. This LCA comparison between two similar different routes for SSR through rolling suggests that the second one, Direct Hot Rolling + ARB technique, is more suitable to reduce the environmental impact of aluminum recycle industry. However, Accumulative Roll Bonding is considered a low productivity process for worldwide industries, considering the difficulty of automation and repeatability of the procedure.
Experimental and computational analysis of 3D printed 2D lattices
Authors: MUSSINI Andrea
Published: April 2024

Abstract. Additive Manufacturing can offer different solutions in terms of bespoke implants and deformable structures tailorable by the geometry design. The prototyping phase consists in a preliminary evaluation of the mechanical performances to find a relation with the geometrical parameters. For these reasons, numerical tools that can relate directly the geometrical features, especially for lattice or cellular structures, to the mechanical properties, are often studied to speed up the design and production process. In this study, the predictability of the deformation of a structure composed by honeycomb unit cells was studied performing compression simulations. Successively, the structure was 3D printed using fused filament fabrication and tested using a positioning stage, the relative displacements of 36 specific points of the structure were extracted using contactless measurement techniques and compared with the simulations. The results demonstrated a good predictability of the model in relation to the deformation of the structure with a stable relationship between the geometry selected and the final mechanical properties.
An investigation into the relationship between hemisphere tooling parameters and thickness changes during the thermoforming of a thermoplastic composite
Authors: WHITE Kari D.
Published: April 2024

Abstract. Thermoforming is an economical and fast means of transforming a flat sheet of thermoplastic composite material into a complex shape. The two-step process consists of a preform phase that transforms the laminates to near net shape ply stacks and of a subsequent consolidation step that employs pressure and heat to join the preforms into a final part. During the preform step, many aspects of the process must be regulated to minimize undesirable affects. A binder ring applies pressure to the material to induce in-plane tension, aiding in the initiation of shear deformation in the laminate. The material increases in thickness as it undergoes in-plane shear to conform to the preform shape. The degree of shear varies over the part, creating variations in thickness and subsequent challenges with uniform consolidation. While material attributes and processing parameters are critical in successful preforming, refining the tool geometry can also lead to significant changes in the preform outcome. Although many of these challenges have been addressed in a design-build-test approach, the goal of this research is to develop a virtual process that can guide design changes in the tooling to achieve a well consolidated part. A discrete mesoscopic modeling approach was implemented in LS-DYNA using thickness-change shell elements (ELFORM25) that can incorporate 3D material properties, including through-plane thickness changes. The current state of the simulation effectively incorporates material behavior, tool/ply friction and thickness changes that reflect variations in pressure. The simulation is used to investigate the significance of the punch/die gap size and the die fillet radius on the tooling geometry. The modeling approach was verified through comparison to experimental results with two types of tooling geometry. A parametric study was then performed to investigate tooling changes in relation to the number of layers, or thickness, of a unidirectional ultra-high molecular weight polyethylene (UHMWPE) material, DSM Dyneema® HB210. The outcomes of the result were evaluated by comparing wrinkle formation, shear deformation and thickness variations. The research shows that the radius of the die fillet has a significant impact on the uniformity of thickness in the preform. A combination of fillet radius and die affects can lead to more desirable outcomes in terms of wrinkle formation and thickness uniformity.