bluuebunny/crossref_metadata_2025 huggingface dataset:
Microrespirometric Validation of a Two-stage Process for Polyhydroxyalkanoates Production from Peanut Oil and Propionate with Cupriavidus necator
Authors: Pérez-Camacho Irazú , Chavarría-Hernández Norberto , del Rocío López-Cuellar Ma , Guerrero-Barajas Claudia , Ordaz Alberto
Published: April 2024

Introduction

Poly(3-hydroxyalkanoates) (PHA) is a biodegradable polyester synthesized by various bacteria, including Cupriavidus necator. The composition of PHA is influenced by the type of microorganism, cultivation conditions, and carbon substrate. The selection of a carbon source is critical for PHA production, significantly impacting process costs. Therefore, the common goal is scalability, with the design and optimization of PHA production relying on experimental determination of constitutive parameters.

Methods

In this work, a two-stage process for PHA production was conducted in shaking flasks functioning as mini reactors with the bacteria Cupriavidus necator. During the first stage, fructose was used as the sole carbon source. Once fructose was exhausted, a second stage commenced with a new carbon source, either peanut oil or propionate, to enhance PHA production. Ex-situ pulse respirometry approach was employed during the two-stage process to follow the kinetics of substrate consumption.

Results

The results indicated that the use of peanut oil would be advantageous over propionate, resulting in 12.2% more biomass and 13.9% more PHA.

Conclusion

Additionally, the growth rate was 88.9% higher with peanut oil. The characterization by pulse respirometry applied in microreactors, i.e., micro respirometry, allowed for the performance of up to 216 biological experiments to determine four important kinetic and stoichiometric parameters, namely maximum oxygen uptake (rO2max), substrate affinity constant (KS), growth yield (YX/S), and substrate oxidation yield (YO2/S). The values of these parameters indicated that peanut oil would be the best carbon source to promote PHA production during the second stage. The implementation of the microrespirometry technique during the screening of carbon sources for PHA production provided reliable information within a short period and with significantly less experimental effort.
Loneliness, Psychological Well-being, Depression, and Social Participation
in the Older Persons: Rural and Urban Differences
Authors: Gümüş Demir Zeynep , Yılmaz Mahmut
Published: April 2024

Introduction:

The purpose of this study is to compare the loneliness, psychological well-
being, depression, and social participation of elderly people living in Turkish society between rural
and urban areas. The sample group of the study, in which a correlational survey model was
used, consisted of 610 elderly adults.

Method:

The study population consists of two groups: the first group consists of individuals over
65 years of age living in the city (Istanbul) (n= 291), and the second group consists of individuals
over 65 years of age living in rural areas (rural areas of Ordu) (n= 319). Socio-demographic Information
Form, Loneliness in the Elderly Scale, Geriatric Depression Scale, Psychological Well-Being
in the Elderly Scale, and Social Inclusion Scale were applied online. Statistical analyses of the
study were conducted using SPSS 27.00, and the Independent Samples t-test and ANOVA test
were used.

Results:

According to the findings of this study, statistically significant results were found in psychological
well-being, social inclusion, social relations, loneliness and depression, and place of
residence. It was observed that the social isolation and social acceptance levels of those living in
urban areas were higher than those living in rural areas. Social, loneliness, and depression scores
of those living in the village/town were found to be higher than those living in the city centre. Furthermore,
the social relationship scores of those living in the village/town were found to be higher
than those living in the city centre.

Conclusion:

The increasing elderly population worldwide has become an issue that requires global
measures. Place of residence is one of the factors thought to affect older people's health and well-
being. It is thought that the study data will contribute to new policies that will ensure the protection
and promotion of elderly health and those working in this field. In addition, the study, which
provides information about Turkish culture, will also enable intercultural comparisons.
Indonesian Football: A Bibliometric Analysis and Perspectives
Authors: Pradana Mahir , Elisa Hanifah Putri , Putra Adrianza
Published: April 2024

Background

Football is one of the most popular sports in Indonesia, where millions of people follow the game. In spite of its popularity, Indonesia has little information about the sport from the academic sector. This study gap is concerning because it limits the scholars’ ability to comprehend the effects of the sport on Indonesian society, culture, and the economy.

Methods

The formulation of plans and programs to raise the caliber and level of competition in Indonesian football is also hampered by a lack of research. In order to give some insights into how academics have so far researched Indonesian football, we undertook a bibliometric study. This article also discusses the difficulty of incorporating a sports context into the literature on social ecosystems, adding contribution by integrating ideas from previous works of literature. To get a deeper understanding of the growth of Indonesian football literature in the 2000s and 2010s, we performed a bibliometric study of football publications in several databases.

Results

The issues raised in this study will be considered in light of recent advancements in sports science, society, and technology.

Conclusion

We inferred numerous relevant subject clusters from this study, such as “training,” “competition,” and “development.” The implications of the research and its potential for future directions are also discussed in this article.
Formulation and Evaluation of Transdermal Niosomal Gel for
Antihyperlipidemic Agent
Authors: Patil Pravin , Bhagwat Priyanka , Sankpal Pournima , Patil Sachinkumar , Dhawale Shashikant
Published: April 2024

Aims:

The current study aims to create a formulation of Fluvastatin sodium (FVS) loaded niosome
for the treatment of antihyperlipidemia using thin film hydration. The developed formulations were
statistically optimized by two factors, three levels by 3-level factorial design and were evaluated for vesicle
size, entrapment efficiency, zeta potential, transmission electron microscopy, and in-vitro drug release.

Methods:

The optimized FVS niosome being transformed to gel formulation was likewise analyzed
for in-vitro skin permeability study, lipase action, and stability study.

Results:

The composition of an improved FVS niosome revealed vesicle size, entrapment effectiveness,
zeta potential of 105.3 ± 12.4nm, 74.5 ± 0.86% and -36.2 ± 7mV, respectively, with spherical morphology.

Conclusion:

The FVS Niosomal gel demonstrated improved skin permeation compared to Orlistat. Furthermore,
lipase activity showed better activity when compared with standard Orlistat drugs. Niosomal
particles were discovered as a reliable nanovesicular carrier for the transdermal administration of FVS.
Formulation Consideration of Medicated Chewing Gum: A Review
Authors: Bobe Kishan , Suryawanshi Yoesh , Gomase Virendra , Kachhi Muizz , Bobade Chandrashekhar
Published: April 2024

In recent times, technological and scientific advances have been made in studying and
developing orally delivered medication. Such studies demonstrate the importance of the oral route
among patients. The accuracy of drug delivery is very important to achieve a successful therapeutic
effect in the case of various pharmaceutical products. A novel drug delivery system adds new benefits
or advantages to a drug. This review covers all the aspects of medicated chewing gum (MCG)
as a new drug delivery method, including the benefits and drawbacks, manufacturing methods, type
of MCG, composition of chewing gum, evaluation parameters, factors that affected the release of
API, its pharmaceutical significance, various marketed chewing gum and chewing gum packaging.
Chewing gum as a drug delivery system has the potential to cure or prevent various indications,
such as analgesic, CNS stimulation, smoking cessation, motion sickness, and treatment and prevention
of dental caries or gingivitis. Pharmaceutical distribution to the oral mucosa can be made more
convenient and enticing with the help of MCG. Compared to conventional techniques, this delivery
system has a longer-lasting effect, which makes it a viable option for treating digestive problems,
headaches, migraines, coughing, anxiety, and allergies.
Modeling fused deposition of PLA by analysis of the layers
Authors: BRUNI C.
Published: April 2024

Abstract. The realization of the additive manufactured components requires the understanding of the variables having an effect on the physical final geometry. One of them is represented by the initial digital information with required tolerance, in particular where the different parts such as planar and curved ones need to be connected together. The other important variable is represented by the extruding conditions in FDM of PLA blend materials. The temperature setting with which to reduce the induced tensions, the volume variation and warpage is determined.
Impact of hot rolling on the r-values of 6000 series aluminium alloys
Authors: SARBAN Ali A.
Published: April 2024

Abstract. Crystallographic texture of sheet metal influences formability significantly. Lankford coefficient or the so-called r-value, a texture related property, is a property often specified as a customer requirement and therefore a property that requires close monitoring and control during the production process. Through systematic experiments, it is demonstrated how hot rolling, especially hot tandem rolling influences r-values of wrought aluminium alloys. A tandem rolling model has been developed that enables control of final r-value for a given 6016 alloy with a given downstream process. The model clearly shows how entry temperature and exit speed of tandem mill can be used to control the final product’s r-value. The model that provides a metallurgical explanation for the effect, can be used to steer the tandem mill in such a manner that a minimum r-value is guaranteed and at the same time, variations of r-value along the length of the strip are minimized or suppressed. The model also provides a better alternative to the existing and conventional tandem mill steering methodology based on constant exit temperature. The proposed methodology is based on keeping a (nearly) constant Zener-Hollomon parameter along the length of the strip during tandem rolling.
Enhancement of fracture strain during abrupt orthogonal strain- path changes in ferrite/martensite dual phase steel
Authors: MATSUNO Takashi
Published: April 2024

Abstract In multistage press forming, the scrutiny of work-hardening behavior attributed to abrupt strain path changes in deformation paths has been pivotal in the context of press formability. However, applying this method to stretch flanging presents a formidable complexity. In such scenarios, substantial deformations resulting from shear-cut processing and subsequent stretch-flange formation significantly influence the local fracture strains, a critical determinant of process success. Therefore, our investigation examined the impact of deformation path variations on the fracture strain of dual-phase steel sheets. A crucial facet of our experimental approach involved manipulating the strain level during the initial tensile deformation. Tensile deformation was extended beyond the onset of necking, culminating in the emergence of microvoids within the material. Following this preliminary extensive strain, successive tensile tests were conducted on diminutive round-bar specimens, subject to a 90º change in the deformation path, to investigate their influence on work hardening and fracture strain. The outcomes of the diameter-measuring tensile tests unveiled a pronounced cross effect during the early stages of deformation, particularly concerning work-hardening behavior. However, as the deformation advanced, the results conformed to the stress-strain curve observed in the same direction of tension. Notably, the fracture strain exhibited an approximately 10% enhancement attributable to the abrupt strain path change, thereby having the potential to augment the practical stretch flangeability.
Numerical assessment of the role of anisotropy on strain localization in uniaxial tension
Authors: CORALLO Luca
Published: April 2024

Abstract. Despite the experimental evidence of the effect of loading direction on the inclination of necking bands in uniaxial tension, theoretical and numerical studies are mainly devoted to isotropic materials. Recently, theoretical, numerical, and experimental works have put into evidence the key role of the material anisotropy on the formation of localized necking bands. In particular, Cazacu and Rodriguez (2019) [1] provided analytical expressions for the orientations of the necking bands that develop under uniaxial tension in flat specimens . It was shown that there is a switch in the orientation of main necking band from acute to obtuse, which is correlated with the anisotropy in yield stresses. In this paper, we conduct a FE study on virtual materials with the same anisotropy in Lankford coefficients but different anisotropy in yield stresses. We show that, although both materials have a very slight anisotropy in yield stresses, it strongly affects the localization behavior.
From strain to stress using full-field data: Computationally efficient stress reconstruction
Authors: HALILOVIČ M.
Published: April 2024

Abstract. Conventional stress reconstruction based on full-field strain measurements presents a major computational burden, especially when using standard implicit stress integration methods. This presents a notable challenge for inverse identification methods used to characterize the plasticity of metallic materials, particularly those reliant on stress reconstruction, such as the nonlinear sensitivity-based Virtual Fields Method (VFM). To reduce the computational effort, the full-field strain data are usually spatially and temporally down-sampled. However, for metals subject to nonlinear strain paths, this practice can lead to errors in the resulting stress states and compromise the accuracy of the nonlinear VFM. In this work, we introduce a highly efficient explicit stress reconstruction algorithm to reduce the computational challenges of repeated stress reconstruction which can be utilized in inverse identification methods such as nonlinear VFM.
Influence of pre-strain on fracture toughness of 3rd generation advanced high strength steels
Authors: GRIFÉ Laura
Published: April 2024

Abstract. The present work investigates the influence of pre-strain on the fracture toughness of 3rd Generation Advanced High Strength Steels (AHSS). Specifically, a Carbide Free Bainitic (CFB) and a Quenching and Partitioning (Q&P) steel have been studied, the properties of which are crucial for lightweight vehicle construction. Fracture toughness, which is a key parameter for crash performance applications, is assessed using the Essential Work of Fracture methodology. The study investigates the pre-straining states of uniaxial tension, plane strain, and equibiaxial tension in 1.5 mm Q&P and 1.4 mm CFB sheet-form steels of 1180 MPa tensile strength. Overall, Q&P steel demonstrates superior fracture toughness compared to CFB steel. Remarkably, the specific essential work of fracture (we) remains unaffected by pre-straining across different strain states. Nevertheless, pre-straining exerts a notable influence on the non-essential plastic work (βwp) due to the plastic energy consumed during pre-deformation. These results suggest that pre-strain has little or no influence on the fracture properties of AHSS, which is relevant for the design and manufacturing of high crash-performance and safety-related components.
Enhanced formability in two-step forming for AA7075 sheet in -T6 and -W tempers
Authors: HA Jinjin
Published: April 2024

Abstract. In response to stringent environmental regulations, the automotive industry is increasingly prioritizing lightweighting, prompting a shift towards high-strength aluminum alloys while the low formability of these alloys remain a limiting factor. This study explores a solution through a two-step forming process applied to AA7075 sheets utilizing -T6 and -W tempers. Firstly, two-step uniaxial tension experiments are performed at two prestraining levels in the -T6 temper followed by subsequent tensions in the -W. Both cases exhibit significant plastic deformation before fracture, overcoming the thinning accumulated in the first step. Additionally, a two-step hole expansion experiment is conducted under the same tempering conditions. Results are compared with single operations in each temper, evaluating force-displacement curves and thickness strain distribution around the hole. The study highlights the substantial contribution to formability enhancement, demonstrating 80% higher cup height and twice greater thinning to fracture compared to conventional single-step operations.
A parameter-free strain estimation method to prevent occurrence of splits in sheet forming of complex CAD designs
Authors: EYCKENS Philip
Published: April 2024

Abstract. Early detection of manufacturability issues in the design stage is key to avoid long lead times in product development. For various sheet forming processes a critical issue is the occurrence of splits, due to forming beyond the intrinsic formability properties represented by the Forming Limit Curve (FLC). Nevertheless, within industrial engineering practice a detailed manufacturing process simulation including forming limit prediction is not obvious. While commercial Finite Element analysis tools for sheet metal forming are readily available on the market, because of current limitations in availability of accurate data, companies may be rather inclined to choose experimental verification over process simulation analysis. For formability analysis, the required accurate data comprises both material data (hardening data, plastic anisotropy data, FLC data) as well as process data (e.g. non-linear friction data in lubricated system; static or dynamic tool elasticity properties).Therefore, we propose a first-order approximation of the forming deformation, without any parameter (e.g. for material, friction), based solely on conformal flattening of the CAD sheet surface. In this work, we show the usefulness of this method in hydroforming of complex-shaped, industrial parts (bipolar plates). It is shown that from the strain estimation, we can identify the most critically strained regions for individual categories of strain, as formability is known to be greatly dependent on strain mode. The tooling assists to compare design alternatives in terms of formability in the absence of FLC or even basic material data.
Massive nitrogen super-saturation into CoCrMo Alloys for improvement of tribological performance
Authors: AIZAWA T.
Published: April 2024

Abstract. The cobalt-chromium-molybdenum (CoCrMo) superalloys have been utilized in the dental, knee, and hip arthroplasty applications because of their unique combination of high strength, high wear and corrosion resistance. A massive nitrogen supersaturation (MNS) process was proposed as a surface treatment to improve these strength, hardness and ductility, further needed for hip replacement and dental prosthesis. CoCrMo disc specimens were prepared for plasma immersion nitriding at 673 K for 21.6 ks by 50 Pa. The nitrogen solute uniformly distributed in the MNS-layer with the average content of 5 mass%. Higher surface hardness than 1550 HV was attained under application of 10 N. The maximum friction coefficient was halved before and after MNS and this low frictional state with μ< 0.45 was preserved although the sliding condition by 0.1 m/s.
Comparative accuracy analysis of continuous fiber composite printers: Coextrusion vs. dual-nozzle technology
Authors: OCHANA Imi
Published: April 2024

Abstract. Material Extrusion (MEX) technology for continuous fiber reinforced thermoplastic composites (CFRTCs) is based on the extrusion of a continuous fiber to create three-dimensional composite objects layer by layer. This technology explores three distinct methods: pre-impregnated filament, dual-nozzle, and coextrusion. The goal of this paper is to compare two printers, one using the dual nozzle technology and another relying on coextrusion. The first printer, Mark Two of Markforged, is based on dual-nozzle technology. The second printer, the Anisoprint Composer A4, stands out for its coextrusion method. Three adaptive Geometrical Benchmark Test Artifacts (GBTA), proposed by Spitaels et al. were fabricated with each printer to determine their dimensional performances. Measurements are taken using a Coordinate Measuring Machine (CMM) Wenzel LH 54. The overall deviation results of the two printers are around the IT14 standard. Deviations for measurements between 1 and 10 mm are greater compared to dimensions exceeding 10 mm, averaging around IT 12. Along the Y-axis, Markforged shows smaller deviations, attributed to its smaller print bed dimension compared to Anisoprint. Additionally, Z-axis deviations are lower than those along other axes, suggesting both printers have better precision in vertical build plate movement compared to print head movement. Notably, significant deviations are observed at the center of the GBTA in comparison to the other three axes (X, Y, and Z) for both printers.
Thermomechanical reverse flow forming of AISI 304L
Authors: ARIAN B.
Published: April 2024

Abstract. In manufacturing, property control ensures efficient part production. However, in reverse flow forming, current practices focus on geometry control rather than property control. To address the complexity of the process and tool machine interaction, process control is crucial for defined component properties. This study focuses on controlling local α’ martensite content in reverse flow forming of seamless AISI 304L steel tubes. Strategies and systems are presented to influence α’ martensite content, creating unique microstructure profiles for 1D and 2D Gradings, with tangible component outcomes.
Numerical and experimental analysis of struts joined by electromagnetic forming for aircraft applications
Authors: Psyk V.
Published: April 2024

Abstract. Joining by electromagnetic forming can provide high-strength connections of tubes and connector parts from different materials. In order to qualify this technology for manufacturing components made of high-strength aluminum alloys typically used in aircraft manufacturing a parameter study was performed on form fit joining of tubes (outer diameter: 70 mm, wall thickness: 1.6 mm) and mandrels (diameter: 66.6 mm) both made of EN AW-2024 (T351). Since some aircraft applications, e. g. the so-called z-struts, which support the passenger floor of the airplane, are related to high axial compressive loads and medium axial tensile loads, this load scenario was considered. In order to increase especially the compressive load-bearing capacity, joint configurations featuring direct support of the tube end via a step or a shoulder of the joining partner were designed and investigated. The axial support can increase the transferable compressive load, while the tensile load remains largely unaffected. Attention must be paid to the gap between tube end and axial support, which cannot be fully avoided due to axial material flow during the electromagnetic joining process. Bending the tube end into a groove providing axial support of the tube end enables compressive load-bearing capacities, which can approximate the strength of the tube material. Here, increasing bending angles improve the load-bearing capacity under tensile force, but reduce the transferable compressive load. Multiple groove configurations can provide acceptable load bearing capacity considering tensile and compressive load. Numerical simulation can predict the general behavior of components joined by electromagnetic forming, help to understand the damage mechanisms of the joint and allow identifying trends for joint design.
Comparison between ALE and Lagrangian finite element formulations to simulate tensile loading for FDM parts
Authors: HOMRANI Mohamed Khalil
Published: April 2024

Abstract. Material Extrusion (MEX) and by extension Fused Deposition Modeling (FDM) is a popular Additive Manufacturing (AM) process used to fabricate complex parts. FDM as of recent is no longer solely utilized for prototyping parts but also used for producing functional components in industrial and research applications. The investigation of material properties of these FDM parts by experimental means is a time-consuming task. Therefore, the use of numerical simulation methods is highly required. Since 1993, various Finite Element Analysis (FEA) models are found in literature attempting to effectively simulate FDM parts utilizing many formulations, each with their pros and cons. The present study aims to compare Lagrangian and Arbitrary Lagrangian-Eulerian (ALE) finite element formulations in simulating tensile loading for FDM parts. The efficiency and precision of the aforementioned methods is evaluated in the numerical simulation of the tensile loading of an ASTM D638 standard geometry ABS specimen utilizing both ABAQUS/Explicit and ABAQUS/Standard. Utilizing a paper from the literature for experimental validation, this study additionally provides insight into explicit and implicit models’ computational efficiency, focusing on the advantages of explicit models for this application. The effects of mesh element type and size on results are also studied for each method. Based on these results, some useful guidelines for selecting the most suitable model of tensile loaded FDM parts are presented.
Study on the numerical prediction quality of material models regarding springback of hollow embossed metallic bipolar half-plates
Authors: BECK Maxim
Published: April 2024

Abstract. Due to the ongoing endeavors to reduce CO2 emissions in the energy sector, particularly through advancements in electric mobility, the demand for thin metallic components is currently increasing. This demand is notably apparent for bipolar plates, which are used in fuel cells. The production of these bipolar plates requires high-precision hollow embossing of thin metallic foils with thicknesses below 100 µm. Even minor variations in this process can result in forming defects and undesirable springback in produced parts. A robust design of manufacturing processes for bipolar plates therefore necessitates the implementation of accurate finite element analysis (FEA), since this is crucial for predicting material behavior during and after the forming process. However, the precision of such simulations is heavily dependent on the material models employed. For this reason, the study presented in this paper specifically focused on the numerical modeling of high-precision hollow embossing of bipolar half-plates. For this purpose, a comprehensive material characterization of a 1.4404 stainless-steel foil with a thickness of 0.1 mm was conducted first. Moreover, an experimental laboratory geometry and a corresponding laboratory tool for the hollow embossing of miniaturized bipolar half-plates was developed in order to enable a comprehensive evaluation of the simulation results. The validation and assessment of widely used material models for metal forming in LS-Dyna, exemplified by MAT_036 Barlat '89 and MAT_133 Barlat 2000, were effectively demonstrated through experimental forming tests. These tests confirmed distinct performance differences between the two material models concerning springback and thinning. Importantly, it was confirmed that the simpler MAT_036 model exhibits high accuracy in predicting both springback and thinning, emphasizing its effectiveness in capturing relevant deformation properties during the hollow embossing process.
Characterization of the wrinkling limit curve using in-plane compression tests
Authors: MAGRINHO João P.G.
Published: April 2024

Abstract. The global need for a green economy and the ongoing challenge of climate change have spurred demand for lightweight construction in various industries. This transition involves redesigning components with intricate geometries and advanced materials to reduce sheet metal thickness and the overall part weight. However, this pursuit of lightweight structures introduces challenges, particularly in wrinkling, raising the need to develop accurate methodologies for determining formability limits by wrinkling. This paper focuses on in-plane compression tests, specifically addressing the compression stress state associated with wrinkling in the flange area in deep drawing or a strip during flexible roll forming. Three physically-based methodologies (A, B, and C) are proposed to detect the onset of wrinkling and characterize the wrinkling limit curve (WLC) through experimental tests. Methodology A involves the analysis of the Z displacement, methodology B focuses on the in-plane minor strain rate evolution, and methodology C employs the analysis of the force-displacement evolution. The experimental work involves the mechanical characterization of AA1050-O aluminum sheets and the in-plane compression tests of rectangular specimens with different lengths. The results reveal distinct behaviors in wrinkling initiation for the different specimen lengths. The critical strain pairs obtained from each methodology are utilized to construct the WLCs in the principal strain space, providing insights into the formability limits by wrinkling.
Stretch forming of isotropic materials: Influence of the ratio between yielding in pure shear and uniaxial tension on the stress state
Authors: REVIL-BAUDARD Benoit
Published: April 2024

Abstract. The formability of metallic sheets could be assessed by performing a hydraulic bulge test. For isotropic materials, interpretation of the bulge test is usually done using the von Mises yield criterion. F.E. simulations of bulge tests were conducted to study how the specificities of the plastic behavior of an isotropic material influences the strain paths and stress paths experienced during hemispherical and elliptical bulging. In this paper, we investigate the role played by the ratio between the yield stresses in pure shear and uniaxial tension of the material, τ_y \/σ_T on the mechanical behavior during hydraulic bulging. To this end, we make used of the Drucker yield criterion, which can describe the mechanical behavior of isotropic materials with different ratios τ_y \/σ_T with a unique parameter c. For c = 0, the Drucker criterion reduces to the von Mises yield criterion (i.e. τ_y \/σ_T=1\/√3 ) while for c ≠0, it involves dependence on the third invariant of the stress deviator, J_3. Finite element predictions using the yield criterion reveals a correlation between the ratio τ_y \/σ_T which is uniquely defined in terms of the parameter c and the level of plastic strains that develop in the dome, the thickness reduction at the top of the apex, and the strain paths achieved in an elliptical bulge test.
Assessment of wire arc additive manufacturing with respect to the repeatability of the process under uncertainties
Authors: PULICKAN Shyam
Published: April 2024

Abstract. Energy Deposition Methods (EDM) is on the rise with its capabilities to manufacture relatively big parts, and Wire-Arc Additive Manufacturing (WAAM) has been on the forefront. Developments in this technology has led to the innovation of WAAM-Cold Metal Transfer (WAAM-CMT), which is much more efficient than its predecessors. Nevertheless, it comes with its own complexities, giving rise to uncertainties, eventually causing variations in the geometry of fabricated parts. But these uncertainties can be traced back to the input parameters involved in the process. Even though, WAAM is influenced by several phenomena and parameters, only a handful of parameters are practically controlled during the process. Among these the most important parameters identified are Wire Feed Rate (V_feed) and Travel Speed (V_T) of the robot, which have a direct influence on the parts fabricated. To quantify the variability of these process parameters and the geometry of the bead, 140 single-layered beads are fabricated with four different set of input parameters. Quantification of the variations and the repeatability aspect of these variables, and thereby the process itself, are then studied using statistical tools like ANOVA. This gives an idea on how these vary from bead to bead. Quantifying these uncertainties and understanding the variations would help improve the process. This would enable better control of the process parameters, thus helping to make better design of the process and better predictions about the variations to expect.
The continuous fibre injection process (CFIP): A novel approach to lightweight design of multi-material structural components
Authors: CRESCENTI Marc
Published: April 2024

Abstract. The combination of different materials enables to achieve highly efficient structures in terms of lightweight and mechanical performance, as well as in terms of manufacturing costs. However, the weakest points of these structures use to be the joints. For this reason, in the last years, many studies have dealt with joining technologies for dissimilar materials. The Reinforce3D’s Continuous Fibre Injection Process (CFIP) technology delivers a unique method to join dissimilar materials. CFIP is based on injecting continuous fibers, such as carbon fibers, simultaneously with liquid resin into tubular cavities within the part. Then the resin is cured and the final composite part is obtained. This work focuses on the characterization of the mechanical properties of CFIP-made specimens and describes the potential lightweight benefits of the technology. Mechanical tests were performed under tensile and bending conditions following standardized methods. The lightweight potential is addressed by developing a representative case study by implementing finite element and topology optimization methods. The results of this case study were finally compared with a monomaterial equivalent component (aluminium) demonstrating the improvement that CFIP provides in terms of lightweight while keeping the strength.
Dissimilar welding of aluminum to AlSi-coated steel sheets using refill friction stir spot welding: A feasibility study
Authors: SHEN Tong
Published: April 2024

Abstract. The main objective of this study was to assess and enhance the weldability of AA6016-T4 to AlSi-coated press-hardened steel (PHS), with a focus on investigating the impact of the AlSi coating on the mechanical properties of welded joints. Variations in tool rotation speed, dwell time, and plunge speed were performed to observe their effects on the joint behavior. It was observed that the protective AlSi-coating significantly influences the mechanical strength of the welded joint. Notably, the removal of the AlSi coating resulted in a substantial increase in joint mechanical strength. To systematically assess joint lap-shear strength under static loading conditions, Design of Experiment technique was employed. The influence of the process parameters on joint strength was thoroughly evaluated.
On the impact welding of dissimilar alloys for use in multimaterial skeletal fixation devices
Authors: SANGUEDOLCE M.
Published: April 2024

Abstract. Multi-material skeletal fixators appear to be a promising approach to reduce failure due to the high stiffness of standard-of-care fixators. Nevertheless, joining different materials is challenging due to their different properties. High-velocity impact welding, a solid-state welding process, involves the collision of a “flyer” (moving) part with a stationary “target” at very high speed (i.e., hundreds of meters per second). In this paper we present a preliminary experimental campaign to use laser impact welding to join NiTi and Mg alloy Mg-1.2Zn-0.5Ca-0.5Mn (wt%) sheets and the parallel development of a finite element model to allow gathering further insights into the complex phenomena involved in the process. Preliminary results show the deposition of the Mg alloy on NiTi sheets by tuning the joining process conditions and promising results of the numerical model in terms of accordance with experiments: these findings provide the basis for further process optimization, numerical model calibration and the application of a valid protocol for multi-material skeletal fixation devices.
Inverse identification of the heterogeneous strain hardening of the friction stir welded aluminum sheets using virtual fields method
Authors: KIM Chanyang
Published: April 2024

Abstract. In this paper, inverse identification of the local heterogeneous strain hardening in friction stir welded aluminum alloy sheets using a single tensile test is presented. During friction stir welding, the mechanical properties of the jointed aluminum sheets are altered from their original states. The finite element-based virtual fields method (FE-VFM) was applied to measure this change in the mechanical properties during the joining. Special numerical schemes were adopted in the FE-VFM for the accurate and numerically efficient identification of the local properties, including a two-step VFM calculation procedure, a sub-zone division approach in the weld-affected zone, quadratic interpolation of the constitutive parameters, and a special type of virtual fields based on the Gauss distribution function. The newly developed method was applied to measure strain-hardening distributions of the friction stir welded AA6061-T6 sheets. The measured distributions of the local strain hardening well captured decreased strength in the narrow thermo-mechanically affected zone (TMAZ). Finally, inversely measured mechanical properties were validated based on finite element analysis.
Surrogate modeling for multi-objective optimization in the high-precision production of LiDAR glass optics
Authors: VU Anh Tuan
Published: April 2024

Abstract. This study addresses the ever-increasing demands on glass optics for LiDAR systems in autonomous vehicles, highlighting the pivotal role of the recently developed Nonisothermal Glass Molding (NGM) in enabling the mass production of complex and precise glass optics. While NGM promises a significant advancement in cost- and energy-efficient solutions, achieving the requisite shape and form accuracy for high-precision optics remains a persistent challenge. The research focuses on expediting the development phase, presenting a methodology that strategically utilizes a sparse dataset for determining optimized molding parameters with a minimized number of experimental trials. Importantly, our method highlights the exceptional ability of a robust surrogate model to precisely predict the accuracy outputs of glass optics, strongly influenced by numerous input molding parameters of the NGM process. This significance emphasizes the surrogate model, which emerges as a promising alternative to inefficient traditional methods, such as time-consuming experiments or computation-intensive simulations, particularly in the realm of high-precision production for LiDAR glass optics. In contributing to optics manufacturing advancements, this study also aligns with contemporary trends in digitalization and Industry 4.0 within modern optics production, thereby fostering innovation in the automotive industry.
VForm-xSteels: virtual materials database
Authors: ANDRADE-CAMPOS A.
Published: April 2024

Abstract. Nowadays, most of the product designs rely on the aid of simulation software, particularly Finite Element Analysis (FEA) programs. However, an accurate simulation requires a proper virtual/numerical material behavior reproduction, meaning a precise material characterization through constitutive models and their parameters. To numerically characterize a material, particularly a metal, (i) experimental tests, (ii) model selection and (iii) inverse procedures are required. All these three tasks can be expensive and time-consuming. Therefore, product development engineers resort to materials databases to obtain the virtual materials, i.e. the constitutive models and their parameters adequate for the desired material. However, the information provided by the materials databases does not include experimental data nor provide information on the testing procedures. Due to this absence, users cannot verify the information nor its accuracy on the material database. Moreover, data related to material constitutive models, required for accurate simulations seems to be absent [1]. This work presents the development of a new material database that revises the previous problem. This database has the focus on virtual materials and their importance in product simulation and design. The presented VForm-xSteels material database includes (a) mechanical models and their implementation in FEA software, (b) experimental data and (c) the parameters identified for each material, and (d) indications concerning the quality of the material behavior reproduction associated with each model/parameters set. This database can be enlarged by the contributions of all users and present the following benefits for the engineering community: (i) increasing the precision and reliability of numerical FEA simulations by providing accurate input data, filling then a gap of the FEA market and answering to the request of the FEA users; (ii) reducing the development lead-time of metallic parts and the development of robust technological solutions with highly improved quality, consequently decreasing cost and time in the overall development process.
Metallization of Vitrimers by cold spray: A preliminary study
Authors: VISCUSI A.
Published: April 2024

Abstract. Cold spray is a promising solution for the production of metallic coatings on polymer substrates. However, the adhesion mechanism between the impacting particle and the polymer in cold spraying depends on the chemical structure of the polymer itself. In this scenario, the emerging vitrimer polymers, which were proved to combine enhanced mechanical and chemical performances with abilities to be healed, welded, reprocessed, and recycled and that show a ductile behavior when exposed to given operating temperatures, can be particularly suitable for being functionalized by cold spray. Therefore, the aim of this work is to experimentally prove the feasibility of the metallization process via cold spray of epoxy vitrimer substrates. For this purpose, an epoxy vitrimer formulation was studied and experimentally characterized. Vitrimer-based panels were manufactured and used as substrates for the surface metallization. A low-pressure cold spray facility was used for the deposition of aluminum alloy particles. Microscope analyses were carried out for the characterization of the samples.
Intelligent control of ISBM process for recycled PET bottles
Authors: HAN William
Published: April 2024

Abstract. To manufacture plastic bottles with an increased ratio of rPET (recycled Polyethylene terephthalate), the ISBM (Injection Stretch Blow Moulding) process must be controlled to account for the variable mechanical and thermal properties. Calibration and optimization of the process have been successfully realized in past works but cannot be used for real-time applications. To address this, a gaussian process regression model of the free blowing step is created. It can calibrate itself using the pressure curve from a previous blowing to obtain near instantaneous predictions of key properties of the bottle. To create the model, the process’ characteristics are studied. Finite element simulations of the blowing where the properties follow a multivariate gaussian distribution are used to train the artificial intelligence. Then, an example is shown using the artificial intelligence predictions to optimize the thickness distribution of a bottle after blowing.
Influence of the sheet thickness variability on the deep drawing of a cylindrical cup
Authors: PEREIRA A.F.G.
Published: April 2024

Abstract. Sheet metal forming processes are widely used in industry. The quality of formed parts can be significantly affected by various sources of uncertainty inevitably associated with the forming process. The objective of this work is to quantify the influence of thickness variability on the forming process of a cylindrical cup. Using numerical simulation, the influence of the sheet thickness variance on the evolution of the punch force versus displacement, the equivalent plastic strain distribution, the earing profile and the thickness around the cup is studied for a given cup height. Four thickness distributions with different variance values and the same average thickness value were studied. It was concluded that an increase in variance leads to an increase in thickness dispersion (at the base and curvature of the cup) and an increase in equivalent strain dispersion along the cup. The earing profile of the cup is also affected by the thickness variability, but to a lesser extent. On the other hand, the development of the punch force is not affected by the thickness variability.
Micro-milling and micro-EDM residual stresses evaluation on post-processed 3D printed samples
Authors: HIKARU Abe
Published: April 2024

Abstract. Micromachining is essential for producing microscopic components or obtaining complicated details in high-precision devices. Micromachining on 3D-printed metal samples is a cutting-edge, interdisciplinary field that blends additive manufacturing with accurate subtractive machining processes at the microscale. This method aims to precisely remove material from 3D-Printed metal items to obtain complicated geometries with strict tolerances, and high-end surface finishes. The surface integrity is not only determined by the surface roughness, but it depends also on the residual stresses caused by the thermo-mechanical loads during the Additive Manufacturing and the Micromachining processes. This paper aims to analyze the residual stresses measurements after Micromachining with both Micro-Milling and Micro-Electrical Discharge Machining of 3D-Printed metal samples. 17-4 PH stainless steel 3D printed samples were produced with Laser Powder Bed Fusion. The analysis of the residual stresses was carried out by producing microchannels of different sizes (200 μm and 800 μm) to also investigate the scale effect.
Effect of the hatch spacing in laser powder bed fusion on the AlSi7Mg aluminum alloy cutting forces and surface finish after turning
Authors: GHINATTI Edoardo
Published: April 2024

Abstract. Applying additive manufacturing (AM) technologies in fabricating aluminum alloy automotive components can significantly enhance vehicle light-weighting through optimized design. By varying the AM process parameters, the resultant microstructure can be substantially altered, even post-heat treatment. Given that machining operations remain essential in many applications, understanding the impact of the AM parameters on the machining performances is vital. This paper explores how hatch spacing in laser powder bed fusion (LPBF) process affects the machinability of the AlSi7Mg aluminum alloy, in terms of cutting forces and machined surface roughness, providing a correlation with the microstructure induced by both the AM and heat treatment steps. In particular, the research reveals that the larger the hatch spacing the smoother the machined surface, underlining the critical role of this LPBF parameter in determining the final surface quality.