bluuebunny/crossref_metadata_2025 huggingface dataset:
Should the Heels Touch the Floor During the Plié in Classical Ballet Jumps
Authors: Souza Wanessa , Pessali-Marques Bárbara
Published: July 2022

This paper aimed to review the literature concerning the correct execution of the plié movement in the performance of different classical dance jumps. Studies about jumping techniques (such as countermovement jump, squat jump, and drop jump), the stretch-shortening cycle of short and long duration, classical dance jump and ballet mechanical action description by Agrippina Vaganova and Balanchine raised questions concerning different forms of plié execution preceding small and big jumps. Depending on the circumstance, they were especially concerning the heels contact on the floor during the plié execution before each jump. Understanding when the contact should happen or not is crucial for the prescription of adequate and specific training.
Survey on Service Placement, Provisioning, and Composition for Fog-Based IoT Systems
Authors: Sadatacharapandi Thiruchadai Pandeeswari , S. Padmavathi
Published: July 2022

In the modern IoT era, time and resource critical applications are more prevalent. Though cloud computing enables fast processing of data and producing results, the time and network overhead are huge. Fog based solutions have proved to eliminate this overhead. However, establishing a scalable fog based architecture for IoT applications involves a number of challenges such as guaranteeing QoS, reducing operational costs etc. Hence a viable fog based architecture must involve optimal service placement facilitated by suitable schemes for resource estimation and reservation, QoS monitoring, data interchange and integration. This paper surveys various service placement and optimization approaches proposed in the literature and compares them. This paper also explores various components that are required for composing a viable fog based architecture and presents a representative fog provisioning framework. Relevance of modern technologies and tools such as RESTful architecture, SDN, Kafka, RabbitMQ, Zookeeper in establishing an efficient framework for fog based IoT applications is discussed
A New Fault-Tolerant Algorithm Based on Replication and Preemptive Migration in Cloud Computing
Authors: Semmoud Abderraziq , Hakem Mourad , Benmammar Badr , Charr Jean-Claude
Published: July 2022

Cloud computing is a promising paradigm that provides users higher computation advantages in terms of cost, flexibility, and availability. Nevertheless, with potentially thousands of connected machines, faults become more frequent. Consequently, fault-tolerant load balancing becomes necessary in order to optimize resources utilization while ensuring the reliability of the system. Common fault tolerance techniques in cloud computing have been proposed in the literature. However, they suffer from several shortcomings: some fault tolerance techniques use checkpoint-recovery which increases the average waiting time and thus the mean response time. While other models rely on task replication which reduces the cloud's efficiency in terms of resource utilization under variable loads. To address these deficiencies, an efficient and adaptive fault tolerant algorithm for load balancing is proposed. Based on the CloudSim simulator, some series of test-bed scenarios are considered to assess the behavior of the proposed algorithm.
From Bureaucracy to Citizen-Centricity
Authors: Saxena Deepak , Muzellec Laurent , McDonagh Joe
Published: July 2022

Organisations, including public service organisations, are increasingly adopting a digital transformation strategy, and deploying digital capabilities to enhance customer experience. However, digital initiatives in public services often focus more on the technology with relatively less regard to the citizen for whom the services are designed. To address this lacuna, this study contextualises the digital transformation of public services by focusing on the citizen. This study is based on data collected in the conduct of two projects involving public services within an EU member state. Based on the analysis of the citizen-journey in availing of public services, five common pain-points are identified – information inconsistencies, intricate website navigation, bureaucratic jargon, disconnected multichannel touchpoints, and a lack of real-time online support. To alleviate the pain-points, we offer five insights based on academic insights and international benchmarking.
Towards a Decision Support System for Optimizing the Location of Warehouses in a Supply Chain by Using the Bee Colony Algorithm
Authors: Belayachi Naima , Yachba Khadidja , Bouamrane Karim
Published: July 2022

One of the goals that a company sets is the customer's satisfaction, which is a priority item. This clearly shows that the concerns of companies are focused on the customer and how this later could be served quickly. This work addresses the problem of optimization of the location of the distribution centers of a final product to customers, in a given region. The problem addressed in this paper is the location of the position (emplacement) to build a new distribution center (warehouses), taking into account the constraint of the distance between a distribution center and the various points of sale, and the constraint of the cost of land to build a distribution center. The optimization method used for this problem is the artificial bee colony algorithm (ABC), which was initially applied to numerical function optimization problems, inspired from the behavioral model bees during foraging.
Spatial Group Decision Support System to Facilitate Site Selection Negotiation Process, Reduce Decision-Maker Conflict, and Augment System Performance
Authors: Benmoussa Khadidja , Hamdadou Djamila , Roukh Zine El Abidine
Published: July 2022

The selection of a suitable land requires careful thought and several criteria must be taken into account to ensure a good decision. Typically, selection processes are based on face-to-face meetings. But this strategy focuses on simple predefined searches and selections according to some basic criteria, such as land price, etc. They do not take into account spatially explicit criteria and spatial analyzes relevant to a site selection process (for example, proximity to hospital). To overcome these limitations, the proposed system relies on the integration of four key concepts: a multi-agent system, a multi-criteria method, geographic and ontological information systems. The results of the implementation provide manageability of large data storage. Despite the large number of approaches integrating geographic information systems and multicriteria analyzes, their use, in practice, is limited because they lack data semantics. As a result, the concept of ontology which introduces the semantics of the proposed approach offers many possibilities in terms of the type of terrain.
Blockchain Potentials to Enhance Identified Data Usability Challenges Generated by Wearables
Authors: Baumann Steffen , Stone Richard Thomas , Abdellal Esraa Saleh
Published: July 2022

Blockchain, the underlying technology behind cryptocurrency, has found use in many industries, such as healthcare, where Internet-of-Things (IoT)-enabled wearables and home use medical devices allow patient data to be collected by the patient themselves, which causes concerns related to data generation, transmission, and storage. The purpose of this quantitative study is to increase the understanding of what concerns medical professionals have about data usability generated by these devices, and if blockchain can eliminate these challenges. An online survey was distributed to 29 medical professionals. The findings that surveyed participants showed that significant concerns that the patients' IT skills, device malfunction, data privacy, the patient's exam skills and environment during the exam are factors that may affect the patient health data. Upon analyzing blockchain capabilities, it was discovered that it can be used as a solution to some of the identified hurdles and help to comply to the health data priorities in healthcare ethics.
A Bibliometric Analysis of Automated Writing Evaluation in Education Using VOSviewer and CitNetExplorer from 2008 to 2022
Authors: Deng Xinjie
Published: July 2022

As technology develops by leaps and bounds, automated writing evaluation (AWE) has caught increasing attention worldwide. This study aims to provide an overview of research literature focusing on AWE used in education through bibliometric analysis. The data of studies (N = 815) published from 2008 to 2022 were analyzed using the VOSviewer and CitNetExplorer software. The results showed that the most cited countries were USA, China, and Canada. The most cited organizations were Georgia State University, University of Delaware, and Educational Testing Service. The most co-cited authors were Graham, Crossley, and Attali. The most used keywords were feedback, automated essay scoring, and natural language processing. It was also indicated that the previous studies mainly revolved around three themes, i.e., the design and development of AWE technology, the application of AWE in education, and the effect of AWE on linguistic features. This study provided references for entry into the AWE field and identifying future research directions.
Teaching Preferences of International Students
Authors: Smith Clayton , Zhou George , Potter Michael , Wang Deena , Menezes Fabiana , Kaur Gagneet , Danko Habriela
Published: July 2022

This article explores promising teaching practices for teaching linguistically and culturally diverse international students by identifying the teaching practices that have high levels of international student satisfaction and student perceptions of learning for science, technology, engineering, and mathematics (STEM) and non-STEM international students. Research was conducted by an international, student-learning community with guidance from a faculty-led research team. Data were collected through a qualitative research design that included focus groups and individual interviews conducted at a mid-sized Canadian comprehensive university. A total of 28 students participated (14 STEM students and 14 non-STEM students). Researchers examined differences between STEM and non-STEM students on 22 promising teaching practices regarding student satisfaction and students' perceptions of learning. Recommendations for professional practice are discussed, along with potential areas for further research.
On the Effect of the Tension-Compression Ratio on Forming of Isotropic Materials
Authors: Oliveira Marta C. , Prcela Ivan , Cvitanić Vedrana , Neto Diogo M. , Alves José Luis , Menezes Luis Filipe
Published: July 2022

It is generally believed that the choice of the yield criterion used to describe the plastic behaviour of isotropic metallic materials does not affect much the accuracy of the predictions of forming operations. For this reason, the von Mises yield criterion is widely used for modelling their plastic behaviour. However, according to the von Mises yield criterion, the ratio between the yield stresses in tension and compression is always 1.0. Nevertheless, materials can present same asymmetry, i.e. a strength differential (SD) effect. In this work, the yield criterion proposed by Cazacu et al. [1], is adopted to describe the mechanical behaviour of isotropic materials, with different levels of tension-compression asymmetry. Numerical simulations of the deep drawing of a cylindrical cup were performed considering these different virtual isotropic materials, in order to evaluate its impact on the thickness distribution and cup height. The analysis of the stress and strain paths, for material points initially located in the flange is performed, enabling the correlation between the thickness distributions predicted and the plastic strain ratios obtained analytically, using the yield function and the normality rule. The results show that even small changes in the tension-compression stress ratio can influence the strains distribution, in isotropic materials.
Influence of the Surrounding Sheet Geometry on a Clinched Joint
Authors: Martin Sven , Kurtusic Kristijan , Tröster Thomas
Published: July 2022

Point-shaped joints of complex assemblies and components are loaded mainly by shear, whereas the actual load in a joint depends on the surrounding sheet geometry and the number and layout of the joints. Within the scope of this paper, the interaction between a joint and its surrounding geometry is investigated on overlapped single clinched specimens. The geometry of the upper sheet near the joint is changed by thickening and by inserting corrugations and rectangular cavities. The investigations show that this causes different stress states in the joint.
Prediction of Forming Limit Diagram Using the Marciniak-Kuczynski Method for Ti-6Al-4V Using Different Material Models
Authors: Lonardi Claudio , Corallo Luca , Verleysen Patricia
Published: July 2022

The forming limit diagram (FLD) is a widely used tool to assess the formability of a metal sheet [1]. The current study aims to investigate the influence of strain rate, material anisotropy and hardening on the FLD of Ti-6Al-4V predicted by the well-known Marciniak-Kuczynski (M-K) method. The tensile data of quasi-static (8 10-5 s-1), intermediate (0.5 s-1) and dynamic experiments (approximately 1000 s-1) on Ti-6Al-4V sheet are available at three different orientations, with respect to the rolling direction: 0°, 45° and 90°. Different hardening models are taken into account. Also, von Mises and Hill yield criterion are considered. The results show that the influence of the hardening law on FLD is significant. In particular, the most conservative limit strains are predicted by the Voce law because of its saturation characteristic. The yield criterion is found to only affect the right part of the FLD. Regarding the strain rate influence, the left part of the FLD is mainly dominated by the amount of uniform elongation, while the right part is strongly dependent on the yield function used. Therefore, for this region the effects of strain rate and yield function are difficult to distinguish. Finally, the effect of material anisotropy on the FLD is significant. Under quasi-static conditions, the Lankford coefficient seems to be the driving factor in uniaxial and equibiaxial deformation. However, in plane strain conditions the effect of the strain hardening exponent is dominant.
CNT/2009Al Aluminum Matrix Composite Sheet Forming for a V-Shaped Skin Part
Authors: Liu Bao Sheng , Cao Feng Chao , Zeng Yuan Song , Wu Wei , Ni Ding Rui , Pan Ran
Published: July 2022

The carbon nanotube (CNT) reinforced aluminum sheet with 2.0 mm thickness was hot rolled. The friction stirring process (FSP) was applied to make the reinforcements dispersion uniform. A finite element simulation was conducted to optimize the forming parameters of a V-shaped skin part. It should be formed in two passes, and the bottom corner radius is advisable to be greater than R = 30 mm in the first pass. The V-shaped skin part was successfully formed and the profile accuracy error was less than 0.2 mm. The part's mechanical properties show that the composite sheet still keeps a high strength after two thermal procedures.
Observations of Polymer Foam Development during Rotational Moulding
Authors: Pritchard Alex , Martin Peter , McCourt Mark , Kearns Mark , Cunningham Eoin
Published: July 2022

Large scale buoyant structures typical of offshore wave energy generation devices may be produced using the rotational foam moulding process. Due to the challenging environmental conditions these parts experience during their lifetime at sea, it is important that the structures are optimised to ensure acceptable mechanical performance. Foams containing large cells suffer a reduction in mechanical properties; therefore, an optimal foam contains small, evenly sized, and well distributed bubbles in large numbers. Due to the lower pressures used in the process, this can be challenging to achieve. Careful selection of material and processing conditions is required to achieve an optimal structure. A unique bench-based rig was used to observe developing foam structures. A camera was used to record the foam height change at intervals. Foam height change was obtained using digital image analysis. Several parameters were studied such as the polymer particle size or the mould pressure for example. In addition to the foam height change, foam density were analysed. It is found that mould pressure, polymer particle size, chemical blowing agent concentration, and polymer rheology may be used to control the foamed structures.
Material Forming Digital Twins: The Alliance between Physics-Based and Data-Driven Models
Authors: Chinesta Francisco , Cueto Elías , Guevelou Simon
Published: July 2022

This paper aims at introducing the main building blocks of a digital twin, embracing physics-based and data-driven functionalities, both enriching mutually. Both should proceed in almost real-time, and the last being able to proceed in the scarce data limit. When applied to materials and processes, model order reduction technologies enable the construction of the so-called “computational vademecum”, whereas data-driven modelling, based in advanced regressions, must be informed by the physics to encompass rapidity and accuracy, in the low data limit. Despite of the recent advances, a lot of functionalities are needed and are under progress, some of them representing real scientific challenges. A number of them, the ones that we estimate being the most crucial, will be discussed in the present work.
Crystal Plasticity Modeling of Al Alloy under Linear and Non-Linear Loading
Authors: Juan Rong Fei , Liu Wen Qi , Inza Xabier Gastañares , Ureta Xabier Dominguez , Mendiguren Joseba , Lian Jun He
Published: July 2022

The crystal plasticity (CP) model is widely used in many applications to link microstructure and mechanical properties. There are varying CP constitutive laws with phenomenological or physical-based formulation to cover a large range of loading conditions. In order to predict the deformation behavior of an Al alloy during the sheet metal forming process with either linear or non-linear strain path, both phenomenological and physical-based CP constitutive laws have been chosen, and the prediction performance of both models is compared. For the linear loading condition, the uniaxial tensile tests are performed on the smooth-dog-bone (SDB) specimens along rolling and transverse directions (RD/TD). The non-linear strain path is achieved by the Marciniak testing followed by uniaxial tension. In the first stage, the Marciniak testing is performed under the stress states of RD-uniaxial, plane strain, and biaxial tension. After being loaded to a certain strain level, mini-SDB specimens are cut along RD and TD from the uniform deformation region and reloaded under RD-uniaxial tension. The digital image correlation (DIC) technique is employed to measure the strain during testing. The electron backscatter diffraction (EBSD) technique is used to characterize the initial microstructure as well as the microstructure evolution of the specimens after the first stage loading in the non-linear strain path. A phenomenological power law and a dislocation-density-based hardening law have been employed in this study. The parameters are calibrated based on the flow curve of the RD uniaxial tension. The model performance is validated by stress–strain response under all the rest loading conditions including the non-linear loading path.
Evaluation of the Patternability of Fibre-Based Materials with Converting Experiments
Authors: Tanninen Panu , Leminen Ville , Matthews Sami , Merabtene Mahdi , Varis Juha
Published: July 2022

Paperboard based packaging products are renewable alternatives for packages made traditionally from oil-based polymer materials and can be used for packaging of various products [1]. Embossing is used in packaging solutions to increase the functionality and appearance of the products. It can also be used to increase product safety by improving distinctiveness and identifiability of packages [2]. The aim of the study was to evaluate the patternability of various fibre-based materials. It was desired that the accuracy and details of the embossed pattern would be the same in all samples, regardless of their different material properties. The realization of this was evaluated by several analyses related to the performance of the materials in the embossing process. Eleven different sample materials were collected for the experiments so that the patternability could be studied extensively. The common denominator of the materials selected for testing was that they were all fibre-based paper and paperboard materials used in the packaging industry. Set of embossing tools were developed, and precision machined from brass, for the experiments. A laboratory scale mechanical embossing device was utilized in modification of sample surfaces to study patternability of selected fibre-based sample materials. The main variables in the forming experiments were pressing force and tool temperature. The samples were observed primarily visually - with the naked eye, with a scanning electron microscope and a 3D-profilometer which was used in the topography analysis of the achieved patterns. The results of the embossing test series confirmed that the height of the pattern increased as a function of pressing force and plate temperature and spring back occurred in all materials after the tool plates opened. It was deduced that the pattern dimensions of the embossing plate somewhat determined the achievable pattern height in the fibre-based sample materials, but the amount of springback did not change as a function of material thickness. Despite this finding, it was consistent that the amount of spring back was regularly reduced with higher tool temperatures. The optimization study of the magnitude of the forming force showed that excessive use of force is not required, which is beneficial in reducing the risk of material damage during processing and adjustment of embossing devices. All samples differing significantly from each other were found to be suitable for embossing, indicating that patterns such as those tested could be added to a variety of packaging applications.
Impact of Die Coatings on Forming Conditions in Electromagnetic Embossing of Thin Sheet Metal
Authors: Beckschwarte Björn , Heidhoff Julian , Langstädtler Lasse , Schenck Christian , Riemer Oltmann , Kuhfuss Bernd
Published: July 2022

In electromagnetic embossing, the interaction of the magnetic field and the induced current density results in body forces that enable the replication of optical microstructures into thin sheet metals. However, as the sheet metal is completely penetrated by the magnetic field, electromagnetic properties of the dies need to be considered in process design, as they influence the forming conditions by changing the field distribution, force vectors and eddy current densities. With die coatings like electroless nickel–phosphorus (NiP), the electromagnetic properties of the die change. Therefore, the effect of both - die substrate and coating material - was studied to find advantageous conditions for electromagnetic embossing. Within two-dimensional electromagnetic field simulation, the electromagnetic properties of coating and substrate material were varied in addition to the coating thickness. To validate the results, electromagnetic embossing experiments were carried out. Here, different dies were fabricated from aluminum (uncoated) and cold work steel with 200 µm and 400 µm thick electroless nickel–phosphorus coatings that were subsequently micro-structured in optical surface quality. It was demonstrated by numerical and experimental results that the coating and the substrate influence the electromagnetic embossing significantly in correspondence to their shielding behavior and field interaction due to electromagnetic properties and coating thickness.
Identification of Swift Law Parameters Using FEMU by a Synthetic Image DIC-Based Approach
Authors: Henriques João , Conde Mariana , Andrade-Campos António , Xavier José
Published: July 2022

Computer-aided engineering systems rely on constitutive models and their parameters to describe the material behaviour. The calibration of more elaborated material models with a larger number of parameters becomes very time and cost consuming. The development of image-based technology has enhanced the interest in inverse identification methods, which, when coupled with full-field measurements, have the potential to reduce the number of experimental tests required to accurately identify material properties. This work aims to identify the Swift hardening law parameters of a dual-phase steel using a tensile test on a heterogeneous dogbone specimen under uniaxial and quasi-static loading conditions using the finite element model updating (FEMU) technique. The numerical results were used to generate synthetic images, which were then processed by digital image correlation (DIC) and used as the reference in the identification procedure. Two different approaches were tested: (i) directly comparing the numerical results to the reference; (ii) using DIC-levelled numerical data by iteratively generating synthetic images and using the DIC filter with the same settings as were used on the reference (virtual experiment). The identification results obtained from both approaches are compared and discussed.
FEM Modelling of Weld Damage in Continuous Cold Rolling of MIG/MAG Butt-Welded Stainless Steel Strips
Authors: Demoulin Leyne , Zahar Zineb , El Mekkaoui Achraf , Reignier Arnaud , Mocellin Katia , Montmitonnet Pierre , Leger Pierre Emmanuel
Published: July 2022

Weld line fracture of butt-welded strips in stainless steel continuous rolling has been studied by numerical simulation using ForgeNxT®. The simulation plan includes weld line geometry as well as weld metal constitutive model parameters. The damage criterion used is the non-dimensional Latham & Cockroft function near the singular points of the weld line. Results are confronted to qualitative observations of fracture frequency and fracture initiation loci on the rolling line. Not surprisingly, the protrusion height of the weld line with respect to the strip top surface is found to be a major factor of risk. A second one pertains to the nature of the alloys used: due to the mushroom-like weld line cross-section geometry, damage at the top surface junction of the base metal and the weld metal becomes critical when the weld metal is harder than the base metal. Finally, on the rolling line investigated, prior to rolling properly speaking, the strip goes through a scale-breaking unit followed by acid pickling to eliminate oxides; the multiple, reverse plastic bending applied there contributes significantly to ductile damage, completing the explanation of why the fracture initiation locus is always found to be the same on the rolling line.
Prediction of Underfilling Defect in Aluminium Profile Extrusion Based on ALE Simulation
Authors: Kniazkin Ivan
Published: July 2022

The paper presents a detailed analysis of metal flow inside the extrusion dies and demonstrates the investigation of the formation of underfilling defects. The stress state in the defect zones has been analyzed by means of simulation based on the Eulerian approach. Based on this, it was found that the mean stress (hydrostatic pressure) is not the only parameter that has to be placed into the criterion to get reliable results. The author proposes a new dimensionless underfilling criterion adapted for Eulerian mesh. It is based on analysis of simulation results obtained by QForm Extrusion FEM software [1] and practical experiments for different types of profiles. This criterion has been approved, and critical values have been obtained using a number of industrial projects from different areas of application.
The Influence of the Sample Size of Bias Extension Tests on the Results of Forming Simulations of Fiber-Reinforced Thermoplastics
Authors: Graef Jasmin , Engel Bernd
Published: July 2022

This work presents sensitivity analyzes of the influence of deviations in the shear stress vs. shear angle curves of bias extension tests of fiber-reinforced thermoplastics on the results of forming simulations. The investigations are carried out on the basis of a double dome benchmark geometry from the Ford Motor Company. Its experimental results of shear angle values and wrinkling are compared to the simulation results. The initial values for sensitivity analyzes are the shear stress-shear angle curves determined within further preliminary investigations on the basis of different sample sizes and cutting directions. Then these are gradually scaled. Finally, it will be discussed which deviations in the shear stress-shear angle curve are permissible in order to achieve a maximum deviation of 20% between simulation results and the real part. This is assumed to be the target value for this study.
Quantitative Assessment of Reactive and Non-Reactive Binder Systems on First Ply Adhesion for Dry Fiber Placement Processes
Authors: Helber Florian , Carosella Stefan , Middendorf Peter
Published: July 2022

Dry fibers or fabrics do not possess an inherent tack, when compared to prepreg materials. In order to fixate dry fiber fabrics onto tooling geometries, auxiliary binder systems are necessary. These tackifying agents vary in terms of chemical composition and reactivity, processing parameters and appearance. One key aspect for most automated fiber placement technologies (incl. Dry Fiber Placement; Abr. DFP) is the adhesion of reinforcement materials on tooling surfaces, also referred to as first ply adhesion. Insufficient prepreg or binder adhesion will lead to fiber slippage thus increased scrap rates and is therefore crucial for high class composite performance. This study reveals quantitative insights on binder performance and indicates that the treatment with solvent-based release agents reduces first ply adhesion by up to 78%. Furthermore, it shows, that elevated tooling temperatures reduces binder adhesion by up to 49%.
Real-Time Quality Control in Thin Glass Forming Using Infrared Thermography and Deep Learning
Authors: Vu Anh Tuan , Vogel Paul Alexander , Siva Subramanian Abimathi , Grunwald Tim , Bergs Thomas
Published: July 2022

Towards the growing trends in lightweight, flexible, and optical advantages, thin glasses become key components in numerous applications such as consumer electronics like foldable smartphones, or automotive interiors. Nonisothermal glass molding promises a viable technology for the cost-efficient production of precision glass components. In the existing production, the quality of the glass products can only be accessed at the end of the hot forming process. Due to high rates of product failures often appeared in the precision glass molding processes, the current quality control of the produced optical products suffers low process efficiency. This work introduces an enabling approach for monitoring the product quality in real-time using thermography and machine learning. Specifically, the acquisition of the temperature fields of the glass components during the hot forming stage enabled by an infrared thermographic camera allows machine learning to predict the final shape of the molded components at the end of the forming process. Several transfer learning models have been investigated to demonstrate the proposed method. To further enhance the prediction performance, self-built convolutional neural network models were developed using different types of image data. By incorporating the time-series image data as an input to the learning models, the prediction performance was achieved. The model built in the present work demonstrates an excellent prediction accuracy where the difference between the measured and predicted shapes of the glass products can be kept at low double-digit micrometers. Such accuracy achieved by our self-developed machine learning model promisingly satisfy the quality control in serial productions of numerous precision optical glass components in automotive and consumer electronics sectors.
Discontinuous Galerkin FEM with Hot Element Addition for the Thermal Simulation of Additive Manufacturing
Authors: Nijhuis Björn , Geijselaers Bert , Havinga Jos , van den Boogaard Ton
Published: July 2022

Despite its promising advantages, the application of directed energy deposition (DED) to produce large metal parts is hindered by challenges inherent to the process. Undesired residual stresses, distortions and heterogeneous material properties mainly originate from a part’s thermal history. Fast part-scale thermal models therefore facilitate improved applicability of DED by enabling the prediction and mitigation of these unwanted effects. In this work, the efficiency of a discontinuous Galerkin-based thermal model with heat input by hot element addition, is evaluated and improved to allow such fast simulations. It is found that the model permits the use of a coarse discretization around the heat source, which significantly reduces simulation time while maintaining accurate solutions. It is also shown that the model naturally facilitates the use of local time stepping, which can considerably improve the efficiency of thermal additive manufacturing simulations.
Preliminary Study of FSW Process of Dissimilar Aluminium Alloys in Battery Pack Assembly for Hybrid Vehicles Production
Authors: Napolitano Francesco , Scherillo Fabio , El Hassanin Andrea , Esperto Vitantonio , Carlone Pierpaolo , Squillace Antonino , Casarin Renzo , Verde Carlo
Published: July 2022

The requirement to join two dissimilar aluminium alloys produced with two different technological processes, extrusion and die casting, is fundamental in the automotive sector. In this research study was proposed the use of the Friction Stir Welding process to replace the traditional welding process. First of all was verified the weldability by using different process parameters and the results are reported in terms of microstructure and join aspect, which influence the Vickers microhardness. They show a suitable combination between the selected process parameters and the tool choice but also suggest to test different process conditions. Tool geometry and workpiece setup have to be redesigned. The final aim of this preliminary study is to find the best process conditions in order to proceed with components and machine tools design in the perspective of procedure industrialisation for hybrid vehicles battery pack assembly.
In-Process Monitoring of Springback in Industrial Bending Using a Laser Sensor-Based Method
Authors: He Xu , Ma Jun , Tronvoll Sigmund Arntsønn , Welo Togeir
Published: July 2022

Bent tubes and profiles are widely used in many industries such as automotive, aerospace and shipbuilding. In bending of tubes and profiles, springback is normally regarded as a challenge, affecting the dimensional accuracy of products. Springback control significantly determines the production route of products, including logistics. At present, effective in-situ measurement methods are lacking. This makes it difficult to realize in-process, closed-loop control of springback for improving product quality and productivity, while putting improved flexibility on the production route. In this research, an in-process measurement technique for monitoring springback in rotary draw bending was developed. A device with a laser transmitter and receiver was installed on a bending machine to detect displacement changes of the part after being released from the tool. The displacement information was collected by a controller that shows the measured displacement. A series of tube bending experiments together with the developed in-line laser sensor measurement and conventional off-line manual measurements were carried out. The result shows that the in-line laser sensor method provides a good capability for springback measurement. Since the laser measurement method is done with no need to remove the workpiece from the tooling system, it facilitates developing an in-process compensation strategy to control springback.
Variance-Based Sensitivity Analysis of the Biaxial Test on a Cruciform Specimen
Authors: Pereira André F.G. , Oliveira Marta C. , Fernandes José Valdemar , Prates Pedro André
Published: July 2022

Parameter identification is a key aspect in the modeling of the material’s mechanical behavior. The identification quality depends on the sensitivity of the test results to the values of the constitutive parameters. In this context, a variance-based sensitivity analysis is performed, in order to quantify the influence of the material parameters on the results of the biaxial test on a cruciform specimen; in particular the influence of the Swift hardening law parameters and the Hill'48 anisotropic yield criterion on the forces, the principal strains, strain path and thickness reduction. In general, it was concluded that the Swift hardening parameters influence the forces and the major principal strain value, while the anisotropy parameters have the most influence in the principal strains, strain path and thickness reduction along the surface of the cruciform specimen.
Silver Nano-Colloid Characterization for Printing Application
Authors: Sreenilayam Sithara Pavithran , McCarthy Éanna , McKeon Lorcan , Ronan Oskar , Fleischer Karsten , Nicolosi Valeria , Brabazon Dermot
Published: July 2022

Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system. Nanoparticle formation with particle size below 50 nm in DI water was confirmed using UV-VIS spectroscopy, Dynamic Light Scattering (DLS) technique, and transmission electron microscopy (TEM). Supercapacitor structure, having dimension 11 mm x 10 mm, was successfully Aerosol Jet printed on an untreated polymer substrate using as produced LASiS silver nano-colloid.
Numerical and Experimental Study of Polymers Microwaves Heating
Authors: Fesharaki Pouya Jafari , Boutaous M'hamed , Xin Shi He
Published: July 2022

Heating polymers by microwaves is not common. In order to quantify the ability of micro-wives to heat different type of polymers, a bench measuring the dielectrics characteristics of polymers is built, and a numerical modeling of the waves-polymers interaction is achieved. Finite elements method is introduced to solve the Maxwell equations [6-8] and the energy equation. A series of numerical simulations test are performed: convergence tests are realized and the heating power distribution in the sample is obtained. Using the power distribution, we studied a transient heating process of a polymer (CAPA) sample by microwave. In order to validate the numerical approach, we set-up an experimental bench to heat the sample by microwave and measure temperature distribution, using optical fiber and pyrometers. A vector analyzer (VNA). [6, 9-12] is used to check the quality of the microwave cavity The results of the numerical simulations of the wave propagation are presented and the amplitude of the electric field is compared to the experimental measurement: good agreement is observed. In terms of polymer heating, numerical results of temperature field and experimental measurements are also compared: an efficient heating is observed.
Special Features of the Non-Conventional Cutting (ECM, EDM) of Wool-Like Material Structures
Authors: Schulze Hans Peter , Herzig Mathias , Kroening Oliver , Schiedung Harald
Published: July 2022

The non-conventional cutting of electrically conductive materials using WEDM and WECM and their hybrid processes is already standard in manufacturing technology. This is essentially based on homogeneous or layered materials. In the future, cellular, wool-like, or similarly structured materials will play a greater role and will be more important; especially the cutting in conjunction with homogeneous materials. In the study, experiments were carried out with a standard WEDM system and a WECM test system. In preliminary tests, various EC machine structures with different flushing and cutting directions have been tested, and because of the static wire arrangement, adjustments to a maximum working current have been tried out. Various feed speeds have been implemented for the test series and the influence of the wool structure on the regulation of the short circuits in the working gap has been analyzed. A modified equivalent circuit diagram has been created from the special features of the processing. The process regulation must be adapted to the special conditions of the spontaneous working gap reduction and thus the higher number of soft short circuits. The study should primarily show where the deviations of the WEDM and WECM from wool structures are; which changes have to be made, especially for process regulation. Secondarily, it was determined which cutting structures arise and whether the partial discharges have a marginal effect on the cutting result in both processes.
From Theory to Practice: Development and Calibration of Micro Pellet Extruder for Additive Manufacturing
Authors: Curmi Albert , Rochman Arif
Published: July 2022

Pellet additive manufacturing (PAM) is in terms of printing process very similar to the widely used fused deposition modelling (FDM) systems. The main difference is the use of pellets instead of filament. In this study, a pellet, single screw extruder is developed. A screw design with variable pitch and depth is modelled analytically to predict the melting behavior of acrylonitrile butadiene styrene (ABS) during steady state extrusion. The extruder screw was designed unconventionally short with a length of 85 mm and a diameter of 20 mm, giving an L:D ratio of 4.25:1. The model predicted the melting profile for ABS being extruder at 235°C at 10 RPM, the result of which was confirmed to a degree by experimentation. The extrusion rate of the screw extruder was measured at barrel temperatures of 225°C to 245°C with 5°C increments and at 5 RPM and 10 RPM. The extrusion was found to increase non-linearly with barrel temperature and screw speeds. The extruder printed adequately on an FDM style motion system with minor upgrades.
Influence of Coulomb’s Friction Coefficient in Finite Element Modeling of Orthogonal Cutting of Ti6Al4V
Authors: Kugalur Palanisamy Nithyaraaj , Rivière Lorphèvre Edouard , Arrazola Pedro José , Ducobu François
Published: July 2022

The reliability of the pertinent parameters set of Johnson-Cook constitutive model is highly linked with the friction condition at the tool-chip-workpiece interface. In the present work, a study on the influence of Coulomb’s friction coefficient on the observables such as forces, chip thickness and chip curvature by FE simulation of orthogonal cutting of Ti6Al4V alloy has been carried out. A FE model with an Arbitrary Lagrangian-Eulerian (ALE) approach is employed to simulate the cutting process for different cutting conditions. The simulated results, for a wide range of friction conditions, are analyzed and compared with experimental results. The analysis show that the Coulomb’s friction coefficient has a direct link with the observables. The paper reveals that for accurate prediction of observables an optimized value of the coefficient of friction in correlation with the parameters values of the constitutive model is imperative.
A Critical Evaluation of Forming Limit Curves Regarding Layout of Bending Processes
Authors: Frohn-Sörensen Peter , Nebeling Daniel , Reuter Jonas , Engel Bernd
Published: July 2022

Forming limit curves (FLCs) are important to predict failure against biaxial deformation in sheet metal forming. Particularly crucial is the detection and evaluation of the stable/instable transition which indicates necking and ultimately leads to rupture. In the past, it has been observed that specific processes, in particular free-form bending processes, might not be predicted well by conventionally evaluated FLCs, i.e. the Nakajima experiment, where tapered sheet metal specimens are stretched over a hemispherical punch until material failure. In the present study, FLCs are evaluated from such Nakajima tests and from notched tension tests (NTT) highlighting large differences in between both results. The differences in between the evaluation methodologies are discussed with respect to contact and bending strain in the forming zone. The FLCs of three tested sheet metal materials are compared to fracture strain resulting from an incremental bending process with free forming zone demonstrating an increased failure prediction accuracy by the NTT FLCs than by the conventional ones. In the light of these results, it is therefore encouraged to critically assess the application of FLCs obtained from NTTs to various free-form bending processes.
Data-Driven Roll Pass Design of Wire Rod Mills
Authors: Overhagen Christian , Fu Kaiqi
Published: July 2022

The classical approach for roll pass design of a wire rod mill employs an iterative technique incorporating spread calculation and rectangular equivalent pass methods. This method comes to its limits in terms of computational efficiency and numerical stability when a complete pass design for a wire rod mill with lots of different final dimensions and materials must be designed. To improve the pass design technique, a fast data-driven method for pass design based on synthetic data generated by the classical pass design model was created. The results are compared to the original training data, as well as newly generated test data. It is shown that the artificial neural network (ANN) is able to predict appropriate oval groove geometries with good precision.
Imprinting of Micro-/Nano-Textures onto Metals and Alloys with Use of the Laser-Printed DLC-Die
Authors: Aizawa Tatsuhiko , Inohara Tadahiko
Published: July 2022

This paper focused a two-step procedure to imprint the tailored emblems, patterns, symbols and codes onto the metallic and polymer product surfaces. The laser printing was first used to form these tailored micro-/nano-textures onto a Diamond-Like Carbon (DLC) coating die. The DLC film with the thickness of 20 mm and the hardness of 22 GPa was utilized as a mother die. Femtosecond laser printing was used to shape the tailored micro-/nano-textures on this die. Seven emblems such as a star-patterned texture with the maximum depth of 4 mm were just cut into the DLC-die to have color-grating by micro-texturing and surface plasmonic brilliance by nanotexturing. In second, Computer Numerical Control (CNC) – stamping was used to imprint these textures onto the aluminum alloy plate with the thickness of 1 mm. Scanning Electron Microscopy (SEM) and three dimensional profilometer were used to investigate the geometric accuracy in this two-step printing procedure. The constituent micro-/nano-textures of each emblem was accurately imprinted onto the aluminum work. The optical properties were also duplicated together with this geometric imprinting.