Virtual Material Research Articles

Size effects in the elastic properties of polycrystalline silicon

AbstractPolycrystalline silicon has a wide range of applications in the semiconductor industry. Instead of components whose dimensions are of the same order of magnitude in all three spatial directions, thin slices are primarily used there. Deviating mechanical properties have been noticed among such thin configurations. In this work, we systematically investigate the size‐dependent effective elastic properties of polycrystalline silicon. This is realized by gradually reducing the thickness of such components, starting from a structure usually referred to as representative volume element. Based on the framework of continuum mechanics, we specify unit cell problems for aggregates whose microstructures are build artificially based on first‐order properties through tessellations. The effective responses of virtual material tests are determined by the aid of the finite element method. Based on a larger number of computational simulations with different but equivalent microstructures, the effective elastic properties of silicon polycrystals are evaluated statistically. The findings are examined with regard to geometrically‐induced symmetries by several methods. For the unconstrained configurations examined here, results show an increase in the scattering of the results where the average stiffness decreases with decreasing structural thickness. These outcomes are also compared to analytical estimates for silicon bulk configurations. This comparison indicates that the average stiffness varies in between a reasonable mean and the isotropic first‐order lower bound of the silicon bulk. Compared to experimental findings, admissible bounds of the stiffnesses are clearly outlined.

ВИКОРИСТАННЯ ІНФОРМАЦІЙНИХ ТЕХНОЛОГІЙ У ВИХОВНІЙ ДІЯЛЬНОСТІ ВЧИТЕЛЯ ПОЧАТКОВИХ КЛАСІВ НОВОЇ УКРАЇНСЬКОЇ ШКОЛИ

The article substantiates the need to update the content of the educational activity of the primary school teacher, while emphasizing the need to take into account the realities of today and the need to use information technologies as a necessary component of the educational process. Based on the definitions of the phenomena of «education», «forms of education», «methods of education», «means of education» and the analysis of the situation in the state and the requirements for the personality of its citizens, the purpose and content of the educational activity of the primary school teacher have been defined as an organization of purposeful influence on cognitive, reflective and affective spheres of personality. Network software tools that can be used for educational (in particular, educational) purposes in the conditions of mixed and distance learning have been monitored, since their use allows organizing, conducting, monitoring and adjusting the educational process in general and educational activities in particular. As a result, distance learning educational platforms, means for conducting video conferences, means for creating effective visualization and virtual didactic materials were selected as educational IT tools: virtual test resources, programs for creating word clouds, mental maps, crosswords, puzzles, comics, network puzzles, virtual tours museums, as well as videos from YouTube etc. The principles of using IT tools in the education of students of primary education have been defended: visibility, individualization and differentiation, interactivity, connection with life, citizenship and national-cultural consciousness. The conditions for the selection of means and network educational IT resources for the education of students of primary education in the conditions of NUSh (their compliance with educational goals, the age of the students of education and, of course, technical and sanitary-hygienic and valeological norms) and the integration of the selected means have been specified. Prospective directions of research in the context of the topic of the publication were also outlined.

Benchmark exercise on image-based permeability determination of engineering textiles: Microscale predictions

Permeability measurements of engineering textiles exhibit large variability as no standardization method currently exists; numerical permeability prediction is thus an attractive alternative. It has all advantages of virtual material characterization, including the possibility to study the impact of material variability and small-scale parameters. This paper presents the results of an international virtual permeability benchmark, which is a first contribution to permeability predictions for fibrous reinforcements based on real images. In this first stage, the focus was on the microscale computation of fiber bundle permeability. In total 16 participants provided 50 results using different numerical methods, boundary conditions, permeability identification techniques. The scatter of the predicted axial permeability after the elimination of inconsistent results was found to be smaller (14%) than that of the transverse permeability (∼24%). Dominant effects on the permeability were found to be the boundary conditions in tangential direction, number of sub-domains used in the renormalization approach, and the permeability identification technique.

Design application learning physics on material newton's law-based virtual lab

Currently the world is experiencing an outbreak of the COVID 19 virus disease, so many people have become victims, so all activities are limited. This happens in the field of education, the learning atmosphere that usually takes place face-to-face has now changed to using online media from elementary to university level. PHYSICS learning in SMA is not only focused on concept theory but to support student centered learning, learning prioritizes the process of discovering and researching these materials and concepts themselves. Thus the existence of a laboratory becomes important where the purpose of holding learning in the laboratory is to develop student skills such as the use of tools, observation, train students carefully and recognize the limits of laboratory measurement abilities, train accuracy in recording, reporting, Results, stimulating critical thinking in experimental analysis, through the interpretation of experiments, deepen knowledge and develop responsibility and honesty as well as train students to plan and conduct experiments. But in reality, with the pandemic, students have difficulty in practical learning in the laboratory. Through the application of learning physics on Newton's law material based on the Virtual Lab, students can interactively interact with the application by choosing virtual practicum tools and materials. This application can be a tool for understanding learning so that it can increase student grades, especially during a pandemic.

How Can Virtual Reality Glasses and Virtual Learning Material be Useful for Final Stage Nursing Students?

Purpose: to describe nursing students’ experiences of learning with help of virtual learning materials and virtual simulations. The aim was to produce knowledge that can be used to develop virtual simulation teaching and counseling further and to support students’ self-debriefing. Methods: This is a mixed method study conducted with 13 final-stage nursing students at a University of Applied Sciences in Finland. Following virtual simulations performed during an acute nursing course, the students completed a questionnaire with qualitative and quantitative items on their experiences and on the usefulness of the simulations. The findings are primarily based on an inductive content analysis of the students’ responses to qualitative items. The quantitative data, analyzed by means of SPSS, was used to support the qualitative analysis. Results: Most participants found virtual simulation learning and the use of virtual reality glasses a welcome change and a meaningful and safe way to promote their theoretical and practical competencies. They appreciated the possibility to choose the topic and the time and place of study. The simulations had been useful in practicing assessment and decision-making skills. Problem-solving, simulation of rare incidents, game-like elements and step-by-step feedback were proposed. A few students disliked the artificial setting and some reported headache and nausea. Conclusion: Virtual simulations and virtual reality glasses can be effectively used to teach final-stage nursing students as part of a blended learning approach. Careful planning of the learning contents and a suitable level of challenge in the simulations increase student motivation. Keywords: experience, nursing student, acute nursing, virtual simulation, virtual reality, VR glasses

Fracture Behavior of AA7075-AA6061 and AA7075-Cu Friction-Stir Welded Joints Containing Blunt V-Notches under Opening-Mode Loading

The purpose of this study is to predict the load-bearing capacity (LBC) of fracture specimens containing V-notched friction-stir welded (FSWed) joints of AA7075-Cu and AA7075-AA6061 materials and subjected to mode I loading conditions. Due to the resulting elastic-plastic behavior and the corresponding development of significant plastic deformations, the fracture analysis of the FSWed alloys requires elastic-plastic fracture criteria, which are complex and time-consuming. Thus, in this study, the equivalent material concept (EMC) is applied, equating the actual AA7075-AA6061 and AA7075-Cu materials to equivalent virtual brittle materials. Then, two brittle fracture criteria, the maximum tangential stress (MTS) and mean stress (MS), are utilized to estimate the LBC of the V-notched FSWed parts. The comparison between the experimental results and the theoretical predictions reveals that both fracture criteria, in combination with EMC, can accurately predict the LBC in the analyzed components.

Artificial neural network model to predict student performance using nonpersonal information

In recent years, artificial intelligence has played an important role in education, wherein one of the most commonly used applications is forecasting students’ academic performance based on personal information such as social status, income, address, etc. This study proposes and develops an artificial neural network model capable of determining whether a student will pass a certain class without using personal or sensitive information that may compromise student privacy. For model training, we used information regarding 32,000 students collected from The Open University of the United Kingdom, such as number of times they took the course, average number of evaluations, course pass rate, average use of virtual materials per date and number of clicks in virtual classrooms. Attributes selected for the model are as follows: 93.81% accuracy, 94.15% precision, 95.13% recall, and 94.64% F1-score. These results will help the student authorities to take measures to avoid withdrawal and underachievement.

A novel integrated framework for reproducible formability predictions using virtual materials testing

Background: Formed aluminium alloy sheet materials are increasingly adopted in production processes such as vehicle manufacturing, due to the potential for weight-saving and improved recyclability when compared to more traditional steel alloys. To maximise these benefits whilst maintaining sufficient mechanical properties, the link between formability and microstructure must be better understood. Virtual materials testing is a cost-effective strategy for generating microstructure-informed formability predictions. Methods: We developed an open-source hybrid framework, combining experimental and computational tasks, for generating reproducible formability predictions. Starting with experimental texture measurements and stress-strain curves, we calibrated crystal plasticity (CP) model parameters. The framework used these parameters to perform a large set of multiaxial full-field CP simulations, from which various anisotropic yield functions were fitted. With these anisotropy parameters, we then employed a Marciniak-Kuczyński finite-element model to predict forming limit curves, which we compared with those from experimental Nakazima tests. Results: We executed the workflow with the aluminium alloy Surfalex HF (AA6016A) as a case study material. The 18-parameter Barlat yield function provided the best fit, compared to six-parameter functions. Predicted forming limits depended strongly on the chosen hardening law, and good agreement with the experimental forming limit curve was found. All of the generated data have been uploaded to the Zenodo repository. A set of Jupyter notebooks to allow interactive inspection of our methods and data are also available. Conclusions: We demonstrated a robust methodology for replicable virtual materials testing, which enables cheaper and faster formability analyses. This complete workflow is encoded within a simple yet highly customisable computational pipeline that can be applied to any material. To maximise reproducibility, our approach takes care to ensure our methods and data — and the ways in which that data is processed — are unambiguously defined during all steps of the workflow.

REFINED ENGINEERING THEORY OF FRACTURE WITH A TWO-PARAMETER STRENGTH CRITERION

We present a refined engineering theory of cracks, based on a two-parameter strength criterion. Unlike the basic theory, the refined approach utilizes an improved algorithm for the regular stress component computation. This improvement allows extending the applicability range of the engineering theory to longer cracks. The two-parameter Leonov-Panasyuk-Dagdale fracture criterion serves as a basis. A coupled fracture criterion includes a strain-based criterion, which is formulated at the tip of the true crack, as well as a stress-based criterion, formulated at the tip of a fictitious crack. Based on the refined criterion, quasi-brittle fracture curves are constructed for a compact specimen, a strip with an edge crack, and a beam under four-point bending. To validate the new refined fracture criterion, we present simulation results of quasi-brittle fracture for structures made from various virtual materials. The corresponding virtual materials are modeled using a nonlocal damage accumulation theory accounting for the average size of the aggregate state of the material. Additionally, various classes of damage accumulation hypotheses are considered. Analysis of various types of virtual materials provides insights into the impact of hypotheses behind the engineering theory. For each type of material, the influence of the microstructural length scale on the overall structural strength is investigated. The analysis shows that the refined engineering theory has a wider range of applicability as compared to the basic theory based on two-parameter strength criteria.

Challenges of visually impaired university students in education: A meta-synthesis study

Along with the expansion of education and laying the foundations of self-sufficiency for all members of society, the visually impaired students continued their education with other students in various fields of higher education. In this process, the limitations caused by visual impairment and the limitations originating from the shortcomings of the environment other than the visually impaired individuals themselves lead to many difficulties, which must be minimised to receive quality education. The aim of the research is to interpret and evaluate the problems and suggest solutions to visually impaired university students and reveal their similar and different aspects and new inferences through a systematic review of qualitative research findings between the years 2000 and 2021, using a meta-synthesis method. The results suggest that accessing campus from residence, accessing information, using technology and virtual materials on campus, social and educational attitudes, educational conditions, and assessment results cause different difficulties for visually impaired university students. Issuing legal regulations, improving the performance level of the visually impaired individuals in orientation and mobility, providing professional staff training, and procuring trained live readers or screen readers, hearing aids, touching aids, and helpers, as well as providing sufficient time for analysing tactile materials such as Braille and carefully answering the questions, are all recommended to solve the rising difficulties.

Effectiveness of Video Lessons Using Mobile Learning Technology

Electronics and communication and manufacturing technology are gaining much importance in the new millennium. The advents in electronics and communication technologies have been offering inexpensive, more convenient and more functionality in a single device. The engineering students and teachers can access data and communicate with each other anytime, anywhere, on any device, and any data and network. The researcher has to implement new technology, new ideas, and innovations in the research area of wireless communication and wireless networks. In wireless and mobile communication, to develop these engineering laboratories into virtual labs and study materials in hand (within a Pocket). This research is focused on and related to engineering education research. The quasi-experimental design has been used in this research study to measure the effectiveness of mobile learning using video lessons in engineering education. The questionnaire is used to evaluate the effectiveness of mobile learning for undergraduate engineering students. This paper describes the main study of the research results shows that 506 students of second year engineering students of Electrical and Electronics Engineering (EEE), Electronics and Communication (ECE), and Bio- Medical Engineering (BME) in Chennai, Tamil Nadu, India their usage of wireless communication technology in mobile learning using video lessons. The video lessons used for this study are Electromagnetism which is common for EEE and ECE and Electrocardiography is common for BME and ECE. During the study smart phones, mobile phones and wireless devices, tablet pc, personal digital assistants, etc are used and the duration of the video lesson is 30 minutes. These video lessons can be transmitted using Bluetooth technology in the classroom, library, and corridors during the free hours. Keywords: E-learning, m-learning,

From representation to reality. Translating the topological space to the euclidian space

The advent of the Digital Turn in architecture calls for reconsidering many conventional design phenomena. Nowadays communication is on computer and computers already alter how we experience design spaces and virtual scenarios. However, implementation brings a rupture to the design process. Even though the expression of any formal intention is possible on the screen, their realisation by industrial construction techniques comes with difficulties. Material-based design research involving manufacturing can also open new approaches to architectural creation. Robotic technologies and 3D printing are translators between the virtual and physical realms, such as construction workers and industrial machines. While representation already follows the digital logic, materialisation is often still industrial, creating a rupture in the design process. This paper seeks to highlight the tension points where materiality can connect computation through new media to create a coherent workflow, where the information of the material is an incentive driver of the design process. The question we are ask is whether virtual and physical materiality are derivatives of each other or is it time to recognise them independently?

Uniaxial compression of dry wood: experiment and modeling

The paper considers the dependence of the load on displacement during uniaxial compression of spruce wood samples with an adjustable deformation rate (1 mm/min); the water content in the samples was equal to 6.4%. The study focuses on the analysis of criteria for brittle destruction of wood and its transition to a plastic state. The concept of virtual material transformation (CoViMT) forms the basis of the research. At the idea level, this concept is a variant of the well-known equivalent material concept (EMC). An integral criterion for brittle fracture was developed. Comparison with experimental data showed that the integral criterion and the known differential criterion lead to mismatched points of brittle fracture and transition of wood to the plastic state. Therefore, it is possible to determine the boundaries of the region of plastic states with the help of these criteria. Experiments confirmed the adequacy of the criteria when compressing wood with 6.4% and 18.0% moisture content. However, the volume of studies of the problem touched upon is small, so further research is necessary to better understand the stages of deformation of wood of different species.

Thermal Field Simulation and Analysis of Tulip Contact Based on Virtual Material Method

In order to analyze the temperature distribution of circuit breaker tulip contact, a thermal field simulation model for tulip contact is built combined with the electromagnetic-stress-thermal coupled finite element simulation and virtual material method which models the contact resistance characteristics of tulip contact. The temperature rise characteristic of tulip contacts under rated current conditions and short-circuit conditions is analyzed with the model. Results show that the virtual material method can describe the contraction resistance and additional resistance at the end of the contact finger simultaneously, so as to simulate the partial high temperature of the contact interface. Then, the influence of spring pressure and pressure uniformity on the thermal field of tulip contact is analyzed. Results show that the decrease of spring pressure and the imbalance of contact finger pressure may lead to an increase in the temperature rise of the tulip contact. The proposed method can be used as a reference for the design and the overheating analysis of tulip contact.

Constitutive model and experimental study of molded pulp material

Molded pulp products can improve the utilization of recycled paper by achieving close to zero waste emission and a 100% recycling rate, while satisfying the national goals for recycled packaging materials of various countries. Molded pulp products are often designed using finite-element simulations to optimize their performance, which requires the input of accurate material properties. However, studies on the constitutive model, an essential factor related to material properties, are still rare. This study investigated the mechanical behavior of the molded pulp material to simplify the parameters and improve the accuracy of the constitutive model. The fiber distribution and connection within the molded pulp material were investigated; treating the pores of the molded pulp as a virtual material enhances the meso-mechanical model and gives a transversely isotropic constitutive model. The elastic modulus in the thickness direction was calculated as 1.5997 MPa, and the experimentally measured value is 1.5368 MPa. The error of proposed model is 4.1%, but significantly smaller than treating molded pulp as an isotropic material, the error of which is ~80 times larger of experimental result.

Development and Implementation of Element Deletion Algorithm into an Open-Source Software Based on the Fracture Locus of Materials

An accurate fracture simulation is often associated with how reliably the material model is represented. Hence, many models dealing with the calibration of ductile damage of materials have already been developed to predict failure initiation. Nevertheless, the challenge remains in obtaining an accurate representation of the fracture growth. Herein, an element deletion algorithm is developed and implemented into finite element open-source software. The deleted elements are replaced by new cells made of a virtual low-stiffness material. To better visualize the failure progression, the final model excludes these virtual cells from the representation. The functionality of the algorithm is tested through a series of two-dimensional simulations on three different geometries with a well-known behavior under uniaxial tension. Moreover, the failure response of a three-dimensional lattice structure is numerically investigated and compared against experimental data. The results of the two-dimensional simulations showed the capability of the algorithm to predict the onset of failure, crack nucleation, and fracture growth. Similarly, the onset and the initial fracture region were accurately captured in the three-dimensional case, with some convergence issues that prevent the visualization of the fracture growth. Overall, the results are encouraging, and the algorithm can be improved to introduce other computational functionalities.

Sanal öğrenme ortamının genç ergenlerin yabancı dil kaygısı üzerindeki etkileri

Foreign language learning is a tough process which contains gaining of knowledge, comprehension and finally employing acquired knowledge into practice. Since acquisition of foreign language knowledge include emotional capabilities as well as mental activities, foreign language anxiety (FLA) is a crucial component of this process. While there has been various research on FLA in literature for years, most of the previous research mainly focuses on adults or young adult learners (aged 18-25) in formal education environment. There exists a certain gap when it comes to FLA levels of learners from different ages and learning activities in various educational environments. In that sense, this study uniquely spotlights young adolescent learners of foreign languages and their FLA levels in virtual classrooms. Considering the fact that young adolescents have a very close relationship with technology, such students’ FLA levels present distinctive variations in virtual classrooms when compared to face-to-face classrooms. This study fundamentally aims to reveal to what extend virtual classrooms and online materials affect young adolescents’ FLA and to explore the reasons lying behind the possible changes in FLA levels by using a sample group of learners of English studying in middle school. A questionnaire and semi-structured interviews were used to obtain data. Based on the collected data, it was discovered that the upsides of virtual education positively affected young adolescents’ FLA levels. However, certain shortcomings of virtual education have also been unveiled during this study. This study presented crucial insights on young adolescents’ FLA levels and how these levels showed an alteration in virtual classrooms.

Metaverse and AI Digital Twinning of 42SiCr Steel Alloys

Digital twins are the most important parts of Cyber-Physical Systems (CPSs), and play a crucial role in the realization of the Metaverse. Therefore, two important factors: flexibility and adaptability, need to be focused on digital twinning systems. From a virtual perspective, constructing buildings, structures, and mechanisms in the Metaverse requires digital materials and components. Hence, accurate and reliable digital models can guarantee the success of implementation, particularly when it comes to completing physical twins in the real world. Accordingly, four Machine Learning (ML) methods to make digital twins of an advanced 42SiCr alloy considering all of its uncertainties and non-linearities have been employed in this paper. These ML methods accelerate the digitalization of the proposed alloy and allow users to employ them for a wide range of similar metals. Based on this technique, producers can borrow these virtual materials and build their structures in the Metaverse. This way, if the properties of the materials were satisfactory, they might buy them and start manufacturing their products. As a case study, we focus on digital twining of an 42SiCr steel with some influential factors in its mechanical properties, making the nature of the alloy complex. Processes, including heat treatment, may restore the material’s deformability; however, Quenching and Partitioning (Q&P) not only eliminates the impact of cold forming but also provides advanced high-strength steel (AHSS) properties. In this research, the combined impacts of different Q&P treatments were investigated on the mechanical properties of 42SiCr steel alloy. The results have shown the acceptability and accuracy of the proposed ML methods in realizing the digital twins of this complex alloy.

A virtual paradise? Platform algorithms, coastal change, and the production of nature in the Philippines

Across parts of Southeast Asia, coastal governance strategies have drawn on ‘ecotourism’ initiatives for ‘sustainable development’ by constructing captivating imaginaries of coastal places and people as sites of touristic production and consumption. Increasingly, representations of exotic and pristine coastal natures are reproduced virtually in support of this campaign through Web 2.0 platforms and their underlying algorithms. As ecotourism expands in the region, growing networks of social media users coproduce and consume abstract virtual natures with profound consequences for coastal peoples and ecosystems. In particular, Instagram, a popular photo sharing social media platform, has become central to reifying and distorting complex coastal realities. Drawing on a case from El Nido, Palawan Island, the Philippines, our paper examines how the virtual representation of coastal places and people on Instagram accelerate coastal transformations. Our results reveal how the political economy of coastal governance and the platform capitalism of social media converge to accelerate ecotourism in ways that realign virtual ideals and material realities. As virtual imaginaries shape coastal realities, new forms of exclusion and misrepresentation of people and places drive the displacement of local fishers, violence against activists, and coastal degradation. Bringing together research exploring (mass) ecotourism, platform capitalism and virtualism, we argue that greater scholarly attention should be placed on how new digital actors and platform algorithms influence how coastal peoples and places are imagined, consumed and subject to violence over time.

Volume 49, No. 1: Art Education- Virtual Material

Volume 49, No. 1: Art Education- Virtual Material