bluuebunny/crossref_metadata_2025 huggingface dataset:
SYSTEMATIC APPROACH FOR STUDENTS OF TECHNICAL SPECIALTIES// Humanitarian and Socio-Economic Sciences Journal 2(13), 2019/ OEAPS Inc.(Open European Academy of Public Sciences); Chief Editor Flora Bertrand - Berlin, Germany. 14.02.2019: OEAPS Inc., 2019. - pp. 35-40.
Authors: Serikbayeva Ulzhamilya Bibatyrovna , Erzhanova Zhanna Borisovna
Published: February 2019

The article deals with the history of the development of English structural linguistics. In the proposed study, the authors rely on the possibility of using a systematic approach in teaching English. The General principles, which are basic and apply to any branch of scientific knowledge, and private, which are used in teaching English, were highlighted. It was emphasized that a systematic approach to the study of English can be applied at any age, starting with adolescence, because this stage of ontogenesis in humans formed abstract theoretical thinking. Particular attention was paid to the study of the three main components of language (vocabulary, grammar and phonetics) based on the application of the basic principles of a systematic approach. They also discussed the use of scientific results, modern hardware and software in teaching a foreign language to students of technical specialties.
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Authors: Syaputra Sigit Dwi
Published: February 2019

Pt santani agro persada
RANCANG BANGUN APLIKASI VISUALISASI KAMUS BAHASA LAMPUNG BERBASIS ANDROID
Authors: Indera
Published: February 2019

Masyarakat lampung saat ini diketahui masih sangat minim pengetahuannya dalam memahami bahasa lampungitu sendiri. Dari data yang diperoleh pada kantor bahasa Provinsi Lampung tahun 2008 diketahui bahwa jumlahpenutur bahasa lampung sekitar 11,92%, dimana 88,08% tidak dapat berbahasa lampung. Oleh karena itupemerintah daerah lampung melakukan berbagai upaya untuk melestarikan budaya lampung salah satunyadengan melestarikan bahasa daerah lampung yang hampir punahHal ini terbukti dengan adanya komitmenpemerintah yang tertuang dalam Peraturan Daerah Nomor 8 Tahun 2008 tentang Pemeliharaan BudayaLampung. Di situ disebutkan bahwa”bahasa dan aksara Lampung sebagai unsur kekayaan budaya wajibdikembangkan.Hal ini dilakukan karena tanpa upaya yang sistematis besar kemungkinan bahasa daerahlampung akan punah. Punahnya bahasa daerah maka berarti akan punah pula budaya daerah yangbersangkutan. Tahapan yang akan dilakukan dalam penelitian ini terdiri dari : tahap analisis, , perancangan,pembuatan perangkat lunak dan testing. Aplikasi yang dihasilkan memiliki kemampuan untuk menterjemahkankata dari dua sumber input, yaitu kata bersumber bahasa Indonesia dan sumber bahasa Lampung yangselanjutnya akan dierjemahkan kedalam kata bahasa lampung dan Indonesia. Selain dalam bentuk kata, visualisasi kata hasil terjemahan juga dapat ditampilkan.Adanya Kamus bahasa lampung berbasis android inidiharapkan dapat membantu program pemerintah dalam upaya peningkatan kemampuan bahasa lampung diberbagai kalangan masyarakat propinsi lampung baik insan akademisi maupun masyarakat umum. Dengan demikian upaya pelestarian bahasa daerah lampung dapat dicapai.
Escala de Autocontrole: Evidências de Validade e Análise de Replicabilidade Interna
Authors: Victorino Luiz , Franco Víthor Rosa
Published: February 2019

O objetivo desse estudo é buscar evidências de validade num contexto brasileiro para a escala de autocontrole de Tangney, Baumeister e Boone (2004). A pesquisa foi realizada com 365 estudantes universitários, sendo 56,7% do sexo feminino. Os participantes responderam a escala de autocontrole e informaram dados pessoais. Inicialmente, a condução de uma análise paralela indicou uma estrutura com cinco fatores. Em seguida, foram realizadas análises fatoriais exploratórias (AFE) por métodos de fatoração de eixo principal (PAF) e análise dos componentes principais (PCA), ambos com rotação varimax. Ambas AFEs apresentaram resultados semelhantes em relação às cargas fatoriais e aos índices de ajuste do modelo. Por fim, foi realizada uma análise de replicabilidade interna com a solução de PCA, onde nove itens não apresentaram cargas similares nos mesmos fatores. Discute-se a estrutura original da escala, além de adequação de seu uso no contexto brasileiro, ao se levar em consideração as diferenças encontradas.
GBT-Based Elastic-Plastic Analysis of Cold-Formed Steel Members
Authors: Abambres Miguel , Camotim Dinar , Silvestre Nuno
Published: February 2019

This paper presents a formulation of Generalised Beam Theory (GBT) intended to perform thorough first-order elastic-plastic analyses of thin-walled members subjected to arbitrary deformations and made of an isotropic non-linear material. The J2-flow theory is used to model plasticity in conjunction with the Euler-Backward return-mapping algorithm. After presenting the formulation, its application is illustrated by means of the first order analysis of a simply supported Z-section beam made of an elastic-perfectly plastic material (e.g., carbon steel) and acted by a load uniformly distributed along the flanges. The set of GBT-based results comprises the load-deflection curves (equilibrium paths), displacement profiles, stress distributions (diagrams and 3D contours), and deformed shapes (modal amplitude functions and 3D configurations). These results are compared with the ones obtained from shell finite element analyses (SFEA) using ABAQUS. It is seen that the GBT results display a very good agreement with the SFEA values.
A Computationally Inexpensive Energy Model for Horizontal Electric Water Heaters With Scheduling
Authors: Nel Philip , Booysen MJ (Thinus) , van der Merwe Brink
Published: February 2019

Electric water heaters (EWHs) remain one of the main contributors to energy consumption in countries where they are used. EWH models serve as a step towards achieving optimised control, and can also be used to inform users of expected savings due to changes, if the model is energy-based. Various models have been proposed, but none of them include more than half of the six key features that the model presented in this paper supports: horizontal orientation; schedule control; low computational complexity; validation of the model; multinodal stratification; and multinodal standing losses. The presented model is validated against six datasets: four comprising 900 hours with multiple water usage events; and two with only standing losses. The results show that the model estimates energy consumption over ten days including usage with an error of less than 2% and 5% for schedule control and thermostat control respectively. The simulation model is simple enough to execute ten days of simulation in less than 100 milliseconds on a standard desktop machine, 150 times faster than a prominent model from literature, making it also suitable for large scale simulations or for use on mobile devices.
PENGEMBANGAN MODEL PENDIDIKAN MENENGAH SEKOLAH KEBANGSAAN DI DAERAH TERPENCIL, TERTINGGAL, TERLUAR, DAN PERBATASAN SEBAGAI IMPLEMENTASI PEMBELAJARAN PKn
Authors: IAIN Palopo Prodi_PGMI FTIK
Published: February 2019

Wilayah perbatasan merupakan kawasan strategis karena letaknya yang langsung berhadapan dengan wilayah negara lain. Persoalanya adalah potensi wilayah perbatasan yang sangat besar tersebut belum dimanfaatkan secara optimal.
MENINGKATKAN KEMAMPUAN GURU SD DALAM MENYAJIKAN PRESENTASI ATRAKTIF MELALUI MEDIA MICROSOFT POWER POINT
Authors: IAIN Palopo Prodi_PGMI FTIK
Published: February 2019

kegiatan pelatihan yang diselenggarakan selama sehari, mendapat sambutan yang baik dari peserta. keadaan ini dapat dilihat dari kehadiran peserta yang cukup memenuhi sekolah. didukung oleh tenaga bantu dari sekolah tersebut.
AVIKASI VERBAL BAHASA INDONESIA
Authors: IAIN Palopo Prodi_PGMI FTIK
Published: February 2019

Bangsa Indonesia terdiri atas berbagai suku bangsa yang memiliki bahasa sendiri atau yang sering disebut dengan bahasa daerah. Dalam kerangka pembelajaran di sekolah diperlukan upaya teoritis dan praktis yang membandingkan sistem bahasa daerah dan bahasa Indonesia.
PENERAPAN MODEL PEMBELAJARAN PICTURE AND PICTURE DALAM PENINGKATAN KETERAMPILAN MEMBACA DAN MENULIS SISWA KELAS II SDN 6 BOGAR PALOPO
Authors: IAIN Palopo Prodi_PGMI FTIK
Published: February 2019

Tujuan dalam penelitian ini adalah untuk meningkatkan kemampuan membaca permulaan melalui penerapan model pembelajaran picture and picture pada siswa kelas II SD Negeri 6 Bogar Palopo tahun pelajaran 2016/2017. Jenis penelitian ini adalah PTK dengan prosedur tiap siklusnya adalah perencanaan, pelaksanaan tindakan, observasi, dan refleksi. Hasil penelitian menunjukkan bahwa model pembelajaran ini dapat meningkat dari kategori sedang dengan nilai rata-rata 63,6 ke kategori tinggi 78.
The Management of Student’s Pocket Money
Authors: Vhalery rendika , Aimon Hasdi , Yulhendri Yulhendri
Published: February 2019

The purpose of this study is to clarify the factors that influence the management of students' pocket money directly and indirectly in Air Tawar Padang City. A sample of 344 students consisting of 130 students and 214 high school students was obtained by completing the questionnaire. The results show that the family environment, peers, gender and self-control have positive and significant effect on the management of students in Padang City.
THE IMPOERTANS
Authors: IAIN Palopo Prodi_PGMI FTIK
Published: February 2019

This paper is focused on the description of technology role in English teaching and learning. Globalization has reacted a new world order for doing business. New information and comunication technologies (ICTs) have dramatically changed the way we live, learn, work, and even think about work.
THE DEVELOPMENT OF RESEARCH-BASED LEARNING MODEL AND JOURNAL AS FOR GRADUATE STUDENTS’ SCIENTIFIC PUBLICATIONS OF M.Pd.E ON ECONOMIC
Authors: Yulhendri Yulhendri
Published: February 2019

The ability of Students in the Master Economic Education - FE UNP in writing the qualified articles are still low. The thesis proposed still only based on previous research, not based on the data and relevant article. The research development aims to develop teaching materials and research-based learning model in the lecture of Economics and Macroeconomics Learning Strategy and as a comparison class were learning accounting. The aims of this research is improving students’ ability in conducting a research and writing scientific journals and. The method used was a research design, which consists of three stages, i.e. preliminary design, teaching experiment, and retrospective analysis to improve the students’ analytical capabilities. Research output is publications of national and international scientific journals.
The Invention and Dissemination of the Spacer Gif: Implications for the Future of Access and Use of Web Archives
Authors: Owens Trevor , Thomas Grace
Published: February 2019

Libraries, Archives, and Museums are preserving and providing access to archives of nearly two decades of web content. The scale of these collections is both impressive and daunting. These collections of billions of resources and petabytes of data can be challenging to engage with. Given that these “born-digital” archives are already computable as data these digital corpora are a natural fit for the potential of computational scholarship/distant reading. In exploring traces a seemingly trivial, but widespread element in the history of web design; the single pixel GIF, also known as a spacer GIF or the Web Beacon, we illustrate potential for engaging with web archives as data sets. This case study underscores the potential value of using fixity information (cryptographic hashes) in tandem with web archive URLs as a means to explore traces of web design practices evident across multiple web archives. The case study suggests both potential methods for distant reading of web archives for scholarship as well as ways that distant reading methods might used by web archivists to refine web harvesting methods, describe the scope and extent of web archives, and enable new forms of use and access.
How do individuals high in psychopathic traits represent others’ beliefs and actions?
Authors: Genschow Oliver , Bardi Lara , Rigoni Davide , Uzieblo Katarzyna , Brass Marcel
Published: February 2019

Individuals high in psychopathic traits are known for manipulating others, while having at the same time a lack of empathy. An open question is whether the lack of empathy leads them to represent other persons’ beliefs and actions less strongly or whether their manipulative character leads them to represent other persons’ beliefs and actions more strongly. Confirming past research, three experiments show a negative correlation between psychopathic traits and self-reported empathy. In addition, the results from an implicit Theory of Mind task (Experiment 1) demonstrate that the higher individuals score on psychopathic traits, the more they represent other persons’ beliefs. Additionally, results from an imitation task (Experiment 1) as well as from a Joint Simon task (Experiment 2) demonstrate that high psychopathic traits are predictive for a stronger representation of other persons’ actions. However, a higher-powered study (Experiment 3) could not replicate the finding that psychopathic traits correlate with implicit Theory of Mind and Joint Simon effects. Theoretical implications and limitations of the experiments are discussed.
A Direct Comparison of the Day Reconstruction Method and the Experience Sampling Method
Authors: Lucas Richard E. , Wallsworth Carol , Anusic Ivana , Donnellan Brent
Published: February 2019

The Day Reconstruction Method (DRM) is an approach to measuring well-being that is designed to approximate the rich data that can be obtained from intensive repeated measures designs like those used in the Experience Sampling Method (ESM). Although some preliminary tests of the validity of the DRM have been conducted, these typically focus on agreement between the two methods at very broad levels, rather than focusing on whether the two methods provide similar information at a moment-to-moment level. This paper reports two studies that use ESM and DRM to assess the same moments. Agreement between the two measures varied considerably depending on the focus of the analysis. For aggregate assessments of total time spent in situations and average affect in situations, agreement was high; for between-person differences in time use and experienced affect, agreement varied across situations; and for within-person differences in both situations and affect, agreement was quite low. In addition, we found preliminary evidence that the DRM may be more influenced by expectations regarding the pleasantness of situations as compared to ESM. These results suggest that for many common purposes, the DRM does not provide the same information as ESM.
Anhedonia in chronic pain and prescription opioid misuse
Authors: Garland Eric , Trøstheim Martin , Eikemo Marie , Ernst Gernot , Leknes Siri
Published: February 2019

BACKGROUND:Both acute and chronic pain can disrupt reward processing. Moreover, prolonged prescription opioid use and depressed mood are common in chronic pain samples. Despite the prevalence of these risk factors for anhedonia, little is known about anhedonia in chronic pain populations.METHODS:We conducted a large-scale, systematic study of anhedonia in chronic pain, focusing on its relationship with opioid use/misuse, pain severity, and depression. Chronic pain patients across four distinct samples (N = 488) completed the Snaith-Hamilton Pleasure Scale (SHAPS), measures of opioid use, pain severity and depression, as well as the Current Opioid Misuse Measure (COMM). We used a meta-analytic approach to determine reference levels of anhedonia in healthy samples spanning a variety of countries and diverse age groups, extracting SHAPS scores from 58 published studies totaling 2664 psychiatrically healthy participants.RESULTS:Compared to healthy samples, chronic pain patients showed higher levels of anhedonia, with ~25% of patients scoring above the standard anhedonia cut-off. This difference was not primarily driven by depression levels, which explained less than 25% of variance in anhedonia scores. Neither opioid use duration, dose, nor pain severity alone was significantly associated with anhedonia. Yet, there was a clear effect of opioid misuse, with opioid misusers (COMM ⩾13) reporting greater anhedonia than non-misusers. Opioid misuse remained a significant predictor of anhedonia even after controlling for pain severity, depression and opioid dose.CONCLUSIONS:Study results suggest that both chronic pain and opioid misuse contribute to anhedonia, which may, in turn, drive further pain and misuse.
Effects of statistical learning in passive and active contexts on reproduction and recognition of auditory sequences
Authors: Krishnan Saloni , Carey Daniel , Dick Frederic , Pearce Marcus Thomas
Published: February 2019

Statistical learning plays an important role in acquiring the structure of cultural communication signals such as speech and music, which are both perceived and reproduced. However, statistical learning is typically investigated through passive exposure to structured signals, followed by offline explicit recognition tasks assessing the degree of learning. Such experimental approaches fail to capture statistical learning as it takes place and require post-hoc conscious reflection on what is thought to be an implicit process of knowledge acquisition. To better understand the process of statistical learning in active contexts while addressing these shortcomings, we introduce a novel, processing-based measure of statistical learning based on the position of errors in sequence reproduction. Across five experiments, we employed this new technique to assess statistical learning using artificial pure-tone or environmental-sound languages with controlled statistical properties in passive exposure, active reproduction, and explicit recognition tasks. The new error position measure provided a robust, online indicator of statistical learning during reproduction; with little carry over from prior statistical learning via passive exposure and no correlation with recognition-based estimates of statistical learning. Error position effects extended consistently across auditory domains, including sequences of pure tones and environmental sounds. Whereas recall performance showed significant variability across experiments, and little evidence of being improved by statistical learning, the error position effect was highly consistent for all participant groups, including musicians and non-musicians. We discuss the implications of these results for understanding psychological mechanisms underlying statistical learning, and compare the evidence provided by different experimental measures.
Bayesian time-series analyses reveal a complex impact of climate change on Classic Maya conflict
Authors: Carleton William , Campbell Dave , Collard Mark
Published: February 2019

Researchers disagree about the impact of climate change on conflict among the Maya during the Classic period (ca. 250-900 CE). Some contend that increasing aridity exacerbated conflict, while others have found that increasing temperature ramped up conflict. Here, we report a study in which we sought to resolve this disagreement. We collated annually-resolved conflict and climate data, and then created a Bayesian time-series model for analysing count-based prehistoric and historic data. We carried out three analyses, one covering more or less the whole of the Classic Period (292-900 CE), one focused on the Early Classic (292-600 CE), and one that concentrated on the Late Classic (600-900 CE). Our analyses indicated that climate change likely did impact Classic Maya conflict levels, but our results differed from those of previous studies in two important ways. First, we found that the impact of climate change is only evident during the Late Classic. Second, we found that while increasing summer temperature exacerbated conflict, increasing aridity suppressed it. Thus, our study offers a new, more complex perspective on Classic Maya climate-conflict dynamics. It also has implications for our understanding of other aspects of Classic Maya history and for the debate about the likely impact of the current bout of climate change on conflict levels.
Questioning Bangladesh's Microcredit
Authors: Molla Rafiqul Islam , Alam Md. Mahmudul , Abu N.M. Wahid
Published: February 2019

The microcredit (MC) program of Bangladesh has been a well-known success story for generation of self-employment, and poverty alleviation. Variants of this MC model are being implemented in more than 60 different countries of the world. It has become almost a universal antidote for poverty especially from 2006 when Professor Muhammad Yunus- the founder of the Grameen Bank (GB) and the bank itself shared the Nobel peace prize. Although the GB is the pioneer of MC program in Bangladesh, there are many other non-governmental organizations (NGO)s that offer the same program in Bangladesh in different forms and names. The providers of MCs claim that the overwhelming majority of the borrowers are using the loan funds profitably for productive purposes, repaying the loans and interest regularly, and thus improving their socio-economic conditions steadily. The findings of the present study are somewhat contrary and disturbing to the claim of the MC programs. This study finds that a bulk of the MC is borrowed for non productive purposes. About one quarter of the borrowers use the credit exclusively for consumption and debt repayment purposes. Nearly half of them use the credits entirely for investment purposes. For all, the return on investment is very meager. About two-third of the borrowers, on average have an impressive 83% net return on investment available for payment of interest and dividend in addition to the principal. But in case of as high as one third of them, average return on investment is not enough even to cover the most minimum or tolerance level of wages for family labors, let alone paying any interest and making any profit after keeping aside the principal.
Mapping Experience: Age and Indigeneity as Mediating Factors in Users’ Experiences with the Algonquian Linguistic Atlas
Authors: Stone Adam
Published: February 2019

To understand how effectively digital maps of Indigenous languages engage a variety of audiences, a mixed-methods user study focused on the experiences of 23 Indigenous and non-Indigenous users aged under and over 30 from a Canadian university as they navigated an online Canadian Indigenous language atlas by completing a series of tasks. An evaluative component assessed the efficacy of the study itself in measuring such experiences. Indigenous participants found the atlas more relevant and useful and focused more on its linguistic content, while non-Indigenous participants focused on the layout and structure of the atlas’s framework. Digital language atlases can better address Canadian Indigenous populations by emphasizing multimodal representations of linguistic content, with easily accessible links to additional resources from the communities represented. While the study did capture multiple dimensions of user experience, low Indigenous participation decreased the efficacy of comparative statistical analyses. Future research can improve Indigenous representation by focusing on recruitment methods that engage and are relevant to Indigenous populations.
“Notorious Abuse,” “Traditious Ignorance,” and “Ambitious Incroachment” in Seventeenth-Century Dutch, English, and French Maps of North America
Authors: Petto Christine M.
Published: February 2019

In consideration of Richard Daniel’s alarmed discourse found in the text accompanying his map of the English empire in America (1679), one must investigate the supposedly offending French, English, and Dutch maps of the second half of the seventeenth century for North America and, in particular, the region of the Atlantic coastline and the rhetorical devices of possession found on or in these geographical works. In addition to looking at territorial boundaries, one should also make note of armorial bearings, ships with naval ensigns, toponyms and their placement on the territory, dedicatory cartouches, legends with geographical or historical information, native scenes, and symbols for settlement. In addition to attention to possible constraints on or from the map trade, one must consider the correspondence between colonial officials and their respective governments regarding boundaries, encroachment, sovereignty, or the need for maps with a particular focus on the North American coastline. This correspondence reflects the state’s point of view, which in turn was often manifested on maps and in geographical works. Interestingly intertwined with this outspoken sense of rightful possession were the contemporary claims from some quarters that the cartographic enterprise of the late seventeenth century now embraced an empirical approach, as well as the seemingly opposing thread of the economic realities of the print trade, which often used old copper plates with little to no cartographic revision, so that long after political, economic, or military actions resulted in an “adjustment” in possession, printed maps, atlases, and other geographical works still reflected earlier circumstances.
The Concentration of Crime at Place in Montreal and Toronto
Authors: Boivin Rémi , de Melo Silas Nogueira
Published: February 2019

The identification of hot spots of crime – areas of high crime intensity – is of primary importance for crime prevention strategies. While the notion of crime hot spots is well accepted in Anglo-Saxon criminology, its empirical foundation is largely drawn from U.S. studies, and comparatively little literature is available for other countries, including Canada. Taking advantage of their respective “open data” initiatives, this study compares the spatial pattern of the two largest Canadian cities, Montreal and Toronto. The authors also review and empirically explore five propositions from the existing literature: (1) that a small proportion of places account for a large proportion of recorded criminal incidents; (2) that crime concentration is inversely correlated with the size of geographic units; (3) that crime concentration drastically varies whether all places or only places where at least one crime occurred are considered; (4) that different hot spots are identified at particular times of the day; and (5) that hot spots of different crime types do not overlap much. Both Toronto and Montreal appear to be very similar in terms of crime concentrations and hot spots. Additionally, this study provides preliminary support for the idea that findings from other countries can be generalized to the Canadian context.
A review of using thermoelasticity for structural integrity assessment
Authors: Marsavina L. , Tomlinson R.A.
Published: February 2019

The advances in the use of thermoelastic stress analysis (TSA) for fracture mechanics assessment are reviewed. The development of techniques to determine stress intensity factor is presented followed by the application of these techniques to fatigue crack growth, crack closure and the study of mixed mode cracks.
Fracture failure analysis of baseplates in a fluidic amplifier made of WC-11Co cemented carbide
Authors: Liu H. , Yin K. , Peng J.M. , Yin Q.L.
Published: February 2019

A fluidic amplifier is a crucial automatic control component in a liquid jet hammer used to drill hard formations in the oil industry. This study aims to determine the true causes of the fracture failure of baseplates in a fluidic amplifier made of WC-11Co cemented carbide in a very short period of time. Computational fluid dynamics (CFD), theoretical estimation, and finite element analysis (FEA) were employed to analyze the effect of static and dynamic loads on the strength of the baseplates. Fractographic, metallographic, and processing defect analyses were also carried out. The FEA results showed that the static and dynamic loads caused stress concentrations at the actual fracture locations, and the effect of working loads on material strength was allowable and safe. Fracture surfaces exhibited typical characteristics of a brittle fracture. The metallographic analysis revealed that a specific amount of brittle eta-phase (?-phase) was present in the material. The microstructure of the processing cutting zone was inspected and the results revealed that some voids, pores, and microcracks were formed on the processing surface. The manufacturing and processing defects resulted in low stress fracture failure of the baseplates.
Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys
Authors: Brotzu A. , Felli F. , Pilone D.
Published: February 2019

The ? -TiAl based intermetallic alloys are interesting candidate materials for high-temperature applications with the efforts being directed toward the replacement of Ni-based superalloys. TiAl-based alloys are characterised by a density (3.5-4 g/cm3) which is less than half of that of Ni-based superalloys, and therefore these alloys have attracted broad attention as potential candidate for high-temperature structural applications. Specific composition/microstructure combinations should be attained with the aim of obtaining good mechanical properties while maintaining satisfactory oxidation resistance, creep resistance and high temperature strength for targeted applications. Different casting methods have been used for producing TiAl based alloys. In our experimental work, specimens were produced by means of centrifugal casting. Tests carried out on several samples characterised by different alloy compositions highlighted that solidification shrinkage and solid metal contraction during cooling produce the development of relevant residual stresses that are sufficient to fracture the castings during cooling or to produce a delayed fracture. In this work, crack initiation and growth have been analysed in order to identify the factors causing the very high residual stresses that often produce explosive crack propagation throughout the casting.
Study of spatial-time inhomogeneity of serrated plastic flow Al-Mg alloy: using DIC-technique
Authors: Tretyakova T. V. , Wildemann V. E.
Published: February 2019

The aim of the present paper is the investigation of temporal instabilities and spatial localization due to the Lüders behavior, the Portevin–Le Chatelier effect and the shoulder or necking effect during uniaxial tension tests of aluminum-magnesium alloy. This paper presents the brief description of the test procedure and experimental results of carrying out research by the combined use of a servo-hydraulic biaxial test system Instron 8850 and a non-contact 3-D digital image correlation measurement system Vic-3D. The digital image correlation is a highly effective computer-vision-based technique, which provides estimation of the displacement and strain fields on specimen surface by matching the reference subsets in the undeformed image (before loading) with the target subsets in the deformed images (captured during test). The evolution of inhomogeneous axial strain and axial strain rate fields has been illustrated for each stage of material’s deformation. To estimate the kinematics of serrated or jerky flow due to the strain bands propagation, the strain versus time curves and strain diagrams are given here. The experimental results show the recurrence in the strain distribution leveling along the specimen gauge. The changing between the macroscopic localization of the plastic flow, namely the running of the Lüders and PLC bands and the recovery of strain field  homogeneity, has been observed.
Mechanical characterization of basalt woven fabric composites: numerical and experimental investigation
Authors: Valentino Piergiorgio , Sgambitterra Emanuele , Furgiuele Franco , Romano Marco , Ehrlich Ingo , Gebbeken Norbert
Published: February 2019

Basalt fabric composite, with different twill wave reinforcements, i.e. twill 2/2 and twill 1/3, have been studied in this work by means of experimental tests and numerical finite element (FE) simulations. As fabric reinforcements show repeating undulations of warp and fill yarn, simple mixtures law cannot be applied. As a consequence, the mesoscopic scale, lying between the microscopic and the macroscopic one, has to be taken into account to mechanically characterize a fabric reinforced composite. The aim of this work is to evaluate the stiffness of a fabric reinforced composite in warp and fill direction. In particular a numerical FE model, assuming elliptical sections and sinusoidal shape of the yarns, has been implemented and experimental tests have been carried out in order to validate the proposed model. Finally, the strength and the failure modes of the composite material, for each analysed structure and textile orientation, have been experimentally investigated.
Relation between the plastic instability and fracture of tensile tested Cu-Sn alloys investigated with the application of acoustic emission technique
Authors: Ozgowicz W. , Grzegorczyk B. , Pawelek A. , Wajda W. , Skuza W. , Piatkowski A. , Ranachowski Z.
Published: February 2019

The work concerns the application of the acoustic emission (AE) method in testing the mechanical properties of continuously cast industrial tin bronze CuSn6P, which reveals tendencies to instable plastic flow connected particularly with the Portevin-Le Chatelier (PLC) effect. The relations between the jerky flow connected with the PLC effect, AE intensity and the evolution of a fracture of the investigated alloy subjected to the tensile test at a strain rate (?? ) of about 1.2·10-3s-1 in the range of temperatures (20÷400?C) has been analyzed. It has been found that the highest intensity of the oscillation of stresses, corresponding to the instability of plastic deformation PLC occurred at 200?C, whereas the maximum of the AE activity is at about 200÷250?C. The brittle intergranular fracture starts in the range of equicohersive temperature (TE) of about 200?C. Plastic deformation of the investigated alloy in the range of the temperature of minimum plasticity, amounting to about 400?C, results in intercrystalline fractures on the entire surface of the stretched samples.
A cohesive zone model to simulate the hydrogen embrittlement effect on a high-strength steel
Authors: Gobbi G. , Colombo C. , Vergani L.
Published: February 2019

The present work aims to model the fracture mechanical behavior of a high-strength low carbon steel, AISI 4130 operating in hydrogen contaminated environment. The study deals with the development of 2D finite element cohesive zone model (CZM) reproducing a toughness test. Along the symmetry plane over the crack path of a C(T) specimen a zero thickness layer of cohesive elements are implemented in order to simulate the crack propagation. The main feature of this kind of model is the definition of a traction-separation law (TSL) that reproduces the constitutive response of the material inside to the cohesive elements. Starting from a TSL calibrated on hydrogen non-contaminated material, the embrittlement effect is simulated by reducing the cohesive energy according to the total hydrogen content including the lattice sites (NILS) and the trapped amount. In this perspective, the proposed model consists of three steps of simulations. First step evaluates the hydrostatic pressure. It drives the initial hydrogen concentration assigned in the second step, a mass diffusion analysis, defining in this way the contribution of hydrogen moving across the interstitial lattice sites. The final stress analysis, allows getting the total hydrogen content, including the trapped amount, and evaluating the new crack initiation and propagation due to the hydrogen presence. The model is implemented in both plane strain and plane stress configurations; results are compared in the discussion. From the analyses, it resulted that hydrogen is located only into lattice sites and not in traps, and that the considered steel experiences a high hydrogen susceptibility. By the proposed procedure, the developed numerical model seems a reliable and quick tool able to estimate the mechanical behavior of steels in presence of hydrogen.
Fatigue life assessment of thin-walled welded joints under non-proportional load-time histories by the shear stress rate integral approach
Authors: Bolchoun A. , Sonsino C. M. , Kaufmann H. , Melz T.
Published: February 2019

Fatigue life tests under constant and variable amplitude loadings were performed on the tube-tube thin-walled welded specimens made of magnesium (AZ31 and AZ61) alloys. The tests included pure axial, pure torsional and combined in-phase and out-of-phase loadings with the load ratio "R ",?"R "? ? ?1. For the tests with variable amplitude loads a Gaußdistributed loading spectrum with LS ? 5?104 cycles was used. Since magnesium welds show a fatigue life reduction under out-of-phase loads, a stress-based method, which takes this behavior into account, is proposed. The out-of-phase loading results in rotating shear stress vectors in the section planes, which are not orthogonal to the surface. This fact is used in order to provide an out-of-phase measure of the load. This measure is computed as an area covered by the shear stress vectors in all planes over a certain time interval, its computation involves the shear stress and the shear stress rate vectors in the individual planes. Fatigue life evaluation for the variable amplitudes loadings is performed using the Palmgren-Miner linear damage accumulation, whereas the total damage of every cycle is split up into two components: the amplitude component and the out-of-phase component. In order to compute the two components a modification of the rainflow counting method, which keeps track of the time intervals, where the cycles occur, must be used. The proposed method also takes into account different slopes of the pure axial and the pure torsional Wöhler-line by means of a Wöhler-line interpolation for combined loadings.
Equi-biaxial loading effect on austenitic stainless steel fatigue life
Authors: Gourdin C. , Bradaï S. , Courtin S. , Le Roux J.C. , Gardin C.
Published: February 2019

Fatigue lifetime assessment is essential in the design of structures. Under-estimated predictions may result in unnecessary in service inspections. Conversely, over-estimated predictions may have serious consequences on the integrity of structures. In some nuclear power plant components, the fatigue loading may be equibiaxial because of thermal fatigue. So the potential impact of multiaxial loading on the fatigue life of components is a major concern. Meanwhile, few experimental data are available on austenitic stainless steels. It is essential to improve the fatigue assessment methodologies to take into account the potential equi-biaxial fatigue damage. Hence this requires obtaining experimental data on the considered material with a strain tensor in equibiaxial tension. Two calibration tests (with strain gauges and image correlation) were used to obtain the relationship between the imposed deflection and the radial strain on the FABIME2 specimen. A numerical study has confirmed this relationship. Biaxial fatigue tests are carried out on two austenitic stainless steels for different values of the maximum deflection, and with a load ratio equal to -1. The interpretation of the experimental results requires the use of an appropriate definition of strain equivalent. In nuclear industry, two kinds of definition are used: von Mises and TRESCA strain equivalent. These results have permitted to estimate the impact of the equibiaxiality on the fatigue life of components.
Atomistic modeling of different loading paths in single crystal copper and aluminum
Authors: Pezer R. , Trapic I.
Published: February 2019

Utilizing molecular dynamics (MD) integration model we have investigated some of the relevant physical processes caused by different loading paths at the atomic level in Cu and Al monocrystal specimen. Interactions among the atoms in the bulk are modeled with the standard realistic Embedded Atom Method (EAM) potentials. MD simulation gives us the detailed information about non-equilibrium dynamics including crystal structure defects, vacancies and dislocations. In particular, we have obtained result that indicate increase in the total energy of the crystal during loading (especially cyclic) that provides us direct quantitative evidence of the metal weakening. For the basic response, we have deformed copper and aluminum single crystal according to the simple loading path and a series of multiaxial loading-paths including cyclic repetition. We compute equivalent stress-strain diagrams as well as dislocation total length vs time graphs to describe signatures of the anisotropic response of the crystal.
Averaged strain energy density-based synthesis of crack initiation life in notched steel bars under torsional fatigue
Authors: Berto Filippo , Campagnolo Alberto , Meneghetti Giovanni , Tanaka Keisuke
Published: February 2019

The torsional fatigue behaviour of circumferentially notched specimens made of austenitic stainless steel, SUS316L, and carbon steel, SGV410, characterized by different notch root radii has been recently investigated by Tanaka. In that contribution, it was observed that the total fatigue life of the austenitic stainless steel increases with increasing stress concentration factor for a given applied nominal shear stress amplitude. By using the electrical potential drop method, Tanaka observed that the crack nucleation life was reduced with increasing stress concentration, on the other hand the crack propagation life increased. The experimental fatigue results, originally expressed in terms of nominal shear stress amplitude, have been reanalysed by means of the local strain energy density (SED) averaged over a control volume having radius R0 surrounding the notch tip. To exclude all extrinsic effects acting during the fatigue crack propagation phase, such as sliding contact and/or friction between fracture surfaces, crack initiation life has been considered in the present work. In the original paper, initiation life was defined in correspondence of a 0.1÷0.4-mm-deep crack. The control radius R0 for fatigue strength assessment of notched components, thought of as a material property, has been estimated by imposing the constancy of the averaged SED for both smooth and cracked specimens at NA = 2 million loading cycles.
Numerical modelling of ductile damage mechanics coupled with an unconventional plasticity model
Authors: Fincato R. , Tsutsumi S.
Published: February 2019

Ductility in metals includes the material’s capability to tolerate plastic deformations before partial or total degradation of its mechanical properties. Modelling this parameter is important in structure and component design because it can be used to estimate material failure under a generic multi-axial stress state. Previous work has attempted to provide accurate descriptions of the mechanical property degradation resulting from the formation, growth, and coalescence of microvoids in the medium. Experimentally, ductile damage is inherently linked with the accumulation of plastic strain; therefore, coupling damage and elastoplasticity is necessary for describing this phenomenon accurately. In this paper, we combine the approach proposed by Lemaitre with the features of an unconventional plasticity model, the extended subloading surface model, to predict material fatigue even for loading conditions below the yield stress.
Tensile and fatigue behaviour of as-forged AZ31B extrusion
Authors: Gryguc A. , Shaha S.K. , Jahed H. , Wells M. , Williams B. , McKinley J.
Published: February 2019

Tensile and stress controlled fatigue tests were performed to investigate the influence of forging at a temperature of 400°C at different rates, on the performance of extruded AZ31B magnesium alloy. The obtained microstructural analysis showed that the extruded AZ31B magnesium alloy possesses a bimodal grain structure with strong basal texture. In contrast, the forged samples showed refined grains and a weaker texture. During tensile testing, a maximum yield and ultimate tensile strength of about 163 MPa and 268 MPa were obtained for the forged samples showing an increase of 102% and 7%, respectively from the as-extruded material. At the same time, a significant improvement of fatigue life was also observed for the sample forged at the rate of 100 mm/min. The fractographic analysis of the fracture surfaces showed that ductile type fractures occurred in both as-extruded and forged samples. However, more dimples and plastic deformation were identified in the fracture surfaces of the forged specimens. It is believed that forging improved the fatigue life by a combination of grain refinement and texture modification resulting in improved yield and ductility. KEYWORDS. AZ31B; Forging; Fatigue Characterization; Fracture; Texture.
40CrMoV13.9 notched specimens under multiaxial fatigue: an overview of recent results
Authors: Razavi S.M.J. , Peron M. , Torgersen J. , Berto F. , Welo T.
Published: February 2019

The multiaxial fatigue strength of circumferentially V-notched and semicircular notched specimens made of 40CrMoV13.9 has been investigated in this paper. The multiaxial load were applied using combined tension and torsion loading, both in-phase and out-of-phase. The axissymmetric V-notched specimens were characterized by a blunt notch tip (radius: 1 mm) and notch opening angle of 90o and the semicircular specimens were characterized by a constant notch tip radius. The net sectional area of both cases was equal with a diameter of 12 mm. The notched specimens were tested under pure mode I (tension), mixed mode I/III and pure mode III (torsion). More than 120 fatigue test data are used in this paper to evaluate the fatigue behaviour of 40CrMoV13.9 alloy. All fatigue data are analysed using the Average Strain Energy Density (ASED) criterion which employs the mean value of the strain energy density evaluated over a finite size semicircular sector surrounding the tip of the notch to predict the fatigue life of the tested specimens.
Fracture toughness investigations of Al6061-Graphite particulate composite using compact specimens
Authors: Doddamani Saleemsab , Kaleemulla Mohamed
Published: February 2019

The objective of this research work is to study the fracture behavior of Al6061 with graphite particulate composite produced by the stir casting technique. For the study different composition of the particulate metal matrix composite used is Al6061 with 3, 6, 9, & 12% of graphite particles. Compact Tension (CT) specimens were utilized to determine fracture toughness for different compositions of Al6061-graphite particulate metal matrix composite. Specimens with different composition will be prepared for different crack length to width (a/w) ratios according to the ASTM E-399 standard testing procedure. The maximum fracture toughness was found for Al6061-9%Gr for a/w =0.45 and the value is 16.74 MPa ?m.
Dynamic debonding in layered structures: a coupled ALE-cohesive approach
Authors: Funari Marco Francesco , Greco Fabrizio , Lonetti Paolo
Published: February 2019

A computational formulation able to simulate crack initiation and growth in layered structural systems is proposed. In order to identify the position of the onset interfacial defects and their dynamic debonding mechanisms, a moving mesh strategy, based on Arbitrary Lagrangian-Eulerian (ALE) approach, is combined with a cohesive interface methodology, in which weak based moving connections are implemented by using a finite element formulation. The numerical formulation has been implemented by means of separate steps, concerned, at first, to identify the correct position of the crack onset and, subsequently, the growth by changing the computational geometry of the interfaces. In order to verify the accuracy and to validate the proposed methodology, comparisons with experimental and numerical results are developed. In particular, results, in terms of location and speed of the debonding front, obtained by the proposed model, are compared with the ones arising from the literature. Moreover, a parametric study in terms of geometrical characteristics of the layered structure are developed. The investigation reveals the impact of the stiffening of the reinforced strip and of adhesive thickness on the dynamic debonding mechanisms.