Temperature and load-ratio dependent fatigue-crack growth in the CrMnFeCoNi high-entropy alloy

Multiple-principal element alloys known as high-entropy alloys have rapidly been gaining attention for the vast variety of compositions and potential combinations of properties that remain to be explored. Of these alloys, one of the earliest, the ‘Cantor alloy’ CrMnFeCoNi, displays excellent damage-tolerance with tensile strengths of ∼1 GPa and fracture toughness values in excess of 200 MPa√m; moreover, these mechanical properties tend to further improve at cryogenic temperatures. However, few studies have explored its corresponding fatigue properties. Here we expand on our previous study to examine the mechanics and mechanisms of fatigue-crack propagation in the CrMnFeCoNi alloy (∼7 μm grain size), with emphasis on long-life, near-threshold fatigue behavior, specifically as a function of load ratio at temperatures between ambient and liquid-nitrogen temperatures (293 K–77 K). We find that ΔKth fatigue thresholds are decreased with increasing positive load ratios, R between 0.1 and 0.7, but are increased at decreasing temperature. These effects can be attributed to the role of roughness-induced crack closure, which was estimated using compliance measurements. Evidence of deformation twinning at the crack tip during fatigue-crack advance was not apparent at ambient temperatures but seen at higher stress intensities (ΔK ∼ 20 MPa√m) at 77 K by post mortem microstructural analysis for tests at R = 0.1 and particularly at 0.7. Overall, the fatigue behavior of this alloy was found to be superior, or at least comparable, to conventional cryogenic and TWIP steels such as 304 L or 316 L steels and Fe-Mn steels; these results coupled with the remarkable strength and fracture toughness of the Cantor alloy at low temperatures indicate significant promise for the utility of this material for applications at cryogenic environments

The 4th industrial revolution's challenges at the wood industrial manufactories

Substantial technological advances appeared in the industrial sector in the last years. Developments are based on the “Internet of things” idea, called as “Industry 4.0” in Europe. The name is referring to the phenomena that many experts think this is the fourth industrial revolution. The goal of these projects are to create live connections among all industrial machines, tools and the central units. Some techniques and tools, e.g., sensors, big data, cloud computing, 3D printing, robotics and artificial intelligence, support the IT developments also. The decision making in the industry will be automated and quick because of the new methods and tools

On the tear resistance of skin.

Tear resistance is of vital importance in the various functions of skin, especially protection from predatorial attack. Here, we mechanistically quantify the extreme tear resistance of skin and identify the underlying structural features, which lead to its sophisticated failure mechanisms. We explain why it is virtually impossible to propagate a tear in rabbit skin, chosen as a model material for the dermis of vertebrates. We express the deformation in terms of four mechanisms of collagen fibril activity in skin under tensile loading that virtually eliminate the possibility of tearing in pre-notched samples: fibril straightening, fibril reorientation towards the tensile direction, elastic stretching and interfibrillar sliding, all of which contribute to the redistribution of the stresses at the notch tip

Real-time observations of TRIP-induced ultrahigh strain hardening in a dual-phase CrMnFeCoNi high-entropy alloy.

Strategies involving metastable phases have been the basis of the design of numerous alloys, yet research on metastable high-entropy alloys is still in its infancy. In dual-phase high-entropy alloys, the combination of local chemical environments and loading-induced crystal structure changes suggests a relationship between deformation mechanisms and chemical atomic distribution, which we examine in here in a Cantor-like Cr20Mn6Fe34Co34Ni6 alloy, comprising both face-centered cubic (fcc) and hexagonal closed packed (hcp) phases. We observe that partial dislocation activities result in stable three-dimensional stacking-fault networks. Additionally, the fraction of the stronger hcp phase progressively increases during plastic deformation by forming at the stacking-fault network boundaries in the fcc phase, serving as the major source of strain hardening. In this context, variations in local chemical composition promote a high density of Lomer-Cottrell locks, which facilitate the construction of the stacking-fault networks to provide nucleation sites for the hcp phase transformation

Aktuelle Bestandsaufnahme des Wiener Walzers in Wien

Die Geschichte des Walzers beginnt im 15. Jahrhundert; seit damals sind volkstümliche Drehtänze im deutschen Sprachraum bezeugt. Die Ansicht, dass der Walzer aus dem Ländler entstanden ist, weiß man heute überholt. Beide Tänze sind eher als Geschwister zu betrachten, deren Wege sich trennten. Der Ländler ist figurenreich und behielt sein gemächliches Tempo. Der Walzer blieb ohne Choreographie und erfuhr eine Beschleunigung des Tempos. Diese Beschleunigung hatte sowohl mit der einfachen Drehung zu tun als auch mit der nachbarock-aufgeklärten Zeit. Der Wiener Walzer wurde vor allem durch Michael Pamer, Johann Strauss und Joseph Lanner berühmt. Lanner und Strauss spielten zunächst in der Kapelle Pamers, bevor sich beide selbständig machten und eigene Wege gingen. Sie behielten ihre Freundschaft – die beiden Herren standen ohnehin nicht in direkter Konkurrenz zueinander: Lanner hielt nämlich am Ländlerhumor fest, während Strauss den Witz in die Musik legte. Ein musikalisches Merkmal des Wiener Walzers ist zweifelsfrei der Rhythmus der Begleitung: Der zweite und dritte Schlag sind nicht immer pünktlich. Die zwei wird vorgezogen und die drei verspätet – das macht den Wiener Walzer aus. Beim Tanz veränderte sich die Haltung des Paares zueinander: Anfangs war aufgrund der Kleidung und Moral großer Abstand zwischen den Tänzern. Mit der Zeit änderten sich die Mode, die moralischen Ansichten und auch das Tempo des Walzers. Um eine gemeinsame Drehachse zu erlangen, brauchte es eine geschlossene Körperhaltung mit Hüftkontakt, wodurch eine detaillierte Fußtechnik wichtig wurde. Auch in der heutigen Zeit spielt der Walzer keine geringe Rolle. Sowohl im touristischen Bereich, für Wiener, wie auch im Rahmen von Ballveranstaltungen ist der Walzer – gerade für die Weltstadt der Musik Wien – von großer Bedeutung. In der vorliegenden Arbeit wird versucht, eine aktuelle Bestandsaufnahme des Wiener Walzers in Wien zu machen. Dabei wird auf die verschiedenen gesellschaftlichen Ebenen eingegangen und aufgelistet, welche Möglichkeiten Wien bietet, damit ein Tourist, ein Wiener und auch ein Ballhungriger auf seine Kosten kommt – sowohl musikalisch als auch tänzerisch.The history of the Viennese Waltz began as early as the 15th century; with folk-like round dances documented throughout the German-speaking region. The waltz was often considered a final dance figure of the Landler, which might imply that the waltz had its origins in the Landler. This theory, however, is outdated. More probably, both dances ought to be considered as siblings going separate ways over the time. The Landler is rich in figures and has maintained its leisurely tempo. The waltz, however, still lacks choreography and has experienced an increase in tempo. This acceleration is due to its simple rotation and with the enlightened atmosphere of the time following the baroque period. Michael Pamer along with Johann Strauss and Joseph Lanner made the Vienna Waltz famous. Lanner and Strauss originally played in Pamer’s orchestra before each of them took up their artistic direction. But they maintained their friendship, as they did not compete directly: Lanner adhered to the humour of the Landler, whereas Strauss put his wit into his music. One of the musical features of the Viennese Waltz is undoubtedly the rhythm of its accompaniment. The waltz is exceptional because of the way the second and third beats are played: mostly unpunctually. Beat two is brought forward and beat three a little bit belated – it is this detail that constitutes the Viennese Waltz. Dancing the waltz changed a couple’s posture: Initially there was a big distance between the dancers due to dress code and moral standards. Gradually both fashion and morals and the tempo of the waltz changed. Sharing the same rotation axis required hip contact and dancing closely, as a result exact footwork became important. Even today the waltz still plays an important role. In tourism and within the civil society, as well as within the framework of a ball the Waltz is still of major importance, above all for the metropolis of music, Vienna. This thesis tries to raise an inventory of the Viennese Waltz in Vienna itself, with due consideration of different social layers and of all the opportunities Vienna offers to tourists, citizens and ball enthusiasts, continuing to meet their expectations as to music and dance

Controlling the relaxation versus rejuvenation behavior in Zr-based bulk metallic glasses induced by elastostatic compression

Elastostatic compression (ESC) has received considerable research attention as a tool to study rejuvenation and relaxation processes for bulk metallic glasses (BMGs). However, little is understood about the conditions that control whether rejuvenation or relaxation will occur, and whether conditions exist that can give structural stability. We address these questions by applying ESC at 90% of the yield stress to both cast and laser powder bed fusion (LPBF) manufactured Zr-based BMG samples in the as-cast, as-built, and different annealed states. The structural state and mechanical properties for each material condition were characterized by differential scanning calorimetry and microhardness, respectively, and two representative groups were also used for compression testing. Initial relaxation or rejuvenation was observed for elastostatically compressed as-cast samples, and the behavior reversed over 72 h of ESC. In contrast, no ESC effect was observed for the as-built LPBF samples. It was found that the onset of either relaxation or rejuvenation by ESC could be better predicted if samples were annealed into a controlled initial state. Five different types of initial response to ESC were observed, corresponding to different initial energy state ranges. Materials in the highest and lowest initial energy states were stable against structural changes by ESC. Close to the highest energy state, rejuvenation was dominant, while relaxation took place close to the lowest energy state. At intermediate initial energy states, both relaxation and rejuvenation were observed after ESC loading, suggesting that the glass structure easily finds different local minima in the potential energy landscape. In all cases, relaxation was associated with BMG hardening and rejuvenation was associated with softening. Overall, the results of this study provide new insights into how ESC impacts the structural state and mechanical properties of BMGs

Calculation of Indirect Electricity Consumption in Product Manufacturing

Electricity consumption has been analysed since 2016 at a Hungarian furniture company. At the beginning of the research, a cyber-physical system was created which is capable of storing and analysing data on energy consumption by the production machines. The speciality of the system is that it can collect not only data on energy consumption by the machines but also the system can compare the energy consumption with production data. The data is received from sensors, which are installed into the building management system via the company’s own computer network. In this building management system, calculations can also be performed. All the collected and calculated data are entered into the company’s big database. The data is analysed with a business intelligence system, and the results are presented to the management and the other employees of the company. With this cyber-physical system all equipment are followed up in terms of energy management. The measured data can be analysed together by manufacturing machines and time; this way production efficiency can be represented by indicators. The goal of this study is not only to aggregate the energy consumption of machines that directly produce, but also to relate the energy consumption of indirectly aggregated production support equipment to production data. To achieve this goal, a completely new sensor environment had to be built to provide data from the supporting devices. One of the key supporting equipment is the extractors. These devices consume a huge part of total annual energy consumption of the factory (~30%). Their energy consumption costs are indirectly related to production, but through research and development, consumption can already be managed directly and aggregate to the creating of a product.Supported by the UNKP-20-3-II new national excellence program of the ministry for innovation and technology from the source of the national research, development and innovation fund

Mechanical Competence and Bone Quality Develop During Skeletal Growth.

Bone fracture risk is influenced by bone quality, which encompasses bone's composition as well as its multiscale organization and architecture. Aging and disease deteriorate bone quality, leading to reduced mechanical properties and higher fracture incidence. Largely unexplored is how bone quality and mechanical competence progress during longitudinal bone growth. Human femoral cortical bone was acquired from fetal (n = 1), infantile (n = 3), and 2- to 14-year-old cases (n = 4) at the mid-diaphysis. Bone quality was assessed in terms of bone structure, osteocyte characteristics, mineralization, and collagen orientation. The mechanical properties were investigated by measuring tensile deformation at multiple length scales via synchrotron X-ray diffraction. We find dramatic differences in mechanical resistance with age. Specifically, cortical bone in 2- to 14-year-old cases exhibits a 160% greater stiffness and 83% higher strength than fetal/infantile cases. The higher mechanical resistance of the 2- to 14-year-old cases is associated with advantageous bone quality, specifically higher bone volume fraction, better micronscale organization (woven versus lamellar), and higher mean mineralization compared with fetal/infantile cases. Our study reveals that bone quality is superior after remodeling/modeling processes convert the primary woven bone structure to lamellar bone. In this cohort of female children, the microstructural differences at the femoral diaphysis were apparent between the 1- to 2-year-old cases. Indeed, the lamellar bone in 2- to 14-year-old cases had a superior structural organization (collagen and osteocyte characteristics) and composition for resisting deformation and fracture than fetal/infantile bone. Mechanistically, the changes in bone quality during longitudinal bone growth lead to higher fracture resistance because collagen fibrils are better aligned to resist tensile forces, while elevated mean mineralization reinforces the collagen scaffold. Thus, our results reveal inherent weaknesses of the fetal/infantile skeleton signifying its inferior bone quality. These results have implications for pediatric fracture risk, as bone produced at ossification centers during children's longitudinal bone growth could display similarly weak points. © 2019 American Society for Bone and Mineral Research

Early Visual Cultures and Panofsky’s Perspektive als ‘symbolische Form’

This paper investigates the historical dimension of perspectival representations. It aims to provide a heterogeneous though comparative picture of culturally unrelated visual con- ceptualizations of pictorial spaces, written with a view toward explaining how the multiple modes of perspective were introduced in antiquity. Point of departure for this critical approach is Erwin Panofsky’s essay Die Perspektive als ‘symbolische Form’ , published in 1927. His essay analyses the pictorial visualization of space and spatiality in different historical contexts, examining their cultural codification in terms of the heuristic category of ‘sym- bolic form’. However, ‘perspective’, which is commonly understood as synonymous with ‘linear perspective’, deserves a new discussion in the context of diverse visual cultures: A ‘naturalisation’ of the gaze as it is suggested by pictorial spaces which function mimetically is primarily associated with the early modern period in Western art. Instead of merely re- reading Panofsky’s canonical text, this paper presents an interdisciplinary re-viewing of a selection of the pictorial examples chosen by Panofsky, commenting upon their perspec- tive(s) from different vantage points