Formability of Tailor-Welded Blanks from Dual-Phase and Bake-Hardened Steels with a Planar Anisotropy Influence

The formability of two types of tailor-welded blanks was analyzed with the concentration on the effects of planar anisotropy on eras forming of deep-drawn parts. The first tailor-welded blank consisted of bake-hardened BH220 steel with different rolling directions, which is applied to the surface car body parts. The second one consisted of dual-phase DP600 steel with different rolling directions, which is applied to supporting parts of automobiles. Stress-strain characteristics of experimental steel sheets were measured using the tensile tests and used in the respective simulations. Simulations via the Dynaform software were compared to the experimental values measured during the deep-drawing process of rectangular boxes.Анализируются формообразующие свойства нестандартных сварных заготовок с акцентом на влияние плоскостной анизотропии на возникновение волнистости в деталях глубокой вытяжки. Одна нестандартная сварная заготовка выполнена из термозакаливаемой стали BH220 с разным направлением прокатки и применяемая в кузовных деталях автомобиля, другая из двухфазной стали DP600 также с разным направлением прокатки и применяемая в несущих элементах конструкции автомобиля. Деформационно-прочностные характеристики листов экспериментальной стали измеряли при испытаниях на растяжение и использовали при моделировании. Результаты моделирования с помощью программного комплекса Dynaform сравнивали с экспериментальными значениями, полученными при глубокой вытяжке прямоугольных коробчатых деталей

Deep-Drawing Process Simulation for Tailor-Welded Blanks with an Elastic Blankholder

Application of tailor welded blanks is proved to be very effective in the current trend of body parts construction. However, their formability is limited to the differences of mechanical properties of individual tailor welded blanks parts. These differences result in non-constant material flow and a deflection of the weld line. This article is focused on the elimination of uneven material flow and weld line instability. The results have been obtained by means of laboratory measurements on the drawing tool as well as material simulation computed by LS-DYNA code. According to acquired results, it can be claimed that the blankholder force values and force distribution have a significant influence on the deep-drawing process of tailor welded blanks. The weld line direction in consideration of the blankholder area size has influence on the deflection value. The simulation provided a reliable prediction of tailor-welded blank formability.Показана эффективность использования нестандартных сварных заготовок при проектировании кузовных деталей. Однако их пластичность ограничена из-за разных механических характеристик отдельных деталей из таких заготовок, что приводит к непостоянной текучести материала и перемещению границы сплавления. Проведены лабораторные измерения вытяжки и моделирование материала с использованием программного комплекса LS-DYNA. Показано, что усилие прижима и его распределение существенно влияют на процесс глубокой вытяжки нестандартных сварных заготовок. С учетом размера площади прижима влияние на величину перемещения границы сплавления оказывает ее направление. При прогнозировании пластичности нестандартных сварных заготовок результаты моделирования были весьма надежными

Kombinace kvalitativních metod při výzkumu tacitních znalostí manažerů

Tacitní znalosti jsou považovány za významnou součást profesních kompetencí, za skrytý potenciál subjektu, který se projevuje při řešení sociálních situací. Závažným problémem je, jak proces utváření tacitních znalostí v profesních, zejména sociálních situacích probíhá.Autoři informují o kombinaci kvalitativních metod při výzkumu tacitních znalostí manažerů. Využili při něm polostrukturovaný rozhovor, metodu dotazníkovou a metodu ohniskové skupiny. Referují o výsledcích první etapy výzkumu a poukazují na možnosti aplikace dalších metod: situační Wagnerův test (dotazník), projektivní techniky a metodu tzv. stimulovaného vybavování profesních situací zaznamenaných na videozáznamu

Butyl­trichlorido{2-[(diisopropyl­ammonio)­meth­yl]phen­yl}tin(IV) dichloro­methane monosolvate

The title compound, [Sn(C4H9)(C13H21N)Cl3]·CH2Cl2, was obtained by recrystallization of [2-(diisopropyl­amino­meth­yl)phen­yl]tin(IV) butyl dichloride from a CH2Cl2/n-hexane mixture (1:4 v/v) in the presence of ambient moisture. Partial hydrolysis led to the title compound, the hydro­chloric acid adduct of the dichloride, having a penta­coordinated Sn atom with a trigonal–bipyramidal C2SnCl3 core. The N atom of the 2-[(diisopropyl­ammonio)­meth­yl]phenyl ligand forms a strong intra­molecular N—H⋯Cl hydrogen bond, resulting in a zwitterionic species, [2-(iPr2HN+CH2)C6H4]SnBuCl3 −·CH2Cl2. Disorder was found in the n-butyl group, which was refined as disordered over three positions, with site occupancies of 0.22 (1), 0.51 (1) and 0.27 (2)

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation.

Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most abundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here we present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations. © 2014 Macmillan Publishers Limited. All rights reserved

The energy gap of intermediate-valent SmB6 studied by point-contact spectroscopy

We have investigated the intermediate valence narrow-gap semiconductor SmB6 at low temperatures using both conventional spear-anvil type point contacts as well as mechanically controllable break junctions. The zero-bias conductance varied between less than 0.01 mikrosiemens and up to 1 mS. The position of the spectral anomalies, which are related to the different activation energies and band gaps of SmB6, did not depend on the the contact size. Two different regimes of charge transport could be distinguished: Contacts with large zero - bias conductance are in the diffusive Maxwell regime. They had spectra with only small non-linearities. Contacts with small zero - bias conductance are in the tunnelling regime. They had larger anomalies, but still indicating a finite 45 % residual quasiparticle density of states at the Fermi level at low temperatures of T = 0.1 K. The density of states derived from the tunelling spectra can be decomposed into two energy-dependent parts with Eg = 21 meV and Ed = 4.5 meV wide gaps, respectively.Comment: 9 pages incl. 13 figure

Miocene waterfowl and other birds from central Otago, New Zealand

Copyright © The Natural History Museum 2007Abundant fossil bird bones from the lower Bannockburn Formation, Manuherikia Group, an Early-Middle Miocene lacustrine deposit, 16–19 Ma, from Otago in New Zealand, reveal the “St Bathans Fauna” (new name), a first Tertiary avifauna of land and freshwater birds from New Zealand. At least 23 species of birds are represented by bones, and probable moa, Aves: Dinornithiformes, by eggshell. Anatids dominate the fauna with four genera and five species described as new: a sixth and largest anatid species is represented by just one bone. This is the most diverse Early-Middle Miocene duck fauna known worldwide. Among ducks, two species of dendrochenines are most numerous in the fauna, but a tadornine is common as well. A diving petrel (Pelecanoididae: Pelecanoides) is described, so extending the geological range of this genus worldwide from the Pliocene to the Middle Miocene, at least. The remaining 16 taxa are left undescribed but include: a large species of gull (Laridae); two small waders (Charadriiformes, genus indet.), the size of Charadrius bicinctus and Calidris ruficollis, respectively; a gruiform represented by one specimen similar to Aptornis; abundant rail (Rallidae) bones, including a common flightless rail and a rarer slightly larger taxon, about the size of Gallirallus philippensis; an ?eagle (Accipitridae); a pigeon (Columbidae); three parrots (Psittacidae); an owlet nightjar (Aegothelidae: Aegotheles sp.); a swiftlet (Apodidae: Collocalia sp.); and three passerine taxa, of which the largest is a member of the Cracticidae. The absence of some waterbirds, such as anserines (including swans), grebes (Podicipedidae) and shags (Phalacrocoracidae), among the abundant bones, indicates their probable absence from New Zealand in the Early-Middle Miocene.T. H. Worthy, A. J. D. Tennyson, C. Jones, J. A. McNamara and B. J. Dougla