Pojava pozitivnog i negativnog elastičnog povrata pri savijanju lima od mateijala St1403 u V-alatu

Today there is widespread usage of high strength steels (HSS), and ultra high strength steels (UHSS) in the manufacturing industry. Especially in the automobile industry for the rigid and light weight chassis components made out of high strength steel. During sheet metal forming material undergoes plastic deformations and after the process of forming and taking out of the tool, formed sheet metal plate try to take previous position and elastically deforms. This deformation is called elastic spring-back. Special version of this elastically unloading is called spring-forward. It can be seen in V-die bending with small punch radius, and small punch angle which is shown in this paper.Danas postoji široka upotreba visoko čvrstih i ultra visoko čvrstih čelika u industriji. Posebno u automobilskoj industriji za izradu krutih i laganih komponenti karoserija automobila izrađenih od visoko čvrstih čelika. Tijekom oblikovanja metalnog lima dolazi do plastičnih deformacija i nakon završenog procesa i vađenja izratka iz kalupa oblikovani lim pokušava zauzeti prethodni oblik pri čemu se elastično deformira. Ta deformacija se naziva elastičan povrat. Poseban oblik elastičnog povrata je negativni povrat. Ova pojava se može vidjeti kod savijanja u V-alatu uz mali radijus vrha alata i malen kut žiga, što je pokazano u ovom radu

Under the Surface of Subcutaneous Adipose Tissue Biology

The global obesity epidemic enhanced contemporary interest in adipose tissue biology. Two structurally and functionally distinct depots, subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), are spread throughout the body. Their distribution was recognized to be a major determinant of metabolic risk. Unlike VAT, SAT showed some protective endocrine and inflammatory features that might explain the occurrence of obese but metabolically healthy persons. The unique developmental gene expression signature, angiogenesis, and adipogenic potential of SAT determines its growth ability under the positive energy balance. The overflow hypothesis suggested that when SAT is unable to expand sufficiently, fat overflows towards metabolically adverse ectopic depots. Besides white adipose tissue, recent studies found important brown adipose tissue activity responsible for thermogenesis and energy dissipation in adults as well. SAT is prone to “browning” – the appearance of particular beige adipocytes that contribute to its favorable metabolic effects. Morbid obesity, aging, hormonal status, nutrition, low physical activity, and other environmental factors impair SAT relative resistance to dysfunctional changes and promote development of metabolic disorders. The popular approach considering SAT mainly as the subject of cosmetic procedures for improving the appearance of body contours should be avoided. Complex heterogeneity of obesity revealed that a tissue of an extreme plasticity and rich interactions with vital functions of the body lies under the surface. Therapeutic manipulations to preserve and enhance healthier fat in order to correct obesity-related metabolic disorders seem to be a relevant but still unexplored opportunity. </p

Application of Hydroforming Process in Sheet Metal Formation

This article deals with the theory and application of a hydroforming process. Nowadays automobile manufacturers use high strength sheet metal plates. This high strength steel sheet metal plates are strain hardened in the process of metal forming. With the use of high strength steel, cars are made lightweight, which is intended for low fuel consumption because of high energy prices. Some examples of application of a hydroforming process are simulated with FEM

Landslide inventory and characteristics, based on LiDAR scanning and optimised field investigations in the Kutina area, Croatia

This paper presents the preliminary results of analyses of landsliding processes derived from detailed LiDAR (Light Detection and Ranging) scans supported by field prospection on the south-western slopes of Mt. Moslavačka gora, in the wider Kutina area. This area is known for frequent landslides, but dedicated regional landslide research has not been previously undertaken. High resolution LiDAR scanning and orthophoto imaging enabled the production of a reliable landslide inventory, but also enabled research on landslide properties and the morphology of the area. Field mapping and prospection, sampling and borehole coring assisted in the collection of information about the material characteristics and specific features of typical landslides. In the research area, which covers more than 71 km2, more than 1200 very small landslides were detected. The majority of landslides were discovered in just several geological units indicating their high susceptibility: Pleistocene silts and sands with clayey interlayers, followed by M2 silty sands and gravels, and M7 sands. Nearly half of the landslides are estimated to be of recent and younger age, while other landslides may be considered as being historical implying a “long tradition” of landslide events in the research area. Preliminary terrain surface roughness analysis also supported the conclusion that the inventory contains landslides of several historical generations which are still detectable. In addition to slides (1123), this research also discovered numerous earthflow processes (143), which are more frequent in the predominantly sandy units. The landslides in this area are largely located on the banks of the gullies and are directly related to the action of water. Regarding that situation and the engineering properties of the encountered geological units, four types of bank instabilities can be differentiated: slides on top of rock masses; slides in firm soil mixtures; landslides in sands; landslides in predominantly coherent soil complexes

Mineral assemblage and provenance of the Pliocene Viviparus beds from the Area of Vukomeričke Gorice (Central Croatia)

Viviparus beds are sediments deposited in lacustrine and fluvial freshwater environments (Lake Slavonia) during the Pliocene and the earliest Pleistocene. A detailed field study and mineralogical, petrographic and chemical analyses were carried out to determine their composition and origin in the area of Vukomeričke Gorice, Central Croatia. Viviparus beds are characterized by the vertical and lateral exchange of mineralogically and chemically mature pelites and sands. Pelitic sediments consist mainly of detrital quartz, calcite, dolomite and feldspar grains, with smectite as the most common clay mineral. Quartz and the most resistant lithic fragments dominate the sandy detritus. The composition of the sediments indicates their origin from the recycled orogen, while their textural immaturity suggests a short transport distance. Most of the material was re-deposited from the underlying Upper Miocene sediments, originally of Alpine provenance. A lesser proportion originated from Palaeogene sediments, Triassic carbonate rocks, basic or acidic magmatic rocks and metamorphites. The Medvednica and Žumberak Mts. were the most important source areas, while a smaller proportion of the material could have come from the Moslavačka gora Mt. and Banovina region. The uniform composition of the Viviparus beds over the entire vertical distribution of the sediments clearly indicates that the source areas did not change during their deposition. A significant change from the texturally and compositionally mature Upper Miocene clastic detritus of alpine origin, to the texturally immature material of the Viviparus beds of local origin is a consequence of compression and inversion of the previously extensional basin resulting in the uplifting and erosion of the mountains within the SW part of the Pannonian Basin System

Effect of spring-back in v-tool bending of high-strength steel sheet metal plates

This paper deals with the effects of technological parameters used in the V-die bending process, on the obtained product properties and dimensions. By variation of the tool geometry, several cases of steel sheet bending process are observed through the FEM simulations. Also by variation of different mechanical material properties, effects on product geometry are observed. Since the automobile manufacturers mostly use the high strength steel sheet metal plates, there is a need for the successful tool construction and optimization in order to produce quality products

Die Gewalt und das Meer

IntroductionEinleitun

Reprezentacije poluprostih Liejevih algebri

Cilj uvodnog dijela ovog rada je bio motivacija za proučavanje kako općenito Liejevih algebri tako i poluprostih Liejevih algebri. U tu svrhu uveden je pojam Liejeve grupe i izneseni su glavni rezultati o vezi Liejeve grupe sa pripadnom Liejevom algebrom. Eksplicitno je konstruiran funktor Lie koji Liejevoj grupi pridružuje Liejevu algebru. Zapravo, taj funktor uspostavlja ekvivalenciju između 1-povezanih Liejevih grupa i konačnodimenzionalnih realnih Liejevih algebri. Dane su definicije svih pojmova važnih za ovaj rad: Liejeve algebre, reprezentacije, derivacije. Uvedene su i određene važne klase ovih objekata poput rješive i poluproste Liejeve algebre, ireducibilne i potpuno reducibilne reprezentacije, unutarnjih derivacija. Nakon uvođenja pojmova dokazani su osnovni rezultati vezani uz Liejeve algebre i reprezentacije, najvažniji medu njima su Engelov teorem, Liejev teorem, Schurova lema i Cartanovi kriteriji rješivosti. Zatim su dana neka važna svojstva poluprostih Liejevih algebri i dokazan je kriterij poluprostote preko Killingove forme. Zatim je uveden pojam Casimirovog operatora reprezentacije i dokazana su njegova osnovna svojstva. Sve navedeno bila je priprema za dokaz fundamentalnog teorema u teoriji reprezentacija i Liejevih algebri, Weylovog teorema, koji kaže da je konačnodimenzionalna reprezentacija poluproste Liejeve algebre potpuno reducibilna. Nakon rezultata iz teorije navedeni su matrični primjeri Liejevih algebri i opisane su reprezentacije od $\mathfrak{sl}_2(\mathbb{F})$ korištenjem Weylovog teorema.The purpose of the introductory part is the motivation to study Lie algebras and particularly semisimple Lie algebras. Therefore the concept of Lie group was introduced, as well as the main results about the close connection between the Lie group and its Lie algebra. We constructed a functor Lie taking Lie groups to Lie algebras. This functor in fact gives an equivalence between simply connected Lie groups and finite dimensional real Lie algebras. Most important definitions are given: Lie algebra, representation, derivation. Also, some important classes of these objects are introduced, like solvable and semisimple Lie algebras, irreducible and completely reducible representations, inner derivations. Afterwards the main results of the theory of Lie algebras and representations are given; the most important are certainly Engel’s theorem, Lie’s theorem, Schur’s lemma and Cartan’s solvability criteria. The main object in this study are semisimple Lie algebras, therefore some important properties of semisimple Lie algebras are given. Also, we got one crucial semisimplicity criterion using the Killing form. To get to the fundamental theorem of this study the concept of Casimir element is introduced and the main properties are proved. Afterwards we are ready to prove Weyl’s theorem, which states that any finite dimensional representation of a semisimple Lie algebra is completely reducible. After the theoretical part, some examples of Lie algebras are mentioned; these examples belong to matrix algebras. Also, using Weyl’s theorem all representations of $\mathfrak{sl}_2(\mathbb{F})$ are described

Reprezentacije poluprostih Liejevih algebri

Cilj uvodnog dijela ovog rada je bio motivacija za proučavanje kako općenito Liejevih algebri tako i poluprostih Liejevih algebri. U tu svrhu uveden je pojam Liejeve grupe i izneseni su glavni rezultati o vezi Liejeve grupe sa pripadnom Liejevom algebrom. Eksplicitno je konstruiran funktor Lie koji Liejevoj grupi pridružuje Liejevu algebru. Zapravo, taj funktor uspostavlja ekvivalenciju između 1-povezanih Liejevih grupa i konačnodimenzionalnih realnih Liejevih algebri. Dane su definicije svih pojmova važnih za ovaj rad: Liejeve algebre, reprezentacije, derivacije. Uvedene su i određene važne klase ovih objekata poput rješive i poluproste Liejeve algebre, ireducibilne i potpuno reducibilne reprezentacije, unutarnjih derivacija. Nakon uvođenja pojmova dokazani su osnovni rezultati vezani uz Liejeve algebre i reprezentacije, najvažniji medu njima su Engelov teorem, Liejev teorem, Schurova lema i Cartanovi kriteriji rješivosti. Zatim su dana neka važna svojstva poluprostih Liejevih algebri i dokazan je kriterij poluprostote preko Killingove forme. Zatim je uveden pojam Casimirovog operatora reprezentacije i dokazana su njegova osnovna svojstva. Sve navedeno bila je priprema za dokaz fundamentalnog teorema u teoriji reprezentacija i Liejevih algebri, Weylovog teorema, koji kaže da je konačnodimenzionalna reprezentacija poluproste Liejeve algebre potpuno reducibilna. Nakon rezultata iz teorije navedeni su matrični primjeri Liejevih algebri i opisane su reprezentacije od $\mathfrak{sl}_2(\mathbb{F})$ korištenjem Weylovog teorema.The purpose of the introductory part is the motivation to study Lie algebras and particularly semisimple Lie algebras. Therefore the concept of Lie group was introduced, as well as the main results about the close connection between the Lie group and its Lie algebra. We constructed a functor Lie taking Lie groups to Lie algebras. This functor in fact gives an equivalence between simply connected Lie groups and finite dimensional real Lie algebras. Most important definitions are given: Lie algebra, representation, derivation. Also, some important classes of these objects are introduced, like solvable and semisimple Lie algebras, irreducible and completely reducible representations, inner derivations. Afterwards the main results of the theory of Lie algebras and representations are given; the most important are certainly Engel’s theorem, Lie’s theorem, Schur’s lemma and Cartan’s solvability criteria. The main object in this study are semisimple Lie algebras, therefore some important properties of semisimple Lie algebras are given. Also, we got one crucial semisimplicity criterion using the Killing form. To get to the fundamental theorem of this study the concept of Casimir element is introduced and the main properties are proved. Afterwards we are ready to prove Weyl’s theorem, which states that any finite dimensional representation of a semisimple Lie algebra is completely reducible. After the theoretical part, some examples of Lie algebras are mentioned; these examples belong to matrix algebras. Also, using Weyl’s theorem all representations of $\mathfrak{sl}_2(\mathbb{F})$ are described