<p> A diffusion cell of the "shearing type" was used to diminish the effect of convection which is always present when two liquid phases are brought into contact with each other in a diffusion cell. Also a special optical arrangement was used to photograph the refractive index distribution of the system. For those systems with refractive index changing linearly with concentration, the concentration profiles were obtained and diffusion coefficients were calculated at different concentrations. </p> <p> This optical method gave only fair reproducibility- the deviation among diffusivities found for systems investigated varying from 3 to 10%- however, it permitted rapid analysis and on this basis is recommended for situations where speed is essential and high accuracy is not required. </p> / Thesis / Master of Engineering (ME)

A physically motivated Internal State Variable (ISV) constitutive model is extended to account for shear influenced void evolution for predicting damage behavior in ductile solids. The revised ISV model is calibrated for an aluminum 7085-T711 alloy using a series of microstructure and mechanical property quantification experiments. The calibrated ISV model for the aluminum alloy is implemented in an implicit finite-element code (Abaqus) to simulate the deformation of notch Bridgman tension specimens at a variety of stress states and temperatures. The model revisions and calibrated aluminum ISV model are validated through successful prediction of mechanical and microstructure evolution for structures subjected to a variety of complex stress state conditions. The extended ISV model framework is used to study shear influenced plasticity and damage mechanisms resulting from ballistic impact of metals. A Rolled Homogeneous Armor (RHA) steel alloy is selected for the impact model due to wide availability of documented penetration characteristics and ballistic performance data of RHA steel. Finite Element Analysis (FEA) simulations of ballistic impact of rolled homogeneous armor (RHA) steel projectiles against RHA steel plates are performed using a calibrated ISV constitutive model for RHA steel. An FEA simulation based parametric study is performed to assess the effect of a variety of microstructure and mechanical properties on the ballistic performance of RHA steel targets. FEA simulations are used to predict a transition in ballistic perforation mechanisms for high hardness steel alloys by accounting for variations in microstructure properties qualitatively documented in the literature.

No description available.

Landslides cause significant damage worldwide and therefore epitomize the most important problems in geotechnical engineering. Hence, perceiving the mechanics involved in the deformation process of landslides is necessary for risk assessment. In addition to the resistance offered by basal shear surfaces, internal shearing also influences the stability and kinematics of compound landslides. For compound landslides, internal shearing is essential to develop feasible sliding mechanisms. The internal distortion is caused by the formation of shear bands that develop within the sliding mass. The strain localization is generally attributed to slope changes along the basal sliding surface (or topography) that constrain the strain field of the landslide. The development of these internal shear bands also controls the energy dissipation, and its distribution determines the final degradation of the material. This work focuses on the study of internal failure mechanisms that develop in compound landslides. A theoretical model of a compound landslide is numerically analyzed using the Material Point Method (MPM), a state-of-the-art numerical technique appropriate to model large deformation problems. The internal failure pattern is identified for different basal sliding geometries. Based on that, a generalized method is proposed to estimate the internal failure mechanism of bi-planar compound geometries. The material degradation and energy dissipation are evaluated in terms of the accumulated deviatoric strain and the reaction forces exerted by the landslide on a vertical wall. Moreover, preliminary studies are conducted to analyze the use of barriers as a mitigation strategy to counter landslide damage, and their efficiencies are investigated. / Master of Science / Landslides consist of movement of rock and debris down a slope. They cause substantial damage each year and therefore represent an important class of problems in geotechnical engineering. Understanding the deformation process and internal shearing pattern occurring in landslides is an important aspect for assessing the risk that a landslide poses. The internal shear is caused due to the formation of shear bands that develop within the mass flowing down the slope and originate at the points of slope change on an incline. These shear bands also affect the amount of energy dissipated and the degradation of flow material. In this work, the internal failure mechanism in landslides is analyzed and effects on landslide kinematics are studied. Material Point Method (MPM) is used to simulate slope instabilities which is an advanced numerical technique appropriate for modeling large deformation problems such as landslides. Several theoretical models of compound landslides are presented considering variation in geometry (roundedness), friction, and slope angle. A generalized failure mechanism of a landslide is proposed based on its geometry and physical parameters. Finally, accumulated strains and reaction forces impacted by moving mass on a wall are calculated for different landslide geometries, and subsequently correlated to energy dissipation material degradation. These results also serve as a precursor to studying the role of barriers in mitigating landslide damage.

In this thesis, methods for improving charge carrier mobility and deposition conditions for the solution shearing of organic semiconductors for organic field-effect transistors (OFETs) are investigated. Electrical performance for OFETs is currently still limited by the charge carrier mobility, especially when high fabrication speeds are required. In this work, adaptations are made to the solution shearing method to enhance charge carrier mobility values and to increase the deposition speed and film uniformity of semiconductor films. The solution shearing method can be easily adapted to large-scale roll-to-roll fabrication, a low-cost and high throughput fabrication process. In this work, the fabrication of OFETs with both crystalline small-molecule and donor-acceptor polymer semiconductors as the active layer is performed, and significant improvements in charge carrier mobility and film formation are achieved. Specifically, the crystalline small-molecule semiconductor TIPS-pentacene is blended with the inert dielectric polystyrene, and solution shearing parameters are optimized to obtain highly-aligned crystalline films. The thin film with optimized morphology is deposited on a very thin polymer dielectric film, demonstrating the feasibility of high-performance OFETs (effective mobility of ~1.2 cm2 V-1s-1) and an ultra-low operating voltage (~1 V) – at the time a record value. To improve crystal growth, the solution shearing method is modified to add vibrations to the liquid during the coating process. The new coating method, named “piezoshearing”, allows the application of vibrations to the liquid during deposition through the attachment of a piezo actuator to the shearing blade. The piezoshearing is implemented to enhance crystal growth during the solution shearing of crystalline materials, and tests of piezoshearing for the material 2,7-Dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) demonstrate that substrate coverage can be increased due to induced stick-and-slip caused by the piezoshearing. Due to the unfavorable wetting conditions of semiconducting donor-acceptor polymer solutions on the commonly used low surface energy OFET substrates, conventional solution shearing is problematic. With piezoshearing, film deposition can be significantly improved. In particular, through piezoshearing the so-called stick-and-slip instabilities are mitigated, allowing the doubling of the shearing speed, and the deposition of smooth and ultrathin films (~7 nm). In addition to enabling higher coating speeds, piezoshearing also lowers the polymer material consumption by up to ~ 70% in comparison to the conventional solution shearing method. For some materials, piezoshearing is also found to increase the charge carrier mobility in OFET devices by up to two orders of magnitude. The piezoshearing is utilized for viscous polymer solutions, which are challenging to coat, and usually, result in non-uniform films. Three donor-acceptor polymer systems were tested, and morphology changes are observed for all materials when piezoshearing is applied. For one of the polymeric solutions, an increase in crystallinity is achieved, possibly accompanied by a change in the degree of alignment of the polymer chains. For two other polymer solutions with higher molecular weight chains, very smooth films were obtained with the piezoshearing – saving 30% of material. Without the application of vibrations, such materials yield very non-uniform films, with significant thickness variations, which is unsuitable for OFET devices. In summary, this work leads to significant improvements in the solution shearing of organic semiconductor materials by adding vibrations in the kHz range to the deposition process. The effects and benefits of utilizing the piezoshearing are demonstrated, and suggestions for further improvement and studies are made.:Contents 7 1.Introduction 11 Motivation 11 Outline 12 2.Theoretical Principles of Organic Electronic Materials and Devices 13 Organic Electronics 13 Organic Semiconductors 14 Charge Transport Mechanisms in Organic Semiconductors 16 Organic Field-effect Transistors 19 Operation 19 The Metal-Semiconductor Interface 22 The Dielectric 25 Film Morphology and Charge Transport in OFETs 27 Small Molecules 27 Semicrystalline Polymers 29 3.Solution Shearing and Control of Film Morphology 33 The Solution Shearing Method 34 Capillary Flow and the Pinned Contact Line. 36 Marangoni Flow 36 Shear Flow 37 Film Formation in Solution Shearing 38 Small Molecules 38 Polymers 43 Stick-and-slip Instabilities 50 Contact Angle Hysteresis and Stick-and-slip 52 Vibration-assisted Thin-film Solution Fabrication Methods 53 Effects on a Liquid stemming from Vibration 53 Relevant Characteristics 57 Vibrations and Thin-film Formation 58 Combining the Solution Shearing and Vibrations 61 4.Experimental Methods 63 Device Fabrication 63 Substrate Preparation 63 Electrode Evaporation . 65 Piezoshearing Setup 65 Thin-film Characterization 68 Cross-Polarized Optical Microscopy 68 Grazing Incidence Wide-Angle X-ray Scattering 71 Electrical characterization 77 Characterization 77 Mobility estimation and overestimation discussion 77 5.Alignment Improvement from Blending the Small molecule TIPS- pentacene with an inert Polymer 81 Introduction 81 Optimization of film morphology for TIPS-pentacene . 82 Device Fabrication 82 Electrical Characterization .. 83 Film morphology characterization 86 Fabrication of Ultra-low-voltage Operation Devices 96 Figure of Merit of this Study 97 6.Piezoshearing of Crystalline Materials 101 Introduction 101 Piezoshearing of Pristine TIPS-pentacene 102 Film Fabrication 102 Thin-film Characterization 102 TIPS-pentacene blended with PS in Toluene: Better Performing Devices 104 Piezoshearing of C8-BTBT 105 7.Addressing Stick-and-Slip Instabilities in solution-sheared films for Introduction 109 Device Fabrication 110 The Effect of Piezoshearing on Stick-and-Slip Instabilities 111 Increasing Shearing Speed 111 Thin-film Characterization 114 Electrical Characterization 116 Energy Barriers and Overcoming them with Vibration 119 Acceleration Threshold for Mitigating Stick-and-slip 122 8.Piezoshearing of Viscous Polymer Solutions 127 Introduction 127 Device Fabrication 128 DPP4DE-TT and Film Morphology 129 DPP6DO-TT, DPP6DO-T, and Faraday Instabilities 137 Thin-film Characterization 141 Piezoshearing as a Parametric Oscillator System 145 Solid Friction 146 Viscosity 146 Transition Between Regimes 147 9.Conclusion and Outlook 149 Conclusion 149 Outlook 150

Organic field-effect transistors (OFETs) are essential devices for the realization of novel electronic applications based on organic materials. Recent years have brought tremendous improvements regarding the organic semiconductor (OSC) with charge carrier mobilities around 10 cm²/Vs. Yet, several challenges are needed to be addressed in order to enable technologies of the future that are based on high-performance organic transistors. In this work, C8-BTBT, a high-mobility material that has gained increasing interest in the last few years, is used to prepare films with state-of-the art charge-carrier mobility and above. For this purpose, the solution-shearing method—a meniscus-guided technique that is capable to produce highly aligned, crystalline films—is applied. Based on these charge-transport layers with an estimated intrinsic mobility of up to 12 cm²/Vs, several strategies towards their exploitation for high-performance organic transistors are investigated. Among the relevant parameter, channel length, contact resistance and gate dielectric capacitance are the three aspects that are addressed. The solution-shearing method is further applied to the realization of solution-deposited polymer dielectrics. High-capacitance films with maximum values of about 280 nF/cm² are fabricated and used to produce low-voltage OFETs that can operate at -1V. In order to increase the devices’ transconductance, a novel patterning methodology to achieve sub-micrometre channel lengths is investigated. Using this technique, working devices with a channel length of 500 nm are shown. The compatibility of this process with the solution-shearing method for the fabrication of high-performance semiconducting and gate dielectric films is one of its major advantages. One of the limiting device parameters is the contact resistance as is clearly observable by the restricted current scaling that is observed for lower channel length. Hence, the interface of OSC and source/drain contacts is investigated. Even though an ultimate solution for very low contact resistance remains to be developed, important aspects for its further enhancement are deduced in this work. As an important first experimental result, this thesis describes a short-channel device architecture that is compatible with solution-shearing of high-performance films with its full potential yet to be explored in future work. / Organische Feld-Effekt Transistoren (OFETs) sind grundlegende Bestandteile für die Entwicklung neuerartiger Technologien auf der Basis von organischen Halbleitermaterialien. Insbesondere während der letzten Jahre haben diese Materialien einschlägige Verbesserungen erfahren und erreichen heute Ladungsträgermobilitäten um die 10 cm²/Vs. Um dies für die Umsetzung neuartiger Technologien zu nutzen, müssen jedoch noch einige Herausforderungen überwunden werden. Diese Arbeit leistet einen Beitrag in diese Richtung. Unter Anwendung eines der wohl populärsten Halbleitermaterialien der letzen Jahre mit der chemischen Bezeichnung C8-BTBT, wird die Herstellung von hochqualitativen Halbleiterfilmen mittels Flüssigprozessierung gezeigt. Mit der sogenannten „Solution-Shearing“ Methode – eine Abscheidetechnik, die über die Kontrolle eines trocknenden Meniskus hochkristalline und ausgerichtete Schichten erzeugen kann – ist es möglich Dünnschichtbauelemente mit abgeschätzten, intrinsischen Ladungsträgermobilitäten von bis zu 12 cm²/Vs zu erzeugen. Um diese hoch-qualitativen Filme für die Herstellung von leistungsfähigen Transistoren zu nutzen, werden mehrere relevante Parameter betrachtet, darunter die Kanallänge, der Kontaktwiderstand und das Gate-Dielektrikum. Im Speziellen wird die Abscheidung des Dielektrikums mittels der „Solution-Shearing“ Methode untersucht. Es kann gezeigt werden, dass dies für die Herstellung von qualitativ hochwertigen Filmen mit Kapazitäten bis zu 280 nF/cm² genutzt werden kann. Angewendet in OFETs erlauben diese Schichten den Betrieb bei sehr geringen Spannungen von -1V. Um die Transkonduktanz der Transistoren zu erhöhen wird zudem eine mit der „Solution-Shearing“ Methode kompatible Source/Drain-Strukturierungsmethode untersucht. Diese ermöglicht Kanallängen unter einem Mikrometer und konnte hier für die Herstellung von funktionierenden Transistoren mit einer Kanallänge bis zu nur 500 nm angewendet werden. Eine der limitierenden Transistorkenngrößen ist der Kontaktwiderstand, wie durch die abweichende Skalierung des Stromes mit verringerter Kanallänge deutlich wird. Aus diesem Grund wurde auch die Grenzfläche zwischen Halbleiter und Source/Drain-Kontakten näher untersucht. Allerdings verbleibt die Entwicklung einer effektiven Methode zur Reduzierung des Kontaktwiderstandes ein Projekt für zukünftige Untersuchungen, auch wenn die vorliegende Arbeit einige wichtige Anhaltpunkte für mögliche Strategien liefert. Als wichtiges erstes Resultat liefert die vorliegende Arbeit eine Beschreibung zur Herstellung funktionsfähiger Kurzkanal-OFETs mittels „Solution-Shearing“, deren volles Potential aber in der Zukunft weiter untersucht werden muss.

The industrial practice of grain refinement of aluminium alloys involves the addition of inoculant particles to initiate alpha-aluminium grains at small undercoolings. This results in a uniformly fine, equiaxed as-cast microstructure and is commonly achieved using Al-Ti-B additions. The phase responsible for initiation of grains in aluminium melts inoculated with Al-Ti-B was determined during the 1990s; since that time, scientific understanding of grain refinement has advanced rapidly. However, one of the main problems of addition inoculants is impurities which is added to the melt and may affect the desired characteristics of the product. With regards to this problem other methods of refinement and the mechanisms of refining have not been fully understood and prediction of as-cast Microstructures in aluminium alloys has much scope for improvement. In this thesis: 1-Factors in establishing equiaxed microstructure were analysed and the origin of equiaxed grains were explored. Then the nucleation process and the involved mechanisms were investigated in depth and control of nucleation process to achieve a fine and uniform structure was set as target. 2-Refinement of microstructure with introduction of shearing was evaluated and the process of refinement in the mushy zone (semisolid state) as a base line was established. Then introduction of shearing above liquidus as a development was analysed and outstanding refinement was seen with shearing above liquidus which have not been investigated properly elsewhere. 3- The mechanisms of refinement by introducing shearing were investigated and the refining mechanisms below and specifically above liquidus were investigated systematically. As results an appropriate understanding about the mechanisms of nucleation and refinement above liquidus was established. 4- Finally, with simulation the most dominant factor in approaching fine grain size by applying shear was identified and the results of experimental examination was verified by simulation.

A demanda da indústria automobilística por aços de boa estampabilidade, para aplicação em peças expostas motivou o desenvolvimento de várias especificações de aços livres de intersticiais (IF) na Companhia Siderúrgica Nacional. A especificação de aço \"IFTi\", pertencente ao grupo de aços para estampagem extra profunda especial (CSN EEPIF), com limite de resistência < 380 MPa está, dentre todos os graus de aço processados nas linhas de laminação a frio, entre os que apresentam a maior porcentagem de desvio por marca de rebarba e outros problemas relacionados ao corte. A geração de uma rebarba com altura excessiva está relacionada a um corte de má qualidade. Durante o processo de laminação a frio essa rebarba pode aumentar ainda mais de tamanho, se desprender, marcar os cilindros de trabalho e conseqüentemente aumentar os custos de produção por desvios e troca precoce de cilindros. Nas linhas de decapagem, a tesoura de pontas final é o equipamento responsável por separar as bobinas soldadas no início do processo e definir a característica de corte das pontas e caudas das mesmas, através de corte por guilhotinamento. Visando aumentar a qualidade, produtividade, diminuir as perdas durante o processo e atender às exigências dos clientes internos e externos, foi necessário desenvolver o processo de corte por guilhotina do aço IF nas tesouras de pontas final das Linhas de Decapagem Contínua 3 e 4 da CSN. Através da simulação de corte em laboratório, usando-se a mesma velocidade de avanço e ângulo de inclinação do equipamento de campo, avaliou-se a relação entre o ajuste de folga entre navalhas e o comportamento força x deslocamento no cisalhamento. Além disso, através da análise por microscopia eletrônica de varredura (MEV) foi possível observar o efeito dos varios ajustes de folga na superfície de fratura, identificando as regiões de corte citadas na literatura e sua relação com as características microestruturais e com as propriedades do material. Constatou-se que a tensão cisalhante durante o corte diminuía a medida em que a folga aumentava de forma linear para uma faixa de folga ajustada entre 6 e 12%t em amostras de aço IF-Ti com 1,5mm de espessura. Nas micrografias feitas em MEV, observou-se que as interfaces entre penetração e fratura ficaram irregulares em todos os casos, sendo uma região intermediária, com aspecto misto entre as regiões de penetração e fratura foi relacionado ao desencontro das frentes de trincas principalmente devido ao grande ângulo de fratura. Tanto os perfis de corte quanto as superfícies de fratura mostraram que a fração da região de corte diminuía com o aumento da folga, até certo ponto, quando a partir da mudança do comportamento da tensão cisalhante, voltava a aumentar. Pode-se verificar também, que a fração da região de deformação aumentava à medida que folgas maiores eram testadas e os valores atingidos eram muito superiores as deformações esperadas para as respectivas características do tipo de corte indicado pelas regiões de penetração e fratura. Os melhores resultados de corte foram obtidos na regulagem de folga entre 4 e 8%t, com rebarbas inferiores a 1,5%t, menores frações da região de deformação e interface corte/fratura mais regulares do que nas demais faixas de folga. / The automotive industry\'s demand for high formability steels for use in exposed body panels motivated the development of several interstitial free (IF) steels specifications at Companhia Siderurgica Nacional. The \"IF-Ti\" steel specification belongs to the special deep drawing steels group (CSN EEP-IF), with yield strength <380 MPa, and among all grades of steel processed in the cold rolling lines is the one with the highest amount of deviation by burr marks and other problems related to shearing. The generation of an excessive burr height is related to a poor cut quality. During the cold rolling process the burr can increase in size, break off, mark the work rolls and therefore increase production costs per deviation and early exchange of cylinders. In the pickling lines, the exit shear is the device responsible for separating the coils welded at the beginning of the process and to define the cutting head and tail characteristics, either through guillotine cutting. Aiming to increase quality, productivity, reduce losses during the process and meet the requirements of internal and external customers, it was necessary to develop the guillotine cutting process of the IF steel sheet extremities (head and tail) in the exit shears of Continuous Pickling Lines #3 and #4 at CSN. Through the cutting simulation in the laboratory, using the same forward speed and rake angle adopted in the field equipment, was evaluated the relationship between the adjustment of clearance between blades and the behavior shear force versus displacement. In addition, through the analysis by scanning electron microscopy (SEM) it was possible to observe the effect of several settings on the fracture surface, identifying the different regions cited in the literature and its relation to the microstructural characteristics and to the material properties. It was found that the shear stress during cutting reduced as the gap increased linearly to a range between 6 and 12%t in samples of IF-Ti steel with 1.5 mm thick. In the micrographs taken by SEM, it was observed that the interfaces between burnished and fracture were irregular in all cases, where an intermediate depth, with mixed aspect between the burnished and fracture depths was related to mismatch of crack fronts mainly due to the large fracture angle. Both cut profiles as the fracture surfaces showed that the burnished depth decreased with increasing the gap to some extent, since from the behavior change of shear stress, it started to increase. It was also possible to verify that the fraction of therollover depth increased as larger gaps were tested and the values achieved were much higher than expected for the rollover characteristics of the respective type of cut indicated by the burnished and fracture depths. The best cutting results were obtained for clearance adjustment between 4 and 8%, resulting in burrs below 1.5%t, smaller rollover depth and more regular burnished/fracture interface than in other clearance ranges tested.

A perda anual de ovelhas em criações de sistema extensivo apresenta altos níveis na região Sul do Brasil. Na Serra Gaúcha essa porcentagem chega a 30% e torna-se um fator alarmante para propriedades com sistemas de produção de carne, leite e lã. As perdas reprodutivas em ovinos desta região estão relacionadas com a baixa taxa de concepção do rebanho e alta mortalidade perinatal de cordeiros (MPC) e frequentemente esses fatores são decorrentes de enfermidades, deficiências nutricionais durante o período gestacional e pós-parto ou por manejo inadequado de ovelhas e cordeiros. A MPC, definida como a morte de recém-nascidos imediatamente antes ou durante o parto e até os primeiros vinte e oito dias de vida é uma das principais causas de baixa taxa de desmame no Rio Grande do Sul (RS). Sua etiologia envolve ações complexas que circundam a ação individual e a interação de muitos fatores relacionados entre si. Estudos sobre as causas de MPC no RS têm apontado o complexo exposição/inanição e hipotermia, além da distocia como as duas principais patologias envolvidas nesses óbitos. Condições ambientais adversas, como o frio severo, também causam a morte em consequência da falta de adaptação do recém-nascido às novas condições de vida. A busca de informações que venham a elucidar as causas dessas perdas motivou a realização do presente estudo e o uso da esquila durante a gestação foi utilizado como uma possível ferramenta para minimizar a MPC. O efeito da esquila préparto (74 dias de gestação) sobre sobre o perfil metabólico e produtivo de ovelhas e no peso e desenvolvimento de seus cordeiros durante o primeiro mês de vida foram avaliados neste estudo. Um rebanho de 40 ovelhas gestantes da raça Corriedale foi dividido aleatoriamente em dois grupos: ovelhas com esquila completa (EC) e ovelhas mantidas com velo ou ovelhas controle (OC). As ovelhas e seus respectivos cordeiros foram avaliados em três momentos distintos durante o experimento: no parto, entre 15 e 21 dias de lactação e entre 22 e 45 dias de lactação. Os parâmetros de escore de condição corporal, dosagem de beta-hidroxibutirato, hematócrito, hemoglobina, lactato, glicose, peso corporal, peso da placenta e produção do leite foram mensurados e correlacionados. Os valores médios de hematócrito, hemoglobina e peso dos cordeiros apresentaram diferenças significativas (p< 0,05) entre os grupos EC e OC. O peso médio da placenta e a produção de leite apontaram diferença significativa enquanto que os achados para escore de condição corporal (ECC) e beta-hidroxibutirato não evidenciaram diferenças entre os grupos EC e OC, considerando todos os períodos em conjunto (p> 0,05). A produção leiteira de ovelhas do grupo EC (1.261,25 mL/dia) foi maior (p <0,05) do que no grupo OC (937,79 mL/dia). A esquila de ovelhas aos 74 dias de gestação mostrou-se como importante ferramenta para o melhor desenvolvimento de cordeiros na fase pós-nascimento de forma a contribuir para a diminuição da taxa de mortalidade perinatal. / The annual loss of sheep in extensive system has expressive levels in southern Brazil. It can reach 30% in some areas and becomes an alarming factor for properties with systems producing meat, milk and wool. Reproductive losses in sheep in this region are related to low conception rate of the herd and a high lamb perinatal mortality (LPM). Often these factors are due to diseases, nutritional deficiencies during pregnancy and postpartum period or inadequate management of ewes and lambs. Perinatal mortality is defined as lambs in the death of the neonate until the first twenty-eight days. The LPM is responsible for the low rate of weaning in Rio Grande do Sul (RS), southern Brazil. Its etiology involves complex actions and interaction of many factors related to each other. Studies about causes of the LPM in RS have showed the complex exposure, hypothermia and starvation, in addition to dystocia as the two main pathologies involved in these deaths. Adverse environmental conditions, such as severe cold, cause death due to the lack of adaptation of the newborn to the new living conditions also. The search for more information that might elucidate the causes of these losses motivated the present study and the use of shearing during pregnancy has been used as a possible tool to minimize LPM. The effect of pre-partum shearing (74 days gestation) on the metabolic and productive profile and weight of ewes and their lambs develop during the first month of life were studied. A flock of 40 pregnant Corriedale ewes were randomly divided into 2 groups: ewes completely sheared (EC) and ewes maintained with fleece or sheep control (OC). The ewes and their lambs were evaluated at three different times during the experiment: at birth, between 15 and 21 days of lactation and between 22 and 45 days of lactation. The parameters such as body condition score, betahydroxybutyrate, PVC, hemoglobin, lactate, glucose, body weight, placental weight and milk production were measured and correlated. The mean values of PVC, hemoglobin and lambs weight showed significant differences (p <0.05) between the EC and OC groups. The average weight of placenta and milk production showed a significant difference while the findings for body condition score (ECC) and beta-hydroxybutyrate showed no differences between groups EC and OC, considering all periods together (p> 0.05). Milk production of ewes of group EC (1261.25 mL / day) was higher (p < 0.05) than in the OC group (937.79 mL / day). Shearing of sheep at 74 days of pregnancy was a important tool for the better development of lambs in the post-birth in order to contribute to reducing the rate of perinatal mortality.

A demanda da indústria automobilística por aços de boa estampabilidade, para aplicação em peças expostas motivou o desenvolvimento de várias especificações de aços livres de intersticiais (IF) na Companhia Siderúrgica Nacional. A especificação de aço \"IFTi\", pertencente ao grupo de aços para estampagem extra profunda especial (CSN EEPIF), com limite de resistência < 380 MPa está, dentre todos os graus de aço processados nas linhas de laminação a frio, entre os que apresentam a maior porcentagem de desvio por marca de rebarba e outros problemas relacionados ao corte. A geração de uma rebarba com altura excessiva está relacionada a um corte de má qualidade. Durante o processo de laminação a frio essa rebarba pode aumentar ainda mais de tamanho, se desprender, marcar os cilindros de trabalho e conseqüentemente aumentar os custos de produção por desvios e troca precoce de cilindros. Nas linhas de decapagem, a tesoura de pontas final é o equipamento responsável por separar as bobinas soldadas no início do processo e definir a característica de corte das pontas e caudas das mesmas, através de corte por guilhotinamento. Visando aumentar a qualidade, produtividade, diminuir as perdas durante o processo e atender às exigências dos clientes internos e externos, foi necessário desenvolver o processo de corte por guilhotina do aço IF nas tesouras de pontas final das Linhas de Decapagem Contínua 3 e 4 da CSN. Através da simulação de corte em laboratório, usando-se a mesma velocidade de avanço e ângulo de inclinação do equipamento de campo, avaliou-se a relação entre o ajuste de folga entre navalhas e o comportamento força x deslocamento no cisalhamento. Além disso, através da análise por microscopia eletrônica de varredura (MEV) foi possível observar o efeito dos varios ajustes de folga na superfície de fratura, identificando as regiões de corte citadas na literatura e sua relação com as características microestruturais e com as propriedades do material. Constatou-se que a tensão cisalhante durante o corte diminuía a medida em que a folga aumentava de forma linear para uma faixa de folga ajustada entre 6 e 12%t em amostras de aço IF-Ti com 1,5mm de espessura. Nas micrografias feitas em MEV, observou-se que as interfaces entre penetração e fratura ficaram irregulares em todos os casos, sendo uma região intermediária, com aspecto misto entre as regiões de penetração e fratura foi relacionado ao desencontro das frentes de trincas principalmente devido ao grande ângulo de fratura. Tanto os perfis de corte quanto as superfícies de fratura mostraram que a fração da região de corte diminuía com o aumento da folga, até certo ponto, quando a partir da mudança do comportamento da tensão cisalhante, voltava a aumentar. Pode-se verificar também, que a fração da região de deformação aumentava à medida que folgas maiores eram testadas e os valores atingidos eram muito superiores as deformações esperadas para as respectivas características do tipo de corte indicado pelas regiões de penetração e fratura. Os melhores resultados de corte foram obtidos na regulagem de folga entre 4 e 8%t, com rebarbas inferiores a 1,5%t, menores frações da região de deformação e interface corte/fratura mais regulares do que nas demais faixas de folga. / The automotive industry\'s demand for high formability steels for use in exposed body panels motivated the development of several interstitial free (IF) steels specifications at Companhia Siderurgica Nacional. The \"IF-Ti\" steel specification belongs to the special deep drawing steels group (CSN EEP-IF), with yield strength <380 MPa, and among all grades of steel processed in the cold rolling lines is the one with the highest amount of deviation by burr marks and other problems related to shearing. The generation of an excessive burr height is related to a poor cut quality. During the cold rolling process the burr can increase in size, break off, mark the work rolls and therefore increase production costs per deviation and early exchange of cylinders. In the pickling lines, the exit shear is the device responsible for separating the coils welded at the beginning of the process and to define the cutting head and tail characteristics, either through guillotine cutting. Aiming to increase quality, productivity, reduce losses during the process and meet the requirements of internal and external customers, it was necessary to develop the guillotine cutting process of the IF steel sheet extremities (head and tail) in the exit shears of Continuous Pickling Lines #3 and #4 at CSN. Through the cutting simulation in the laboratory, using the same forward speed and rake angle adopted in the field equipment, was evaluated the relationship between the adjustment of clearance between blades and the behavior shear force versus displacement. In addition, through the analysis by scanning electron microscopy (SEM) it was possible to observe the effect of several settings on the fracture surface, identifying the different regions cited in the literature and its relation to the microstructural characteristics and to the material properties. It was found that the shear stress during cutting reduced as the gap increased linearly to a range between 6 and 12%t in samples of IF-Ti steel with 1.5 mm thick. In the micrographs taken by SEM, it was observed that the interfaces between burnished and fracture were irregular in all cases, where an intermediate depth, with mixed aspect between the burnished and fracture depths was related to mismatch of crack fronts mainly due to the large fracture angle. Both cut profiles as the fracture surfaces showed that the burnished depth decreased with increasing the gap to some extent, since from the behavior change of shear stress, it started to increase. It was also possible to verify that the fraction of therollover depth increased as larger gaps were tested and the values achieved were much higher than expected for the rollover characteristics of the respective type of cut indicated by the burnished and fracture depths. The best cutting results were obtained for clearance adjustment between 4 and 8%, resulting in burrs below 1.5%t, smaller rollover depth and more regular burnished/fracture interface than in other clearance ranges tested.