Cartan geometry of spacetimes with a nonconstant cosmological function Lambda

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Geometry effects on the electronic properties of multi-open dots structures

In this paper we show that the electronic properties of multi-open dots structures are strongly modified by even smalt changes in their geometries. Our discussion of these effects is done in terms of the interaction among localized states (dot-like) and extended states (channel-like), from which a Fano resonance situation arises.

Analise mecânica e microestrutural em estruturas tubulares aeronáuticas soldadas de aço ABNT 4130

Airplane Motor Cradles have a complex geometry, since they require different conbinations between different tubes and TIG welded in several angles. In T-25 aircraft and Universal T-27 Tucano (EMBRAER / FAB), besides having to bear the engine balance, these components maintain fixed the nose landing gear in another extremity. They are considered critical to flight safety, and for this reason, the aviation standards are extremely rigid in their production, imposing a zero index” of defects on the final weld metal quality. These structures may be containing an historical of welding repairs, whose effects on their structural integrity are not computed. In this work we analyzed the standardised AISI 4130 steel and the raw steel of tubes to the Airplane Motor Cradles. First of all, microscopy and microanalysis of the base steel, then we analyzed the effects of the TIG weld. Tensile testing was conducted to measure the difference between the mechanical properties of standardised steel and without this treatment

Finite element analysis of the influence of geometry and design of zirconia crowns on stress distribution

Purpose: To evaluate the influence of the geometry and design of prosthetic crown preparations on stress distribution in compression tests, using finite element analysis (FEA). Materials and Methods: Six combinations of 3D drawings of all-ceramic crowns (yttria-stabilized zirconia framework and porcelain veneer) were evaluated: F, flat preparation and simplified crown; FC, flat preparation and crown with contact point; FCM, flat preparation and modified crown; A, anatomical preparation and simplified anatomical crown framework; AC, anatomical preparation and crown with contact point; and ACM, anatomical preparation and modified crown. Bonded contact types at all interfaces with the mesh were assigned, and the material properties used were according to the literature. A 200 N vertical load was applied at the center of each model. The maximum principal stresses were quantitatively and qualitatively analyzed. Results: The highest values of tensile stress were observed at the interface between the ceramics in the region under the load application for the simplified models (F and A). Reductions in stress values were observed for the model with the anatomical preparation and modified infrastructure (ACM). The stress distribution in the flat models was similar to that of their respective anatomical models. Conclusions: The modified design of the zirconia coping reduces the stress concentration at the interface with the veneer ceramic, and the simplified preparation can exert a stress distribution similar to that of the anatomical preparation at and near the load point, when load is applied to the center of the crown.

Caracterização de juntas soldadas em PAW e GTAW de chapas finas em aço maraging 300 submetidas a vários reparos

Pós-graduação em Engenharia Mecânica - FEG

Influência do aporte térmico da soldagem GTAW no balanço de fases Ferrita/Austenita do Aço Inoxidável Duplex UNS S32205

Pós-graduação em Engenharia Mecânica - FEIS