Estudo da distribuição das tensões internas, pelo método dos elementos finitos, em uma raiz com um retentor intra-radicular pré-fabricado, rosqueado e com fenda apical

Pós-graduação em Odontologia Restauradora - ICT

FEA and microstructure characterization of a one-piece Y-TZP abutment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The fracture resistance of a CAD/CAM Resin Nano Ceramic (RNC) and a CAD ceramic at different thicknesses

Objective. This study aimed to investigate the influence of restoration thickness to the fracture resistance of adhesively bonded Lava (TM) Ultimate CAD/CAM, a Resin Nano Ceramic(RNC), and IPS e. max CAD ceramic.Methods. Polished Lava (TM) Ultimate CAD/CAM (Group L), sandblasted Lava (TM) Ultimate CAD/CAM (Group LS), and sandblasted IPS e.max CAD (Group ES) discs (n=8, phi=10 mm) with a thickness of respectively 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, and 3.0 mm were cemented to corresponding epoxy supporting discs, achieving a final thickness of 3.5 mm. All the 120 specimens were loaded with a universal testing machine at a crosshead speed of 1 mm/min. The load (N) at failure was recorded as fracture resistance. The stress distribution for 0.5 mm restorative discs of each group was analyzed by Finite Element Analysis (FEA). The results of facture resistances were analyzed by one-way ANOVA and regression.Results. For the same thickness of testing discs, the fracture resistance of Group L was always significantly lower than the other two groups. The 0.5 mm discs in Group L resulted in the lowest value of 1028 (112) N. There was no significant difference between Group LS and Group ES when the restoration thickness ranged between 1.0 mm and 2.0 mm. There was a linear relation between fracture resistance and restoration thickness in Group L (R = 0.621, P < 0.001) and in Group ES (R = 0.854, P < 0.001). FEA showed a compressive permanent damage in all groups.Significance. The materials tested in this in vitro study with the thickness above 0.5 mm could afford the normal bite force. When Lava Ultimate CAD/CAM is used, sandblasting is suggested to get a better bonding. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A method for calculating the compliance of bonded-interfaces under shrinkage: Validation for Class I cavities

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A smooth evolutionary structural optimization procedure applied to plane stress problem

Topological optimization problems based on stress criteria are solved using two techniques in this paper. The first technique is the conventional Evolutionary Structural Optimization (ESO), which is known as hard kill, because the material is discretely removed; that is, the elements under low stress that are being inefficiently utilized have their constitutive matrix has suddenly reduced. The second technique, proposed in a previous paper, is a variant of the ESO procedure and is called Smooth ESO (SESO), which is based on the philosophy that if an element is not really necessary for the structure, its contribution to the structural stiffness will gradually diminish until it no longer influences the structure; its removal is thus performed smoothly. This procedure is known as "soft-kill"; that is, not all of the elements removed from the structure using the ESO criterion are discarded. Thus, the elements returned to the structure must provide a good conditioning system that will be resolved in the next iteration, and they are considered important to the optimization process. To evaluate elasticity problems numerically, finite element analysis is applied, but instead of using conventional quadrilateral finite elements, a plane-stress triangular finite element was implemented with high-order modes for solving complex geometric problems. A number of typical examples demonstrate that the proposed approach is effective for solving problems of bi-dimensional elasticity. (C) 2014 Elsevier Ltd. All rights reserved.

Modelagem e simulação do mecanismo biela manivela e análise estrutural de biela automotiva

Nowadays, the automotive industry is working to optimize the design of engines, in order to reduce the fuel consumption with acceptable efficiency ratio. This undergraduate thesis is aimed at perform a kinematic/dynamic analysis of a slider-crank mechanism that is part of a four stroke internal combustion engine, the same engine that was used in the analysis described by Montazersadhd and Fatemi (2007). Two algorithms were developed based on Kane’s method to calculate velocities and accelerations of the mechanism bodies, and provide the acting forces at connecting rod joints. A SimMechanics model was developed to simulate the engine, and monitoring the same parameters that were calculated with the algorithms. The results obtained with both approaches were satisfactory and showed good agreement with the values provided by Montazersadhd and Fatemi (2007). The obtained results showed that the axial component of the rod joint efforts was caused by the pressure exerted on the piston head,whereas the radial component was related with the action of inertia loads. Besides, this thesis presents a connecting rod assembly mesh that is going to be used for static and fatigue finite element analysis in the future

Efeito de diferentes espessuras, técnicas de aplicação e protocolos de resfriamento na resistência à fratura da cerâmica de cobertura aplicada sobre infraestrutura de y-tzp

Pós-graduação em Odontologia Restauradora - ICT

Análise de fadiga em rodas automotivas utilizando método dos elementos finitos

The increasing search for better performance at the automotive industry, especially on the matter of fuel consumption, caused a progressive evolution of industrial technology. For the wheel this study is based on the try of reducing mass and decreasing the moment of inertia, characteristics that directly reflect on the performance parameter, as consumption and acceleration, so that it also is effective on the growth of the profit margin, since it reduces the costs of the locomotion. In this paper will be applied the Finite Element Analysis to explain the wheel behavior and identify ways to improve the performance. To the analyze it will be simulated a test condition established by ABNT NBR 6751:2009 foreseeing a possible collapse through general yielding and fatigue. The load here presented results from the equation presented on the norms and in the datas provided by the manufacturer

Efeito de protocolos de cimentação na carga de fratura para uma cerâmica de dissilicato de lítio

Pós-graduação em Odontologia Restauradora - ICT

O impacto do preparo, da cerâmica e do contato oclusal na distribuição de tensões em facetas

Pós-graduação em Odontologia Restauradora - ICT

Influência de tratamentos de superfície e agentes cimentantes na sobrevivência de coroas de Y-TZP recobertas por porcelana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the parafunctional occlusal loading and crown height on stress distribution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Implantes curtos do tipo cone-Morse: proporção coroa-implante

The purpose of this study was to analyze the biomechanical interactions in bone tissue between short implants and implant-supported crowns with different heights. Two models were made using the programs InVesalius 3.0, Rhinoceros 4.0 and Solidworks 2010. The models were established from a bone block with the short implant (3.75 x 8.5 mm) with geometry Morse taper connection (MT). The height of the crown (cemented) was set at 10.0 mm and 15.00 mm. The models were processed by programs and 10 NEiNastran Femap 10.0. The force applied was 200N (vertical) and 100N (oblique). The results were plotted on maps Voltage Maximum Principal. Statistical analysis was performed using ANOVA. The results showed that the increase in crown height, increased stress concentration in the crown of 15 mm under oblique loading (p <0.001), the oblique loading has significantly expanded the area of stress concentration (p <0.001). Conclusion:the increase of the crown increased the stress concentration, being statistically significant for short implants Morse taper. The mesial and distal region had the highest concentration of stresses under oblique loading. The oblique loading was more harmful when compared with axial loading, being statistically significant.

Comportamento biomecânico dos sistemas de retenção de overdentures

Objective: to the purpose of this study was to compare the stress distribution in the peri-implant hard tissue on different attachment systems for mandibular or maxillary implant-retained overdentures. Material and methods: the search for published studies was performed on PubMed/Medline database covering the period of January 2000 to April 2014. The selection of the eligible studies was performed according to including and excluding criteria. Results: a total of 140 studies were screened and according to the search strategy, 21 studies were selected for this review. Eight studies perfomed strain-gauge analysis, 5 evaluated the stress distribution though photoelastic test and 7 performed tridimensional finite element analysis. Only one study in vivo was included. Non-splinted O-rings showed better stress distribution than other bar-clip attachment systems. Conclusions: the present study did not find sufficient evidences regarding the most indicated attachment system for overdentures with better stress distribution for the peri-implant hard tissue. The methodologies analyzed should be complemented with other tests and used as a tool for further clinical studies.

Influence of crown-to-implant ratio, retention system, restorative material, and occlusal loading on stress concentrations in single short implants

Purpose: The aim of this study was to assess the contributions of some prosthetic parameters such as crown-to-implant (C/I) ratio, retention system, restorative material, and occlusal loading on stress concentrations within a single posterior crown supported by a short implant. Materials and Methods: Computer-aided design software was used to create 32 finite element models of an atrophic posterior partially edentulous mandible with a single external-hexagon implant (5 mm wide × 7 mm long) in the first molar region. Finite element analysis software with a convergence analysis of 5% to mesh refinement was used to evaluate the effects of C/I ratio (1:1; 1.5:1; 2:1, or 2.5:1), prosthetic retention system (cemented or screwed), and restorative material (metal-ceramic or all ceramic). The crowns were loaded with simulated normal or traumatic occlusal forces. The maximum principal stress (σmax) for cortical and cancellous bone and von Mises stress (σvM) for the implant and abutment screw were computed and analyzed. The percent contribution of each variable to the stress concentration was calculated from the sum of squares analysis. Results: Traumatic occlusion and a high C/I ratio increased stress concentrations. The C/I ratio was responsible for 11.45% of the total stress in the cortical bone, whereas occlusal loading contributed 70.92% to the total stress in the implant. The retention system contributed 0.91% of the total stress in the cortical bone. The restorative material was responsible for only 0.09% of the total stress in the cancellous bone. Conclusion: Occlusal loading was the most important stress concentration factor in the finite element model of a single posterior crown supported by a short implant.