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  1. 1

    Modelling of elastic modulus of CaZrO3-MgO composites using isotropic elastic and anisotropic models

    Publication
    by Nunes-Pereira, João
    Other Authors: Carneiro, Pedro; Maceiras, Alberto; Baudin, Carmen; Pereira Silva, A
    Origin: uBibliorum
    Starting from synthetic raw materials (CaZrO3 and MgO), microstructural and mechanical properties were optimised in order to obtain dense multiphasic ceramic, then finite element method (FEM) of an equimolar (1:1) CaZrO3-MgO composite was performed in order to obtain the effective elastic modulus. Composite presents two main phases of orthorhombic CaZrO3 (81.5 wt.%) and cubic MgO (18.5 wt.%); For 1500 °C, relative density of 99.9%, characteristic strength of 168 MPa, hardness of 7.8 MPa and toughness of 2.5 MPa.m1/2 were obtained. FEM simulation was performed using two representative volume elements (RVE’s) with edge lengths of 14 μm (933 grains) and 17 μm (1670 grains), using isotropic elastic model, and anisotropic on specific set of crystallographic planes. The results of FEM using isotropic approach for the two RVE’s are perfectly aligned with the experimental (245 GPa), while the anisotropic model shows a difference of 6.5%.
    2020 article Portugal restricted access
  2. 2

    Experimental analysis and finite element modeling of the piston-on-three balls testing of Y-TZP ceramic

    Publication
    by Silva,P. C.
    Other Authors: Moreira,L. P.; Alves,M. F. R. P.; Campos,L. Q. B.; Simba,B. G.; Santos,C. dos
    Origin: Oasisbr
    Abstract The objectives of this study were to characterize and evaluate the physical and mechanical properties of an experimental zirconia for dental application and compare the biaxial flexural strength results with the finite element simulation (FEM). Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic samples were sintered at 1475 °C/2 h and characterized by X-ray diffraction, scanning electron microscopy, relative density, flexural strength using piston-on-three balls (P-3B) test and Young’s modulus. From the flexural strength results, numerical simulations were performed using Abaqus software. The complete model used 70216 elements, considering the components of the test. The results indicated full densification of sintered samples, ZrO2-tetragonal and ZrO2-cubic as crystalline phases, and average grain size of 0.6±0.2 μm. Mechanical characterization of sintered samples indicated Young’s modulus of 195±4 GPa, flexural strength of 1191±9 MPa and Weibull modulus m=16.3. FEM simulation indicated a flexural strength close to 1100 MPa, with a difference lower than 7% in relation to the experimental results. The results were compared associating the physical and mechanical properties of Y-TZP with its intrinsic phenomena such as tgm transformation and ferroelastic domain.
    2020 article Brazil open access
  3. 3

    A characterization for the constitutive relationships of 42CrMo high strength steel by Artificial Neural Network and its application in isothermal deformation

    Publication
    by Quan,Guo-zheng
    Other Authors: Liang,Jian-ting; Lv,Wen-quan; Wu,Dong-sen; Liu,Ying-ying; Luo,Gui-chang et al.
    Origin: Oasisbr
    In hot working process, the prediction of material constitutive relationship can improve the optimization design process. Recently, the artificial neural network models are considered as a powerful tool to describe the elevated temperature deformation behavior of materials. Based on the experimental data from the isothermal compressions of 42CrMo high strength steel, an artificial neural network (ANN) was trained with standard back-propagation learning algorithm to predict the elevated temperature deformation behavior of 42CrMo steel. The inputs of the ANN model are strain, strain rate and temperature, whereas flow stress is the output. According to the predicted and experimental results, it indicates that the developed ANN model shows a good capacity of modeling complex hot deformation behavior and can accurately tracks the experimental data in a wide temperature range and strain rate range. In addition, the predicted data outside of experimental conditions were obtained, indicating good prediction potentiality of the developed ANN model. The θ -σ curves outside of experimental conditions indicate that the predicted strain-stress curves exhibit a typical dynamic recrystallization softening characteristic of high temperature deformation behavior. Through the coupling of the ANN model and finite element model, the hot compression simulations at the temperature of 1273 K and strain rates of 0.01~10 s-1 were conducted. The results show that the predicted constitutive data outside the experimental conditions successfully improved the prediction accuracy of forming load during the FEM simulation.
    2014 article Brazil open access
  4. 4

    Finite Element Simulation of Welding Distortion in Dissimilar Joint by Inherent Deformation Method

    Publication
    by Farajpour,Mehdi
    Other Authors: Ranjbarnodeh,Eslam
    Origin: Oasisbr
    Abstract Fusion welding is widely used to join different parts to each other in various industries. However, welding-induced distortions sometimes cause problems such as misalignment during assembling and impose costs for their removal. Thus, it is imperative to predict and mitigate these problems to improve weldment quality and also reduce fabrication costs. In this study, a dissimilar welded structure was first simulated with 3D solid and shell elements in ANSYS finite element software, and welding-induced deformations were then calculated. Afterwards, the constructed weldment was simulated using an inherent deformation method, and its results were compared with experimental measurements and 3D answers. This comparison showed that it was possible to simulate a dissimilar welded joint using an inherent deformation method in order to reduce the time and cost of modeling evenat the expense of a small error.
    2018 article Brazil open access
  5. 5

    Experimental analysis and finite element modeling of the piston-on-three balls testing of Y-TZP ceramic

    Publication
    by Silva, P. C.
    Other Authors: Moreira, L. P.; Alves, M. F. R. P.; Campos, L. Q. B.; Simba, B. G.; Santos, C. Dos
    Origin: Oasisbr
    Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
    2021 article Brazil open access
  6. 6

    Predicting mechanical behavior of novel sandwich composite panels based on 3D warp : knitted spacer fabrics using Finite Element Method (FEM)

    Publication
    by Velosa, J. C.
    Other Authors: Rana, S.; Fangueiro, Raúl; Marques, S.
    In the present work, mechanical behavior of novel sandwich composite panels based on 3D knitted spacer fabrics has been predicted using Finite Element Method (FEM). Composite panels were produced using three different types of spacer fabrics having different structural parameters. The sandwich panels were fabricated based on an unsaturated polyester resin using a modified vacuum assisted resin transfer molding (VARTM) process which allowed the formation of low density core structures. The produced sandwich composite panels were simulated for flexural, compressive and flatwise tensile strength using Abaqus 6.9.3 FEM package.
    2012 conference paper Portugal restricted access
  7. 7

    Improving FEM crash simulation accuracy through local thickness estimation based on CAD data

    Publication
    by Ferreira, Vânio
    Other Authors: Santos, Luís Paulo; Franzen, Markus; Ghouati, Omar; Simões, Ricardo
    In this paper, we present a method for estimating local thickness distribution in finite element models, applied to injection molded and cast engineering parts. This method features considerable improved performance compared to two previously proposed approaches, and has been validated against thickness measured by different human operators. We also demonstrate that the use of this method for assigning a distribution of local thickness in FEM crash simulations results in a much more accurate prediction of the real part performance, thus increasing the benefits of computer simulations in engineering design by enabling zero-prototyping and thus reducing product development costs. The simulation results have been compared to experimental tests, evidencing the advantage of the proposed method. Thus, the proposed approach to consider local thickness distribution in FEM crash simulations has high potential on the product development process of complex and highly demanding injection molded and cast parts and is currently being used by Ford Motor Company.
    2014 article Portugal open access
  8. 8

    Desenvolvimento de uma máquina hidráulica semiautomática, componente mecânica, para o fabrico de componentes a partir de derivados de madeira

    Publication
    by Moreira, André Carvalhido
    Este trabalho incide sobre a necessidade gerada de criação de um equipamento que permita produzir pequenas peças de aglomerado de partículas com reaproveitamento de resíduos de madeira, especialmente a serradura de pinho, resultante da serração de toros de pinheiro. A inexistência ou total desconhecimento da existência de um equipamento que possa servir de base para o atual projeto, levou à necessidade de inovar e realizar de um projeto de raiz em que a Engenharia de Produto existente, obtida de uma forma mais artesanal, produz parte dos requisitos necessários ao projeto do equipamento. O modelo escolhido de equipamento criado foi dimensionado satisfazendo os requisitos, com recurso a métodos analíticos, validados ao longo do trabalho a partir de diversas ferramentas informáticas e ensaios experimentais. Para análises pelo método dos deslocamentos foi utilizado o software CYPE e para análises pelo método de elementos finitos foi utilizado o software Solidworks Simulation.
    2013 master thesis Portugal open access
  9. 9

    Two-dimensional integrated mixed-mode smeared crack model for simulating FRC structures

    Publication
    by Matos, Luís M. P.
    Other Authors: Barros, Joaquim A. O.; Gouveia, António Ventura; Calçada, Rui A. B.
    This paper describes the implementation and assessment of the predictive performance of a two dimensional mixed-mode fracture smeared crack model (MMFSCM) in a finite element method (FEM) based software. The referred constitutive model is based on the integration of the aggregate interlock and fibre pullout resisting mechanisms to simulate the behaviour of Fibre Reinforced Concrete (FRC) in both fracture mode I and II. The models used to simulate the contribution of each resisting mechanism predict the normal and shear stresses at the crack level based on the crack opening and sliding displacements. For this purpose, two aggregate interlock models and three fibre pullout models are used. The appraisal of this approach is conducted by simulating two numerical case studies consisting of a three-point notched beam bending test (3PNBBT) for assessing the structural behaviour in mode I, and shear panel tests to appraise the predictive performance of the model in mode II. In addition, modifications to the original formulation of the fibre pullout models are proposed, and a multi-linear branch model is also developed and implemented in order to facilitate the use of inverse analysis tools for defining the mode I behaviour. The numerical simulations have predicted with good accuracy the experimental responses, both in mode I and mode II, capturing not only the peak loads but also the evolution trend of the post-peak responses of the analysed scenarios. The modifications proposed to the fibre pullout models enhanced the overall predictive performance of the MMFSCM. The multi-linear branch model exhibited excellent performance, capturing the experimental response with very good accuracy in all 3PNBBT simulations.
    2023 article Portugal open access
  10. 10

    Numerical Simulation Applied to PVD Reactors: An Overview

    Publication
    by Pinto, Gustavo Filipe
    Other Authors: Silva, Francisco; Porteiro, Jacobo; Mínguez, José; Baptista, Andresa
    The technological evolution in the last century also required an evolution of materials and coatings. Therefore, it was necessary to make mechanical components subject to heavy wear more reliable, improving their mechanical strength and durability. Surfaces can contribute decisively to extending the lifespan of mechanical components. Chemical vapor deposition (CVD) and physical vapor deposition (PVD) technologies have emerged to meet the new requirements that have enabled a remarkable improvement in the morphology, composition and structure of films as well as an improved adhesion to the substrate allowing a greater number of diversified applications. Thin films deposition using PVD coatings has been contributing to tribological improvement, protecting their surfaces from wear and corrosion, as well as enhancing their appearance. This process can be an advantage over other processes due to their excellent properties and environmental friendly behavior, which gives rise to a large number of studies in mathematical modelling and numerical simulation, like finite element method (FEM) and computational fluid dynamics (CFD). This review intends to contribute to a better PVD process knowledge, in the fluids and heat area, using CFD simulation methods focusing on the process energy efficiency improvement regarding the industrial context with the sputtering technique.
    2018 article Portugal open access