Papers by Keyword: Finite Element Modeling

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Authors: Saida Ghoggali, Outtas Toufik, Saber Latrèche
Abstract: A successful osseointegration involves the simultaneous optimization of the primary stability of the implant and the minimization of interfacial stresses bone - implant. In this context, the modeling of these stresses reports a great interest for researchers in last decades.The aim of this work is to study the effects of geometric parameters of a new model of titanium dental implant on the evolution of interfacial stresses bone /implant. For this, a dental implant of the second premolar in the lower jaw was considered, with different diameters, thread pitches and different thread forms. The profile of the interfacial stresses was presented for each case study, the results show a great similarity in the areas concerned, cortical bone, threaded region and cancellous bone, with the results obtained in the literature for other types of geometries.
Authors: Mei Jiao Qu, Ke Ming Wang, Yang Sun, Gui Yu Xin
Abstract: This paper selects a load-bearing stage of an aeroengine compressor stator as study object to describe the model simplification method. Based on the criterion of cross section equivalence, the stator vanes are simplified into three versions of rectangular beams with variable cross section, using eight sections, four sections, and two sections respectively, to set up finite element model of the structure. Natural frequencies of the three simplified models are calculated and the results are compared with that of the original model. Comparison results show that the largest calculation errors of the first 10 natural frequencies using the three simplified models are-3.22%, -4.97% and-5.38%, respectively, but with this method, the model scale and computing time reduce significantly down to 3-4%, and 1-2% of the original model. The result shows that, the proposed method is applicable to relevant practical engineering.
Authors: Romana Piat, Pascal A. Happ
Abstract: Metal-ceramic composites offer many advantages over monolithic metals and their alloys such as high specific stiffness, strength and good thermal properties. In this paper, stress fields in a single-domain sample of metal-ceramic composite containing multiple cracks in the ceramic layer are investigated. In our previous studies the cracked microstructure for different stage of damage is modeled by analytical and computational approaches. In this paper the assumptions of the analytical model were verified using FE-models for different crack widening.
Authors: Michal Kotoul, Petr Skalka
Abstract: The main drawback still impairing the use of bioactive glasses in load-bearing applications is their intrinsic brittleness. The addition of coating constituted by polyvinyl alcohol (PVA) and microfibrillated cellulose (MFC) PVA/MFC led to a 10 fold increase of compressive strength and a 20 fold increase of tensile strength in comparison with non-coated scaffolds. Crack bridging by polymer coating was identified by fractographic observations as a main toughening mechanism. In this contribution a detailed computational analysis of crack bridging due to coating film fibrils is presented and an improvement of fracture resistance of coated scaffolds is explained.
Authors: František Lofaj, Dušan Németh, Rudolf Podoba, Michal Novák
Abstract: The FIB/SEM investigations of the microstructure changes in the hard brittle W-C based coating deposited on softer steel substrate after nanoindentation tests revealed that a set of approximately equidistant circular cracks forms in the coating in a sink-in zone around the indent and single cracks appear under the indenter tip. Finite element modeling (FEM) indicated development and concentration of the highest principal tensile stresses in the sink-in zone and in the zone below the indenter, which are considered to be the reason for the experimentally observed cracking. The distance from the indenter tip to the first circular crack combined with the calibration curve obtained from the FEM of the location of tensile stress maxima in sink-in zone can be used as a simple method for the determination of the strength of the studied coatings.
Authors: Vandana Sharma, S.L. Shimi, Saleem Khan, Sandeep Arya
Abstract: In this proposed work, the design and analysis of a flow sensor to be integrated into a micro-channel is presented. A finite element analysis is carried out to simulate fluid-structure interaction and estimate cantilever deflection under different fluidic flows at constant flow rate. The design of device is based on the determination of geometrical dimensions. A mathematical analysis describing the fluid mechanics and their interaction with the beam is also proposed. The mathematical model is done using finite-element analysis, and a complete formulation for design analysis is determined. Finite element method based Comsol Multiphysics simulations are used to optimize the design in order to determine the fluid velocities after interaction with the free end of the micro-cantilever beam. The device is successfully designed for sensing different fluids.
Authors: Xiao Bin Liang, Fan Tang, Jie Wu, Wei Zhen
Abstract: Electronic current transformer is one of the key equipment of intelligent substation and has a direct impact to the correct operation of relay protection devices. In order to accurately establish the dynamic response model of electronic current transformer, it is needed to extract electromagnetic parameters of Rogowski coil, which is the electromagnetic coupling part of electronic current transformer. This paper builds the electromagnetic parameters model and extracts the electromagnetic distribution parameters of Rogowski coil based on the finite element method, then we use the equivalent method to calculate the lumped electromagnetic parameter. At last, comparing with the experimental results, a good accuracy of the simulation results based on finite element method is presented.
Authors: Gerald Winter, Jürgen Klarner, Peter Staron, Bruno Buchmayr, Jozef Keckes
Abstract: Abstract. Residual stress gradients across the wall of seamless steel tubes influence decisively the mechanical stability and reliability of automotive and industrial constructions. Irreversible bending moments imposed on the tubes induce gradual and asymmetric elasto-plastic deformation across the tube cross-sections which result in very complex residual stress distributions. The aim of this contribution is to present a novel methodology as well as complementary modeling approach to assess the three-dimensional distribution of triaxial residual stresses in bent steel tubes. The stress characterization was performed using high energy X-ray diffraction at the HEMS beamline of PETRAIII synchrotron source in Hamburg as well as using laboratory Drill-hole method. For the complementary modeling of the stress distribution, a FEM software package DEFORM HT was used. The results reveal that the stress gradients across the tube wall are primarily influenced by the martensite profile predetermined by the parameters for thermo-mechanical treatment of the tubes. The tube bending causes the formation of continually varying compressive and tensile stresses across the tube circumference whereas the stress magnitude across the wall thickness scales again with the martensite appearance. Finally the results document the importance of the cooling process control and the influence of the applied bending radius on the resulting stress distributions as well as related mechanical parameters like fracture toughness and fatigue behavior.
Authors: Lijo Paul, P.V. Pradeep, Donald Antony
Abstract: Electro Chemical Discharge Machining (ECDM) process has been developed as an innovative machining process for machining non-conductive materials. The various application of this hybrid process is used in many industries like nuclear, medical and automobile industries. The scope of ECDM in micro machining of semiconducting materials is still found to be promising challenge for researchers. Due to many advanced properties of silicon, its use in MEMS industries is enormous. Many researchers have carried out lot of empirical estimation for discharges in ECDM. However very less work has been reported in the modelling of the ECDM process. Present work mainly concentrates on Finite Element Modelling (FEM) of micro holes machined on silicon wafers with ECDM process. A thermal FEM of spark discharge in the ECDM is carried out. The results from FEM are compared with experimental results and are found to be satisfactory. The model developed can be used for prediction of MRR for a particular combination of workpiece-tool arrangement.
Authors: Klaudia Szkoda, Celina Pezowicz
Abstract: All segments of the spine are characterized by a corresponding curvature in the sagittal plane and different geometrical parameters of vertebrae, which affects the complicated structure of transition between subsequent segments. The aim of the study was to assess changes occurring in the thoracolumbar spine, as a result of application of the transpedicular fixation. The research was conducted on finite element model, which was constructed on the basis of CT images. Five different configurations of the model were analyzed: focusing on vertebral compression fractures and degeneration of intervertebral discs. The analysis showed that the highest displacement occurred for a segment with intervertebral disc degeneration. Transpedicular fixation of injured thoracolumbar spine is given the opportunity to improve the stability and stiffness of the segment under consideration.
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