1,721,096 research outputs found
FEM AND BEM STRESS ANALYSIS OF MANDIBULAR BONE SURROUNDING A DENTAL IMPLANT
No full textIn this work the structural behavior of a mandible with a dental implant, considering a unilateral occlusion, is numerically analyzed by means of the Finite Element Method (FEM) and the Boundary Element Method (BEM). The mandible, whose CAD model was obtained by computer tomography scans, is considered as completely edentulous and only modeled in the zone surrounding the implant. The material behavior is assumed as elastic and isotropic. A model of a commercial implant was digitized by means of optical 3D scanning process, and fully reconstructed in all geometrical features. Particular attention was posed on the mathematical reconstruction of the CAD model in order to facilitate the meshing process in the BEM environment and reduce the geometrical imperfections generated during the CAD to CAE translation process. The results of FEM and BEM analysis in terms of stress distribution on the mandible are qualitatively compared in order to provide a benchmark between the two methodologies against run times, accuracy and preprocessing efforts
DBEM crack propagation for nonlinear fracture problems
No full textA three-dimensional crack propagation simulation is performed by the Dual Boundary Element Method (DBEM). The Stress Intensity Factors (SIFs) along the front of a semi elliptical crack, initiated from the external surface of a hollow axle, are calculated for bending and press fit loading separately and for a combination of them. In correspondence of the latter loading condition, a crack propagation is also simulated, with the crack growth rates calculated using the NASGRO3 formula, calibrated for the material under analysis (steel ASTM A469). The J-integral and COD approaches are selected for SIFs calculation in DBEM environment, where the crack path is assessed by the minimum strain energy density criterion (MSED). In correspondence of the initial crack scenario, SIFs along the crack front are also calculated by the Finite Element (FE) code ZENCRACK, using COD, in order to provide, by a cross comparison with DBEM, an assessment on the level of accuracy obtained. Due to the symmetry of the bending problem a pure mode I crack propagation is realised with no kinking of the propagating crack whereas for press fit loading the crack propagation becomes mixed mode. The crack growth analysis is nonlinear because of normal gap elements used to model the press fit condition with added friction, and is developed in an iterative-incremental procedure. From the analysis of the SIFs results related to the initial cracked configuration, it is possible to assess the impact of the press fit condition when superimposed to the bending load case
3D non-linear MSD crack growth simulation for a riveted aeronautic reinforcement by DBEM
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Advances in Vibroacoustics and Aeroacustics of Marine, Aerospace and Automotive Systems
No full textThis Special Issue highlights the latest enhancements in vibroacoustics and aeroacustics of marine, aerospace, and automotive systems. Topics covered in this Special Issue deal with com-putational, instrumentation, and data analysis of acoustics and vibrations of aircrafts, satellites, spacecrafts, automotives, trains, ships, etc., ranging from aerodynamically generated noise to engine noise, vibration transmission, sound absorption, acoustic treatments, modelling procedures and vi-broacoustic properties of materials. The focus of this Special Issue is related to industrial aspects as dedicated numerical studies, experimental testing campaigns, and optimization problems. Procedures and algorithms useful to reach the abovementioned objectives in the most efficient way are illustrated in the collected papers
Impiego di Tecniche Numeriche nello Studio Affidabilistico del Danneggiamento Progressivo in Condizioni MSD
No full textAeroacustic and vibroacoustic advancement in aerospace and automotive systems
No full textThis Special Issue highlights the latest enhancements in the abatement of noise and vibrations of aerospace and automotive systems. The reduction of acoustic emissions and the improvement of cabin interior comfort are on the path of all major transportation industries, having a direct impact on customer satisfaction and, consequently, the commercial success of new products. Topics covered in this Special Issue deal with computational, instrumentation and data analysis of noise and vibrations of fixed wing aircrafts, satellites, spacecrafts, automotives and trains, ranging from aerodynamically generated noise to engine noise, sound absorption, cabin acoustic treatments, duct acoustics and vibroacoustic properties of materials. The focus of this Special Issue is also related to industrial aspects, e.g.,: numerical and experimental studies have been performed for an existing and commercialized engine to enable design improvements aimed at reducing noise and vibrations; moreover, an optimization is provided for the design of low vibroacoustic volute centrifugal compressors and fans whose fluids should be strictly kept in the system without any leakage. Existing procedures and algorithms useful to reach the abovementioned objectives in the most efficient way are illustrated in the collected papers
A two parameter model for crack growth simulation under variable spectrum load by combined FEM/Analitical approach
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