Search results for "Finite Element Method"
showing 10 items of 746 documents
On the Elastic Behavior of a Cross-Ply Composite Pin-Joint with Clearance Fits
1999
The effect of pin/hole clearance fits on the elastic membranal behavior of a cross-ply fiber glass-reinforced epoxy laminate plate loaded in tension through a pin is examined by a finite element nonlinear contact analysis. No a priori assumption is made on the distribution of the contact pressure on the surface of the hole. Friction effects are not included. The numerical results correlate well with Hertzian theory of contact. It is demonstrated that clearance increases the peak compressive stress in the plate up to a factor of 3000% with respect to the perfect-fit case. Clearance also shifts the location of the peak tensile stress towards the pin/hole contact arc and decreases its magnitu…
On the Effect of Interference Fits in Composite Pin-Joints
1999
The Finite Element Method is used to determine the effect of pin/hole interference fits on the elastic membranal behavior of an orthotropic plate loaded in tension through a pin. A complete contact analysis is performed to handle the nonlinear contact problem. The study encompasses two levels of interference fits, two degrees of anisotropy of the plate, and two load levels. Friction effects are not included. Experimental results from Digital Speckle Pattern Interferometry are also presented. It is shown that the stress changes in the plate vary linearly with load when no pin/plate separation occurs. It is also shown that interference fits can have beneficial effects on the static and fatig…
A Study on the Effects of Clearance and Interference Fits in a Pin-Loaded Cross-Ply FGRP Laminate
1998
The elastic behavior of a cross-ply fiber glass-reinforced epoxy laminate loaded in tension through a pin fitted with clearance and interference is examined. A nonlinear contact analysis using the Finite Element Method and an experimental study by Speckle Interferometry are performed, showing fairly good correlation. An interesting comparison is performed between FEM results and Hertzian contact theory. Major conclusions are: (I) clearance causes high compressive stress in the bearing area, and does not influence the peak tensile stress; (2) interference has beneficial effects on the joint, as (a) it lowers the peak circumferential stress, and (b) it decreases the change of stress due to t…
Residual stresses and FCP prediction in FSW through a continuous FE model
2009
Abstract Residual stresses prediction is definitively a relevant and open issue in welding processes. In the last years, different numerical models are proposed by many researchers to predict the residual stress field in FSW butt joint. However, most of these works are based on properly tuned analytical models and neglect the effect of the mechanical action due to the presence of the tool pin. In the present paper, a continuous 3D FE model, which was previously developed by some of the authors, was used to simulate the FSW process of butt joints with a single block approach, and predict the residual stress field by considering both thermal and mechanical actions. Then, the residual stress e…
On the theoretical–numerical study of the HEXCALIBER mock-up thermo-mechanical behaviour
2010
Abstract Within the framework of the R&D activities promoted by European Fusion Development Agreement on the Helium-Cooled Pebble Bed Test Blanket Module to be irradiated in ITER, ENEA Brasimone and the Department of Nuclear Engineering of the University of Palermo (DIN) performed intense research activities on the modelling of the thermo-mechanical behaviour of both beryllium and lithiated ceramics pebble beds, that are envisaged to be used, respectively, as neutron multiplier and tritium breeder. In particular, the DIN developed a thermo-mechanical constitutive model for these pebble beds to be validated against the HEXCALIBER mock-up test campaign, carried out at the ENEA HE-FUS3 facilit…
Temperature control during Spark Plasma Sintering and application to up-scaling and complex shaping
2013
International audience; The determination and the homogeneity of the sample temperature during consolidation of powders by Spark Plasma Sintering (SPS) are addressed. Densifications were carried out in three different facilities differing by their constructors and their size. A structural transformation activated in a TiAl alloy was used as a marker of the sample temperature and finite element modeling were performed to evaluate the temperature at each point of the set-up. A good agreement between experimental and simulated data is exhibited. Alloys with identical microstructures were sintered and the homogeneity of the microstructure was better in the largest machines or when the sample wa…
Friction Stir Welding of steels process design through a continuum based fem model
2009
AbstractFriction stir welding (FSW) has been reaching a continuously increasing popularity among joining processes since its invention in 1991. Although mainly used for aluminium alloys, it has been successfully applied also to steels. In the present paper, a continuum based FEM model for FSW of steels is proposed, which is three-dimensional Lagrangian implicit, coupled, rigid viscoplastic. The model, whose potential has been analysed through temperature distribution comparisons, is able to predict temperature, strain and strain rate distributions, together with thermal and mechanical loads on the welding tool, at varying main process variables. In this way, the FEM model can be used for pr…
Material Flow in FSW of AA7075 - T6 butt joint: numerical simulations and experimental verifications
2006
Friction stir welding (FSW) has reached a large interest in the scientific community and in the recent years also in the industrial environment, owing to the advantages of such solid state welding process with respect to the classic ones. Advanced finite element method tools are needed in order to develop an effective engineering of the processes; quantitative results can be acquired from numerical simulations once the basic information such as the material flow is certain. A 3D Lagrangian implicit coupled rigid viscoplastic model has already been developed by the authors to simulate FSW of butt joints. In the present paper the material flow in the FSW of AA7075–T6 butt joints is investigat…
Determination of the residual stresses in composite laminate using the compliance method
2005
Residual stresses play an important role on the mechanical behavior of composite laminate. The development of new methods to determine the residual stresses gradient within the laminates is necessary. This article presents the adaptation of the compliance method in the case of composite laminates carbon/epoxy [02/902]s. The incremental drilling of a constant width groove allows for each increment to measure the strains (using strain gages) and displacements (using an optical device) of particularly points of the structure surface. These experimental data are compared with results given by a finite elements simulation. This comparison allows to raise the residual stresses in the composite la…
Numerical model for the characterization of biocomposites reinforced by sisal fibres
2018
Abstract Although several works have been recently published in literature about biocomposites, i.e. on innovative and ecofriendly polymer matrix composites reinforced by natural fibers, there are not studies on the influence of the waviness that various natural fiber present after their extraction. In order to give a contribution to the knowledge of the effects of the fiber waviness on the main mechanical properties of biocomposites, as the longitudinal Young modulus, in the present study a systematic numerical analysis has been carried out by using parametric models properly developed, that let the user to consider the effects of the key influence parameters as the fiber concentrations an…