Search results for "Finite element method"
showing 10 items of 746 documents
Prediction of flow patterns during silo discharges using a finite element approach and its preliminary experimental verification
2015
Abstract Obtaining a reliable discharge of particulate solids from a storage silo is a prerequisite to securing operational adequacy in solids handling processes. If a silo is poorly designed, an unreliable interrupted discharge often occurs. In this study, an in-house finite element (FE) program was modified to predict the particulate solids flow patterns during discharges from silos, and the effect of a double-cone insert on such flow patterns. In FE modeling, a Eulerian approach was adopted with an assumption of steady-state flow—a state that greatly facilitated investigations on the effects of double-cone inserts on the flow of particulate solids. Predictions were carried out on whether…
Hygro-elasto-plastic model for planar orthotropic material
2015
An in-plane elasto-plastic material model and a hygroexpansivity-shrinkage model for paper and board are introduced in this paper. The input parameters for both models are fiber orientation anisotropy and dry solids content. These two models, based on experimental results, could be used in an analytical approach to estimate, for example, plastic strain and shrinkage in simple one-dimensional cases, but for studies of the combined and more complicated effects of hygro-elasto-plastic behavior, a numerical finite element model was constructed. The finite element approach also offered possibilities for studying different structural variations of an orthotropic sheet as well as buckling behavior…
A linear approach for the nonlinear distributed parameter identification problem
1991
In identifying the nonlinear distributed parameters we propose an approach, which enables us to identify the nonlinear distributed parameters by just solving linear problems. In this approach we just need to identify linear parameters and then recover the nonlinear parameters from the identified linear parameters. An error estimate for the finite element approximation is derived. Numerical tests are also presented.
On thermo-mechanical issues induced by irradiation swelling inside the back-plate of the IFMIF target assembly
2011
Abstract Within the framework of the IFMIF R&D program and in close cooperation with ENEA-Brasimone, at the Department of Nuclear Engineering of the University of Palermo a research campaign has been launched to investigate the thermo-mechanical issues potentially induced by irradiation swelling in the threaded connections between frame and back-plate of IFMIF target assembly. The main aim of the research campaign has relied in the assessment of the maximum swelling-induced volumetric strain that may be accepted in order to allow screws to withstand thermo-mechanical stresses and work in safe conditions or to avoid unduly high unscrewing torques during back-plate remotely handled maintenanc…
On superconvergence techniques
1987
A brief survey with a bibliography of superconvergence phenomena in finding a numerical solution of differential and integral equations is presented. A particular emphasis is laid on superconvergent schemes for elliptic problems in the plane employing the finite element method.
Subsurface treatment of a contact subjected to a hertz pressure
2013
Abstract The study proposes an approach allowing the favorable modification of the stresses field of a structure subjected to a Hertzian contact. It is based on the study of a classic Hertzian contact in the presence of subsurface circular defects. The idea is to limit the field of tangential stresses without large increasing of the global stress (Von Mises) of the system. The location of the defects is made according to the mechanical parameters of the contact (Fn, has, z). The results of the numerical calculations (FEM) are compared with photoelastic measurements and highlight an excellent correlation. The location of the defect on the symmetry axis (x=0) is the dominating parameter for t…
Numerical simulations and experimental measurements of the stress intensity factor in perforated plates
2008
A numerical procedure, which combines two hybrid finite element formulations, was developed to analyse the stress intensity factors in cracked perforated plates with a periodic distribution of holes and square representative volume elements. The accuracy of the method in predicting the stress intensity factor was verified by a comparison with experimental measurements, carried out by a photoelasticity method, and by commercial finite element software. Several simulations were executed by varying both the crack length and the hole diameters, and the effects of the holes on the stress intensity factor are illustrated. The method shows high accuracy and efficiency, as small differences were ob…
An Ultrasonic Lens Design Based on Prefractal Structures
2016
The improvement in focusing capabilities of a set of annular scatterers arranged in a fractal geometry is theoretically quantified in this work by means of the finite element method (FEM). Two different arrangements of rigid rings in water are used in the analysis. Thus, both a Fresnel ultrasonic lens and an arrangement of rigid rings based on Cantor prefractals are analyzed. Results show that the focusing capacity of the modified fractal lens is better than the Fresnel lens. This new lens is believed to have potential applications for ultrasonic imaging and medical ultrasound fields.
Use of Prandtl-Ishlinskii hysteresis operators for Coulomb friction modeling with presliding
2017
Prandtl-Ishlinskii stop-type hysteresis operators allow for modeling elasto-plasticity in the relative stress-strain coordinates including the saturation level of the residual constant-tension flow. This lies in direct equivalence to the force-displacement characteristics of nonlinear Coulomb friction, whose constant average value at unidirectional motion depends on the motion sign only, after the transient presliding phase at each motion reversal. In this work, we analyze and demonstrate the use of Prandtl-Ishlinskii operators for modeling the Coulomb friction with presliding phase. No viscous i.e. velocity-dependent component is considered at this stage, and the constant damping rate of t…
Eulerian models of the rotating flexible wheelset for high frequency railway dynamics
2019
Abstract In this paper three formulations based on an Eulerian approach are presented to obtain the dynamic response of an elastic solid of revolution, which rotates around its main axis at constant angular velocity. The formulations are especially suitable for the study of the interaction of a solid with a non-rotating structure, such as occurs in the coupled dynamics of a railway wheelset with the track. With respect to previous publications that may adopt similar hypotheses, this paper proposes more compact formulations and eliminates certain numerical problems associated with the presence of second-order derivatives with respect to the spatial coordinates. Three different models are dev…