Search results for "finite element method"
showing 10 items of 746 documents
Thermal stress analysis of different full and ventilated disc brakes
2015
During the braking phase, the heat produced by friction between pads and disc cannot be entirely dissipated. Consequently, the brake disc, especially if very hard braking occur, can accumulate large amounts of heat in a short time so producing high gradients of temperature on it. Under these conditions, functionality and safety of the brake system can be compromised. The object of this study is to investigate, under extreme working conditions, the thermomechanical behaviour of different brake rotors in order to evaluate their efficiency and stability and to identify any compromising weakness on them. In particular, by means of FEM thermo-mechanical coupled analyses, one full disc and three …
The effect of manufacturing tolerances on a tubular linear ferrite motor
2015
This study presents a numerical and experimental study on the effect of permanent magnet tolerances on the performances of a Tubular Linear Ferrite Motor. The statistical distribution of the magnetic characteristic of a set of commercial magnets is obtained experimentally while the performances of a the tubular motor are numerically evaluated. The performances that have been considered are: cogging force, end effect force and generated thrust. It has been shown that: 1)the statistical variability of the magnets modifies the time behavior of the cogging force; 2)the value of both the end effect cogging force and the generated thrust are directly linked to the values of then remanence field o…
Piezoelectric energy harvesting from raised crosswalk devices
2015
This paper presents the main characteristics of an experimental energy harvesting device that can be used to recover energy from the vehicular and pedestrian traffic. The use of a piezoelectric bender devices leads to a innovative approach to Henergy Harvesting. The study focuses on the definition and specification of a mechanical configuration able to transfer the vibration from the main box to the piezoelectric transducer. The piezoelectric devices tested is the commonly used monolithic piezoceramic material lead-zirconate-titanate (PZT). The experimental results estimate the efficiency of this device tested and identify the feasibility of their use in real world applications. The results…
Unified formulation for a family of advanced finite elements for smart multilayered plates
2016
AbstractFamilies of layer-wise and equivalent single-layer advanced finite elements for the analysis of smart multilayered plates are formulated in a unified framework. The proposed modeling strategy reduces the multifield problem to an effective mechanical plate by the condensation of the electromechanical state into the plate kinematics, which is assumed as a variable order expansion along the plate thickness. Carrera Unified Formulation is invoked to derive the elemental stiffness and mass matrices and the mechanical and magneto-electric equivalent forces. The obtained smart plate finite element equations involves kinematical variables only and this extends the tools developed for multil…
3D simulations and experiments of guided wave propagation in adhesively bonded multi-layered structures
2010
Understanding guided wave propagation in multi-layered plates and interaction with discontinuities can be difficult, as well as the interpretation of the ultrasonic signals. Propagation of guided waves can be studied analytically solving the equations of motion with the proper boundary conditions; nevertheless analytical models can be difficult to solve for complex multi-layered structures or having inner discontinuities. The problem can be efficiently studied using numerical techniques. Simulation of guided wave propagation in multi-layered structures, for ultrasonic waves in the MHz range, is solved here with the finite element analysis based on an explicit integration rule to solve the e…
Guided Wave Propagation in a Plate Edge and Application to NDI of Rail Base
2012
The analysis of guided wave propagation in a plate edge can be useful for some applications, such as for the inspection of the rail base. Here guided waves generated by a laser beam hitting, on the inclined surface, a solid media with trapezoidal cross-section have been studied. We have found that, for the geometry investigated, two guided waves propagate along both free surfaces of the plate, with same velocity and frequency. The analysis of the trajectories of the two material points, due to waves propagation, shows that the wave packets can be identified as Rayleigh waves. The presence of S0 Lamb mode, with low frequency and low amplitude, has been revealed too. As an example of a possib…
Influence of secondary torsion on curved steel girder bridges with box and I-girder cross-sections
2015
Steel curved girder bridges are largely used today in motorways and railways. They are often composed of thin-walled crosssections, entirely made of steel or with an upper concrete slab. The deck may have I-girders or box cross-sections: in any case curved girders are subjected to twisting moment, associated with bending, even for dead loads. Moreover, in thin-walled sections the influence of non-uniform torsion becomes sizable with respect to Saint Venant torsion, modifying the state of tangential stresses in the section and introducing axial stresses due to warping being prevented. Open sections of I-girder bridges are especially subject to these phenomena and warping can be significant n…
GA-based Off-Line Parameter Estimation of the Induction Motor Model Including Magnetic Saturation and Iron Losses
2020
This paper, starting from recent papers in the scientific literature dealing with Rotating Induction Motor (RIM) dynamic modelling, as a first step, improves its space-vector dynamic model, including both the magnetic saturation and iron losses; The main original aspects of the proposed model are the following: 1) the magnetic saturation of the iron core has been described on the basis of both current versus flux and flux versus current functions, 3) it includes the iron losses, separating them in hysteresis and eddy current ones, 4) it includes the effect of the load on the magnetic saturation. Afterwards, it proposes an off-line technique for the estimation of electrical parameters of thi…
A boundary element model for structural health monitoring using piezoelectric transducers
2013
In this paper, for the first time, the boundary element method (BEM) is used for modelling smart structures instrumented with piezoelectric actuators and sensors. The host structure and its cracks are formulated with the 3D dual boundary element method (DBEM), and the modelling of the piezoelectric transducers implements a 3D semi-analytical finite element approach. The elastodynamic analysis of the structure is performed in the Laplace domain and the time history is obtained by inverse Laplace transform. The sensor signals obtained from BEM simulations show excellent agreement with those from finite element modelling simulations and experiments. This work provides an alternative methodolog…
Modular device for determining forming limit curves – a cost effective aproach
2010
Abstract The paper presents the realising and functioning of a modular device for testing the formability of metal sheets. By using the device it is possible to realise experimentally the tests needed for drawing the forming limit curves using the Nakajima and Marciniak methods, but there can be also done researchs on deep-drawing. The results gathered from the tests were validated by numerical simulations using the finite element method. The device was designed at the Research Center for Metal Forming of the “Lucian Blaga” University of Sibiu and realised with the support of S.C. Uzina Mecanica Marsa – Sibiu