Search results for "Computer simulation"
showing 10 items of 1054 documents
A simulation model for electromagnetic transients in lightning protection systems
2002
This paper deals with the evaluation of electromagnetic transients in a lightning protection system (LPS). A field approach is used, based on the numerical solution of a modified version of the thin-wire electric field integral equation in the frequency domain. Time profiles of interesting electromagnetic quantities are computed by using a discrete fast Fourier transform algorithm. The model takes into account coupling effects among aerial parts and ground electrodes in order to correctly estimate the quantities which can determine electromagnetic hazard inside the LPS; transient touch and step voltages can be easily evaluated also taking into account the human body presence on the soil sur…
Dynamic shakedown of structures under repeated seismic loads
1995
Elastic, perfectly plastic structures are considered under the action of repeated short-duration exitations of seismic type acting in an unknown time sequence, but belonging to a given polyhedral excitation domain. The basic excitations (vertices of the polyhedron) are chosen as discrete-spectrum waves each with frequencies coincident with the first natural frequencies of the structure, and amplitudes related to the ground features and earthquake intensity (according to the Kanai and Tajimi filter model) in such a way that every admissible excitation-obtained as a linear convex combination of the basic ones-has a maximum power not exceeding a given value. In the framework of unrestricted dy…
3D finite element analysis of tool wear in machining
2008
Abstract The paper is focused on the 3D numerical prediction of tool wear in metal cutting operations. In particular, an analytical model, able to take into account the diffusive wear mechanism, was implemented through a specific subroutine. Furthermore, an advanced approach to model heat transfer phenomena at the tool–chip interface was included in the numerical simulation. The adopted simulation strategy gave the possibility to properly evaluate the tool wear. The 3D FEM results were compared with some experimental data obtained turning AISI 1045 steel using uncoated WC tool; a good agreement was found out.
Central Bursting Defects in Drawing and Extrusion: Numerical and Ultrasonic Evaluation
1993
Abstract A new approach for the prediction of central bursting defects in extrusion and drawing is proposed: a finite element analysis of the processes has been carried out, and the obtained results have been elaborated by means of a post-processor, which, employing a proper ductile fracture criterion, is able to suggest if and where the central burst occur. An ultrasonic control system able to detect the insurgence of defects with a resolution of 0.2 mm. has been setup in order to verify the predictive capability of the model. The experimental results show a good agreement with the numerical predictions confirming the effectiveness of the proposed approach, whose industrial application app…
Measuring of Geometrical Precision of Some parts Obtained by Asymmetric Incremental Forming Process After Trimming
2007
Asymmetric Incremental Forming exalts the advantages of Incremental Forming process since no dies are strictly necessary. In this way complex geometries may be manufactured with a very simple clamping equipment. On the other hand, this characteristic determines some intrinsic drawbacks which penalise its industrial suitability; first of all, the dimensional control of the manufactured part is a still open point for researchers all over the world. Several approaches have been already proposed in the last years to solve the problem, resulting only in partial solutions. At the same time, up to now, the numerical simulation did not supply significant aid to the designers, due to the problem com…
DEPENDENCE OF MACHINING SIMULATION EFFECTIVENESS ON MATERIAL AND FRICTION MODELLING
2008
Numerical simulation of cutting processes is still a very difficult matter, although some relevant geometrical simplifications and high-performance codes are used. A large number of technical papers have been focused on the predictive capability of the codes: nevertheless the prediction quality is not very satisfactory if the problem is analyzed in a wide sense. In this paper the simple orthogonal cutting process of a plain-carbon steel is investigated taking into account different process conditions (cutting speed and feed rate). Furthermore, four material constitutive equations and three friction models were implemented and a sensitivity analysis was carried out comparing the numerical pr…
Full-wave analysis of industrial microwave applicators: TM modes
2004
In this paper, full-wave analysis of the TE modes of an industrial cylindrical microwave applicator is presented. The dispersion characteristics and fields configurations are shown. These results are obtained by a numerical simulation based on the residue theory. The authors have obtained particular modes called loop modes, which have a complex propagation constant that describes a loop within the complex plane. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 46–50, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20203
Machining Economics in FMS by a Fuzzy Approach
1995
Abstract In a conventional manufacturing system, cutting parameters have to be fixed in order to pursue the economical and productive target related to each cutting operation. In a Flexible Manufacturing System (FMS), as a consequence of the unbalanced workload due to the mutual interaction among the shared resources, the optimization of each operation does not allow the optimum of the global production system to be reached. A fuzzy programming model is developed in this paper in order to select cutting speeds of the operations in the production plan as a satisfying compromise solution between single operation and the integrated system targets.
FDTD simulation for electromagnetic radiated emissions in 42 V vehicle electrical systems
2005
In this paper a full 3D approach, based on finite difference time domain method, is used to predict the electromagnetic radiated emissions from 42 V vehicle electrical loads. An experimental set-up has been arranged on purpose. A comparative analysis among measured and computed results is performed. The good agreement obtained among simulated and measured data enables to validate the numerical scheme. The proposed methodology contributes to predict electromagnetic emissions in the automotive environment since the design stage. Moreover, the proposed numerical tool can be used to define, for new vehicle electrical architectures, low cost test methods for electromagnetic compatibility and sui…
Comparison of different uncertainty techniques in urban stormwater quantity and quality modelling
2011
Abstract Urban drainage models are important tools used by both practitioners and scientists in the field of stormwater management. These models are often conceptual and usually require calibration using local datasets. The quantification of the uncertainty associated with the models is a must, although it is rarely practiced. The International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, has been working on the development of a framework for defining and assessing uncertainties in the field of urban drainage modelling. A part of that work is the assessment and comparison of different techniques generally used in the uncertainty assessm…