Papers by Keyword: FEM Modeling

Abstract: Among many methods of particle concentration in liquid, acoustic concentrator uses ultrasonic standing wave to concentrate microparticles in liquid. In order to determine its performance on particle concentration, estimation of acoustic energy density inside the concentrator is important since energy density is the main contributing factor in calculating the primary acoustic radiation force acting on the particles. The balance between the primary radiation force and hydrodynamic force acting on the particles inside the acoustic concentrator determine the performance of the acoustic concentrator. Therefore, this study focuses on the measurement of acoustic energy density inside the h-shaped acoustic concentrator and characterization of performance of the concentrator. First, energy density is estimated by curve-fitting the experimental particle position in the ultrasonic field with one-dimensional theoretical position. Second, two-dimensional acoustic and hydrodynamic fields are determined using two-dimensional simulation model in COMSOL Multiphysics. Integrating the governing equation for particle motion in the balance of acoustic and hydrodynamic forces result in the particle trajectory and it is compared with the experimental observation. The results would provide deeper insight into the operation of acoustic concentrator and the detailed phenomenon of particle motions inside the concentrator.

Abstract: Electrophoretic deposition (EPD) has traditionally been viewed as a thin film deposition technique for coating conductive surfaces. Recently, there have been reports of producing functional parts with EPD to near net shape, often containing gradients in material properties normal to the conductive deposition surface. By using reconfigurable electrode systems, a few researchers have gone beyond purely out-of-plane gradients and demonstrated gradients in material properties in the plane of the deposition electrode, a necessary condition for 3D additive manufacturing. In this work, we build upon a previously published technique called light directed electrophoretic deposition (LD-EPD) in which the deposition electrode is photoconductive and can be activated with light, leading to a patterned deposit. Here, we demonstrate that the LD-EPD technique can also lead to patterned deposits on any conductive surface by utilizing the photoconductive electrode as the counter electrode. This eliminates several issues with standard LD-EPD by allowing the potentially expensive photoconductive electrode to be reused, as well as mitigates post-processing material compatibility issues by allowing deposition on any conductive surface. We also detail the results of a finite element simulation of the deposition process in LD-EPD systems that captures key features seen experimentally in the final deposit.

Abstract: The aim of this study is to realize a simple simulation tool, in order to predict the form defect of cylinder block bore liners in the moment of rough boring process. Geometrical defect prediction is critical for Process Engineering in order to optimize all machining sequences in the production line, to grantee the finale product, according to the norms defined by the Design Engineering. In revenge, Process Engineering can suggest a new product design according to geometrical defect predictions. Simulation can significantly reduce the time of Process-Product parameters adjustment (pre-project).In this study a simple static FEM model, based on the cylinder block geometry, is proposed to predict the form defect of the bore liners in the moment of process. The cutting tool is supposed as a rigid part in this model. The clamping condition and meshing information are applied on the part in the initial state. Calculation of cutting force components is performed through the Kienzle cutting law and applied on the bore liners by means of a Python script. The Python script runs the calculation automatically by means of ABQUS software. Another Python script is in charge of simulation results post-processing. The interface of this tool is an Excel sheet which allows us to inter the process parameters and automatically run the FEM calculation. Out-put excel file contains the form defect of each bore according to 3 levels of bore (top, middle and the bottom) and different angular position.The simulation results put forward that the clamping condition plays an import role in the bore distortion. Consequently, optimizing the clamping pressure and its localization is critical, before cutting parameters adjustment, in line boring process. Experimental validation is performed in parallel with the simulation. The first correlation between experimentation and simulation results shows that the first influent factor which disturbs the correlation is the initial form defect of rough part due to the casting process. Integration of casting form defect in the simulation is crucial and should be taken into account in the next studied.

Abstract: The deformation load is the most important parameter in the press design as it affects the structure and the general integrity of the final product. Therefore, every other parameter such as die shape, friction, type of process (hot or cold), and speed considered in modeling is optimized to cut back on the metal forming load. The flow of metal is largely influenced by the geometry of the die and hence the geometric shape of the tools is the main factor by which an optimum load can be evaluated. In extrusion process the strain distribution, resulting from deformation load, and other important variables that influence material structure, such as a hydrostatic stress, are strongly dependent on the geometry of the die. In the present investigation using linearly converging die profiles, the extrusion of symmetric and asymmetric polygons such as circular, square, triangular, hexagonal, heptagonal, octagonal, and L-, T-and H-, respectively sections from round billet have been numerically simulated. Mathematical equations describing the die profiles were derived, and then using MATLAB R2009b the co-ordinate of the die profiles was evaluated. A solid CAD model for the linearly converging die profile was made using Autodesk Inventor 2013 software and numerical analysis using DEFORM software for extrusion of the above sections from round billet was then performed to predict, for dry and lubricated condition, the extrusion load during deformation. It is found that the predictive loads for asymmetric shapes are found to be higher than that of the symmetric shapes. While there is no marked difference between the predictive loads for symmetric shapes that of the asymmetric shapes is significant where L-section has the highest extrusion load, followed by T-section and the H-section given the least pressure.

Abstract: The present investigation deals with the development of a methodology to predict the flow behaviour of the ZM21 magnesium alloy in given intervals of temperature and strain rate by FEM simulation of torsion testing. Equations based on the hyperbolic sine of flow stress and on the multiple linear regression were proposed and implemented into the finite element code. The flow curve shapes obtained by simulation were compared with experimental ones that were not used in the building phase of the equations. It was found that the simulation of torsion tests allows, under given conditions of temperature, strain rate and deformation levels, to obtain flow curve shapes very similar to those obtained by experiments under conditions not included in the building of the models.

Abstract: In this paper is presented a 2D approach to finite element modeling of a single lap bonded joint. As adherent material a sheet wood was selected and as adhesive, Bison Super Wood D3. In the article a combined method is described, consisting in the placement of piezoelectric actuators on the surface of bonded joint, in order to determine the tensile stress in the overlap joint. A comparison between the experimental, analytical and numerical results has been achieved through a multiphysics modeling - electrical and mechanical coupled problem, in order to evaluate the experimental outcomes. The experimental technique used to measure the mechanical parameters (displacements) was the three-point bending test, where different forces were applied in the mid-span of the structure, in order to maintain a constant displacement rate. The length of the overlap joint was modified from 20 to 50 mm.

Abstract: This paper presents a study on the influence of material parameters of concrete on the mechanical response of prestressed monoblock railway sleepers used on Czech railway tracks. The influence of selected mechanical/fracture parameters of concrete on the structural behaviour of the studied precast structural members is investigated by means of numerical modelling of standardized static loading tests, which are used as a tool for quality control during the manufacture of sleepers according to the European Standards for railway applications. The tests are numerically simulated using ATENA nonlinear finite element method software. The results of the simulations are compared with experimental data obtained via static loading tests performed on sleepers both before their use according to their designated purpose and after 17 years in operational service.

Abstract: Widespread survey, aiming at the evaluation of both vulnerability of the structures and usability of the buildings, have been carried out after the seismic events occurred on May 2012 in Emilia-Romagna districts. During the surveys, several cover typologies have been verified, which often evidenced lack in terms of earthquake-proof features. In contrast, some ancient timber roofs showed an original construction technology, according to the seismic mitigation measures. Clearly, the attention to the behaviour of the covering structures against the horizontal actions was due to the historic memory related to earthquakes occurred in the past or simply due to a good construction practice lost during the following years.This paper it is devoted to explain the analysis campaign carried out on an ancient timber covering structure located in the historic centre of the town of Cento (FE), aiming at the characterisation of its seismic behaviour. The study consists on three subsequent steps: 1) in-depth visual and geometrical survey; 2) in-situ non-destructive tests for material characterization; 3) Finite Element modelling of the complex structure.

Abstract: The paper deals with thermal analysis, modeling and simulation of the Shape Memory Alloy (SMA) actuator with temperature sensor. Because the capabilities of analytical description of SMA system are limited, numerical simulations of model have to be performed. Two different numerical models are investigated - lumped and continuous model. Simple parametric lumped model of actuator thermal field is developed in order to describe thermal field at the measuring point. The characteristic parameters of the lumped model are set up according to continuous coupled electric-thermal model made in ANSYS FEM program.

Abstract: Plasma arc bending of laminated clad metal sheets (LCMS) is a newly developed technique that produces deformation in the LCMS by thermal stress instead of external mechanical force. Since the temperature field leads to the thermal stress, a FEM mode was developed to study the temperature variations in the plasma arc bending of the LCMS which was validated robustness by the experiments. The results show that the temperature variations of the LCMS include the preheating, temperature dramatically changing and cooling stages. The lowest temperature is in the inlet whereas the highest temperature is in the outlet along the heating line. It needs to regulate the energy input of the plasma arc to avoid the possible partial melting of the LCMS.