Papers by Keyword: FEM Modeling

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Authors: Gheorghe Paltanea, Veronica Paltanea, Dorina Popovici, George Papanicolaou, Mihael Sultan
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.
127
Authors: Min Htike Thein, Kian Meng Lim
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.
217
Authors: Guy Sutter, Gautier List, Xue Feng Bi, Jean Jacques Arnoux, Adbenbi Bouthiche
Abstract: An experimental method using a specifically set-up is presented in order to investigate dry friction phenomena, which occurs in the cutting process at the tool chip contact, in a wide range of sliding speed. A ballistic set-up using an air gun launch is used to measure the friction coefficient for the steel/carbide contact between 15 m/s and 80 m/s. A series of tests are conducted according to the sliding velocity and the normal pressure. These measurements are also introduced in a finite element simulation. The focus of this work is to determine the relevance of the friction modeling in the finite element method of the high speed machining. Modeling results are compared with cutting forces measured on a similar experimental device, which can reproduce perfect orthogonal cutting conditions. Measurement of temperature fields during the cutting process complete the parameter required for modeling. The results show that in high cutting speed, the friction modeling usually used in the FE codes is limited and that novel formulations are needed.
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Authors: Wiesław Szymczyk, Anna Boczkowska, Tadeusz Niezgoda, Konrad Zubko
Abstract: This paper deals with the development of magnetoactive elastomers (MREs) based on the carbonyl iron particles-filled polyurethane resin. Their stiffness can be changed easily by magnetic field. Such a property can be useful in construction of active vibration damping structural elements. For the needs of numerical modelling methods validation the elementary case of the two magnetic particles was investigated experimentally. Special “macro samples” were prepared with pairs of ferromagnetic particles of spherical shape of diameter of 12.7 mm. They provided easy observations and measurements. The gap distance between particles was established on the level of ¼ of the diameter. After application of the magnetic field particles started to attract each other like magnetic dipoles. The mutual displacement of the dipoles was recorded in function of the magnetic field intensity, which was varied in the range100÷300 [mT]. The deformation field was also obtained from the digital image processing (DIC). Then the experiment was simulated numerically with the use of the 3D FEM models. The dipoles were loaded by forces which were increased gradually until displacements reached values that were measured experimentally. Calculations were performed on the MSC Patran-MARC platform. The Neo-Hookean material model was used to describe properties of the resin matrix. Magneto-mechanical coupling was taken into consideration with the use of an iterative method. The results of calculations were compared with the experimental results. The validation of the base modelling concept was successfully completed.
113
Authors: Wen Fang Peng, Qiang Li, Yu Yan
Abstract: Trip steel is broadly used in automobile manufacturing with its high strength and enhanced formability. For the variable section parts with protrusion and hole, roll forming is a kind of feasible way to realize continuous parts manufacturing, In the paper, with deep understanding of roll forming process and reasonable simplification, the FEM model of a multi-step variable section roll forming of 600MPa trip steel parts with protrusion and hole is established to analyze the mechanics and the deformation characteristics of the forming procedure. Equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained to guide the design of the variable section roll forming product line.
299
Authors: Yu Yan, Qiang Li
Abstract: Flexible roll forming is a new forming process that produces parts with variable cross sections. This forming process is proposed to meet the need in the weight reduction of automobiles. With deep understanding of this process and reasonable simplification, the FEM model of a nine-step flexible roll forming of an ultra-high-strength steel bumper is established. In order to analyze the mechanics and the deformation characteristics of the flexible roll forming, equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained which can guide the design of the flexible roll forming product line.
132
Authors: Wen Qing Song, Jing Fu Chai, Wen Ji Xu
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.
468
Authors: Wiesław Szymczyk, Danuta Miedzińska
Abstract: . The paper deals with the numerical analysis of foam materials. Open cell foam is investigated. Numerical simulations enable prediction of failure process and assessment of effective properties of the modeled foam structures [1]. Metal as well as polyurethane foams exhibit interesting properties. They are light, possess good acoustic and/or magnetic isolation, have ability to absorb energy of vibration and impacts [2]. They are used for sandwich panels, hit absorbers (i.e. as elements of buffer constructions in rail vehicles), fillers of construction parts, bodies of vehicles (i.e. floating combat vehicles), dividing walls on vessels and others. Specially prepared open cell foams demonstrate auxetic properties [3] and shape memory effect [4]. Such materials are very good for seats in aircrafts, which may protect pilots and passengers during crashes and restrict heavy backbone injuries. Foams are also applied for filtering purposes. Foams themselves or in combination with different types of fillers (i.e. elastomers) or ceramic reinforcement may be used for impact energy absorbing panels for military purposes (protection against explosion shock wave and splinters).
400
Authors: Eleonora Atzeni, Rosolino Ippolito, Luca Settineri
Abstract: The present paper aims at defining a numerical tool for the efficient design of the selfpiercing riveting process by means of FE simulations. Abaqus Explicit v.6.4 software has been used to establish a model for 3D simulation of the joining process and of the shearing test on the riveted joint, in order to understand the joint formation and failure mechanisms. The obtained indications have been validated experimentally through joint sectioning and comparison between real geometry and numerical results. Furthermore, shear tests have been performed to compare the experimental and numerical results in terms of joint resistance.
655
Authors: Carlo Bruni, Mohamad El Mehtedi, Filippo Gabrielli
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.
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