FEM Technology Research Articles

Dynamic Reliability Assessment of Heavy Vehicle Crossing a Prototype Bridge Deck by Using Simulation Technology and Health Monitoring Data

Overloads of vehicle may cause damage to bridge structures, and how to assess the safety influence of heavy vehicles crossing the prototype bridge is one of the challenges. In this report, using a large amount of monitored data collected from the structural health monitoring system (SHMS) in service of the prototype bridge, of which the bridge type is large-span continuous rigid frame bridge, and adopting FEM simulation technique, we suggested a dynamic reliability assessment method in the report to assess the safety impact of heavy vehicles on the prototype bridge during operation. In the first place, by using the health monitored strain data, of which the selected monitored data time range is before the opening of traffic, the quasi dynamic reliability around the embedded sensor with no traffic load effects is obtained; then, with FEM technology, the FEM simulation model of one main span of the prototype bridge is built by using ANSYS software and then the dynamic reliability when the heavy vehicles crossing the prototype bridge corresponding to the middle-span web plate is comprehensively analyzed and discussed. At last, assuming that the main beam stress state change is in the stage of approximately linear elasticity under heavy vehicle loads impact, the authors got the impact level of heavy vehicles effects on the dynamic reliability of the prototype bridge. Based on a large number of field measured data, the dynamic reliability value calculated by our proposed methodology is more accurate. The method suggested in the paper can do good for not only the traffic management but also the damage analysis of bridges.

Numerical simulation of separated flows around a hybrid rigid-flexible thin plate

The VIV (Vortices-induced vibration) created by trailing vortices shedding is a typically natural phenomenon that may cause structural fatigue damage. The objective of this paper for the VIV is to study the so-called vortices shedding mode arising from separated flows around a blunt body by designing a hybrid rigid-flexible thin plate. Furthermore, we construct the modeling for the fluid-structure interaction in viscous flows, which helps to elucidate the relevant mechanism. The fluid and solid domains are established according to CFD and FEM technology, respectively, for which the data mapping at the fluid-solid interface is achieved with the implementation of the least square method plus the shape function interpolation. This work presents a series of numerical simulations to study the fluid-solid interaction of blunt body-flexible/rigid plate in uniform flows, considering with and without flexible plate, different velocities, and different blunt-body shapes. The numerical model is validated against the available literature values, and it reveals good accuracy in simulating blunt body-flexible plate-uniform flow interactions. Results show that the introduction of a thin plate leads to notable drag reduction for the blunt body, and the vortices shedding show significant randomness and instability under typical flow velocities and blunt body shapes.

WITHDRAWN: The simulations using real-time finite of element method

Abstract This paper presents a survey showing the various applications of FEM technology on a wide range of practical uses that cannot be comprehensively covered. Fem technology has emerged with merit and increased the strength and reputation of numerical mathematics, which has been characterized by the admiration of researchers in terms of effectiveness and adaptation in the field of fundamental analysis. Despite the fact that the normal use of FE-specific component software assumes the use of separate mathematical analysis and “separate” calculations, the rapid leaps of scientific progress in practical applications in various fields over recent decades have been an important incentive for various specialists to think about the continued trend towards the use of such techniques, which are based on FE models (specified component technique models). The limitations and limitations imposed on different sectors of work that can be accessed at varying periods of scientific progress require scoring prowess by using numerical analysis tests. Different methodologies for the implementation of FEM technology were proposed, determined by the requirements of the specific areas of use. Despite the fact that so far, fem technology has proven to be the latest and most comprehensive in the world, providing accurate and fast calculations of a vast area of work that requires the use of a comprehensive and accurate program.

Procedures Based on Composite FEM Technology for the Resolution of Concrete-Framed Structures with Masonry In-Fills: Comparison with Mexican Building Code

AbstractThe construction of confined masonry buildings has become a good choice to meet the housing needs of low-income families in big cities. Despite this, current building codes for such constru...

Vibration modes of the rotor system of turbocharger with floating-ring bearing

In this paper, in order to investigate the natural modes of the rotor system of turbocharger, the analytical model of floating-ring bearing, the FEM and modal test technology were employed. Firstly, based on Reynolds equations of the dynamic oil layer of floating-ring bearing, the oil layer pressure was obtained by using the finite difference algorithm. Then the stiffness coefficients and damping coefficients were calculated by using integration method. Next the FEM model of rotor system with supporting stiffness of floating-ring bearings was established. Then the natural modes of rotor system were simulated with considering the oil layer stiffness of the floating-ring bearings and the rotor’s rotating speeds. Lastly, the natural modes were identified with modal test technology and furthermore the FEM calculation results were verified. The investigation shows that the oil layer stiffness of the floating-ring bearings and rotating speeds of the rotor have great influences on vibration modes of the rotor system.

General-purpose FEM and Simulation Technology

General-purpose FEM and Simulation Technology

Effect of Process Parameters on Thermal History in Hot Rolling Process

Thermo-mechanical coupled FEM and isoparametric technology are used to build FEM model of hot-strip rolling and the coupled equation is solved using updated-Lagrange method in this paper. All kinds of thermal transfer phenomena are considered, such as conduction at the rolls-workpiece interface, convection and radiation between the workpiece and the surrounding environment, water cooling and heat generation due to plastic deformation and friction work. Numerical simulations are carried out to examine the effect of reduction rate, friction factor, radius of the work-roll, rotating speed of the roll, initial strip thickness and tension on rolling temperature of the strip. It is found that rolling temperature increases with the increases of reduction rate, friction factor, tension and rolling speed. The initial strip thickness and roll radius have also major effect on temperature distribution. In addition, the thermal cycles at the different points of the strip are simulated, which provides reasonable agreement with the reported results available in the literature.

Effect of stiffeners on crashworthiness of square aluminium columns considering damage evolution

Combining the optimization and FEM technology, crashworthiness of aluminum extrusions was studied for an automobile safety plan. The effects of longitudinal stiffeners on the crushing of stiffened square columns were studied considering the damage evolution. The numerical analysis was carried out by ABAQUS software. Subsequently, the collapse behavior of aluminum extrusion damage was validated by comparing against solution published in literature. Finally, in order to find more efficient and lighter crush absorber and achieving minimum peak crushing force, response surface methodology (RSM) has been applied for optimizing the aluminum extrusion tube.

Using FEM technology for optical surfaces polishing

The aim of this article is optical surfaces polishing on the 6-axis computer-controlled (CCM) machine Optotech MCP 250 CNC using FEM technology, which is suitable for aspheric elements polishing. The main attention is dedicated to the choice and to the precise adjustment of major process parameters. The possibility of usage the multi wave interferometer Luphoscan as a data source for the2D surface correction is solved too.

Crack Propagation and Simulation of Thermal Fatigue

In this paper, the thermal fatigue damage phenomenon in the comprehensive temperature environment is studied by means of thermal fatigue damage mechanics and FEM technology, the thermal-stress analysis modal under the comprehensive thermodynamic boundary conditions is established, the regularities of distribution of temperature fields, thermal stress fields effected by the comprehensive coupled variables are investigated. According to the modify of material characteristics under the high-temperature alternating thermal impact conditions and the integrated influences of environment, mechanical parameter and material microstructure to the fatigue fracture, numerical modal of thermal fatigue crack initiation and propagation are developed, so the characteristics of thermal fatigue crack propagation are studied, which are verified by the experiments, it is very significant to study thermal damage question of working equipments in the similar conditions.

Integrated Process Design for Two Robots Based Incremental Sheet Metal Forming

With the use of two industrial robots, Roboforming is a dieless incremental forming process, which is developed by the Chair of Production Systems at the Ruhr-University of Bochum. Connected to a cooperating robot system, these two robots hold respectively a forming and a supporting tool. Suitable for rapid prototyping and manufacture of small batch sizes with low costs, this forming process is based on flexible shaping through the synchronous movement of two industrial robots. Different from other single point incremental forming (SPIF) methods, the supporting tool used here greatly increases the geometric accuracy and the limited draw angle. A new processing technology always needs the computer-aided planning and simulation, which could accelerate the whole process and also give users the possibility to analyse and improve the process. In this paper, the whole integrated process design is introduced. After the modelling of the target CAD geometry, a self-developed CAM solution is used to get both tools’ positions and orientations according to the points on the geometrical surface. Based on the different forming strategies used, the supporting tool can even be synchronously placed at different positions on the sheet backside. After the tool path planning, the paths are first inputted into a simulation environment, which is consistent with the settings in the pilot plant. The tool positions and each robot’s postures can be seen and validated during the simulation. Before the final forming experiment, the tool paths are also sent into another simulation model for the forming analysis with the use of FEM technology. With consideration of many real material properties like springback and the subsequent deformation, the formed CAD geometry from the simulation is compared with the target CAD geometry and the forming results can be forecasted.

Fault Analysis on Crosshead Fracture of the Reciprocating Piston Compressor C102B

The C102B reciprocating piston compressor is an important equipment widely used in methanol production. Because of the complexity of exact dynamics analysis, the traditional and common way to find the reason of fracture is only based on metallographic structure analysis of crosshead material. In this paper, after metallographic structure analysis of crosshead material of the C102B compressor, the maximum loads on it are also calculated and two dangerous crosshead positions with maximum load are determined. Finally, stress analysis of the crosshead in two dangerous positions is implemented by FEM technology. Based on the above study, the reasons of crosshead fracture of the C102B compressor are found. The results has an inportant significance for judging the resaon of crosshead failure.

Preventive Suggestion and Fault Analysis on Piston Fracture of the Methanol Fresh Air Compressor C102B

The piston is a key moving-part of the reciprocating piston compressor with a high failure rate. Because of the difficult exact calculation of machinery dynamic, the traditional and common way to find the reason of fracture is based on metal-lographic phase of piston material. The C102B reciprocating piston compressor is an important equipment in methanol plant. In this paper, in connection with the piston fracture of the C102B fresh air compressor on service , besides a lot of analysis on metal-lographic phase, the 3-D model of piston and cylinder were built-up, and the two dangerous places where the piston suffered max-force were found. Bases on ANSYS and FEM technology, the value of max-force on piston at the two places were carried out. Finally, the reasons of piston fracture of the C102B fresh air compressor were found and some preventive suggestion was proposed.

롱 스트로크 정밀 스테이지용 원통형 리니어모터의 설계 및 운전 특성

This paper presents the design and operating characteristics of the novel cylindrical linear motor which is designed for the long stroke XY stage. In the long stroke structure, the air gap is changed by the distortion and bending effects, and it makes additional position error in the XY stage. In order to consider the distortion and bending effects of the long stroke, the field part of the cylindrical linear motor is designed as an open structure, and the stroke is supported by the bridge guide which is positioned in the open field part. The mechanical bridge guide can reduce the bending effects of the stroke and can keep a constant air gap.BR The detailed design process of the proposed cylindrical linear motor is presented in this paper. The proposed motor is analyzed by the 3D FEM technology. The practical XY stage which uses the proposed motor is tested to verify the propose novel cylindrical linear motor. The FEM and experimental results show the effectiveness of the proposed motor.

Postbuckling Analyses of Elastic Cylindrical Shells under Axial Compression

For the buckling problem of circular cylindrical shells under axial compression, experimental results show that after the primary buckling, the secondary buckling takes place accompanying successive reductions in the number of the circumferential waves at every path jumping. In this paper we traced this successive buckling of circular cylindrical shells using the latest in general-purpose FEM technology with the static stabilizing method with the aid of artificial damping for the local instability. The studies accomplish a fully automatic and seamless simulation of the successive path jumping in the deep postbuckling region, and show a good agreement with Yamaki's experimental results.

Elastodynamic infinite elements with united shape functions for soil–structure interaction

In this paper, new formulations of 2D four and five node elastodynamic infinite elements with united shape functions ( EIEUSF) are proposed. Such elements can be treated as family elastodynamic infinite elements, appropriate for dynamic soil–structure interaction (SSI) problems and can be used directly as finite elements. The common characteristic of the proposed infinite elements is the so-called united shape function, which is based on a finite number of wave shape functions. The idea of the united shape function is presented and discussed in details. It is demonstrated that if only one wave function is used (only one wave frequency) these elements are transformed to single-wave elastodynamic infinite elements. The basic difference between the four and five node formulations is the number of nodes for interpolation of the displacement field in the finite direction of the element. The EIEUSF elements are given in decay and mapped form. Fundamental advantage of the proposed infinite elements is that such elements can directly be used in the FEM concept. Once generated the EIEUSF mass and stiffness matrices can be addressed, introduced appropriately in the FEM equation of motion. After the mapping such elements can be recognized and treated, in the FEM technology, as finite elements. The elements are tested for multi-wave soil–structure interaction problems. The results give the guarantee for adequate numerical simulation.

冷間ロール成形FEM技術の開発と新FFXミルの実用化

冷間ロール成形FEM技術の開発と新FFXミルの実用化

Numerical Simulation of Wire-Rod Hot Continuous Rolling Process with Multi-Field Coupling

High speed wire-rod rolling is a typical large deformation process which includes geometry, material and boundary condition non-linearity, thus it belongs to a highly nonlinear problem. The finite element models of the billet and the rollers in the intermediate rolling region had been established based on actual sizes by using 3-D thermo-mechanical coupling FEM and advanced contact analysis technology. The deformation field, stress, strain, temperature field and rolling force of the billet were calculated and analyzed in the rolling passes precisely. The distribution and change characteristics of temperature had been discussed especially. The results of the simulation are reliable and precise, which are useful for practical manufacture and the optimization of process-parameters.

Numerical Study on Welding Line Behavior of Deep Drawing TWB Process

The FEM technology is used to analyze the welding line movement behavior of deep drawing TWB sheet with different thickness. It is found that high stress fields are concentrated around the welding line and large residual stresses are left. The effect of the welding line movement is like a rigid string and the selected nodes of the thin part near the welding line show the related larger strain.

The Application of FEM Technology on the Deformation Analysis of the Aero Thin-Walled Frame Shape Workpiece

Many thin-walled structure components widely used in aero industries not only have complex structure and large size, but also need high machining accuracy. However, because of their poor rigidity, it is easy to bring machining deformation caused by the existence of the initial residual stresses, the fixing stresses, cutting forces and cutting heat. The difficulty in ensuring their machining accuracy becomes a big problem, so that how to effectively predict and control the machining deformation has become an important subject in the development and production of our national defense weapons. This paper established a 3-D Finite element model with consideration of milling forces, clamping forces and initial residual stress field. By using this model, machining deformation of thin-walled frame shape workpieces has been computed. The simulated results are compared with experimental data, and the correctness of the simulation is verified. The study is helpful to the prediction and the control of machining deformation for thin-walled parts.