Coupled FE Analysis Research Articles

Coupled thermomechanical FE analysis of multi-pass welding in thick pipe

Coupled thermomechanical FE analysis of multi-pass welding in thick pipe

Coupled hydromechanical analysis of sparsely fractured crystalline rocks

This paper addresses the issue of evolution and coalescence of localized damage zones in sparsely fractured crystalline rocks. The approach incorporates a constitutive law with embedded discontinuity, which is phrased in terms of both the hydraulic and mechanical response. The formulation takes into account the hydromechanical interaction in regions intercepted by discontinuities. An internal length scale parameter is employed in the definition of equivalent hydraulic conductivity and the tangential stiffness operators, and the onset of newly developed macrocracks is detected by the bifurcation analysis. An enhanced mixed u-p finite element formulation is derived which considers the effect of progressive evolution of the fracture aperture in the weak statements of balance equations. Fully implicit temporal discretization is employed, and the finite element formulation is stabilized by invoking the Polynomial-Pressure-Projection (PPP) technique. A coupled FE analysis is conducted examining the response of Luc du Bonnet granite, with pre-existing fracture network, subjected to plane strain compression that triggers the crack propagation and coalescence. The approach is first verified on some benchmark problems that involve the presence of a dominant fracture. The results of simulations are compared with those obtained using a very fine mesh incorporating interface elements. Later, a series of coupled analyses are carried out examining the hydromechanical response in the presence of multiple fractures.

3D Coupled Thermo-Mechanical FE analysis of effect of process parameters in ring rolling process

3D Coupled Thermo-Mechanical FE analysis of effect of process parameters in ring rolling process

Thermal-Mechanical Coupled FE Analysis for Rotary Shaft Seals

The aim of this paper is to model the steady-state condition of a rotary shaft seal (RSS) system. For this, an iterative thermal-mechanical algorithm was developed based on incremental finite element analyzes. The behavior of the seal’s rubber material was taken into account by a large-strain viscoelastic, so called generalized Maxwell model, based on Dynamic Mechanical Thermal Analyses (DMTA) and tensile measurements. The pre-loaded garter spring was modelled with a bilinear material model and the shaft was assumed to be linear elastic. The density, coefficient of thermal expansion and the thermal conductance of the materials were taken into consideration during simulation. The friction between the rotary shaft seal and the shaft was simplified and modelled as a constant parameter. The iterative algorithm was evaluated at two different times, right after assembly and 1 h after assembly, so that rubber material’s stress relaxation effects are also incorporated. The results show good correlation with the literature data, which state that the permissible temperature for NBR70 (nitrile butadiene rubber) material contacting with ~80 mm shaft diameter, rotating at 2600/min is 100°C. The results show 107°C and 104°C for the two iterations. The effect of friction induced temperature, changes the width of the contact area between the seal and the shaft, and significantly reduces the contact pressure.

유한요소법을 활용한 평판압연에서의 롤 판 연계 해석 - Part II: 적용

A general approach is proposed for 3-D coupled FE analysis of the deformation of the strip and rolls in flat rolling. FE formulation, schemes for the treatment of contact occurring in a cluster of deforming objects, and the solution strategy are described in detail. The validity of the approach is examined through comparison with observed measurements. The approach is applied to the analysis of deformation in a four-high and six-high mill.

A three-dimensional soil–water coupled FE analysis of hollow cylinder test concerning non-uniform deformation

The hollow cylinder shear test is somewhat controversial due to its non-uniform stresses and strains, and has been analyzed by simple theoretical methods and two-dimensional FE calculations. In this paper, the hollow cylinder test under strain control was carried out numerically by treating the specimen as a three-dimensional initial-boundary value problem considering the inertial forces. At first, besides the known nonuniform strain, the non-uniformities of excess pore water pressure and overconsolidation ratio have been shown to benefit from a soil–water coupled analysis that employs the SYS Cam-clay model. Then, the influence of the specimen geometries, including wall thicknesses, heights and outer diameters on the non-uniformity was investigated sequentially. A new method for evaluating non-uniformity was proposed, which is suitable for the three-dimensional analysis. The response under a uniform deformation field, which is indicated by “the perfect path”, was presented to draw a comparison with the apparent behaviors, with non-uniformities taken into consideration. It should be noted that there is a critical height to prevent failure at the specimen ends according to the apparent behavior. Finally, the torque-controlled experiment indicated that 4 ribs could not transfer the torque reliably while 6 or 8 ribs were feasible.

3D Coupled Thermo-Mechanical FE Analysis of Surface Defects in Continuously Casting Slab

The behaviour of the surface defects on the continuous casting slab during hot rolling is investigated using the commercial FE-code LS-DYNA. The thermo-elastic-plastic material model is chosen in the simulation models, and the material implemented in the simulation is the austenitic stainless steel 304. The numerical results show the significant morphological changes of the surface defects during hot rolling and afford valuable indications for a deeper understanding of the underlying process. An accelerated crack growth and propagation are observed for the edge cracks, and the closure behaviour is found in the transverse and longitudinal cracks. The effect of temperature is significant on both the roll and the strip in hot rolling process. The developed models consider different types of mesh and element, thermal conditions, and rolling schedules. The predicted relationship between rolling conditions, the temperature distribution of crack, and the full history of temperature variation are discussed in this study.

Thermo-mechanically coupled FE analysis and sensitivity study of simultaneous hot/cold forging process with local inductive heating and cooling

The numerical investigation of the production of a stub shaft is presented, where the highly innovative metal forming technology of the simultaneous hot and cold forging is applied in combination with a hardening process performed directly in the closed forging dies after the forging step similar to press hardening of sheet metal. This complex forging process is completely analysed by means of a finite element simulation including the local inductive heating phase of the workpiece as well as the cooling process of the final stub shaft inside the forging dies. All relevant process parameters and the whole simulation model are documented in detail and the simulation results are discussed and validated by means of experimentally measured data, showing good agreement. Parameter studies for various properties of the model are carried out in order to investigate their influence on the geometry and the temperature field development, whereby a deeper understanding of the entire process is gained. Thus, a finite element benchmark analysis is provided for such a complex thermo-mechanically coupled structuring process.

Converter Coupled Finite Element Analysis of Single Phase Switched Reluctance Motor

This paper deals with the characteristic analysis of the single phase switched reluctance motor based on the converter coupled FE analysis. The converter comprises a rectifier, LC filter and switching power device. A computational technique for the converter coupled FE analysis is introduced and its validity is proven by the experiment.

Towards the three-dimensional FE analysis of rapid prototyping tools for sheet metal stamping process

For low volume production or for rapid prototyping, sheet metal stamping tools can be made by an assemblage of steel sheets or layers and joined by several techniques (such as screws, bolts, brazing, adhesive). However, an important problem in the design and the production of such tools is their mechanical behaviour, in particular the strength of joining techniques which is crucial in the aim of achieving the high required reliability of tools. If tools mechanical behaviour can be mastered and accurately predicted this can increase the tools life duration and be more beneficial for the manufacturing community. In order to properly predict the mechanical behaviour of tools, numerical simulation of stamping taking into account, elastic deformation of tools within a coupled FE analysis is needed. However, simulation results show that the effort and computational times required for such a coupled simulation, in particular in a general three-dimensional (3D) case, could be prohibitive and unrealistic. In this paper, the authors proposed and developed a numerical procedure in two steps, which has the advantage of decoupling the simulation of the blank forming and the stress analysis of the elastic tools. Numerical application is presented for a layered stamping punch, based on the Stratoconception ® rapid prototyping process, joined by screws in addition to an epoxy adhesive. The results are focussed on the screws behaviour, showing the potential interest of the developed procedure and numerical modelling technologies in designing layered tools joined by screws.

The Dynamic Performance Analysis Model of EMS-MAGLEV System Utilizing Coupled Field-Circuit-Movement Finite Element Method

Many electro-mechanical motional systems include parts that can move relative to the others. EMS-Maglev system is one of the examples, which combines the devices for propulsion, levitation and on-board electric power transfer in a single electromagnetic structure. The analysis of its mechanical dynamic characteristics is very important for the design of the configuration and the control system. Because of the complexity of the time-varying magnetic configuration, analytical method can hardly obtain the dynamic performance. Therefore, analysis of the electromagnetic field is necessary. Moreover, with ordinarily transient finite element method, it is also difficult to consider the external power supply of linear synchronous motors and the working status of linear generator. In this paper, a modified transient finite element algorithm for the performance analysis of magnetically levitated vehicles of electromagnetic type is presented. The algorithm incorporates external power system and vehicles movement equations into FE model of transient magnetic field computation directly. Sliding interface between stationary and moving region is used during the transient analysis. The periodic boundaries are implemented in an easy way to reduce the computation scale. Unfortunately, this directly coupled FE analysis is very time-consuming. To overcome this problem, a fast solving technique for the mechanical dynamic characteristic of electromechanical motional systems is also proposed in this paper. Based on a sequence of finite element analysis, and a set of equivalent electrical circuit parameters extracted, the method incorporates electrical equation and vehicles movement equation into state equations. It is proved that this method can be used for both electromotional static and dynamic cases. Through test of a transformer and an EMS-MAGLEV system, it reveals that the method gives reasonable results at very low computational costs comparing with transient finite element analysis.

Analyses of Lateral Displacement of a Pile Supported Abutment Constructed in a Soft Subsoil Profile

A case study on the measurement of lateral movement of an abutment supported by pile groups constructed in a cohesive soil is reported in this paper. Based on prediction at the design stage and observational construction control, the abutment was successfully constructed within the range of allowable lateral movement. After the completion of construction, the 3D elasto-plastic coupled FE analysis based on the Cam-clay model was applied to the problem. Although the analysis overpredicted the lateral movement, it was indicated that such analysis is useful for evaluating the mechanism of lateral movement of such an abutment and the effect of the weak surface soil, replaced by more “competent” material.