Experimental and numerical studies on flow behavior of surface defects in the heavy rail rolling

2018 ◽  
Vol 35 (3) ◽  
pp. 1279-1300
Author(s):  
Chenggang Pan ◽  
Zizheng Ding ◽  
Qingming Chang ◽  
Jialin Zhou
Keyword(s):  
Finite Element ◽  
Continuous Casting ◽  
Surface Defect ◽  
Surface Defects ◽  
Flow Behavior ◽  
Modified Model ◽  
Content Type ◽  
Explicit Dynamic ◽  
Heavy Rail ◽  
Good Agreement

Purpose Surface defects are often present on the surface of continuous casting slabs and rolled products. A lot of surface defects of hot rolled products are inherited from initial defects on continuous casting slabs. This work aims to trace the original surface defect during the whole heavy rail rolling and avoid black line surface defect that appears on the surface of heavy rail finial product. Design/methodology/approach Artificial round hole-shaped surface defects on the surface of continuous casting slab during the hot rolling of 60 kg/m heavy rail are analyzed experimentally and by means of explicit dynamic finite element method (FEM) and modified model rebuilding method. Findings The calculated results of surface defect locations of heavy rail finial product are in good agreement with the experimental ones. It is shown that the explicit dynamic FEM and modified model rebuilding method can be used effectively to predict the flow behavior of surface defects in the hot rolling of 60 kg/m heavy rail. Originality/value The three-dimensional finite element model for whole heavy rail rolling is built using explicit dynamic code and modified model rebuilding method. Flow behavior of black lines is studied in the 60-kg/m heavy rail rolling. The simulation results of six typical points are in good agreement with the experimental results.

Numerical investigation of in-mold electromagnetic stirring process for fluid flow and solidification

2017 ◽  
Vol 36 (4) ◽  
pp. 1106-1119 ◽  
Author(s):  
Ambrish Maurya ◽  
Pradeep Kumar Jha
Keyword(s):  
Finite Element ◽  
Fluid Flow ◽  
Continuous Casting ◽  
Finite Volume ◽  
Flow Behavior ◽  
Hybrid Approach ◽  
Liquid Core ◽  
Electromagnetic Stirring ◽  
Solid Shell ◽  
Content Type

Purpose The purpose of present investigation is to analyze the in-mold electromagnetic stirring (M-EMS) process and the effect of stirrer frequency on fluid flow and solidification in a continuous casting billet caster mold. Design/methodology/approach A hybrid approach involving finite element and finite volume method has been used for the study. Finite element model is used to calculate time variable magnetic field, which is further coupled with fluid flow and solidification equations for magneto-hydrodynamic analysis with finite volume model. Findings Results show that though superheat given to steel before its entry into the mold is quickly removed, solid shell formation is delayed by the use of M-EMS. Final solid shell thickness, however, is slightly reduced. Increase in frequency is found to increase the magnetic flux density and tangential velocity of liquid steel and decrease in diameter of liquid core. Practical implications The work is of great industrial relevance. The model may be used to design industrial setup of in-mold electromagnetic stirrer and process could be analyzed and optimized numerically. Originality/value The paper evaluates the influence of M-EMS and its frequency on solidification and flow behavior in the continuous casting mold. The iso-surface temperatures from pouring temperature to liquidus temperature inside the mold have been shown. The findings may be useful for the steelmakers to reduce the defect in continuous casting.

Homogenization of multi-turn coil with elliptic cross-section using complex permeability

2019 ◽  
Vol 38 (3) ◽  
pp. 999-1008 ◽  
Author(s):  
Shogo Fujita ◽  
Hajime Igarashi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Elements ◽  
Cross Section ◽  
Fe Analysis ◽  
Complex Permeability ◽  
Elliptic Cross Section ◽  
Content Type ◽  
Elliptic Cross ◽  
Good Agreement

Purpose The tensor complex permeability of a multi-turn coil with elliptic cross-section is analytically expressed. In field analysis, a multi-turn coil can be modeled by the uniform material that has the present tensor complex permeability. It is shown that the frequency characteristic of the present tensor complex permeability is in good agreement with that evaluated by finite element method applied to a unit cell of the multi-turn coil region. Design/methodology/approach The authors introduce a new method to evaluate the complex permeability of a multi-turn rectangular coil. To obtain the complex permeability of a rectangular coil in a closed form, it is approximated as an elliptic coil. Because the rectangular coil has different complex permeabilities in the vertical and horizontal directions, the complex permeability have to be defined in a tensor form. It suffices to discretize the coil region into rather coarse finite elements without considering the skin depth in contrast to the conventional finite element method. Findings The proposed method is shown to give the impedance of multi-turn coils which is in good agreement with results obtained by the conventional finite element (FE) analysis. By extending the proposed approach, the authors can easily perform 3D FE analysis without difficulty in discretization of the coil region with fairly fine finite elements. Moreover, they found that the approximation of rectangular coils as the elliptic coils is valid for analysis of quasi-static fields using this homogenization method. Originality/value The novelty of this study is in the approximation of the rectangular coils with elliptic coils, and the complex permeability for them is formulated here in a closed form. The proposed formula includes that for the round coils. Using the present method, the authors analyze the rectangular coils without fine discretization.

Experimental and finite element investigation of a local dent on a pressurized pipe

1992 ◽  
Vol 27 (3) ◽  
pp. 177-185 ◽  
Author(s):  
L S Ong ◽  
A K Soh ◽  
J H Ong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Surface Defect ◽  
Peak Stress ◽  
Plastic Collapse ◽  
Hoop Strain ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Local Dent ◽  
Good Agreement

The problem of a local dent on a pressurized pipe is studied in this paper. Two case problems of dent are considered - a plain local dent (a smooth local dent without a surface defect), and a local dent associated with a loss of thickness defect. The strain gauging test and the finite element analysis on the plain local dent showed that the strain distributions in the local dent are different from those of a long and continuous dent. The maximum hoop strain in the local dent is located at the flank of the dent, along the dent axial axis, whereas in the case of the long dent, it is located at the root of the dent. In addition, the peak stress in the local dent is generally lower than that in the long dent. To estimate the stress concentration in the local dent using the analysis for the long dent would be grossly overestimated. The burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents. The pipe failures were found to be due to the loss-of-thickness defect. The comparison of results between the burst pipe tests and the plastic collapse formula shows reasonably good agreement.

A semi-analytical analysis on beam-column ultimate strength with different initial deflections

2016 ◽  
Vol 13 (6) ◽  
pp. 487-493
Author(s):  
Zhongwei Li ◽  
Xiaochuan Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Ultimate Strength ◽  
Design Methodology ◽  
Computer Code ◽  
Element Analysis ◽  
Content Type ◽  
Beam Columns ◽  
Different Shapes ◽  
Good Agreement

Purpose A new beam-column ultimate strength calculation method has been developed and compared with nonlinear finite element analysis by ANSYS and ABAQUS. Design/methodology/approach A computer code ULTBEAM2 based on this method has been used for one and three span beam-columns with I-shaped cross-section under axial compression. Findings This paper studies the ultimate strength of beam-columns with various initial deflections of different shapes and magnitudes. Originality/value The comparison of ULTBEAM2 and finite element analysis shows good agreement for all cases with different initial deflections.

scholarly journals Measurement of Molten Steel Velocity near the Surface and Modeling for Transient Fluid Flow in the Continuous Casting Mold

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 36 ◽  
Author(s):  
Tao Zhang ◽  
Jian Yang ◽  
Peng Jiang
Keyword(s):  
Continuous Casting ◽  
Molten Steel ◽  
Casting Speed ◽  
Surface Defects ◽  
Transient Flow ◽  
Flow Behavior ◽  
Surface Velocity ◽  
Phase Method ◽  
Mold Surface ◽  
Continuous Casting Mold

In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, a mathematical model combining the computational fluid dynamics (CFD) and discrete phase method (DPM) has been developed to calculate the transient flow field in a CC mold. The simulation results are compared and validated with the plant measurement results. Reasonable agreements between the measured and simulated results are obtained, both in the trends and magnitudes for the flow velocities of molten steel near the mold surface. Based on the measured and calculated results, the velocity of molten steel near the surface in the mold increases with increasing casting speed and the casting speed can change the flow pattern in the mold. Furthermore, three different types of flow patterns of molten steel in the mold can be obtained. The pattern A is the single-roll-flow (SRF) and the pattern C is the double-roll-flow (DRF). The pattern B is a transition state between DRF and SRF, which is neither cause the vortices nor excessive surface velocity on the meniscus, so the slag entrainment rarely occurs. Argon gas injection can slow down the molten steel velocity and uplift the jet zone, due to the buoyancy of bubbles. Combination of the measurement and numerical simulation is an effective tool to investigate the transient flow behavior in the CC mold and optimize the actual operation parameters of continuous casting to avoid the surface defects of the automobile outer panels.

Surface Defect Inspection of Pressure Equipment Based on Indentation and Numerical Simulation

2017 ◽  
Vol 734 ◽  
pp. 285-292
Author(s):  
Heng Rui Zhao ◽  
Guang Xu Cheng
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Surface Defect ◽  
Surface Defects ◽  
Indentation Test ◽  
Characteristic Size ◽  
Pressure Vessels ◽  
Finite Element Models ◽  
Pressure Vessel Steel ◽  
Vessel Steel

Surface defects caused by damage or corrosion are major factor in petrochemical pressure vessels and line pipes failure. The characteristic size of typical surface defect is from micron to submillimeter which belongs to mesoscopic scale, leading to difficulties for inspection and evaluation. The instrumented indentation method has widely used in the characterization of micro-zone mechanical behavior which could be effective in surface defects analysis. This paper aims at investigating the correspondence between indentation experimental results and distribution characteristics of surface defects. Mechanical properties of pressure vessel steel with surface defects are measured by indentation, and corresponding finite element models are established. Finite element simulation results of equivalent mechanical properties under indentation and three dimensional deformations are compared, and the applicability of finite element models for indentation test of steel with surface defects is analyzed. The effect of randomized surface defects on measuring result is studied subsequently using stochastic finite element models. The relation of equivalent mechanical properties and description of surface defects is proposed. The achievement could used to estimate the degree of damage or corrosion by miniature indentation testing techniques for safety assessment.

scholarly journals Circumferential defect detection using ultrasonic guided waves

2020 ◽  
Vol 37 (6) ◽  
pp. 1923-1943 ◽  
Author(s):  
Yihui Da ◽  
Guirong Dong ◽  
Yan Shang ◽  
Bin Wang ◽  
Dianzi Liu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Guided Waves ◽  
Surface Defects ◽  
Ultrasonic Guided Waves ◽  
Content Type ◽  
Dispersion Equations ◽  
Circular Annulus ◽  
Equidistant Surface ◽  
Element Method

Purpose Quantitatively detecting surface defects in a circular annulus with high levels of accuracy and efficiency has been paid more attention by researchers. The purpose of this study is to investigate the theoretical dispersion equations for circumferential guided waves and then develop an efficient technique for accurate reconstruction of defects in pipes. Design/methodology/approach The methodology applied to determine defects in pipelines includes four steps. First, the theoretical work is carried out by developing the appropriate dispersion equations for circumferential guided waves in a pipe. In this phase, formulations of strain-displacement relations are derived in a general equidistant surface coordinate. Following that, a semi-analytical finite element method (SAFEM) is applied to solve the dispersion equations. Then, the scattered fields in a circular annulus are calculated using the developed hybrid finite element method and simulation results are in accord with the law of conservation of energy. Finally, the quantitative detection of Fourier transform (QDFT) approach is further enhanced to efficiently reconstruct the defects in the circular annuli, which have been widely used for engineering applications. Findings Results obtained from four numerical examples of flaw detection problems demonstrate the correctness of the developed QDFT approach in terms of accuracy and efficiency. Reconstruction of circumferential surface defects using the extended QDFT method can be performed without involving the analytical formulations. Therefore, the streamlined process of inspecting surface defects is well established and this leads to the reduced time in practical engineering tests. Originality/value In this paper, the general dispersion equations for circumferential ultrasonic guided waves have been derived using an equidistant surface coordinate and solved by the SAFEM technique to discover the relationship between wavenumber of a wave and its frequency. To reconstruct defects with high levels of accuracy and efficiency, the QDFT approach has been further enhanced to inspect defects in the annular structure.

scholarly journals A Load Identification Application Technology Based on Regularization Method and Finite Element Modified Model

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bingrong Miao ◽  
Feng Zhou ◽  
Chuanying Jiang ◽  
Yaoxiang Luo ◽  
Hui Chen
Keyword(s):  
Finite Element ◽  
Estimation Error ◽  
Element Model ◽  
Identification Accuracy ◽  
Load Identification ◽  
Noise Levels ◽  
Application Technology ◽  
Modified Model ◽  
Ill Posed ◽  
Good Agreement

An improved load identification technology of a beam based on different regularization methods and model modifying methods is presented in an attempt to minimize the estimation error at several periodic loads. A hybrid model is developed to simulate such ill-posed problem interactions under different noise levels. The finite element model is modified with the different optimization algorithms to obtain the equivalent constraint condition. Experimental verification is also carried out to obtain correct modes and frequencies by considered vibration response and different boundary conditions. The measured results demonstrate the good agreement with the identification results. The results are shown that the improved method not only has more adaptive range and higher identification accuracy but also has effective identification ability for loads under different noise levels.

Assessment Techniques Using the R6 Procedure: Investigation of Limit Load Approach for Pipe Branch Connections

2010 ◽  
Author(s):  
Peter A. Frost
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Surface Defect ◽  
Surface Defects ◽  
Local Limit ◽  
Limit Load ◽  
Elliptic Surface ◽  
Element Analysis ◽  
Limit Loads ◽  
Failure Assessment

The R6 Revision 4 Procedure ‘Assessment of the Integrity of Structures Containing Defects’, states that the use of the finite element ‘global’ limit load derived for pipe branch components can be non-conservative when used with the Option 1 and 2 failure assessment curves but that ‘local’ limit loads, based on the spread of plasticity through the pipe wall, should lead to conservative results. The current advice of R6 is based on separate studies by Fox and Connors of pipe branch components with fully extended surface defects. Their studies provide two distinct methods for calculating a suitably conservative local limit load. However, there is concern that these two methods may provide an overly conservative local limit load with therefore a less realistic prediction of defect tolerance. Furthermore, typical defectiveness is perhaps most commonly characterised as a semi-elliptic surface defect and it is therefore necessary to adapt both these methods in order to accommodate such defects. The purpose of this study was therefore to investigate local limit load approaches for pipe branch components with postulated semi-elliptic surface defects. A typical pipe branch component was chosen for assessment during this study, as part of a series of separate studies on a variety of pipe branch components. Local limit loads were calculated using two approaches. The first approach adapted the ‘Connors’ method by applying an adjustment to allow for the semi-elliptic surface defect; this is referred to as the ‘Modified Connors’ approach. The second approach used cracked body finite element analysis and evaluated the local limit load by consideration of the onset of plasticity at the crack ligament. The global limit load was also derived from the cracked body finite element analysis. Assessment points were developed using global and local limit loads, both obtained by cracked body finite element analysis, and also by using the ‘Modified Connors’ local limit load approach. R6 Option 3 failure assessment curves were produced for each limit load approach in order to investigate the extent of any non-conservatism in the Option 1 and 2 failure assessment curves with the chosen limit load approach.

Analysis of the Contact Deformation of Tread Blocks

1992 ◽  
Vol 20 (4) ◽  
pp. 230-253 ◽  
Author(s):  
T. Akasaka ◽  
K. Kabe ◽  
M. Koishi ◽  
M. Kuwashima
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Deformation Behavior ◽  
Contact Deformation ◽  
The Finite Element Method ◽  
The Road ◽  
Loss Of Contact ◽  
Tread Rubber ◽  
Good Agreement ◽  
Rubber Block

Abstract The deformation behavior of a tire in contact with the roadway is complicated, in particular, under the traction and braking conditions. A tread rubber block in contact with the road undergoes compression and shearing forces. These forces may cause the loss of contact at the edges of the block. Theoretical analysis based on the energy method is presented on the contact deformation of a tread rubber block subjected to compressive and shearing forces. Experimental work and numerical calculation by means of the finite element method are conducted to verify the predicted results. Good agreement is obtained among these analytical, numerical, and experimental results.

Sign in / Sign up

Export Citation Format

Share Document