scholarly journals VOID EVOLUTION BEHAVIOR AND CLOSURE CRITERION INSIDE LARGE SHAFT FORGINGS DURING A FORGING PROCESS

2021 ◽  
Vol 55 (3) ◽  
Author(s):  
Yongxing Jiao ◽  
Cunlong Zhou ◽  
Jiansheng Liu ◽  
Xuezhong Zhang ◽  
Wenwu He
Keyword(s):  
Effective Stress ◽  
Shape Change ◽  
Effective Strain ◽  
Great Influence ◽  
Hydraulic Press ◽  
Stress Deviator ◽  
Void Closure ◽  
Forging Process ◽  
Void Shape ◽  
Simulation Results

In this study, the effects of different void positions, void shapes and sizes on the evolution of voids were discussed in detail using experiments and simulations. The results show that the influence of the void size on the void closure can be ignored, while the void position and void shape have a great influence on the closure of a void. Considering the complexity of the void-shape change in a forging process, we proposed a quantitative expression of the void-shape coefficient, which is affected by the effective stress and effective strain. Meanwhile, the void-shape evaluation parameter, defined as a function of the stress deviator, effective strain and effective stress, was proposed to describe the changes in the void aspect ratio. Finally, WHF (wide die heavy blow) forging experiments were conducted using a 5MN hydraulic press to verify the numerical-simulation results. Based on the experimental and simulation results, a new mathematical model for void-closure determination was established during a forging process of large shaft forgings. The experimental results were consistent with the simulation results, showing that the void-closure model can accurately determine whether a void is closed or not.

Validation of the Tabulated Johnson-Cook Model for a Dynamic Compression Simulation

2015 ◽  
Vol 782 ◽  
pp. 245-251
Author(s):  
Guo Ju Li ◽  
Qun Bo Fan ◽  
Rui Hua Gao ◽  
Jin Tao Liu ◽  
Cheng Miao
Keyword(s):  
Effective Stress ◽  
Dynamic Compression ◽  
Effective Strain ◽  
Element Model ◽  
Strain Rates ◽  
Fitting Procedures ◽  
Data Points ◽  
Simulation Results ◽  
The Stability ◽  
Cook Model

MAT224 is a tabulated version of the Johnson-Cook model in LS-DYNA. Compared with the original Johnson-Cook material, MAT224 was developed to simulate the dynamic response of a material by just defining the effective stress as a function of effective plastic strain at different strain rates and temperatures, thus avoiding the tedious parameter fitting procedures in the traditional Johnson-Cook model. However, the stability and precision of solution is strongly dependent on the effective stress versus effective strain curves in MAT224, and unreasonable curve data will lead to warnings or errors in the process of solution. In the current study, a two-dimensional axisymmetric finite element model for the Ti-6Al-4V titanium alloy under dynamic compression was built, and MAT224 was employed. By investigating the effects of the curve numbers, strain ranges, data points, as well as changing tendencies, on the simulation results, the stability and the reliability for MAT224 are systematically studied.

scholarly journals Establishment and Application of the Void Closure Prediction Model of 316LN

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Min Qin ◽  
Jiansheng Liu ◽  
Jingdan Li
Keyword(s):  
Stainless Steel ◽  
Prediction Model ◽  
Large Scale ◽  
Effective Strain ◽  
Fem Simulation ◽  
Closure Model ◽  
Forming Process ◽  
Void Closure ◽  
Forging Process ◽  
316Ln Stainless Steel

The presence of voids in the ingot affects the mechanical properties of the final products of the forging process. It is essential to establish a void closure model to predict cavity closure in the forging process to optimize the forging process and improve forging quality. The main purpose of this study is to obtain an accurate prediction model of void closure for 316LN stainless steel. Using the FEM simulation method to study the closure of spherical voids during forging compression of 316LN materials, we can accurately characterize the state of void closure. The void closure ratio K under different deformations at 1,200°C was counted, and the relationship between K and the effective strain was established to obtain the void closure prediction model of 316LN stainless steel. The void closure prediction model is implanted into DEFORM software through the secondary development method to generate the void closure ratio K. In the postprocessing module of DEFORM software, the void closure status of each part during the forming process can be directly observed. Comparing the results of large-scale upsetting experiments and simulation results, the closure error of each part was only 3%, which indicates that the void closure model established in this paper has higher accuracy, which is helpful for the optimization of the forging process and the control of forging quality.

Forging Process Design of Al Rotating Arm Holder by FE Analysis

2007 ◽  
Vol 26-28 ◽  
pp. 99-102
Author(s):  
Kwan Do Hur ◽  
Hyo Young Lee ◽  
Hong Tae Yeo
Keyword(s):  
Structural Analysis ◽  
Safety Factor ◽  
Effective Stress ◽  
Process Design ◽  
Aluminium Alloys ◽  
Fuel Efficiency ◽  
Effective Strain ◽  
Fe Analysis ◽  
Passenger Car ◽  
Forging Process

Aluminium alloys have been widely used in the structure of aircraft and passenger car because of its lightweight. It is also interested in the lightweight products to improve the fuel efficiency. In this research, forging design of Al rotating arm holder has been studied by FE analysis. Structural analysis of the model was performed at first. From the results of the analysis, effective stress, effective strain and safety factor acting on the component were obtained.

Simulation of Void Defect Evolvement during the Forging of Steel Ingot

2010 ◽  
Vol 97-101 ◽  
pp. 3079-3084 ◽  
Author(s):  
Kun Chen ◽  
Yi Tao Yang ◽  
Ke Jia Liu ◽  
Guang Jie Shao
Keyword(s):  
Steel Ingot ◽  
Effective Strain ◽  
Simulation Method ◽  
Experimental Results ◽  
Void Closure ◽  
Void Defect ◽  
Forging Process ◽  
Calculation Results ◽  
Critical Reduction

Simulation method of void defect evolvement during the forging of steel ingot was determined by comparing simulated and experimental results of void closure in the cylinder specimens during forging. Calculation results of long and short void defect evolvement during forging indicated that effective strain required for void closure was induced by the integration of stress. The closure of tetrahedral void is the most difficult with the maximal values of critical reduction on void closure during forging, on the basis of which, theory basis is provided for making forging process.

Optimization of the Hot Forming Processes for the Connecting Rod

2012 ◽  
Vol 461 ◽  
pp. 721-724
Author(s):  
Xia Chen ◽  
Yang Yi ◽  
Qing Ming Chang ◽  
Yun Xiang Zhang ◽  
Sheng Liu
Keyword(s):  
Stress Field ◽  
Effective Stress ◽  
Strain Field ◽  
Effective Strain ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Connecting Rod ◽  
3D Fem ◽  
Forging Process ◽  
Deform 3D

A three-dimensional thermo-mechanically coupled FEM-simulation of the production of a connecting rod has been performed between dies (pre- and final-forging). According to the part’s characters and its dimensions, a hammer die forging process was determined. According to the hammer die process, three-dimensional connecting nod model was built in UG software and two different cases for pre-forging was designed. Different forming case was simulated by Deform-3D FEM program, the effective stress field and effective strain field were analyzed by comparison; it proved that optimized performing process was reasonable and can be used as reference in production.

scholarly journals Numerical and Experimental Investigation on the Effect of Billet Preforming in the Flange Forming

2018 ◽  
Vol 7 (4.7) ◽  
pp. 188
Author(s):  
Abdullah M.N ◽  
. .
Keyword(s):  
Finite Element ◽  
Effective Stress ◽  
Effective Strain ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
Hydraulic Press ◽  
Filling Material ◽  
Cold Forming ◽  
Lead Metal ◽  
Flange Forming

Finite element method and experiments have been used to study a cold forming method for fabrication of a flange using the effect of billet preforming. Three dimensional finite element methods carried out to obtain the forming load, die filling, material flow,  effective stress, effective strain  with DEFORM-3D software, and a series of experimental works has been performed using lead metal with four types of  billet preforming in the first stage. Pressing process has been done using computerized hydraulic press machine with 100 tons. The forming sequence is carried out in two stages. In the first stage, the cylindrical billet is preformed by upsetting and in the second stage forming it in a die. Results indicate that the process of formation is influenced by preforming of billet with fixed volume in the final stage of pressing, improve the mechanical properties of the metal and thus facilitates the final deformation process with less stress and better flow of the metal inside the die. Simulation results show that the effective stress, maximum principal stress, effective strain, velocity and damage are maximum at locations where flange open out and rib growth begins across the geometrical interlocking between the two halves of die-set and the component surface.  

scholarly journals Microstructure evolution of 20Cr steel spider during cold forging using cellular automaton method

2018 ◽  
Vol 24 (1) ◽  
pp. 43
Author(s):  
Kun Xia Wei ◽  
Ling Niu ◽  
Wei Wei ◽  
Qing Bo Du ◽  
Igor V. Alexandrov ◽  
...  
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Effective Strain ◽  
Numerical Approach ◽  
Cold Forging ◽  
Forging Process ◽  
Microhardness Distribution ◽  
Ca Model ◽  
Simulation Results ◽  
Cellular Automaton Method

<p class="AMSmaintext"><span lang="EN-GB">The microstructure evolution of 20Cr steel spider in the cold forging process was simulated and analyzed by CA method, and verified by the experimental results. The CA simulation results show that the grain size becomes smaller with an increase of forging reduction. When the reduction is 60%, the grain size is the smallest. After that, the microstructure is inhomogeneous. At the same forging reduction, the microhardness at the root of the pin is higher than that at the head of the pin. It is well agreed with the distribution of the effective strain. The CA results agree well with the experimental data in terms of microstructure evolution and microhardness distribution, suggesting that the CA model is a reliable numerical approach for predicting microstructure evolution during cold forging for 20Cr steel spider.</span></p>

Modeling and Numerical Simulation Research on Hollow Steel Ingot Forging Process of Heavy Cylinder Forging

2013 ◽  
Vol 712-715 ◽  
pp. 627-632
Author(s):  
Min Liu ◽  
Qing Xian Ma
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Shear Zone ◽  
Grain Refinement ◽  
Steel Ingot ◽  
Effective Strain ◽  
Meridian Plane ◽  
Forging Process ◽  
Forming Load ◽  
Average Grain Size

Aiming at the disadvantages of low utilization ratio of steel ingot, uneven microstructure properties and long production period in the solid steel ingot forging process of heavy cylinder forgings such as reactor pressure vessel, a new shortened process using hollow steel ingot was proposed. By means of modeling of lead sample and DEFORM-3D numerical simulation, the deformation law and grain refinement behavior for 162 ton hollow steel ingot upsetting at different reduction ratios, pressing speeds and friction factors were investigated, and the formation rule of inner-wall defects in upsetting of hollow steel ingots with different shape factors was further analyzed. Simulation results show that the severest deformation occurs in the shear zone of meridian plane in the upsetting process of hollow steel ingot, and the average grain size in the shear zone is the smallest. As pressing speed increases, the forming load gradually increases and the deformation uniformity gets worse, while the average grain size decreases. An increase in friction factor can increase the peak value of effective strain, but it significantly reduces the deformation uniformity, increases the forming load and goes against grain refinement. Moreover, the four kinds of defects on the inner wall of steel ingot can be eliminated effectively by referring to the plotted defect control curve for hollow steel ingot during high temperature upsetting.

Investigations of The Hybrid Effects of The Operational Parameters In The Radial Forging Process Based On The Validation of The Hardness Test

2022 ◽  
Author(s):  
Saeed Darki ◽  
Evgeniy Yurevich Raskatov
Keyword(s):  
Effective Strain ◽  
Three Dimensional ◽  
Hardness Test ◽  
Radial Forging ◽  
Operational Parameters ◽  
Three Dimensional Model ◽  
Temperature Changes ◽  
Forging Process ◽  
Specimen Tube ◽  
Radial Forging Process

Abstract In this study, considering all the parameters in radial forging and a three-dimensional model has been simulated using the finite element method. By implementing an elastoplastic state for the specimen tube, parameters such as friction type, residual stress distribution, effective strain distribution, material flow velocity and its effect on the neutral plate and the distribution of force in the die have been studied and analyzed. The effects of angle on the quality and characteristics of the specimen and the longevity of the die have also been obtained. Experimental results have been used to confirm the accuracy of the simulation. The results of the hardness test after forging were compared with the simulation results. Good agreement between the results indicates the accuracy of the simulation in terms of hardness. Therefore, this validation allows confirming the other obtained results for the analysis and prediction of various components in the forging process. After the validation and confirmation of the results through the hardness test, the hardness distribution was obtained by considering temperature changes and the effective strain on the specimen.

Finite Element Simulation and Experimental Study on Isothermal Forging Technology for a Complex-Shaped Titanium Alloy Wing

2013 ◽  
Vol 575-576 ◽  
pp. 523-526
Author(s):  
Feng Cheng ◽  
Hong Yan Jiang
Keyword(s):  
Titanium Alloy ◽  
Variable Cross Section ◽  
Hydraulic Press ◽  
Asymmetric Structure ◽  
Variable Cross ◽  
Forming Process ◽  
Isothermal Forging ◽  
Filling Ability ◽  
Simulation Results ◽  
Mechanical Performances

A closed isothermal forging process was adopted for precision forming of the Ti-6Al-4V wing with a variable cross-section asymmetric structure. Firstly, simulations under different process parameters, such as the deformation temperature, punchs velocity et al. were analyzed with DEFORM-3D software to eliminate the defects in the isothermal forming process. The simulation results demonstrated that the loads during isothermal deformation were determined not just by the forging temperature but the punchs velocity, the less velocity of punch, the better filling ability, and yet temperatures from 900 to 950°C had less influence on filling ability. To verify the validity of simulation results, the isothermal forging experiment was carried out on an isothermal forging hydraulic press (THP10-630). It is demonstrated that the optimized billet dimension can ensure the quality of forging part and the titanium alloy wing component with complex shape was successfully forged with the punch speed of 0.1mm/s at 950°C and its mechanical performances were improved.

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