Assessment of ductile fracture criteria with respect to their application in the modeling of cross wedge rolling

Pater, Z.; Tomczak, J.; Bulzak, Tomasz; Wójcik, Łukasz; Walczuk, Patrycja

doi:10.1016/j.jmatprotec.2019.116501

Cited by 39 publications

(25 citation statements)

References 38 publications

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“…21) The occurrence of ductile fractures can be modelled by calculating the damage function, which ought to be smaller than the critical damage value obtained in the calibrating test. [22][23][24] In this analysis normalised Cockcroft-Latham criterion was used for modelling damage. The damage function is described from the dependency: 2) where: f CL -damage function according to the normalised Cockcroft-Latham criterion, -; σ 1 -maximum principal stress, MPa; σ i -effective stress, MPa; ε -effective strain, -.…”

Section: Determining the Critical Damage Value Of 42crmo4 Grade Steelmentioning

confidence: 99%

Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles

et al. 2021

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Section: Determining the Critical Damage Value Of 42crmo4 Grade Steelmentioning

confidence: 99%

Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles

et al. 2021

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“…It turns out that performing the rolling process with the use of three tools leads to reducing the value of the Cockcroft-Latham criterion. When parts are skew rolled with two tools [28,29], the Cockcroft-Latham criterion is very high (above 2), which poses a high risk of material cracking. By changing the rolling pattern (three tools are used), the Cockcroft-Latham criterion can be reduced by several times, and therefore the probability of internal cracking in the steps of rolled shafts can be reduced, too.…”

Section: Fem Analysis Of a Skew Rolling Process For Stepped Axles Andmentioning

confidence: 99%

Design and technological capabilities of a CNC skew rolling mill

Tomczak

Pater

Bulzak

et al. 2021

Archiv.Civ.Mech.Eng

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Results of a study investigating a skew rolling process for elongated axisymmetric parts are presented. Despite the fact that the skew rolling technique for producing such parts was developed and implemented in the mid-twentieth century, there are no studies on this problem. The first part of this paper presents the results of FEM modelling of skew rolling stepped axles and shafts (solid and hollow). The FEM analysis was performed using the MSC Simufact Forming software. The numerical simulation involved the determination of metal flow patterns, the analysis of thermal parameters of the material during rolling, and the prediction of cracking by the Cockcroft-Latham ductile fracture criterion. Force parameters of rolling solid and hollow parts were also determined. The aim of the FEM analysis was to determine initial design assumptions and parameters for the development of the skew rolling mill. Later on in the paper, a design solution of a CNC skew rolling mill for rolling parts based on their envelope profile is proposed. FEM strength test results of a mill stand, obtained with MSC. NASTRAN, are presented. Finally, the performance test results of the constructed rolling mill are presented. The experiments involved rolling real stepped shafts that were modelled numerically. Obtained results show that the proposed skew rolling method has considerable potential. The designed and constructed rolling mill can be used to perform the rolling process according to the proposed method, with the tool and material kinematics being controlled based on the set parameters of a workpiece envelope.

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“…The temperature of the tools during the rolling process was maintained constant at 50 °C. The exchange of heat between the tools and the material was described by the coefficient of heat exchange set equal to 10,000 W/m 2 K [ 19 , 21 , 45 ].…”

Section: Numerical Analysis and Validation Of The Numerical Modelmentioning

confidence: 99%

“…Conducted under hot forming conditions, the tests showed that the critical damage depends greatly on temperature. Using the developed calibration tests, Pater et al [ 19 ] evaluated fracture criteria in terms of their suitability for modelling CWR processes. It was found that the criteria which take into account, at least indirectly, the effect of shear stresses yield better results.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Critical Value of Material Damage in a Cross Wedge Rolling Test

et al. 2021

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This study investigates the problem of material fracture in cross wedge rolling (CWR). It was found that this problem could be analysed by means of well-known phenomenological criteria of fracture that are implemented in commercial FEM (Finite Element Method) simulation programs for forming processes. The accuracy of predicting material fracture depends on the critical damage value that is determined by calibration tests in which the modelled and real stresses must be in good agreement. To improve this accuracy, a new calibration test is proposed. The test is based on the CWR process. Owing to the shape of the tools and test piece used in CWR, the forming conditions in this process deteriorate with the distance from the centre of the test piece, which at a certain moment leads to fracture initiation. Knowing the location of axial crack initiation in the specimen, it is possible to determine the critical value of material damage via numerical simulation. The new calibration test is used to determine the critical damage of 42CrMo4 steel subjected to forming in the temperature range of 900–1100 °C. In addition, 12 criteria of ductile fracture are employed in the study. The results show that the critical damage significantly increases with the temperature.

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Assessment of ductile fracture criteria with respect to their application in the modeling of cross wedge rolling

Cited by 39 publications

References 38 publications

Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles

Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles

Design and technological capabilities of a CNC skew rolling mill

Determination of the Critical Value of Material Damage in a Cross Wedge Rolling Test

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