Simulative Study of Evolution Behavior of Transverse Surface Crack in Rolling Process

2011 ◽  
Vol 403-408 ◽  
pp. 88-92
Author(s):  
Ya Gao ◽  
Jian Lin Sun ◽  
Bing Yun
Keyword(s):  
Tensile Stress ◽  
Surface Crack ◽  
Rolling Direction ◽  
Crack Tip ◽  
Element Model ◽  
Rolling Process ◽  
Friction Coefficients ◽  
High Crack ◽  
Explicit Finite Difference ◽  
Evolution Behavior

Based on explicit finite difference algorithm, finite element model of steel plate with transverse surface crack in rough rolling was found. The evolution regularity of transverse surface crack in rolling process was calculated with the model, and effect of different crack sizes, different friction coefficients and different roll diameters on crack evolution were studied. The research indicated that, in rolling direction, the crack tip stress changed from tensile stress to compression stress and then tensile stress again; length and depth of crack both had effect on the healing and propagation of the crack, and mostly in the way of influencing displacement of freedom surface of the crack; different friction coefficients showed no effect on crack tip propagation, but low friction coefficient would be in favor of crack healing at crack bottom; small roll diameter would lead to high crack tip tensile stress and more propagation at crack tip.

Research on Behavior of Slab Surface Defects in Forward Slip Zone during V-H Rolling Process

2008 ◽  
Vol 575-578 ◽  
pp. 243-248 ◽  
Author(s):  
Hai Liang Yu ◽  
Xiang Hua Liu ◽  
Chang Sheng Li ◽  
Li Qing Chen
Keyword(s):  
Contact Pressure ◽  
Surface Defects ◽  
Rolling Direction ◽  
Longitudinal Crack ◽  
Crack Tip ◽  
Rolling Process ◽  
Slab Surface ◽  
Forward Slip ◽  
Significant Information ◽  
Forward Slip Zone

Behavior of the transversal crack and the longitudinal crack on slab surface during V-H rolling was simulated by the FEM. The contact pressure on crack surfaces and the crack-tip stress change rules during rolling were analyzed. Results show that the contact pressure on crack surfaces decreases and the tensile stress appears at crack tip in the zone of slippage on the delivery side, which may make the cracks propagation. For the phenomenon, the stress distribution along rolling direction and along width direction in rolling are analyzed, and the influence of forward slip on the closure and growth of the surface transversal crack and the surface longitudinal crack are discussed. Results support some significant information for researching the behavior of the slab surface defects in rolling process.

Closure behavior of spherical void in slab during hot rolling process

2018 ◽  
Vol 115 (3) ◽  
pp. 301 ◽  
Author(s):  
Rong Cheng ◽  
Jiongming Zhang ◽  
Bo Wang
Keyword(s):  
Plastic Strain ◽  
Hot Rolling ◽  
Rolling Direction ◽  
Element Model ◽  
Rolling Process ◽  
Slab Thickness ◽  
Hot Rolling Process ◽  
Roller Diameter ◽  
Width Direction ◽  
The Relationship

The mechanical properties of steels are heavily deteriorated by voids. The influence of voids on the product quality should be eliminated through rolling processes. The study on the void closure during hot rolling processes is necessary. In present work, the closure behavior of voids at the center of a slab at 800 °C during hot rolling processes has been simulated with a 3D finite element model. The shape of the void and the plastic strain distribution of the slab are obtained by this model. The void decreases along the slab thickness direction and spreads along the rolling direction but hardly changes along the strip width direction. The relationship between closure behavior of voids and the plastic strain at the center of the slab is analyzed. The effects of rolling reduction, slab thickness and roller diameter on the closure behavior of voids are discussed. The larger reduction, thinner slab and larger roller diameter all improve the closure of voids during hot rolling processes. Experimental results of the closure behavior of a void in the slab during hot rolling process mostly agree with the simulation results..

The Plastic Deformation Characteristics of Crystalline Polymer Materials via Rolling Process

2011 ◽  
Vol 391-392 ◽  
pp. 585-589 ◽  
Author(s):  
Jian Hui Qiu ◽  
Takuya Murata ◽  
Kenji Takahashi ◽  
Xue Li Wu
Keyword(s):  
Plastic Deformation ◽  
Tensile Stress ◽  
Sharp Increase ◽  
Molecular Orientation ◽  
Mechanical Characteristics ◽  
Rolling Direction ◽  
Crystalline Polymer ◽  
Rolling Process ◽  
Polymer Materials ◽  
Deformation Characteristics

The present work investigated the variation of internal structure, molecular orientation, crystallinity and mechanical characteristics of polypropylene(PP) after rolling process. The materials plate became narrow when rolled from entrance to exit, and the internal crystalline gradually deformed and at last destroyed. Plastic deformation was discovered along the rolling direction. In this direction, the crystallinity and vickers hardness were decreased, and molecular orientation was increased. Moreover, molecular orientation had a sharp increase at the second half part of rolling sample. The tensile stress of rolled samples increased by 80% parallel to rolling direction and decreased by 22% perpendicular to rolling direction.

Visualization of Tensile Stress Induced Material Response at a Crack Tip in Polymers under Critical Load by NMR Imaging

2000 ◽  
Vol 33 (13) ◽  
pp. 4836-4841 ◽  
Author(s):  
P. Adriaensens ◽  
L. Storme ◽  
R. Carleer ◽  
D. Vanderzande ◽  
J. Gelan ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Critical Load ◽  
Crack Tip ◽  
Nmr Imaging ◽  
Material Response

scholarly journals Fracture Mechanical Analysis of Thin-Walled Cylindrical Shells with Cracks

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 592
Author(s):  
Feng Yue ◽  
Ziyan Wu
Keyword(s):  
Fracture Mechanics ◽  
Tensile Stress ◽  
Failure Modes ◽  
Cylindrical Shells ◽  
Crack Tip ◽  
Mechanical Analysis ◽  
J Integral ◽  
Thin Walled Structures ◽  
Circumferential Tensile Stress ◽  
Thin Walled

The fracture mechanical behaviour of thin-walled structures with cracks is highly significant for structural strength design, safety and reliability analysis, and defect evaluation. In this study, the effects of various factors on the fracture parameters, crack initiation angles and plastic zones of thin-walled cylindrical shells with cracks are investigated. First, based on the J-integral and displacement extrapolation methods, the stress intensity factors of thin-walled cylindrical shells with circumferential cracks and compound cracks are studied using linear elastic fracture mechanics, respectively. Second, based on the theory of maximum circumferential tensile stress of compound cracks, the number of singular elements at a crack tip is varied to determine the node of the element corresponding to the maximum circumferential tensile stress, and the initiation angle for a compound crack is predicted. Third, based on the J-integral theory, the size of the plastic zone and J-integral of a thin-walled cylindrical shell with a circumferential crack are analysed, using elastic-plastic fracture mechanics. The results show that the stress in front of a crack tip does not increase after reaching the yield strength and enters the stage of plastic development, and the predicted initiation angle of an oblique crack mainly depends on its original inclination angle. The conclusions have theoretical and engineering significance for the selection of the fracture criteria and determination of the failure modes of thin-walled structures with cracks.

scholarly journals An Investigation into the Effect of Rolling Reduction on 3D Curved Parts Rolling Process

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1209
Author(s):  
Xiang Chang ◽  
Wenzhi Fu ◽  
Mingzhe Li ◽  
Xintong Wang ◽  
Weifeng Yang ◽  
...  
Keyword(s):  
Element Model ◽  
Rolling Process ◽  
Rolling Reduction ◽  
Shape Accuracy ◽  
Bending Deformation ◽  
Good Shape ◽  
Longitudinal Bending ◽  
Gap Height ◽  
Roll Gap ◽  
Forming Tools

Rolling technology based on arc-shaped rollers is a novel method for rapid manufacturing of 3D curved parts. The method uses a pair of arc-shaped rollers (a convex roller and a concave roller) as forming tools, forming an unevenly distributed roll gap. The sheet metal has both transverse bending and longitudinal uneven extension during rolling, so that surface parts with double curvature are processed. The curvature of the formed surface part can be changed by changing the rolling reduction. Changing the vertical distance between the rollers will cause the overall change of the roll gap height, which will inevitably have a great impact on the forming effect of formed 3D curved parts. In this paper, a finite element model and experiment with different rolling reductions was designed; the influence of rolling reduction on the bending deformation and shape accuracy of formed 3D curved parts was studied. The results show that, with the slight increase of rolling reduction (from 0.04 to 0.12 mm), the longitudinal bending deformation of the formed 3D curved part increases significantly, but its transversal bending is almost not affected. When the maximum rolling reduction is 0.04 and 0.06 mm (the corresponding minimum rolling reduction is less than or equal to zero), the shape accuracy of the formed 3D curved parts is not good enough; when the maximum rolling reduction is greater than 0.06 mm (the corresponding minimum rolling reduction is greater than zero), the shape accuracy of the formed 3D curved parts is significantly better. This indicates that, for the rolling of 3D curved parts based on arc-shaped rollers, ensuring that the minimum rolling reduction is greater than zero is the key to ensuring good shape accuracy of the formed 3D curved parts.

Texture Control of Aluminum and Magnesium Alloys by the Symmetric/Asymmetric Combination Rolling Process

2011 ◽  
Vol 702-703 ◽  
pp. 68-75 ◽  
Author(s):  
Hirofumi Inoue
Keyword(s):  
Rolling Direction ◽  
Solution Treatment ◽  
Rolling Process ◽  
Warm Rolling ◽  
Fiber Texture ◽  
Drawing Ratio ◽  
Asymmetric Rolling ◽  
Automotive Body ◽  
Solution Treated ◽  
Aluminum And Magnesium Alloys

In order to develop favorable textures for deep drawing of Al-Mg-Si and Mg-Al-Zn alloys that are promising as automotive body panels, we have adopted the symmetric/asymmetric combination rolling (SACR) process consisting of conventional symmetric rolling and subsequent asymmetric rolling at relatively low reduction. The combination of symmetric cold rolling and asymmetric warm rolling for AA6022 sheets leads to the formation of “TD-rotated β-fiber texture”, resulting in the evolution of {111} recrystallization texture after solution treatment at a high temperature. The SACR processed and solution-treated sheets show a high average r-value with small in-plane anisotropy, and consequently the limiting drawing ratio increases significantly, compared to that of the cold-rolled and solution-treated sheets. In the case of AZ31 magnesium alloy, the SACR process by hot rolling causes the formation of a unique texture, which shows two (0001) poles with tilt angles of 0 and −40 degrees from the normal direction (ND) toward the rolling direction (RD). In addition, subsequent annealing weakens intensity of the double-peak texture, so that the drawability is greatly improved in comparison with that of the conventional warm-rolled sheets with a strong basal texture. At the same time, yield strength decreases to some extent, but the SACR processed and annealed sheets exhibit a good balance of strength and formability due to a mixed texture with basal and tilt components.

Study on the Microstructure and Texture of Warm Rolled ZK60 Magnesium Alloy Sheet

2012 ◽  
Vol 557-559 ◽  
pp. 1344-1348
Author(s):  
Hong Mei Chen ◽  
Hua Shun Yu ◽  
Guang Hui Min ◽  
Yun Xue Jin
Keyword(s):  
Shear Bands ◽  
Rolling Direction ◽  
Rolling Process ◽  
Warm Rolling ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Rolling Reduction ◽  
Basal Pole ◽  
Zk60 Alloy ◽  
Twin Roll

The microstructure and macrotexture of ZK60 alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast ZK60 alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled ZK60 alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.

Determination of the Biaxial Anisotropy Coefficient Using a Single Layer Sheet Metal Compression Test

2021 ◽  
Vol 883 ◽  
pp. 303-308
Author(s):  
Peter Hetz ◽  
Matthias Lenzen ◽  
Martin Kraus ◽  
Marion Merklein
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Sheet Metal ◽  
Compression Test ◽  
Test Procedure ◽  
Rolling Direction ◽  
Single Layer ◽  
Material Behavior ◽  
Biaxial Tensile ◽  
Biaxial Tensile Stress

Numerical process design leads to cost and time savings in sheet metal forming processes. Therefore, a modeling of the material behavior is required to map the flow properties of sheet metal. For the identification of current yield criteria, the yield strength and the hardening behavior as well as the Lankford coefficients are taken into account. By considering the anisotropy as a function of rolling direction and stress state, the prediction quality of anisotropic materials is improved by a more accurate modeling of the yield locus curve. According to the current state of the art, the layer compression test is used to determine the corresponding Lankford coefficient for the biaxial tensile stress state. However, the test setup and the test procedure is quite challenging compared to other tests for the material characterization. Due to this, the test is only of limited suitability if only the Lankford coefficient has to be determined. In this contribution, a simplified test is presented. It is a reduction of the layer compression test to one single sheet layer. So the Lankford coefficient for the biaxial tensile stress state can be analyzed with a significantly lower test effort. The results prove the applicability of the proposed test for an easy and time efficient characterization of the biaxial Lankford coefficient.

Numerical analyses on mechanical performance of flat buried approach slab and soil deformation

2021 ◽  
Author(s):  
Junqing Xue ◽  
Dong Xu ◽  
Yufeng Tang ◽  
Bruno Briseghella ◽  
Fuyun Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Parametric Analysis ◽  
Mechanical Performance ◽  
Element Model ◽  
Soil Deformation ◽  
Longitudinal Deformation ◽  
Expansion Joints ◽  
Approach Slab ◽  
Jointless Bridges

<p><br clear="none"/></p><p>The vulnerability problem of expansion joints could be fundamentally resolved using the concept of jointless bridges. The longitudinal deformation of the superstructure can be transferred to the backfill by using the approach slab. The flat buried approach slab (FBAS) has been used in many jointless bridges in European countries. In order to understand the mechanical performance of FBAS and soil deformation, a finite element model (FEM) was implemented in PLAXIS. Considering the friction between the FBAS and soil, the buried depth, the FBAS length and thickness as parameters, a parametric analysis was carried out. According to the obtained results and in order to reduce the soil deformation above the FBAS, it is suggested to increase the friction between the FBAS and sandy soil, and the buried depth of FBAS. Moreover, it should be paid attention to the vertical soil deformation and the concrete tensile stress of FBAS in pulling condition.</p>

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