Experimental validation of contact models for cold-rolling processes

Mekicha, Melkamu Awoke; Rooij, M.B. de; Jacobs, L.; Matthews, D.T.A.; Schipper, Dirk J.

doi:10.1016/j.jmatprotec.2019.116371

Cited by 21 publications

(5 citation statements)

References 17 publications

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“…This is because a smaller ball has a smaller contact area, which can deform the asperities on the surface and produce more plastic deformation. 21,22 In addition, it is worth mentioning that increasing the ball diameter also leads to a slightly deeper compressive–tensile crossover point, which may be due to increased contact pressure caused by the larger ball size at the same hydraulic pressure. This result was confirmed by Abrão et al 23 Similar trends were observed from the experimental results in Figure 15(b), which indicates that the influence law obtained from the FE simulation is also reliable.…”

Section: Resultsmentioning

confidence: 99%

Investigation of residual stress distribution induced during deep rolling of Ti-6Al-4V alloy

Han

Zhang

Yao

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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To clarify the effects of deep rolling parameters on residual stress, two-dimensional and three-dimensional finite element models were developed using the Chaboche hardening model. Both two-dimensional and three-dimensional simulation results were compared with experimental results. The three-dimensional model is more accurate, especially the 90° cut-out model. The maximum errors in the longitudinal and circumferential directions of 90° cut-out are 8.9% and 15.6%, respectively. Compared to 20 MPa, a rolling pressure of 38 MPa results in larger and deeper compressive residual stress in both directions, but lower surface residual stress in the circumferential direction. Compared to 30% overlap, 60% overlap produces larger compressive residual stress in the near surface region in the longitudinal direction and deeper residual stress with lower maximum compressive residual stress in the circumferential direction. The friction coefficient only slightly affects residual stress in the circumferential direction; increasing the rolling speed induces higher near surface residual stress in the circumferential direction. Compared to the HG6 tool, the HG8 tool generates decreasing surface residual stresses and deeper residual stress in both directions. Compared to one pass, two passes significantly increase the residual stress in circumferential direction, but only slightly increase the residual stress in the longitudinal direction.

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Section: Resultsmentioning

confidence: 99%

Investigation of residual stress distribution induced during deep rolling of Ti-6Al-4V alloy

Han

Zhang

Yao

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…the work roll force, the entry and exit strip tension, the entrance velocity, etc. High industrial interest has led researchers to develop models that are used to better predict, analyze and understand the rolling process [3,4,[6][7][8][9][10][11]. However, most of these models don't take into account some key phenomena that are known to occur in the deformation zone: (i) pre-deformation in the material before it first touches the work roll, (ii) elastic recovery (spring-back) after the strip is processed, (iii) the gradient in strip velocity over the strip thickness.…”

Section: Introductionmentioning

confidence: 99%

Accurate Strain Field Measurement During Strip Rolling by Exploiting Recurring Material Motion with Time-Integrated Digital Image Correlation

et al. 2021

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Background 95% Of all metals and alloys are processed using strip rolling, explaining the great number of existing strip rolling optimization models. Yet, an accurate in-situ full-field experimental measurement method of the deformation, velocity and strain fields of the strip in the deformation zone is lacking. Objective Here, a novel time-Integrated Digital Image Correlation (t-IDIC) framework is proposed and validated that fully exploits the notion of continuous, recurring material motion during strip rolling. Methods High strain accuracy and robustness against unavoidable light reflections and missing speckles is achieved by simultaneously correlating many (e.g. 200) image pairs in a single optimization step, i.e. each image pair is correlated with the same average global displacement field but is multiplied by a unique velocity corrector to account for differences in material velocity between image pairs. Results Demonstration on two different strip rolling experiments revealed previously inaccessible subtle changes in the deformation and strain fields due to minor variations in pre-deformation, elastic recovery, and geometrical irregularities. The influence of the work roll force and entry/exit strip tension has been investigated for strip rolling with an industrial pilot mill, which revealed unexpected non-horizontal material feed. This asymmetry was reduced by increasing the entry strip tension and rolling force, resulting in a more symmetric strain distribution, while increased distance between the neutral and entry point was found for a larger rolling force. Conclusions The proposed t-IDIC method allows for robust and accurate characterization of the strip’s full-field behavior of the deformation zone during rolling, revealing novel insights in the material behavior.

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“…With regards to temperature and strain rate effects, there seems to be no experimental agreement for the real dependence of hardness with the former [ 21 ] or extensive investigation on the effects of the latter. Nonetheless, the relation

with

is frequently used in the metal forming tribology literature [ 22 , 23 , 24 ], implying that

with

is assumed.…”

Section: Introductionmentioning

confidence: 99%

Influence of the 6061 Aluminium Alloy Thermo-Viscoplastic Behaviour on the Load-Area Relation of a Contact

et al. 2021

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The contact between solids in metal-forming operations often involves temperature-dependent viscoplasticity of the workpiece. In order to estimate the real contact area in such contexts, both the topography and the deformation behaviour should be taken into account. In this work, a deterministic approach is used to represent asperities in appropriately shaped quadratic surfaces. Such geometries are implemented in indentation finite element simulations, in which the indented material has thermo-viscoplastic properties. By creating a database of simulation data, investigations in terms of contact load and area for the specifically shaped asperities allow for an analysis on the influence of the material properties on the load–area relation of the contact. The temperature and viscoplasticity greatly define how much load is supported by a substrate due to an indenting asperity, but the description of the deformation behaviour at small values of strain and strain rate is also relevant. The pile-up and sink-in regions are very dependent on the thermo-viscoplastic conditions and material model, which consequently affect the real contact area calculation. The interplay between carried load and contact area of a full surface analysis indicates the role that different sized asperities play in the contact under different thermomechanical conditions.

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Experimental validation of contact models for cold-rolling processes

Cited by 21 publications

References 17 publications

Investigation of residual stress distribution induced during deep rolling of Ti-6Al-4V alloy

Investigation of residual stress distribution induced during deep rolling of Ti-6Al-4V alloy

Accurate Strain Field Measurement During Strip Rolling by Exploiting Recurring Material Motion with Time-Integrated Digital Image Correlation

Influence of the 6061 Aluminium Alloy Thermo-Viscoplastic Behaviour on the Load-Area Relation of a Contact

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