Influence of the contact with friction on the deformation behavior of advanced high strength steels in the Nakajima test

Kasaei, Mohammad Mehdi; Oliveira, M. C.

doi:10.1177/03093247211021257

Cited by 15 publications

(13 citation statements)

References 30 publications

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“…In the regions near the hole sheet edges where higher plastic deformations occur, a reduced element size of 0.2 mm was utilized. Frictional interactions between the punches, dies, and sheets were characterized by employing a penalty-based contact model [22], incorporating the Coulomb law with a coefficient of 0.08. The simulation consisted of three steps: applying displacement to the upper die, followed by the flanging punch, and then the hemming punch.…”

Section: Hole Hemmingmentioning

confidence: 99%

Ductile Fracture Prediction in Hole Hemming of Aluminum and Magnesium Sheets

Kasaei,

Pereira,

Carbas

et al. 2023

Metals

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The present work proposes a suitable approach for predicting ductile fracture in a new joining process by plastic deformation called hole hemming. This process creates a combined form- and force-fit joint and enables the joining of lightweight materials with varying formability without requiring heating or auxiliary elements. In this process, the joinability of materials is limited by the occurrence of fracture in the outer sheet, highlighting the crucial need to accurately predict its damage during the process design phase. In this study, five different fracture criteria, including the McClintock, Rice–Tracey, Normalized Cockroft–Latham, and Brozzo and Modified Mohr–Coulomb (MMC) criteria, are examined during the joining of a challenging combination of lightweight materials (aluminum AA6082-T4 and magnesium AZ31). These criteria are calibrated by a hybrid experimental–numerical method using three tests with distinct stress states. These criteria are then implemented into the finite element model of the hole hemming process, utilizing an appropriate user subroutine. The results show that the flange edge of the outer sheet is the most prone region to fracture during the joining process, and a criterion must be able to model the fracture behavior of the material from uniaxial tension to shear to accurately predict fracture in this area. Among the examined criteria, only the MMC criterion was capable of such modeling and accurately predicted the critical displacement of the punch in the hemming stage with a negligible error (about 1%). On the other hand, the prediction accuracy of the other criteria varied significantly depending on the calibration test, resulting in errors ranging from 8.6% to 75.5%. The error of 8.6% was achieved with the Normalized Cockroft–Latham criterion calibrated by a uniaxial tension test. Thus, based on the results, the MMC criterion is recommended for ductile fracture prediction in the hole hemming process, offering valuable insights to assist in process design.

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Section: Hole Hemmingmentioning

confidence: 99%

Ductile Fracture Prediction in Hole Hemming of Aluminum and Magnesium Sheets

Kasaei,

Pereira,

Carbas

et al. 2023

Metals

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“…It is worth noting that the sticking friction leads to a greater thinning as reported in Nakajima tests for characterizing the formability limits of metal sheets. 15 Park et al 16 presented an new sealing system to prevent leakage in tube hydroforming and obtained more precise hydroformed parts. Xu et al 17 reduced the wrinkling defect in tube hydroforming of aluminium T-shaped parts by creating different friction conditions in the four zones of the die.…”

Section: Introductionmentioning

confidence: 99%

Improvement of material flow in tube hydroforming by advanced sealing methods

Kasaei

Naeini

Abbaszadeh

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part B:

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In this paper, two advanced sealing methods are proposed to enhance the formability of aluminium alloys in the tube hydroforming process. These methods are aimed at omitting friction force at the contact area between the tube and the die in the feed region and facilitating the material flow to the deformation region. The advanced sealing methods are numerically and experimentally examined against the conventional sealing method by conducting the free bulge test on AA6063 aluminium tubes. The deformation mechanics are deeply analysed in the principal strain space to identify the influence of the sealing methods on deformation paths. In addition, the effectiveness of the advanced sealing methods is evaluated under different lubrication conditions and contact lengths in the feed region. Results show that in the advanced sealing methods compared to the conventional one, the thickness in the feed region does not increase and the necking occurs in larger in-plane strains, leading to a higher bulge height. Results also allow concluding that a higher bulge height is formed using the second advanced sealing method, in which the tube is pressurized from both sides in the feed region. Thus, the advanced sealing methods are recommended for tube hydroforming of aluminium alloys with low formability.

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“…Nowadays, the automotive industry is receiving increasing pressure to reduce the weight of automotive bodies for the improvement of fuel consumption and air pollution performances while maintaining collision safety. 1 To this end, new materials, e.g. advanced high-strength steels, aluminium alloys, magnesium alloys and composites have been continuously developed and applied to manufacture lightweight structures in this industry.…”

Section: Introductionmentioning

confidence: 99%

Joining sheets made from dissimilar materials by hole hemming

Kasaei

Silva

2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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This research work presents a new joining process based on the hemming process for attaching sheets made from dissimilar materials with very different mechanical properties. The process is termed ‘hole hemming’ and consists in producing a mechanical interlock between pre-drilled holes which can be made anywhere on the sheets. The process is carried out in a two-stage operation including flanging the hole of an outer sheet and bending the flange over the hole of an inner sheet. First, the joining stages and the required tools are designed. Then, the joining of DP780 steel and AA6061-T6 aluminium alloy sheets, which are applied to manufacture lightweight structures in the automotive industries, is investigated using finite element analysis. Results show that the hole hemming process is able to successfully join these materials without fracture. The hole-hemmed joint withstood the maximum forces of 2.5 and 0.5 kN in single-lap shear and peel tests, respectively, and failed with hole bearing mode which is known as a gradual failure mode. The results demonstrate the applicability of the hole hemming process for joining dissimilar materials.

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Influence of the contact with friction on the deformation behavior of advanced high strength steels in the Nakajima test

Cited by 15 publications

References 30 publications

Ductile Fracture Prediction in Hole Hemming of Aluminum and Magnesium Sheets

Ductile Fracture Prediction in Hole Hemming of Aluminum and Magnesium Sheets

Improvement of material flow in tube hydroforming by advanced sealing methods

Joining sheets made from dissimilar materials by hole hemming

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