Analysis of the influence of stress triaxiality on formability of hole-flanging by single-stage SPIF

Martínez-Donaire, A.J.; Morales-Palma, Domingo; Centeno, Gabriel; Vallellano, C.

doi:10.1016/j.ijmecsci.2018.11.006

Cited by 36 publications

(21 citation statements)

References 29 publications

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“…The obtained Fracture Limit Curve has been revealed the limiting maximum fracture strain values at a maximum speed of 600 rpm and a tool diameter of 12 mm. There is a direct dependency between the increase and decrease of speed and vertical step depth with limiting major true strain value as obtained in the Forming Limit Diagram [14].…”

Section: Recent Achievements In Sheet Metal Forming Researchmentioning

confidence: 82%

“…But it's low formability compared to titanium grade 2 makes the interest for the latest to increase in academic and industry community. It has been experimentally proven that in SPIF process the rotational shear stress is influencing void coalescence, growth and length wise fracture of titanium grade 2 sheet materials [14]. Further research for optimizing formability of titanium alloys would be necessary.…”

Section: Future Reasearch Directionsmentioning

confidence: 99%

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Tendencies in Forming Sheet Metal Parts Using Incremental Forming Advanced Technologies

CIOFU¹,

Chirita²,

LUPU³

et al. 2019

JESR

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Stretch forming of sheet metal materials is a highly required process in aerospace industry for manufacturing skin parts. Automation of some processes such as cutting, punching, forming, shearing and nesting in conventional manufacturing tends to combine these forming methods. Some researches are made on the formability of sheet metal materials obtained in incremental forming process with stretch forming and water jet incremental micro-forming with supporting dies. This paper is an attempt to review the newly researches made on optimization of manufacturing metal skin parts to achieve geometrical accuracy.

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Section: Recent Achievements In Sheet Metal Forming Researchmentioning

confidence: 82%

Section: Future Reasearch Directionsmentioning

confidence: 99%

Tendencies in Forming Sheet Metal Parts Using Incremental Forming Advanced Technologies

CIOFU¹,

Chirita²,

LUPU³

et al. 2019

JESR

View full text Add to dashboard Cite

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“…The mechanical properties of the AA7075-O sheets of 1.6-mm thickness are summarized in Table 1. A Hollomon type law σ = 314•ε 0.13 MPa was used to describe the hardening behaviour of the aluminium alloy, as recently described by the authors [33,34]. The sheet blank was meshed with 944 square elements of size 0.2 mm.…”

Section: Numerical Simulationmentioning

confidence: 99%

Analysis of formability in conventional hole flanging of AA7075-O sheets: punch edge radius effect and limitations of the FLC

et al. 2019

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Hole flanges are commonly manufactured in mass production by conventional press-working. In an industrial context, the process limits are usually evaluated by means of the Limiting Forming Ratio (LFR), which defines the maximum attainable diameter of the flange related to the initial pre-cut hole. Nevertheless, the LFR does not provide enough information about material deformation, thickness distribution or the expected onset and type of failure. In this sense, a systematic investigation using the Forming Limit Diagram (FLD) is needed. Under these circumstances, the aim of this work is to provide a better understanding of the deformation process in conventional hole flanging, analysing the effect of the punch edge radius as well as the influence of the strain distribution along the hole flange on formability. An experimental campaign on 1.6 mm thickness AA7075 annealed sheet was completed using cylindrical punches with different profile radii. In addition, numerical modelling of the process using finite elements was developed. The results allow better understanding of the physical mechanisms governing material deformation and process formability in very ductile materials. In this regard, this research work contributes to the current state of the art in conventional hole flanging by establishing the modes of failure that prevail in the process and the influence of the bending induced by the tool radius in the flange formability. In addition, the limitations of using conventional FLD for providing a limiting threshold for the strain states attained in the flanges deformed with different punch profiles are also identified.

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“…For round bar notched specimens, the stress triaxiality at the center of net section can be calculated by the formula η = 1 3 + ln 1 + a 0 2R 0 , which was proposed by Bridgman [45], where a 0 is the round radius of the net section and R 0 is the notch radius. In practice, plate structures with notch are very common, but the theoretical solution of stress triaxiality for non-axisymmetric structures can hardly be solved.…”

Section: The Evolution Of Stress Triaxiality For the Notched Specimenmentioning

confidence: 99%

“…influences the damage process of mechanical structure. Stress triaxiality is a quantitative parameter to evaluate the stress constraint, which is an important factor to the plastic damage evolution and failure mode [1,2]. Kato et al [3] applied three kinds of miniature tensile specimen shapes to the investigation of plastic deformability, and found that the ductility and the plastic strain at the fracture position decreased with stress triaxiality increasing.…”

Section: Introductionmentioning

confidence: 99%

Effect of Stress Triaxiality on Plastic Damage Evolution and Failure Mode for 316L Notched Specimen

Peng

Wang

Dai

et al. 2019

Metals

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To reveal the effect of stress triaxiality on plastic damage evolution and failure mode, 316L notched specimens with different notch sizes are systematically investigated by digital image correlation (DIC) observation, plastic damage analysis by finite element simulation, and void mesoscopic observation. It was found that the plastic damage evolution and failure mode are closely related with notch radius and stress triaxiality. The greater the stress triaxiality at the root is, the greater the damage value at the root is and the earlier the fracture occurs. Moreover, void distribution by mesoscopic observation agrees well with damage distribution observed by finite element simulation with the Gurson-Tvergaard-Needleman (GTN) damage model. It is worth noting that, with the increase in stress triaxiality, the failure mode of notched specimen changes from ductility fracture with void coalescence at the center position to crack initiation at the notch root, from both mesoscopic observation and damage simulation.

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Analysis of the influence of stress triaxiality on formability of hole-flanging by single-stage SPIF

Cited by 36 publications

References 29 publications

Tendencies in Forming Sheet Metal Parts Using Incremental Forming Advanced Technologies

Tendencies in Forming Sheet Metal Parts Using Incremental Forming Advanced Technologies

Analysis of formability in conventional hole flanging of AA7075-O sheets: punch edge radius effect and limitations of the FLC

Effect of Stress Triaxiality on Plastic Damage Evolution and Failure Mode for 316L Notched Specimen

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