Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings

Liu, Wei; Guines, Dominique; Leotoing, Lionel; Ragneau, Eric

doi:10.1016/j.msea.2016.08.125

Cited by 23 publications

(11 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The identification of DP600 steel behaviour, subjected to in-plane equibiaxial loadings, was performed in a previous work [30] for a strain rate ranging from quasi-static to intermediate strain rate. In [30], the hardening law of DP600 was identified for high strain levels which makes reliable the calculation of stress field in the range of limit strains. This point will be essential for the numerical evaluation of ductile fracture criteria.…”

Section: Numerical Simulationmentioning

confidence: 99%

Characterization of forming limits at fracture with an optimized cruciform specimen: Application to DP600 steel sheets

Song

Leotoing

Guines

et al. 2017

International Journal of Mechanical Sciences

View full text Add to dashboard Cite

International audienceIn order to identify experimental limit strains at fracture for metallic sheets under in-plane biaxial loadings, a specific specimen shape has to be defined. Ideally, the proposed geometry must lead to fracture at the specimen center whatever the strain path imposed by the experimental device. If such condition is ensured, the whole strain paths ranging from equi-biaxial to uniaxial could experimentally investigated. Based on literature review, four in-plane cross specimen shapes have been selected owing to strong potential to reach large strain and fracture in their central point. From finite element simulations, the behavior of these different shapes is evaluated. Based on these numerical results, a new shape is proposed and optimized for determining the forming limits at fracture of DP600 sheet metal with a thickness of 2mm. The forming limit strains at fracture are identified by a time-dependent method and the forming limit strains at necking are determined by a position-dependent method. The experimental forming limit strains at fracture of DP600 sheet metal are fitted by a forming line. Three ductile fracture criteria are then calibrated with experimental points. The Oyane criterion with two parameters gives the best prediction

show abstract

Section: Numerical Simulationmentioning

confidence: 99%

Characterization of forming limits at fracture with an optimized cruciform specimen: Application to DP600 steel sheets

Song

Leotoing

Guines

et al. 2017

International Journal of Mechanical Sciences

View full text Add to dashboard Cite

show abstract

“…The identification of DP600 sheet behaviour under in‐plane equibiaxial loadings has been performed in previous work for a strain rate ranging from quasi‐static to intermediate strain rate. Based on this work, the material constants and material models used in the present work are briefly recalled hereafter.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…The general strain rate‐dependent hardening law on the basis of Ludwick formulation has been used:

\overset{σ}{true} = σ_{0} {\overset{ε}{true}}^{m_{1}} + K {ε_{p}}^{n} {\overset{ε}{true}}^{m_{2}} .

…”

Section: Numerical Simulationmentioning

confidence: 99%

Effect of continuous strain path changes on forming limit strains of DP600

Song

Leotoing

Guines

et al. 2019

Strain

Self Cite

View full text Add to dashboard Cite

The strain path may change in actual sheet metal-forming processes, so the determination of formability of sheet metal should consider the nonlinear strain path. For identifying the forming limit (FL) strains under nonlinear strain path, a conventional two-step procedure with unloading is classically used to produce the strain path change, which results in no continuous measure of strain. The in-plane biaxial tensile test with a cruciform specimen is an interesting alternative to overcome the drawbacks of conventional method.The strain path change can be made without unloading during a single test. In this work, the experimental FL strains of DP600 sheets under two types of nonlinear strain path are investigated and then compared with those under linear strain paths. The Oyane ductile fracture criterion is used in the finite element simulation to predict the experimental results. KEYWORDS FLCF, FLCN, in-plane biaxial tensile test, nonlinear strain path | INTRODUCTIONMost of the forming limit curves at necking (FLCNs) and the forming limit curves at fracture (FLCFs) have been experimentally determined using methods that produce proportional loading with insignificant changes in strain paths. However, in some innovative forming processes, such as single point incremental forming, complex strain paths with several changes have been identified by different authors. As an example, Figure 1 shows the evolution of the strain path during an incremental forming operation of a truncated aluminium cone with a wall angle of 60°. [1] As can be seen, drastic changes in the strain path are observed during the forming operation, without unloading, and a very high level of deformation can be achieved, well beyond the conventional forming limit strains at necking. In addition, it has been demonstrated that strain path change has an influence on the FLCN and more specifically on the high level of forming limits (FL). [2] Because the strain path change obviously affects the FL strains at necking, no unified FLCN exists in the strain space to represent the formability of sheet metal. [3] The strain paths in sheet metal forming are classically divided into two types: Linear strain path and nonlinear strain path. Traditionally, the identification of strain-based FLCN or FLCF is limited to the sheet metal undergoing linear strain paths. Three types of experimental FLCN (Figure 2) are concluded by Barata da Rocha et al. [2] to investigate the effect of strain path change on the FL strains at necking. For Type 1, the FLCN is determined under proportional loading. Every point of the FLCN is defined by major and minor strains at necking. As shown in Figure 2a, the whole FLCN (ABCD) is produced by different strain paths from biaxial stretching (OA) to uniaxial tension (OD) through plane-strain tension (OC). The red dash line shows the FLCF, which is higher than the FLCN. [4] For Type 2, the FLCN is identified under two steps of proportional loading. Different prestrain levels

show abstract

“…Nevertheless, this kind of test is unable to reach high level of deformation or complex strain paths such as the ones obtained during SPIF process. Alternative solutions such as hydraulic bulge test or biaxial tensile tests extend significantly the strain range reached during the test, compared to uniaxial tension [22]. Then, it seems necessary to find the relevant material characterization tests for the SPIF process, taking into account the high level of deformation and the complex strain paths.…”

Section: Introductionmentioning

confidence: 99%

Relevant material characterization for load prediction in incremental forming

Abdelkefi

Guines²,

Leotoing³

et al. 2022

Int J Mater Form

View full text Add to dashboard Cite

Robotic incremental sheet forming has arisen a recent industrial interest, as a more flexible and cost-effective solution to the process using rigid computer numerical control (CNC) machines.However, the numerical prediction of the forming loads and final geometry coupled to an elastic modeling of the robot is essential to optimize the robot trajectory and thus to ensure the geometrical accuracy of the final part. Within this context, the aim of this study is to investigate the accuracy of the load prediction in the case of a single point incremental forming process of a commercially pure (CP) titanium alloy sheet. The mechanical behavior is characterized at room temperature under two strain states, i.e., uniaxial and biaxial tension, and a truncated cone of the same material is obtained by single point incremental forming. A 3D cell records all the components of the applied load during the forming and the part is laser scanned at the end of the process, though still clamped along the outer edge. A numerical model of the process is developed assuming some symmetries to reduce the computational time. The influence of the hardening law, either identified from the uniaxial or biaxial tensile tests, on the forming load prediction is investigated, with a focus on the strain path during single point incremental forming.

show abstract

Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings

Cited by 23 publications

References 32 publications

Characterization of forming limits at fracture with an optimized cruciform specimen: Application to DP600 steel sheets

Characterization of forming limits at fracture with an optimized cruciform specimen: Application to DP600 steel sheets

Effect of continuous strain path changes on forming limit strains of DP600

Relevant material characterization for load prediction in incremental forming

Contact Info

Product

Resources

About