Tensile Test of very thin Sheet Metal and Determination of Flow Stress Considering the Scaling Effect

Hoffmann, Hartmut; Hong, Seok-Pyo

doi:10.1016/s0007-8506(07)60412-0

Cited by 47 publications

(22 citation statements)

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“…The tendency was also observed for different materials such as Cu and Al foil. 18) The size effect of specimen geometrical dimension on micro-tensile test can be explained by into the Swift model, 19) Where, K is hardening index, ¾ 0 is initial strain and n is working hardening index. The material parameters related to the Swift model for each thickness are presented in Table 3 and Fig.…”

Section: Processmentioning

confidence: 99%

Specimen Dimension and Grain Size Effects on Deformation Behavior in Micro Tensile of SUS304 Stainless Steel Foil

Guo

Shan

et al. 2013

Mater. Trans.

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Size effects are the main problem in micro-forming process and material behavior with miniaturization of feature size. In the paper, size effects of grain size and foil thickness on deformation behavior and fracture were investigated by using micro tensile test of SUS304 foil. The results show that the yield strength of SUS304 stainless foil increases with the decrease of foil thickness and grain size in micro tensile tests. Meanwhile, the fracture mechanism of SUS304 foil changes from ductile fracture with lots of dimples to ductile fracture with slip separation with the decrease of foil thickness. A compound material model by considering grain size, foil thickness and surface effects is proposed and constitutive relation of SUS304 foil is established. The calculation curves well match with experimental results.

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Section: Processmentioning

confidence: 99%

Specimen Dimension and Grain Size Effects on Deformation Behavior in Micro Tensile of SUS304 Stainless Steel Foil

Guo

Shan

et al. 2013

Mater. Trans.

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“…Regarding that, the properties of the material are also affected by size effects [8,9]. For the determination of the bending force in this investigation the flow stress is required.…”

Section: Introductionmentioning

confidence: 99%

Determination of size-dependent friction functions in sheet metal forming with respect to the distribution of the contact pressure

Vollertsen

2008

Prod. Eng. Res. Devel.

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The aim of this paper is to optimize the analytical model developed in previous work (Hu et al. in Determination of the friction coefficient in deep drawing, process scaling. In: Vollertsen F, Hollmann F (eds) Proceeding of the 1st colloquium of DFG priority program process scaling. BIAS-Verlag, ISBN 3-933762-14-6, Bremen, pp 27-34, 2003; Hu and Vollertsen in J Technol Plast 29:1-9, 2004; Vollertsen and Hu in Annu CIRP 55(1): [291][292][293][294] 2006) with respect to the distribution of the contact pressure at the drawing radius. A size-dependent friction function was acquired based on the experimentally measured punch force from strip drawing with deflection, which can identify the tribological size effects in sheet metal forming. This function was implemented in the FEM-simulation. The distribution of the contact pressure at the drawing radius was assumed to be uniform in the previous analytical model, which is not right, since the simulated punch force versus punch travel curve showed a difference of about 11% from the experimental curve (Vollertsen and Hu in Annu CIRP 55(1): [291][292][293][294] 2006). In the new analytical model the non-uniform distribution of contact pressure between the work piece and the tools was taken into account. The simulated curve using the friction function from the new model shows a better agreement with the experimental curve.

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“…[7] and t eff given by Eq. [10]. Moreover, the experimental value t m was also measured with a micrometer with an accuracy of 1 lm.…”

Section: E Surface Roughness In Tension and Simple Shearmentioning

confidence: 99%

“…From an industrial point of view, an ultra-thin sheet has usually a thickness ranging from 13 lm up to 200 lm. [8,9] This division depends in fact on the ratio N ¼ t d between the thickness t and the average grain size d. By investigating the behavior of pure copper with a thickness ranging from 500 lm down to 10 lm, Hoffmann et al [10] showed that the stress-strain curves for a sheet thickness of 200 lm (N ' 10) and 500 lm (N ' 25) have similar shape and level. Specimens thicker than 200 lm were classified as macro scale specimens, while specimens thinner than 200 lm, from 100 lm and N ' 3:3 down to 10 lm and N ' 0:3, exhibited a lower stress level typical of ultra-thin sheet.…”

Section: Introductionmentioning

confidence: 99%

“…To analyze this effect in tension, Hoffmann et al [10] changed the width for three different thicknesses. It was observed that the conventional initial yield stress was either approximately constant (t ¼ 200 lm) or tended to decrease when the width CONG-HANH PHAM, Post-doctorate, and SANDRINE THUILLIER and PIERRE-YVES MANACH, Professors, are with the LIMATB, Universite´de Bretagne-Sud, EA 4250, 56100 Lorient, France.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties Involved in the Micro-forming of Ultra-thin Stainless Steel Sheets

Pham

Thuillier

Manach

2015

Metall Mater Trans A

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The objective of this paper is to characterize the mechanical behavior of an ultra-thin stainless steel, of 0.15-mm thickness, that is commonly used in the manufacturing of miniature connectors. The main focus is the relationship between some microstructural features, like grain size and surface roughness, and the macroscopic mechanical behavior investigated in uniaxial tension and simple shear. In tension, adaptations to the very small sheet thickness, in order to hold the specimen under the grips, are presented. Yield stress, initial elastic modulus, and evolution of the loading-unloading slope with plastic deformation were evaluated. Moreover, the kinematic contribution to the hardening was characterized by monotonic and cyclic simple shear test and reproduced by a mixed hardening law implemented in Abaqus finite element code. Then, the evolution of surface roughness with plastic strain, both in tension and simple shear, was analyzed. It was shown that in the case of an ultra-thin sheet, the stress levels, calculated either from an average thickness or when considering the effect of the surface roughness, exhibit a significant difference. Finally, the influence of surface roughness on the fracture of a tensile specimen was also investigated.

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Tensile Test of very thin Sheet Metal and Determination of Flow Stress Considering the Scaling Effect

Cited by 47 publications

References 4 publications

Specimen Dimension and Grain Size Effects on Deformation Behavior in Micro Tensile of SUS304 Stainless Steel Foil

Specimen Dimension and Grain Size Effects on Deformation Behavior in Micro Tensile of SUS304 Stainless Steel Foil

Determination of size-dependent friction functions in sheet metal forming with respect to the distribution of the contact pressure

Mechanical Properties Involved in the Micro-forming of Ultra-thin Stainless Steel Sheets

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