Influence of microstructure on the mechanical properties and the forming behaviour of very thin metal foils

Diehl, A.; Engel, Ulf; Geiger, Manfred

doi:10.1007/s00170-008-1851-4

Cited by 72 publications

(31 citation statements)

References 7 publications

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“…For the determination of the true stress true strain curves of thin metal sheets with thicknesses smaller than 0.4 mm, the hydraulic bulge test has been applied to enable the experimental determination of the material plastic behaviour up to larger strains [19]. This method is applied for the mechanical characterisation of the investigated materials in this study.…”

Section: Mechanical Characterisation Of the Materialsmentioning

confidence: 99%

“…The curvature radius at the pole was calculated using a parabolic approximation considering all measured points. For the determination of the true stress true strain curves, dies with circular opening with a diameter of 115 mm were used for the bulge tests, a detailed description of the experimental set up and procedure has been given in previous publications [19].…”

Section: Mechanical Characterisation Of the Materialsmentioning

confidence: 99%

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Size effects in bending processes applied to metal foils

Diehl

Engel

Merklein

et al. 2009

Prod. Eng. Res. Devel.

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Ongoing development in the miniaturisation field leads to an increasing understanding interest in the forming behaviour of thin metal sheets since forming technology is well suited in particular for mass production. In case of micro forming, i.e. reducing the sheet thickness to the order of micrometers, established know-how of conventional sheet metal forming cannot directly be transferred to metal foil forming due to the phenomenon known as size effect. In this paper a bending concept, which enables the investigation of the two contrary size effects originating from the share of surface grains and the strain gradient via scaled experiments, is introduced. The forming behaviour is characterised by the spring-back angle which gives an indirect measure of the present bending moment and is an important factor for production accuracy. The experimental results are compared with analytical solutions and an approach to implement strain gradient dependent material behaviour in the analytical description of bending processes is presented.

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Section: Mechanical Characterisation Of the Materialsmentioning

confidence: 99%

Section: Mechanical Characterisation Of the Materialsmentioning

confidence: 99%

Size effects in bending processes applied to metal foils

Diehl

Engel

Merklein

et al. 2009

Prod. Eng. Res. Devel.

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“…Flow stress decreases as workpiece size decreases [5,11,12]. Surface grains of the deformed material have lesser constraints compared to internal ones.…”

Section: Flow Stressmentioning

confidence: 99%

“…This phenomenon is the resulted of different properties of individual grains and their less number in the workpiece volume [11,44]. The deformation behavior of a single grain has an anisotropic nature.…”

Section: Repeatabilitymentioning

confidence: 99%

Numerical Simulation in Microforming for Very Small Metal Elements

Mogielnicki¹

2016

Modeling and Simulation in Engineering Sciences

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Microforming is a technology of very small metal elements production, which are required as a parts for many industrial products resulting from microtechnology. This chapter gives a review of the state-of-the-art microforming of metals and its numerical simulations. Phenomena occurring in the miniaturization of microbulk-forming technologies are described. The main problems in microforming are size effects, which have physical and structural sources and directly affect the material flow mechanics in microscale. Size effects must be taken into account in all areas of the forming process chain, demanding new solutions, especially in workpiece structure and die surface numerical modeling.

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“…When the thickness of the material is less than 350µm, the springback angle increase with a decrease of t/d ratio [2]. Diehl et al [3] found that springback behavior of SE-CU 58 was different for the thickness less than 100µm and larger than 100µm. This result caused by the different dominant factor that influences the amount of springback angle.…”

Section: Introductionmentioning

confidence: 99%

Preliminary Investigation of Micro-V-Bending

2017

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Abstract. Bending in sheet metal forming is defined as uniformly straining process around a linear axis. A V-bending process is normally used in sheet metal working due to the tool and process simplicity. The main problem in bending process is a springback occurrence which causes an error in part dimension. In a micro level, the springback angle is difficult to be assessed because of the influence of size effects in all aspects of the system. The springback behavior has been investigated in many previous kinds of research. However, the springback correction is still needed to be studied extensively so that it can be implemented reliably in micro-bending. The purpose of this research is to investigate the influence of punch velocity and holding time to the springback angle. The process is performed to the 0.1 mm thickness of copper foil. The punch velocities are 0.1 mm/s, 1 mm/s, and 10 mm/s. While the variation of holding time, which is set during the bottoming stage, are 7 s, 9 s, and 11 s. The result shows that the punch velocity clearly influences the springback angle. In addition, the holding time during the bottoming stage is a potential factor in springback angle correction.

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Influence of microstructure on the mechanical properties and the forming behaviour of very thin metal foils

Cited by 72 publications

References 7 publications

Size effects in bending processes applied to metal foils

Size effects in bending processes applied to metal foils

Numerical Simulation in Microforming for Very Small Metal Elements

Preliminary Investigation of Micro-V-Bending

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