Evaluation of the VDA 238-100 Tight Radius Bending Test using Digital Image Correlation Strain Measurement

Cheong, K; Omer, Kaab; Butcher, Cliff; George, Ryan; Dykeman, James

doi:10.1088/1742-6596/896/1/012075

Cited by 46 publications

(24 citation statements)

References 5 publications

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“…Though, fracture under bending is a local process on the outer fibre. Therefore, the measurement of local fracture strains on the bending line, as conducted by [ 25 ] would be a more characteristic measure for bendability instead of the bending angle α. Another reason favouring the local bending strain or the related radius as an objective measure for the material-specific performance in bending is the fact that different materials exhibit a substantially different bending line.…”

Section: Characterization and Classification In Terms Of Mechanicamentioning

confidence: 99%

“…Kurz et al [ 24 ] showed a good correlation between determined bending angles and crash behaviour of press hardened steels (PHS). In recent research, Cheong et al [ 25 ] improved the test set-up to determine local fracture strains for the plane-strain stress state via DIC besides the bending angle. Another way to achieve a plane-strain stress state is the usage of notched tensile specimens.…”

Section: Introductionmentioning

confidence: 99%

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Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels

et al. 2018

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The usage of high-strength steels for structural components and reinforcement parts is inevitable for modern car-body manufacture in reaching lightweight design as well as increasing passive safety. Depending on their microstructure these steels show differing damage mechanisms and various mechanical properties which cannot be classified comprehensively via classical uniaxial tensile testing. In this research, damage initiation, evolution and final material failure are characterized for commercially produced complex-phase (CP) and dual-phase (DP) steels in a strength range between 600 and 1000 MPa. Based on these investigations CP steels with their homogeneous microstructure are characterized as damage tolerant and hence less edge-crack sensitive than DP steels. As final fracture occurs after a combination of ductile damage evolution and local shear band localization in ferrite grains at a characteristic thickness strain, this strain measure is introduced as a new parameter for local formability. In terms of global formability DP steels display advantages because of their microstructural composition of soft ferrite matrix including hard martensite particles. Combining true uniform elongation as a measure for global formability with the true thickness strain at fracture for local formability the mechanical material response can be assessed on basis of uniaxial tensile testing incorporating all microstructural characteristics on a macroscopic scale. Based on these findings a new classification scheme for the recently developed high-strength multiphase steels with significantly better formability resulting of complex underlying microstructures is introduced. The scheme overcomes the steel designations using microstructural concepts, which provide no information about design and production properties.

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Section: Characterization and Classification In Terms Of Mechanicamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels

et al. 2018

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“…Other applications of DIC in metal forming are found in the determination of the formability limits in the bending of sheets 4 and tubes. 5 In bulk metal forming, the applications of DIC are scarce and almost exclusively focused on the determination of stress-strain curves.…”

Section: Introductionmentioning

confidence: 99%

New methodology for the characterization of failure by fracture in bulk forming

Magrinho

Silva

Alves

et al. 2018

The Journal of Strain Analysis for Engineering Design

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This article is focused on the formability limits by fracture obtained from standard bulk metal forming tests performed with cylindrical, tapered and flanged specimens. A total of two novel features are presented: the use of digital image correlation to determine strain paths and immersion of steel specimens in liquid nitrogen after the onset of crack formation to reveal the mode of fracture. A new methodology to determine the fracture loci in principal strain space is proposed based on the combination of experimental force-displacement evolutions with in-plane strain measurements. The experimental work is performed in cold-drawn steel AISI 1045 and two new formability tests with different values of stress triaxiality are proposed for obtaining strains at fracture in regions of principal strain space that are not sufficiently well covered by standard bulk metal forming tests.

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“…At the laser weld line in the TWB parts, the nodes in the adjacent materials were made coincident and no weld properties were assigned. The fracture locus adopted to describe the Usibor ® 1500-AS was developed by ten Kortenaar [9] and updated using plane strain bend data by Cheong et al [10]. The flow curves for Usibor ® 1500-AS were generated from the "Tailored Crash Model" (TCM) due to Bardelcik et al [11].…”

Section: Numerical Model Setupmentioning

confidence: 99%

Dynamic and Quasi-Static Testing and Modeling of Hot Stamped Tailor-Welded Axial Crush Rails

Peister

O’Keeffe

Imbert

et al. 2018

The 18th International Conference on Experimental Mechanics

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In the current research, the use of tailor-welded blanks (TWBs) comprising Usibor® 1500-AS laser welded to more ductile Ductibor® 500-AS is considered. The TWBs were hot stamped to form top-hat cross-section channels with axially tailored properties. Axial crush rails were assembled by spot welding together two of these hot stamped channels along their flanges. The tailored rails were crush tested under dynamic (crash) and quasi-static conditions using an 855 kg crash sled facility at 10.6 m/s impact speed, and a 670 kN servo-hydraulic press at 0.5 mm/s, respectively. Non-tailored channels composed entirely of Ductibor® 500-AS were also tested for base material characterization and as a comparison to the tailored conditions. Numerical models of the crash experiments were developed. The material models include measured fracture loci using the generalized incremental stress state dependent damage model (GISSMO), with rate sensitive constitutive behavior. Spot weld failure was also considered based on tests of spot welded coupons. The accuracy of the predicted force-displacement and energy absorption response, extent of parent metal cracking, and extent of weld failure are evaluated in comparison to the experiments. The difference in response between quasi-static and dynamic testing is also evaluated.

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Evaluation of the VDA 238-100 Tight Radius Bending Test using Digital Image Correlation Strain Measurement

Cited by 46 publications

References 5 publications

Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels

Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels

New methodology for the characterization of failure by fracture in bulk forming

Dynamic and Quasi-Static Testing and Modeling of Hot Stamped Tailor-Welded Axial Crush Rails

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