Optical Method to Study Material Behaviour at High Strain Rates

Kajberg, Jörgen; Sjödahl, Mikael

doi:10.1007/978-94-010-0109-0_6

Cited by 9 publications

(9 citation statements)

References 7 publications

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“…Since noise tends to get magnified by numerical differentiation, strains need to be calculated with some care. Therefore a first-order Savitsky-Golay filter (Press et al, 1992;Kajberg and Sj€ odahl, 2003) is applied to the displacement components u and v. This filter is basically a method to fit a plane to local data in a leastsquare sense. The local data chosen in this experiment consist of displacement data for 3 · 3 square grids.…”

Section: Displacement and Strain Measurement Through Speckle Photographymentioning

confidence: 99%

Characterisation of materials subjected to large strains by inverse modelling based on in-plane displacement fields

Kajberg

Lindkvist

2004

International Journal of Solids and Structures

226

165

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Section: Displacement and Strain Measurement Through Speckle Photographymentioning

confidence: 99%

Characterisation of materials subjected to large strains by inverse modelling based on in-plane displacement fields

Kajberg

Lindkvist

2004

International Journal of Solids and Structures

226

165

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“…A calibration procedure is therefore introduced for relating evaluated displacements to physical displacements on the object. It involves comparison of frames taken of a stationary pattern at instants with known rigid displacements and is described in detail in Kajberg and Sjö dahl (2003).…”

Section: Set-up and Specimen Type For The Dynamic Testsmentioning

confidence: 99%

“…Wattrisse et al (2001), Jernkvist and Thuvander (2003), and Molin et al (2004). However, the combination of a high-speed camera and DSP in high-strain rate experiments has been used, to the authors' knowledge, only in Grantham et al (2003) and Kajberg and Sjö dahl (2003).…”

Section: Introductionmentioning

confidence: 97%

Viscoplastic parameter estimation by high strain-rate experiments and inverse modelling – Speckle measurements and high-speed photography

Kajberg

Wikman

2007

International Journal of Solids and Structures

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A methodology based on inverse modelling for estimating viscoplastic material parameters at high strain-rate conditions is presented. The methodology is demonstrated for a mild steel exposed for compression loading in a split Hopkinson pressure bar arrangement. By using dog-bone shaped specimens nonhomogeneous states of deformation are obtained throughout the entire deformation process. The resulting nonhomogeneous deformation of the specimens is evaluated using digital speckle photography (DSP) to give in-plane point-wise displacement and strain fields. The photographs are captured with a high-speed camera of image converter type, which acquire time resolved images during the impact loading. The experiments are simulated using finite element analysis (FEA), where the material model suggested by Johnson-Cook for high-strain rate conditions are utilised. Experimental and FE-calculated field information are compared in order to estimate the viscoplastic parameter in the Johnson-Cook material model. The estimation is performed by minimising least-square functions that contain the differences in displacements and strains, respectively. The quality of the estimated parameters is studied from statistical point of view.

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“…With the development of digital high-speed cameras, 2D-DIC has become popular for monitoring dynamic tests since the early 21st century (see e.g., Refs. [28,29,24,30,31,32,33]). …”

Section: Incremental Dicmentioning

confidence: 99%

On the Use of Digital Image Correlation for the Analysis of the Dynamic Behavior of Materials

Hild

Bouterf

Forquin

et al. 2017

The Micro-World Observed by Ultra High-Speed Cameras

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The present chapter is devoted to the analysis of the mechanical behavior of materials subjected to dynamic loadings via digital image correlation (DIC). This measurement technique provides 2D or 3D displacement fields that can be evaluated thanks to the use of high-speed cameras. Various declinations of DIC are first presented. Uncertainty quantifications are also discussed. Last, different examples illustrate how DIC can be used to analyze and quantify deformation, damage and fracture mechanisms of brittle and ductile materials.

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Optical Method to Study Material Behaviour at High Strain Rates

Cited by 9 publications

References 7 publications

Characterisation of materials subjected to large strains by inverse modelling based on in-plane displacement fields

Characterisation of materials subjected to large strains by inverse modelling based on in-plane displacement fields

Viscoplastic parameter estimation by high strain-rate experiments and inverse modelling – Speckle measurements and high-speed photography

On the Use of Digital Image Correlation for the Analysis of the Dynamic Behavior of Materials

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