High strain rate characterisation of unidirectional carbon-epoxy IM7-8552 in transverse compression and in-plane shear using digital image correlation

Koêrber, H.; Xavier, José; Camanho, P.P.

doi:10.1016/j.mechmat.2010.09.003

Cited by 293 publications

(228 citation statements)

References 22 publications

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“…In this case, the most basic use of the full-field data consists in using it as a noncontact strain gauge by averaging the strains over the field of view (e.g. [12][13][14][15][16]) while checking that the strain field was reasonably uniform. Such measurements have also been used to have better insights into strain localization in uniaxial tests [17,18].…”

Section: Introductionmentioning

confidence: 99%

Beyond Hopkinson's bar

Pierron

Zhu

Siviour

2014

Phil. Trans. R. Soc. A.

122

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In order to perform experimental identification of high strain rate material models, engineers have only a very limited toolbox based on test procedures developed decades ago. The best example is the so-called split Hopkinson pressure bar based on the bar concept introduced 100 years ago by Bertram Hopkinson to measure blast pulses. The recent advent of full-field deformation measurements using imaging techniques has allowed novel approaches to be developed and exciting new testing procedures to be imagined for the first time. One can use this full-field information in conjunction with efficient numerical inverse identification tools such as the virtual fields method (VFM) to identify material parameters at high rates. The underpinning novelty is to exploit the inertial effects developed in high strain rate loading. This paper presents results from a new inertial impact test to obtain stress–strain curves at high strain rates (here, up to 3000 s −1 ). A quasi-isotropic composite specimen is equipped with a grid and images are recorded with the new HPV-X camera from Shimadzu at 5 Mfps and the SIMX16 camera from Specialised Imaging at 1 Mfps. Deformation, strain and acceleration fields are then input into the VFM to identify the stiffness parameters with unprecedented quality.

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Section: Introductionmentioning

confidence: 99%

Beyond Hopkinson's bar

Pierron

Zhu

Siviour

2014

Phil. Trans. R. Soc. A.

122

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“…It is therefore natural to expect that this new wealth of information will lead to an in-depth revisit of the high strain rate testing procedures. In the past few years, DIC has been used to acquire full-field information in the SHPB tests [8][9][10]. However, full-field deformation measurements were mainly used to provide average strains over a certain area like a non-contact strain gauge, which did not take full advantage of the strain imaging capability to measure nominally heterogeneous strain states.…”

Section: Introductionmentioning

confidence: 99%

Exploration of Saint-Venant’s Principle in Inertial High Strain Rate Testing of Materials

Zhu

Pierron

2015

Exp Mech

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Current high strain rate testing procedures of materials are limited by poor instrumentation which leads to the requirement for stringent assumptions to enable data processing and constitutive model identification. This is the case for instance for the well known Split Hopkinson Pressure Bar (SHPB) apparatus which relies on strain gauge measurements away from the deforming sample. This paper is a step forward in the exploration of novel tests based on time and space resolved kinematic measurements obtained through ultra-high speed imaging. The underpinning idea is to use acceleration fields obtained from temporal differentiation of the full-field deformation maps measured through techniques like Digital Image Correlation (DIC) or the grid method. This information is then used for inverse identification with the Virtual fields Method. The feasibility of this new methodology has been verified in the recent past on a few examples. The present paper is a new contribution towards the advancement of this idea. Here, inertial impact tests are considered. They consist of firing a small steel ball impactor at rectangular free standing quasi-isotropic composite specimens. One of the main contributions of the work is to investigate the issue of through-thickness heterogeneity of the kinematic fields through both numerical simulations (3D finite element model) and actual tests. The results show that the parasitic effects arising from non-uniform through-the-thickness loading can successfully be mitigated by the use of longer specimens, making use of Saint-Venant's principle in dynamics.

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“…This effect becomes significant, particularly for transverse directions, in cases where polymer matrix is the primary loadbearing member [18][19][20][21][22]. Many test methods have been developed to facilitate the dynamic characterisation of composite materials at high deformation rates.…”

Section: Modelling Rate-dependencymentioning

confidence: 99%

“…Many test methods have been developed to facilitate the dynamic characterisation of composite materials at high deformation rates. Previous test studies 8 highlighted the increase in stiffness and strength of composites with an increasing strain rate in matrix-dominated regions [17][18][19][20][21]. In some cases, explicit empirical relations were formulated to derive such material properties at corresponding strain-rates [20][21].…”

Section: Modelling Rate-dependencymentioning

confidence: 99%

Optimising curvature of carbon fibre-reinforced polymer composite panel for improved blast resistance: Finite-element analysis

et al. 2014

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Numerical studies were conducted to investigate the optimum curvature of a carbon fibrereinforced polymer (CFRP) panel that would provide an improved blast resistance. A dynamic finite-element (FE) model that incorporates fluid-structure interaction was developed to evaluate the response of these panels to blast in commercial finite-element software ABAQUS/Explicit. Previously reported experimental data by authors were utilised to validate a FE model, where a shock-tube apparatus was utilized to apply a controlled shock loading to quasi-isotropic composite panels with different radii of curvature. A threedimensional digital image correlation (DIC) technique coupled with high-speed photography was employed to measure out-of-plane deflections and velocities, as well as in-plane strains at the back face of panels. Macroscopic post-mortem analysis was performed to compare the deformation in these panels. The numerical results were compared to the experimental data and demonstrated a good agreement. The validated FE model was further used to predict the optimal curvature of CFRP panel with the aim to improve its blast-mitigation characteristics.

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High strain rate characterisation of unidirectional carbon-epoxy IM7-8552 in transverse compression and in-plane shear using digital image correlation

Cited by 293 publications

References 22 publications

Beyond Hopkinson's bar

Beyond Hopkinson's bar

Exploration of Saint-Venant’s Principle in Inertial High Strain Rate Testing of Materials

Optimising curvature of carbon fibre-reinforced polymer composite panel for improved blast resistance: Finite-element analysis

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