Projection-based measurement and identification

A recently developed Projection-based Digital Image Correlation (P-DVC) method is here extended to 4D (space and time) displacement field measurement and mechanical identification based on a single radiograph per loading step instead of volumes as in standard DVC methods. Two levels of data reductions are exploited, namely, reduction of the data acquisition (and time) by a factor of 1000 and reduction of the solution space by exploiting model reduction techniques. The analysis of a complete tensile elastoplastic test composed of 127 loading steps performed in 6 minutes is presented. The 4D displacement field as well as the elastoplastic constitutive law are identified. Keywords: Image-based identification, Model reduction, Fast 4D identification, In-situ tomography measurements. INTRODUCTION Identification and validation of increasingly complex mechanical models is a major concern in experimental solid mechanics. The recent developments of computed tomography coupled with in-situ tests provide extremely rich and non-destructive analyses [1]. In the latter cases, the sample was imaged inside a tomograph, either with interrupted mechanical load or with a continuously evolving loading and on-the-fly acquisitions (as ultra-fast X-ray synchrotron tomography, namely, 20 Hz full scan acquisition for the study of crack propagation [2]). Visualization of fast transformations, crack openings, or unsteady behavior become accessible. Combined with full-field measurements, in-situ tests offer a quantitative basis for identifying a broad range of mechanical behavior.Comment: SEM 2019, Jun 2019, Reno, United State

Model-based 4D tomography for mechanical testing

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On the use of regularized DVC to analyze strain localization

International audienceFor an in-depth understanding of the failure of structural materials the study of the deformation mechanisms in the bulk is fundamental. In situ synchrotron radiation computed laminography provides 3D images of thin plates subsequently processed by digital volume correlation to measure displacement and strain fields by using the natural contrast of the material. Difficulties arise from the lack of data, which is intrinsic to laminography and leads to several artifacts, and the weak absorption contrast in the 3D image texture of the studied material. To lower uncertainty levels and to have a better mechanical admissibility of the measured displacement fields, a regularized digital volume correlation procedure is introduced and applied to analyze localized displacement and strain fields

Data-model dialectic: the case of 4D mechanical tests

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Measurement of 3D displacement field from few tomographic projections

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Measurement of 3D displacement field from few tomographic projections

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Data-model dialectic: the case of 4D mechanical tests

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Contributions of volume correlation to the study of brittle and ductile damage

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