# Projection-based measurement and identification

## TL;DR

This paper extends the Projection-based Digital Image Correlation (P-DVC) method to 4D displacement measurement and mechanical identification using minimal data, enabling rapid analysis of complex elastoplastic tests with high data reduction.

## Contribution

The paper introduces a novel 4D P-DVC approach that significantly reduces data acquisition and solution space, allowing fast in-situ tomography measurements and mechanical model identification from minimal radiographs.

## Key findings

- Achieved 4D displacement field measurement with a single radiograph per step.
- Identified elastoplastic constitutive law from a 127-step test in 6 minutes.
- Reduced data acquisition by a factor of 1000 using model reduction techniques.

## Abstract

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.

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Source: https://tomesphere.com/paper/1905.08905