Institute of Fundamental Technological Research
Polish Academy of Sciences

Staff

Adi Adumitroaie, PhD

Department of Intelligent Technologies (ZTI)
Division of Safety Engineering (PIB)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 455
room: 416
e-mail:

Recent publications
1.  Vaitkunas T., Griskevicius P., Adumitroaie A., Peridynamic Approach to Digital Image Correlation Strain Calculation Algorithm, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app12136550, Vol.12, No.13, pp.6550-1-21, 2022

Abstract:
Digital image correlation is an experimental optical non-contact full field displacement and strain evaluation method based on the surface subsets tracking with photo cameras, digital images processing, and numerical computation. However, the full field of strain computation is a challenging problem, mainly because the displacement field to be differentiated is not continuous, individual subsets are tracked by the optical digital image correlation system. Moreover, the numerical differentiation can also amplify the noise of the displacement field inducing thus strain errors when the displacement data are poor. The peridynamics theory (which equations are cast in terms of spatial integrals of displacements, instead of spatial derivatives in the classical continuum mechanics) based algorithm is considered in this study and applied for the experimental digital image correlation displacement field to analyze possible peridynamic differentiation method advantages. A strains convergence analysis between the digital image correlation and peridynamic differentiation methods is done in this study. The integro-differential strain calculation as an alternative method is validated against digital image correlation and finite element simulation strain fields. It is also shown that the digital image correlation, a noisy displacement field, still provides an accurate and low level noise strain evaluation based on the proposed method.

Keywords:
strain field, digital image correlation, peridynamics, differentiation, peridynamic differential operator

Affiliations:
Vaitkunas T. - Kaunas University of Technology (LT)
Griskevicius P. - Kaunas University of Technology (LT)
Adumitroaie A. - IPPT PAN
2.  Vaitkunas T., Griskevivius P., Adumitroaie A., Peridynamic material model calibration based on digital image correlation experimental measurements, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2022.2089934, pp.1-14, 2022

Abstract:
The non-local theory of peridynamics, based on integral equation of motion, offers a computation alternative for materials with discontinuities. In this study, the peridynamic material model parameters are calibrated using full field Digital Image Correlation measurements applied to simple tensile test experiments, circumventing thus the need for more challenging test setups/methods for the determination of the peridynamic material parameters (especially the critical stretch failure parameter). A two stage algorithm in the optimization software LS-Opt together with a MATLAB stage for performing the peridynamic simulation and an Excel stage for defining the outputs of the simulation are implemented to minimize the differences between the peridynamic model and experimental results. The material model parameters determined based on the simple test setup and the calibration procedure proposed here can then be used for modeling more challenging geometries and load cases in peridynamics.

Keywords:
peridynamics, failure parameters, discontinuous field, digital image correlation, model calibration, LS-Opt

Affiliations:
Vaitkunas T. - Kaunas University of Technology (LT)
Griskevivius P. - Kaunas University of Technology (LT)
Adumitroaie A. - IPPT PAN

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