Non-parametric material state field extraction from full field measurements

Leygue, Adrien; Seghir, Rian; Réthoré, Julien; Coret, Michel; Verron, Erwan; Stainier, Laurent

doi:10.1007/s00466-019-01725-z

Cited by 31 publications

(45 citation statements)

References 9 publications

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“…Designing tests to exhibit simultaneous kinematic and thermal heterogeneities in order to enrich the experimental database is certainly a promising route. Finally, the problem of the assessment of quality of the constitutive model is the large gaping hole in the current state of the art, as also nicely pointed out in Roux and Hild [76] . Novel non‐parametric approaches are emerging, [140‐143] piecewise‐defined models have been explored [60] but in spite of these promising efforts, there is a need for ways of either discriminating between models or formulating models based on MT2.0 methodologies. This is still an open problem.…”

Section: Discussionmentioning

confidence: 99%

Towards Material Testing 2.0. A review of test design for identification of constitutive parameters from full‐field measurements

Pierron

Grédiac

2020

Strain

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Full‐field optical measurements like digital image correlation or the grid method have brought a paradigm shift in the experimental mechanics community. While inverse identification techniques like finite element model updating or the virtual fields method have been the object of significant developments, current test methods, inherited from the age of strain gauges or linear variable displacement transducers, are generally not well adapted to the rich information provided by these new measurement tools. This paper provides a review of the research dealing with the design and optimization of heterogeneous mechanical tests for the identification of material parameters from full‐field measurements, christened here Material Testing 2.0 (MT2.0).

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Section: Discussionmentioning

confidence: 99%

Towards Material Testing 2.0. A review of test design for identification of constitutive parameters from full‐field measurements

Pierron

Grédiac

2020

Strain

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“…Those will thus have no effect on computational performance either. For material behaviors presenting irreversibilities and/or history dependence, first results have been established, both in DDI [11] and DDCM [3].…”

Section: Discussion and Perspectivesmentioning

confidence: 99%

Model-free data-driven methods in mechanics: material data identification and solvers

2019

Self Cite

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This paper presents an integrated model-free data-driven approach to solid mechanics, allowing to perform numerical simulations on structures on the basis of measures of displacement fields on representative samples, without postulating a specific constitutive model. A material data identification procedure, allowing to infer strain-stress pairs from displacement fields and boundary conditions, is used to build a material database from a set of mutiaxial tests on a nonconventional sample. This database is in turn used by a data-driven solver, based on an algorithm minimizing the distance between manifolds of compatible and balanced mechanical states and the given database, to predict the response of structures of the same material, with arbitrary geometry and boundary conditions. Examples illustrate this modelling cycle and demonstrate how the datadriven identification method allows importance sampling of the material state space, yielding faster convergence of simulation results with increasing database size, when compared to synthetic material databases with regular sampling patterns.

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“…Recently, it has been proposed that the stress field be evaluated without a priori information on the constitutive law [38]. However, this so-called data-driven approach is limited to the non-linear elastic case [39], which is not suitable for the present contribution. Instead, the stress identification procedure is divided into two steps.…”

Section: Stress Field Estimationmentioning

confidence: 99%

Tensile and ductile fracture properties of as-printed 316L stainless steel thin walls obtained by directed energy deposition

Margerit

Weisz-Patrault

Ravi‐Chandar

et al. 2021

Additive Manufacturing

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Mechanical properties of as-printed 316L stainless steel thin-walled structures obtained by directed energy deposition are investigated. In-situ tensile and fracture tests are performed on small samples obtained from a additively manufactured square section tube and extracted with three different orientations with respect to the part build direction. Despite a strongly oriented microstructure resulting from the process, as-printed specimens exhibit a reduced anisotropy in comparison with thick or polished samples commonly reported in the literature. Moreover, it is shown using a simple model that the reduced dentified anisotropy can be explained by considering the material thickness variation pattern only, resulting from the layer stacking process. Fracture tests are analyzed using an adapted digital image correlation procedure that evaluates the specimen fracture toughness from experimentally computed J-integrals. Using time reversal, strain fields in regions close to the crack path are identified. Stress fields are then computed from the constitutive behavior identified in tensile tests. A regularization procedure is proposed to enforce the stress equilibrium. Finally, the J-integral is computed using various integration contours in order to validate its path-independance. On this basis, a nearly isotropic fracture toughness is identified. Additional scanning electron microscope observations show that fracture surface features are independent from specimen orientation. This apparent isotropy is explained by the isotropic distribution of lack-of-fusion defects driving crack initiation and propagation.

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Non-parametric material state field extraction from full field measurements

Cited by 31 publications

References 9 publications

Towards Material Testing 2.0. A review of test design for identification of constitutive parameters from full‐field measurements

Towards Material Testing 2.0. A review of test design for identification of constitutive parameters from full‐field measurements

Model-free data-driven methods in mechanics: material data identification and solvers

Tensile and ductile fracture properties of as-printed 316L stainless steel thin walls obtained by directed energy deposition

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