Material Testing 2.0 (MT2.0) couples full‑field deformation measurements (Digital Image Correlation, DIC) with inverse identification methods (Virtual Fields Method, VFM) to extract constitutive parameters from a small number of heterogeneous experiments. This paper presents the Cut‑Clamp‑Play concept: an integrated industrial MT2.0 solution that unifies specimen design, automated testing hardware, and a computationally efficient VFM identification chain to deliver fast, user‑friendly sheet‑metal characterization. A perforated cruciform specimen is optimized for parameter identifiability of the Yld2000‑2d anisotropic yield function and used in a single biaxial test. A working prototype has been built at KU Leuven and used to collect representative DIC data; the measured displacement/strain response is double‑symmetric, confirming correct mechanical operation. Projected and early prototype results indicate that the Cut‑Clamp‑Play approach can reduce operator actions by roughly 70% and produce identification results within one hour for typical sheet‑metal cases, while further work is required to make the fully automated “Play” stage robust for industrial deployment.

This contribution presents a combined approach for in-situ experimental characterisation and numerical modelling of thermo-mechanical behaviour in directed energy deposition (DED). Full-field temperature and substrate deformation are measured simultaneously using infrared (IR) thermography and stereo digital image correlation (DIC) during laser-beam powder deposition on a thin substrate. The experimental data are used to calibrate thermal boundary conditions and to validate a macroscopic finite-element model. The validated framework is then applied to compare different deposition strategies, demonstrating the capability of the coupled measurements and simulations to capture transient thermal fields, deformation evolution and toolpath-dependent effects relevant for process optimisation.

This paper revisits the long-standing question of how to fully characterise the in-plane plastic anisotropy of sheet metals without assembling evidence from multiple standardised tests. The central idea is pragmatic: a single, well-designed heterogeneous biaxial experiment can replace the conventional combination of uniaxial and equibiaxial tests if the specimen and the inverse identification method are co-designed to (i) activate informative stress states and (ii) maintain low strain gradients for accurate digital image correlation measurements. The proposed cruciform specimen is deliberately conceived as a benchmark configuration for full-field inverse identification, with known locations and stress-strain states at which relevant material information is embedded. The approach is coupled with a Finite Element Model Updating framework, enabling all anisotropy parameters of the YLD2000-2d model to be identified from a single full-field dataset. Sensitivity and identifiability analyses demonstrate that a physically based parameter formulation significantly improves the conditioning of the inverse problem. Virtual experimentation confirms the robustness and accuracy of the proposed “one-test” identification strategy.

This study presents an experimental and numerical investigation of warpage in injection-moulded ABS plates, with emphasis on the influence of modelling assumptions and residual stress development on warpage prediction. Two sets of processing conditions with different mould-temperature balances were investigated experimentally, and warpage was measured using a coordinate measuring machine (CMM). Filling and packing were simulated using Moldex3D, while warpage was predicted using two integrated Moldex3D solvers and a coupled Moldex3D-Abaqus thermomechanical approach. Although identical thermal input data were used, the three approaches produced noticeably different warpage predictions. The Moldex3D enhanced solver consistently over-predicted warpage magnitude, while the Moldex3D nonlinear solver captured the nonlinear effects but showed unrealistic localised deformation. The thermomechanical approach predicted the warpage shape more accurately for both parameter sets and showed the closest overall agreement with the experimental results.

Accurate representation of plastic anisotropy is essential for reliable sheet metal forming simulations. However, calibration of advanced anisotropic yield functions typically relies on multiple mechanical tests performed along different loading directions and under various multiaxial stress states. The extensive experimental effort required conflicts with the short lead times demanded by industry. Moreover, many of the stress states that need to be characterized are not relevant to the forming process of interest. Material Testing 2.0 (MT2.0) addresses these limitations by reducing the experimental burden while enabling the design of application-specific experiments that reproduce the stress states encountered during the target forming process. In this paper, we demonstrate the potential of the MT2.0 approach for the efficient and targeted calibration of the widely used Yld2000-2d anisotropic yield function for sheet metals. The proposed methodology requires only a single heterogeneous biaxial tensile test, thereby significantly reducing the required experimental effort. Furthermore, the experiment is specifically designed to probe the first quadrant of the stress space, which is relevant for the targeted forming applications. To this end, a novel cruciform specimen is designed to identify all anisotropy parameters through inverse analysis based on full-field strain measurements. The specimen geometry provides complementary information on the plastic anisotropic response by combining regions subjected to predominantly uniaxial tension along the rolling, transverse, and diagonal directions with regions experiencing biaxial tension. The design minimizes strain gradients, ensuring reliable Digital Image Correlation (DIC) measurements and comparable plastic strain levels across the informative regions. The performance of the identification scheme, based on Finite Element Model Updating (FEMU), is assessed using synthetic DIC data to quantify parameter sensitivity, identifiability, and robustness against measurement noise. For the proposed MT2.0 approach, it is demonstrated that a physically motivated parameterization of the Yld2000-2d yield function significantly improves parameter identifiability. The method is benchmarked against a state-of-the-art calibration procedure for a low-carbon steel sheet, relying on biaxial tensile tests performed under seven different stress ratios. The inversely identified anisotropic yield locus closely reproduces the benchmark response. These findings demonstrate the feasibility of reliable single-test identification of planar plastic anisotropy. Furthermore, they highlight that efficient and robust MT2.0 specimen designs must be developed in conjunction with the selected inverse identification method and full-field measurement technique.

This paper presents a thermo-mechanical finite element (FE) modelling framework for laser-based directed energy deposition (DED-LB) that is validated and calibrated using a novel full-field, in-situ experimental approach. The measuring setup combines infrared (IR) thermography and stereo digital image correlation (DIC) to enable continuous, non-intrusive, full-field measurement of transient temperature and displacement fields on the substrate without interfering with the DED process. These measurements provide direct input for reliable model calibration and a consistent basis for full-field validation of both thermal and mechanical response of the numerical model. The calibrated FE model accurately reproduces the measured thermal histories and the evolution of substrate deformation throughout the process. Based on the validated model, the dominant deformation mechanisms are identified, highlighting the combined effects of thermal gradients, contraction of the solidifying deposited material, and mechanical boundary conditions. The study further introduces a new analytical bead-geometry modelling method that estimates the geometry of initial and overlapping beads without additional experiments and establishes a consistent link between realistic and simplified bead representations while preserving deposited mass and heat input. Comparative simulations demonstrate that simplified rectangular bead profiles can reduce computational cost by up to 70% with only minor loss of accuracy, making them suitable for parametric studies. Finally, different DED strategies are evaluated, showing that an inward-spiral strategy leads to the lowest substrate deformation and the most uniform residual-stress distribution, whereas unidirectional and bidirectional strategies produce larger deflections and stronger springback.

This study introduces four inverse methodologies for reconstructing the strain field within a dent in a thin-walled metallic structure. Using exclusively the dent's deformed shape and the initial undamaged panel shape, the proposed inverse approaches enable the reconstruction of the dent strain field. The accuracy of the methods is investigated based on simulated data, which serves as the ground truth. To this end, a hail impact simulation is conducted with ABAQUS, mimicking typical dent dimensions observed in aircraft. Furthermore, a Digital Virtual Twin (DVT) of the Projection-based Digital Image Correlation (Pb-DIC) dent shape measurement is used to investigate the robustness of the inverse strain reconstruction methods. The results show that the methods effectively capture the displacement fields and thus exhibit good predictive accuracy of the strain field. The methodology provides an opportunity for better-grounded damage assessment of dents in aircraft.

The accuracy of numerical predictions in sheet metal processes involving multiaxial stress-strain states (e.g., blanking, riveting, and incremental forming) heavily depends on the characterisation of plastic anisotropy under multiaxial loading conditions. A fully calibrated 3D plastic anisotropy model is essential for this purpose. While in-plane material behaviour can be conventionally characterised through uniaxial and equi-biaxial tensile tests, calibrating out-of-plane material behaviour remains a significant challenge. This behaviour, governed by out-of-plane shear stress and associated material parameters, is typically described by out-of-plane shear yielding. These parameters are notoriously difficult to determine, leading researchers to frequently assume isotropic behaviour or identical shear parameters for in-plane and out-of-plane responses. Although advanced calibrations may utilise crystal plasticity modelling, there remains a critical need for macro-mechanical characterisation methods. This paper presents an out-of-plane shear testing and material characterisation procedure based on full-field strain measurements using digital image correlation (DIC). Strains within the shear zone are measured via DIC and employed in the Finite Element Model Updating (FEMU) to identify out-of-plane shear parameters of a 2.42 mm thick, cold-rolled AW5754-H22 aluminium alloy sheet, using the Yld2004-18p yield criterion. Given that the characteristic strain response at this scale may be influenced by local crystal structure behaviour on the surface, this paper evaluates the feasibility of such measurements. Finally, to test the validity of the full-field-based approach, the FEMU-identified parameters are compared against results obtained through a classical optimisation procedure based on force-elongation measurements from the shear zone.

Accurate characterisation of through-thickness shear resistance is essential for high-quality simulations of sheet metal forming processes such as blanking, riveting, and incremental forming. This resistance is closely linked to the plastic behaviour of materials in the thickness direction, necessitating precise modelling of strain hardening and plastic anisotropy. While simplified assumptions of isotropy or equal in- and out-of-plane shear parameters are often made, advanced approaches rely on crystal plasticity models, which themselves require calibration. This study introduces a novel out-of-plane shear test procedure based on macro-mechanical testing and Digital Image Correlation (DIC) to inversely calibrate the YLD2004-18p yield function. Using a specially designed double-bridge shear specimen, identical in geometry for all tests, the method enables consistent shear testing across all material planes, facilitating direct comparisons of anisotropic behaviour. A sensitivity analysis was used to establish criteria for evaluating test quality and improving future designs. Testing on 2.4 mm thick AA 5754-H22 aluminium alloy reveals that shear responses in the yz and xz planes are 8% and 12% lower than in the xy plane, respectively. The method effectively captures the force-extension response’s sensitivity to variations in out-of-plane shear parameters, enabling a complete characterisation of plastic anisotropy in medium-thick sheet metals. This approach potentially enhances the accuracy of metal forming simulations by providing robust calibration for out-of-plane behaviour.

The paper presents a novel experimental and numerical methodology for calibration of out-of-plane shear behaviour of moderate thick sheet metals by double bridge shear test. By conducting tests, it is shown that shear response of sheet metal in all three principal material planes can be characterised by the same specimen design with the shear detail or material oriented in a specific direction. For a 2.4 mm thick AA5754-H22 sheet material it is shown that the shear response is the highest in the rolling-transverse (RD-TD) plane, followed by the transverse-normal (TD-ND) plane, and the lowest in the rolling-normal (RD-ND) plane.

The accurate description of sheet metal forming processes such as blanking, riveting, incremental forming, and ironing strongly depends on understanding the material's through-thickness shear resistance and plastic behavior. A three-dimensional model of plastic anisotropy is required to capture this behavior, but calibrating the out-of-plane shear parameters is often challenging. Researchers frequently assume isotropy or set the in-plane and out-of-plane shear parameters equal. More advanced approaches use a crystal plasticity model, which also requires calibration based on available material texture data. In this work, we introduce an out-of-plane shear test procedure that combines a macromechanical test with digital image correlation to inversely calibrate the shear anisotropy parameters of the YLD2004-18p yield function. This method efficiently characterizes both in- plane and out-of-plane shear anisotropy in medium-thick sheet metals.

Finite element model updating (FEMU) is an advanced inverse parameter identification method capable of identifying multiple parameters in a material model through one or a few well-designed material tests. The method has become more mature thanks to the widespread use of full-field measurement techniques, such as digital image correlation. Proper application of FEMU requires extensive expertise. This paper offers a review of FEMU and a guide to practice. It also presents FEMU-DIC, an open-source software package. We conclude by discussing the challenges and opportunities in this field with the intent of inspiring future research.

This paper presents a novel methodology for the analytical determination of the uniaxial tensile/compressive stress-strain curve derived from the four -point bending test without a pre -assumed constitutive model. While the concept of extracting the stress-strain curve from a bending test is not new, the proposed methodology differs from existing methods by recognising the force equilibrium in a deformed configuration, resulting in a temporal variation of both a bending moment and an axial force. In addition, the deformation of the beam cross-section is taken into account according to the principles of finite strain theory either via Poisson's ratio or by assuming volume conservation. The crucial data for this methodology are obtained from an experimentally conducted bending test in which the loading force, displacement and strain fields at the top, bottom and front faces of the specimen are measured using a stereo DIC. While the method is completely analytical, it reconstructs the stress-strain curve in discrete form by solving a system of linear equations. While the existing methods for the four -point bending test allow extraction of the stress-strain curve from a single experiment only for strains up to a few per cent, our methodology allows the extraction of the stress-strain curve in tension and compression up to five times the strains obtained with methods that neglect the above features.

Stress reconstruction based on experimentally acquired full-field strain measurements is computationally expensive when using conventional implicit stress integration algorithms. The computational burden associated with repetitive stress reconstruction is particularly relevant when inversely characterizing plastic material behaviour via inverse methods, like the nonlinear Virtual Fields Method (VFM). Spatial and temporal down-sampling of the available full-field strain data is often used to mitigate the computational effort. However, for metals subjected to non-linear strain paths, temporal down-sampling of the strain fields leads to erroneous stress states biasing the identification accuracy of the inverse method. Hence, a significant speedup factor of the stress integration algorithm is required to fully exploit the experimental data acquired by Digital Image Correlation (DIC). To this end, we propose an explicit stress integration algorithm that is independent on the number of images (i.e. strain fields) taken into account in the stress reconstruction. Theoretically, the proposed method eliminates the need for spatial and temporal down-sampling of the experimental full-field data used in the nonlinear VFM. Finally, the proposed algorithm is also beneficial in the emerging field of real-time DIC applications.

Digital image correlation (DIC) is a powerful tool for characterising materials and determining material model parameters. To assess the reliability of the full-field measurement-based inverse identification procedures, it is crucial to investigate the impact of the measurement errors on the identified material model parameters. Literature indicates that conventional error propagation models, which rely on Gaussian noise-contaminated data, significantly overestimate the confidence for inversely identified material model parameters, resulting in misleadingly narrow confidence intervals. A more precise assessment of systematic errors originating from the experimental setup leads to an improved prediction of the confidence intervals, but this requires specific information about the DIC equipment, post-processing details, and a skilled experimentalist. In this work, we propose an alternative two-stage error propagation model that yields more realistic confidence interval predictions based solely on a database of past mechanical experiments conducted with the specific stereo DIC system set up in a particular way. We have validated the proposed procedure numerically using the open-hole test and an orthotropic elastic material model. Our predictions reveal a non-Gaussian probability distribution of the inversely identified material model parameters, with confidence intervals considerably wider than those obtained by considering random Gaussian noise. Furthermore, these predictions were experimentally validated in an extensive experimental campaign investigating a pultruded carbon fibre epoxy composite.

High Strength Steel grades are indispensable for the development of heavy-duty constructions and components with high specific strength. In these applications, a profound understanding of the plastic material behavior up to fracture is required to assess the structural integrity through numerical simulations. In this paper, we investigate the plastic behavior of S700 with a nominal thickness of 12 mm. The steel production process of a hot rolled, heavy gauge material inherently results in a through-thickness variation of the mechanical properties: i) solidification of the continuously cast slab starts from the outer surface, causing a gradient of the chemical composition across the thickness, ii) subsequent thermomechanical controlled rolling results in a variation of microstructure and texture over the thickness. To enhance the predictive accuracy of numerical simulations, we are examining the manifestation of this inhomogeneity across a range of plasticity experiments.

The success of inverse material model identification depends on the interaction between the adopted material model, the design of the heterogeneous specimens, the quality of the full-field measurements and the employed inverse identification method. Although inverse identification with full fields usually uses either FEMU or nonlinear VFM algorithms, a range of specimen designs and heterogeneity indicators have been proposed to assess the quality of the measured field and specimen design. While many studies investigate the effects of strain field heterogeneity on material model identification, few of them address the comprehensive interaction of all the above features and investigate their interactions during inverse identification through identifiability analysis. In this study, we analyze the identifiability of the parameters of the YLD2000-2d model used to describe the plastic anisotropy of steel sheet DC04 using a perforated biaxial specimen with the nonlinear VFM method. For this purpose, we performed a virtual DIC experiment with known material parameters by simulating the test in ABAQUS/Standard, generating synthetic images and reconstructing the strains via stereo DIC. Before inverse identification with a nonlinear sensitivity-based VFM, we analyzed the sensitivity of the virtual work to parameter changes and performed an identifiability analysis.

This paper presents a new methodology for characterising the out-of-plane plastic anisotropy behaviour of sheet metal, based on indentation testing. Conventionally, advanced yield criteria are used to describe plastic anisotropy, requiring multiple in-plane mechanical tests (such as uniaxial and biaxial tests) to calibrate a model. However, in certain forming applications (e.g. blanking, ironing and incremental forming), the influence of mechanical behaviour through thickness cannot be ignored, necessitating the characterisation of out-of-plane material behaviour. To do this, a 3D plastic anisotropy model must be used and calibrated for the out-of -plane shear parameters, which can be difficult to determine. Researchers often assume an isotropic case or equal shear parameters for in-plane and out-of-plane behaviour. More advanced calibrations involve the crystal plasticity model. In this work, we propose a two-stage calibration procedure. In the first stage, we calibrate the in-plane parameters of the YLD2004-18p yield function conventionally. In the second stage, after fixing the in -plane parameters, we determine the remaining out-of-plane shear parameters based on the results of the ball indentation test. We show for the first time that out-of-plane shear parameters can be determined from a macro -mechanical test for a 2.42 mm thick cold-rolled AA5754-H22 series aluminium sheet.