Virtual Extensometer Research Articles

Mechanical analysis of polyester resin using digital image correlation and finite element method

The primary objective of this study is to perform a comprehensive mechanical analysis of unsaturated polyester (UP) resin under unidirectional tensile loading. The Digital Image Correlation (DIC) technique was employed to accurately determine the mechanical properties of the material, with full-field strain measurements used to extract both transverse and longitudinal strains through virtual extensometers. This approach facilitated the precise calculation of the Poisson’s ratio of the UP resin. The results obtained via DIC demonstrated strong correlation with the experimental data obtained through the machine’s control software, particularly in capturing vertical displacement and longitudinal strain with high precision. The Poisson’s ratio was found to be 0.46. To further validate the DIC findings, Finite Element Analysis (FEA) was conducted. The FEA results aligned closely with the experimental data, confirming the reliability and accuracy of the DIC method in this context. The values of Young’s modulus determined from experimental tests and FEA data were 3620.02 MPa and 3598 MPa, respectively, with a percentage error of only 0.61%.

A hybrid continuum-beam optimisation model: the virtual extensometer method for efficient optimisation of lattice materials

AbstractAdditive manufacturing (AM) enables the fabrication of complex lattice structures that are infeasible with traditional manufacturing processes. These structures are typically implemented with constant cross-sectional strut elements; this strategy is expedient but leads to sub-optimal structural efficiency. Numerical continuum models allow robust mechanical modelling of complex lattice geometry but provide equally complex data fields that are ill-suited for traditional optimisation techniques. By contrast, numerical beam models represent the fundamental tensile and bending stress states but are incapable of capturing nuanced geometrical effects that lead to local stress concentrations. In this research, a hybrid continuum-beam method is proposed for the systematic optimisation of strut cross section: a representative unit cell is simulated by continuum elements, and the local strut stress tensor is acquired by embedded beam elements that act as virtual extensometers. By integrating a computationally inexpensive beam model into a more robust continuum model, the volume and the quality of data returned are significantly increased whilst being provided in a readily usable format for optimisation techniques, for a trivial increase in computational cost. The presented method is generalised and can be applied to any strut-based lattice structure. Body-centred cubic (BCC) and BCC with z-strut (BCCZ) lattice structures optimised by the proposed method are fabricated using laser-based powder bed fusion (LB-PBF) in AlSi10Mg and are mechanically evaluated. On average, performance for BCC lattice structures improves by 33% and 26% for relative yield strength and relative Young’s modulus respectively. BCCZ lattice structures saw a performance improvement of 25% and 19% for relative yield strength and relative Young’s modulus respectively, thus confirming superior performance at lower relative densities when compared to incumbent designs.

Spatial-temporal response and precursor characteristics of tensile failure on disc coal samples of different sizes combining AE, EMR and DIC techniques

Tensile fractures in deep coal and rock mass can readily trigger dynamic calamities like rock bursts, significantly impacting the safety of coal mining. To enhance our understanding of coal’s tensile failure mechanism, Brazilian splitting failure experiments were conducted on coal samples with prefabricated cracks of different sizes. Acoustic emission (AE), electromagnetic radiation (EMR) and digital image correlation (DIC) techniques were used to analyze the instability failure process and precursor characteristics of coal samples. The results showed that, for coal samples of the same thickness, the tensile strength and peak strain gradually decreased with the increase of coal sample size, whereas the elastic modulus increased gradually, highlighting more pronounced brittleness characteristics and revealing a noticeable size effect. The time-varying evolution of AE energy, EMR energy and VE (virtual extensometer) elongation during the tensile failure process of coal samples is closely correlated to the stress evolution trend, exhibiting distinct characteristics at various loading stages. The failure modes of coal samples of varying sizes exhibited a strong correlation with the spatial distribution of AE events, as well as the strain and displacement field measured by DIC. With the coal sample’s growing size, the percentage of AE high energy events rose while the total number of AE positioning events fell, the proportion of DIC strain concentration area decreased, displacement zoning characteristics became more obvious, and the critical opening displacement of cracks increased. The variance of AE, EMR and DIC related parameters in coal samples showed significant critical slowing down characteristics. Based on their response timescales, EMR energy was identified as an “Early warning”, AE energy as a “Medium warning”, and VE elongation as a “Short-imminent warning”. A comprehensive analysis of multi-parameter monitoring information proved beneficial in accurately pinpointing precursory response points of coal mine dynamic disasters, thereby enhancing monitoring precision.

Dynamic mechanical behaviours of frozen rock under sub-zero temperatures and dynamic loads

Dynamic mechanical behaviours of frozen rocks are essential for dealing with the design and stability of various engineering structures in cold regions. A dynamic-cryogenic testing system integrated with high-speed Digital Image Correlation (DIC) is adopted to investigate the dynamic mechanical behaviours of rock subjected to ambient room and sub-zero temperatures, along with high-rate loading. Dynamic compression, tensile and Mode I dynamic fracture tests were performed at 20, -20, −50 and −70 °C using dry and saturated sandstone from Yulong Copper Mine at high-altitude cold region. A DIC-based approach using pixel-based virtual extensometers is proposed to accurately capture the real-time cracking speed with high precision. The proportion of ice and unfrozen water in rock pores across various temperatures is quantified using the nuclear magnetic resonance (NMR) method. The results indicate significant temperature and rate dependencies in dynamic fracture toughness, crack propagation velocity, dynamic tensile strength, dynamic compressive strength, and failure modes; These parameters exhibit an increase with decreasing ambient temperature as unfrozen water transitions into ice, demonstrating the frozen effect of ice filling pores, supporting the rock skeleton, and bonding ice-rock interfaces. With decreasing temperature, crack branching becomes more pronounced in dynamic notched semi-circular bending (NSCB) tests. Additionally, dynamically compressed frozen rocks tend to transition from pulverization (Type II) to splitting (Type I) with multiple elongations, attributed to the strengthening effect. The findings elucidate the failure mechanisms observed in a higher proportion of larger blast blocks and hold valuable implications for blasting designs and dynamic disaster prevention in cold regions.

Static and dynamic fracture toughness of graphite materials with varying grain sizes

Graphite materials play critical roles as moderators, reflectors, and core structural components in high-temperature gas-cooled nuclear reactors. During the reactor operation, graphite materials may experience a variety of loads, including thermal, radiation, fatigue, and dynamic loads, potentially leading to crack initiation and propagation. Therefore, it is imperative to investigate their fracture properties. Despite this, there remains a paucity of comprehensive studies on the fracture toughness of graphite materials with varying grain sizes, particularly concerning dynamic fracture toughness. This study addresses this gap by employing a digital-image-correlation-based virtual extensometer to analyze crack propagation in graphite materials of different grain sizes, enabling precise measurement of crack propagation length and fracture toughness. Findings reveal that static fracture toughness increases with larger grain sizes, while under dynamic loading, smaller grain sizes exhibit greater fracture toughness. Additionally, dynamic fracture toughness shows a near-linear increase with impact speed. Scanning electron microscopy analysis of fracture surface morphology highlights the impact of grain size and impact speed on fracture toughness. Nuclear graphite specimens with larger grain sizes have more irregular grain and pore distributions, enhancing crack deflection and propagation resistance, thereby increasing fracture toughness. The observed loading rate dependence of dynamic fracture toughness is attributed to a gradual transition from intergranular to transgranular fracture modes with increasing impact speed.

Material Characterization Augmented with Artificial Intelligence.

The present paper investigates the application of artificial intelligence to improve the results from simple, non-instrumented, tensile tests, performed with a desktop-size MaCh3D smart universal testing machine. Non-instrumented tensile tests, performed on any testing machine, are affected by both deterministic and random factors that introduce errors in the test results. Specific features of the MaChh3D tester minimize random factors effects on test results while introducing a larger effect of deterministic factors. Artificial intelligence is identified as a novel approach to correct errors in non-instrumented tensile test, capable of simulating a direct strain measure onto the test, replacing traditional contact or non-contact instrumentations (like strain-gages, extensometer and optical measures) that introduce complexity into test procedure and require time for setup. The resulting AI model implementation is described and its performance evaluated in comparison with instrumented tests, also comparing different training strategies. The developed AI-extensometer (artificial intelligence virtual extensometer), is capable of a precise mechanical properties evaluation, with errors from 0 to 10% depending on the specific parameter.

Retardation mechanisms and modeling of fatigue crack growth of a high-strength steel after single overload

This study investigated the retardation mechanisms and modeling methodology for the fatigue crack growth (FCG) of a high-strength Q500qE steel after a single overload. Different stress ratios (R = 0.1, 0.3, and 0.5) and overload ratios (OLR = 1.5, 2.0, and 2.5) were considered as key parameters. The digital image correlation (DIC) testing technique was used to capture the deformation at the crack tip during the tests. The crack closure response in the crack wake region was investigated using a virtual extensometer. The results show that, under an identical stress ratio, the fatigue life was increased as the OLR increased. The FCG was completely arrested when OLR reached 2.5 when R ≥0.3. Under an identical stress ratio, the residual strain before the crack tip and the residual deformation in the crack wake region increased with the rise of the overload ratio after a single overload. It’s found that the FCG was retarded or completely arrested due to the constraint of the crack tip plastic zone caused by single overload. Finally, a modified Wheeler model was proposed to predict the FCG rate based on the measured plastic zone size at the crack tip, and the predicted results agree well with the experimental findings.

Experimental assessment of the functional fatigue in biocompatible Ti67Zr19Nb11.5Sn2.5 shape memory alloy in the vicinity of drilled holes

Shape memory alloys (SMA) exhibit desirable and unique functionalities that are suitable for a plethora of applications in the automotive, aerospace, and biomedical industries. The TiNbZrSn SMA has been specifically developed for biomedical applications owing to its enhanced biocompatibility compared to the widely available and heavily investigated NiTi-based SMA. In this work, the effects of mechanical rolling, heat treatment, and grain size on the functional fatigue properties of TiNbZrSn are investigated under cyclic loading conditions. Superelasticity was observed for samples rolled to reduction levels exceeding 90 %. However, the recovery magnitudes improved significantly following 96.6 % rolling due to the optimization of the grain size. The reduction in grain size, from about 400 μm in the homogenized conditions to 50 μm for the 96.6 % rolled state, increases slip resistance which consequently promotes superelasticity. The functional superelastic properties were also evaluated for samples with geometric stress concentration (drilled hole). Using full-field measurement techniques, the applied, recoverable, irreversible strains, and their evolution under cyclic loading conditions were carefully measured. The use of virtual extensometers located in multiple locations around the geometric stress concentration provides means to not only evaluate the functional degradation of local superelastic properties, but also the transition to structural damage through the initiation and propagation of fatigue cracks.

A novel DIC-based methodology for crack identification in a jointed rock mass

Crack identification in brittle rocks is a challenging problem in rock mechanics. To represent the details of jointed rock masses, rock-like specimens containing inclined joint sets were generally prepared by three-dimensional (3D) printing using sand. Digital image correlation (DIC) was employed for full-field deformation measurement during loading. The results show that the sand 3D-printed specimen has distinct advantages in the preparation of jointed rock masses. DIC was extended to measure the displacement vector field around newly propagated cracks. Two types of cracks are recognized: tensile and shear cracks. Two different coalescence patterns are classified: step-path failure and planar failure. A covariance matrix-based multivariate measure, the rate of effective variance change (REVC), was proposed to quantify the dispersion of strain data. The variation in the strain dispersion measure was found to be closely related to the crack type. For the first occurrence of tensile and shear cracks, the rates of mutation (RMs) are within the ranges of 1.56–3.42 and 14.54–86.44, respectively, which can be considered a new crack identification criterion. A virtual extensometer method based on DIC was established to interpret the variation mechanism of the REVC associated with different crack types.

An experimental–numerical study on the evolution of the Taylor–Quinney coefficient with plastic deformation in metals

When plastic deformation of metals occurs by dislocation motion, a part of the plastic work is stored in the material while the remainder is dissipated as heat. The fraction of the plastic work dissipated as heat can be observed on a macroscopic scale as infrared radiation. Typically, this fraction of plastic work converted into heat is assumed to be constant and around 90%. In this study, an experimental–numerical approach was used to calculate the Taylor–Quinney coefficient as a function of plastic deformation. The experimental foundation was obtained by performing tension tests at slightly elevated strain rates on notched specimens from two dual-phase steels and an aluminium alloy in three temper conditions. The temperature on the surface of the specimens was obtained using an infrared camera, and these temperature recordings were correlated to displacement measurements from a virtual extensometer enabled by digital image correlation. A user material model was used in combination with the thermo-mechanical solver in Abaqus/Standard to perform numerical simulations of the tension tests. Simulations were carried out with both constant and strain-dependent values of the Taylor–Quinney coefficient to examine the effect on the surface temperature in the centre of the specimen during the deformation process. Furthermore, numerical simulations were conducted to find a numerical expression for the Taylor–Quinney coefficient as a function of equivalent plastic strain, such that the temperature evolution in the simulations matches with the temperature measurements from the experiments.

A comparison study on experimental characterization of unidirectional fiber reinforced composites using strain-gauges and virtual extensometers

Abstract The aim of this study is to characterize E-glass/epoxy unidirectional fiber reinforced composites using the digital image correlation method with virtual extensometer, which is a less laborious method than strain gauges, compare the results and investigate whether virtual extensometers can be used instead of strain gauges. Measurements in tensile and Iosipescu shear tests were made with both strain gauge and virtual extensometer. Unlike full-field strain measurements in literature, the strains were measured using virtual extensometers. Tensile test and in-plane shear test results gave very consistent results. The differences between the strain gauge and the virtual extensometer for the tensile and in-plane shear tests were less than 3% in the linear region. However, the out-of-plane shear test showed a larger difference of 8.6%. This study showed that the 2D digital image correlation method with virtual extensometers is highly sufficient to find the elasticity moduli and shear moduli in tensile and shear tests in the linear region. In addition, after the damage has started, more measurement data can be obtained with virtual extensometers than with strain gauges.

Stability of Postcritical Deformation of CFRP under Static ±45° Tension with Vibrations.

The paper presents an experimental study on regularities of postcritical deformation of carbon-fiber-reinforced plastic (CFRP) under static ±45° tension. The employed test method is based on ASTM D3518. Displacement and strain fields were identified by a digital image correlation method (DIC) using a VIC-3D contactless optical video system. Acoustic emission signals were obtained using an AMSY-6 system. The surface analysis of samples was carried out using a CarlZeiss SteREO Discovery. V12 optical stereomicroscope and a DinoLite microscope. Three experimental test types were considered: active loading, deformation with unloadings, and tension under additional torsion vibrations with various amplitudes. Loading diagrams were constructed; they showed a number of stages in the damage accumulation process. It was analyzed how heterogeneous strain fields develop; a neck development during softening process was observed. It was noted that the loading system rigidity influences the failure moment. The research considered various shear strain calculation methods using a "virtual extensometer" instrument. Composite mechanical properties were obtained. A shear modulus reduction during a plastic strain increase was revealed. The acoustic emission signals were analyzed; three characteristic frequency bands were observed. Most of the contribution to cumulative energy was made by matrix cracking. A reduction of the number of AE signals associated with the violation of adhesion between the fibers and the matrix during postcritical deformation was observed. The research identified basic surface defects. An appearance of the defects corresponds with their identification by the AE system. It was revealed that the presence of additional torsion vibration leads to an increase in the softening stage length. It was concluded that due regard for the postcritical deformation stage and the loading system rigidity is reasonable during the structure strength analysis.

Research on the Evolution Law Physical Short Fatigue Crack and Tip Deformation Fields during Crack Closure Process of the Q&P Steel.

In this paper, a novel dual microscopic fatigue-crack and tip-deformation-fields measurement method based on a hybrid image-processing technique is proposed that was used to research the physical short fatigue crack (SFC) closure effect and the evolution law of the tip deformation fields of Quenching–Partitioning (Q&P) steel during the crack-closure process. The measurement problems are solved, such as the small SFC tip region, large deformation gradient, and strong material anisotropy. Microscopic crack and speckle images are acquired simultaneously on both sides of a compact tensile (CT) specimen of Q&P steel by dual microscopic cameras. A digital image processing (DIP) method is used to identify crack-growth morphology and measure crack length in Q&P steel, and the SFC growth rates are analyzed under different stress ratios. Microscopic digital image correlation (Micro-DIC) is used to analyze displacement fields at the crack tip of SFC and, combined with virtual extensometer technology, analyze the evolution law of crack closure and the evolution of crack-growing morphologies during the closure process under different lengths and stress ratios. Accordingly, the evolution of strain fields at the crack tip in one load cycle for different crack lengths and stress ratios during the SFC closure process is analyzed. The results show that the stress ratio affects the crack-closure behavior and crack growth rate of Q&P steel in the physical SFC crack-growing stage. The crack-closure effect has an obvious influence on the evolution process of displacement and strain fields at the crack tip. The evolution of short-fatigue-crack-tip morphology and strain field of Q&P steel conforms to the crack-closure law. The research results provide experimental and theoretical support for the further study of the SFC growth mechanism and fatigue life prediction of Q&P steel.

Improved virtual extensometer measurement method in complex multi-fracture situation

To overcome the limitation of the virtual extensometer method in measuring the crack opening displacement (COD) in the process of complex multi-crack propagation of rock, the measurement error of Digital Image Correlation (DIC) local deformation is theoretically analyzed. An improved virtual extensometer method for measuring the COD is proposed, which considers the temporal and spatial characteristics of crack development in the process of complex crack propagation. The accuracy of the proposed method is verified by the strain localization band numerical simulation test and indoor single crack simulation test. Furthermore, the method is applied to the two-dimensional similarity simulation test of simulating complex multi-fractures in rock stratum. The COD obtained by the traditional and improved methods is compared with the measured COD. The results show that in the case of multiple complex cracks, to obtain the COD accurately, the relative distance between the virtual extensometer measuring point and the crack should be greater than half of the sum of the width of the crack strain localization zone and the subset size. With the development of the crack, the relative distance between the virtual extensometer measuring point and the crack should increase with the increase of the width of the crack strain localization zone. The error of the COD measured by the traditional method increases with fracture development, and the maximum is 21.20%. The maximum relative error between the COD measured by the improved method and the measured crack opening is 3.61%. The research results improve the accuracy of the virtual extensometer in measuring the COD under complex multi-crack conditions.

A reconstruction method to determine crack length based on virtual extensometers

The laboratory measurement accuracy of crack length has an influence on the study of material properties and behaviors. There are some defects in the existing methods for determining crack length, such as strong subjectivity, complex experimental process and difficult data processing. To solve the above problems, based on the surface deformation data recorded by DIC, a method of reconstructing the virtual extensometers and measuring the crack length is proposed by fixing the virtual extensometers along the crack growth path. The fracture process is analyzed based on the plastic hinge hypothesis, and the whole deformation data of the specimen is obtained by analyzing the length change of the virtual extensometers. The rigid components of virtual extensometers deformation along the crack growth path are reconstructed and compared with the original elongation curve to determine the crack length. It shows that the reconstruction method has a high reliability to compare the prediction results with those of the curvature method, the direct-reading method and the Martinelli-Venzi model method. The characteristic of virtual extensometers fixed after experiment and programming design of analysis process are applied to simplify the experiment and data processing. On the basis, the influence of the initial length of the virtual extensometer and the decomposition process on the results is discussed. The results show that reconstruction method has good adaptability to tunneling effect, and it is expected to realize automatic data collection and processing based on this method.

Effects of rivet hole arrangement on fatigue performance of thin sheets for fuselage: DIC and numerical calculation

The fatigue performance and fracture mechanics of 2198-T8 Al-Li thin sheet with multi-diameter rivet holes were studied experimentally and numerically, which is mainly used in the new generation of C919 aircrafts. Firstly, the fatigue crack propagation mode under uniaxial fatigue load was investigated based on digital image correlation and virtual extensometer. Then, the Stress Intensity Factor (SIF) formula was modified and the applicable range was determined based on the tests and finite element method simulation results for the specimen with single rivet hole. Finally, the modified SIF formula was applied to predict the fatigue life of specimen with multi-diameter rivet holes. The results show that the crack propagation mode transforms from mode I to mode I+II, and the modified SIF formula could be used to obtain a more conservative fatigue result for single rivet hole when the angle of pre-crack is less than 5°. For the specimen with multi-diameter rivet holes, the fatigue life decreases with the rise of diameter of the larger rivet hole Φ1, and it also decreases with the increase of difference between larger and smaller hole Φ1−Φ2 when larger diameter Φ1 is constant. The fatigue life of HH-type specimen is generally smaller than that of the SS-type under the same rivet hole arrangement. The prediction result is conservative with a maximum relative error less than 7.0%

Low cycle fatigue properties assessment for rotor steels with the use of miniaturized specimens

The article deals with the development of advanced techniques of low cycle fatigue testing (LCF) using miniature test samples, which has the potential to be used to assess the degree of material degradation of large in-service components in the power industry. For this purpose, the results of a wide portfolio of test samples geometries have been investigated. Using the advanced techniques involving a special sampling device, a DIC virtual extensometer and test rig, a new possibility in strain-controlled LCF testing is presented. The results indicated that cyclic-strain and strain-life curves of proposed minisample geometries are almost of the same shape for both investigated rotor steels. Also the cyclic parameters obtained indicate a good consistency of results despite of a wide range of sample volumes and utilization of two different strain-control methods.

Strain by virtual extensometers and video-imaging optical coherence tomography as a repeatable metric for IOP-Induced optic nerve head deformations

PurposeTo determine if in vivo strain response of the Optic Nerve Head (ONH) to IOP elevation visualized using Optical Coherence Tomography (OCT) video imaging and quantified using novel virtual extensometers was able to be provided repeatable measurements of tissue specific deformations. MethodsThe ONHs of 5 eyes from 5 non-human primates (NHPs) were imaged by Spectralis OCT. A vertical and a horizontal B-scan of the ONH were continuously recorded for 60 s at 6 Hz (video imaging mode) during IOP elevation from 10 to 30 mmHg. Imaging was repeated over three imaging sessions. The 2D normal strain was computed by template-matching digital image correlation using virtual extensometers. ANOVA F-test (F) was used to compare inter-eye, inter-session, and inter-tissue variability for the prelaminar, Bruch's membrane opening (BMO), lamina cribrosa (LC) and choroidal regions (against variance the error term). F-test of the ratio between inter-eye to inter-session variability was used to test for strain repeatability across imaging sessions (FIS). ResultsVariability of strain across imaging session (F = 0.7263, p = 0.4855) and scan orientation was not significant (F = 1.053, p = 0.3066). Inter session variability of strain was significantly lower than inter-eye variability (FIS = 22.63, p = 0.0428) and inter-tissue variability (FIS = 99.33 p = 0.00998). After IOP elevation, strain was highest in the choroid (−18.11%, p < 0.001), followed by prelaminar tissue (−11.0%, p < 0.001), LC (−3.79%, p < 0.001), and relative change in BMO diameter (−0.57%, p = 0.704). ConclusionsVirtual extensometers applied to video-OCT were sensitive to the eye-specific and tissue-specific mechanical response of the ONH to IOP and were repeatable across imaging sessions.

Characterization of heterogeneous creep deformation in vanadium-modified 2.25Cr1Mo steel weldments by digital image correlation

Low alloy ferritic steels are widely used to manufacture critical components that operating at elevated temperatures in the process industry, but a better understanding of the creep responses of their weldments are still needed to provide guidance for the design of high-temperature welded structures. In the present paper, the heterogeneous creep behavior of vanadium-modified 2.25Cr1Mo ferritic steel weldments was investigated by using the digital image correlation (DIC) technique. Three-dimensional plot of creep strain across the weld joint was constructed to intuitively represent the spatio-temporal evolution of creep strain for the base metal (BM), weld metal (WM) and the heat affected zone (HAZ). Combining the analysis of strain contour evolution during creep with the microstructural examination, it is found that creep strain was primarily concentrated in the HAZ, resulting in the creep cavitation at grain boundaries of the coarse-grain bainitic HAZ. In addition, BM exhibited a faster deformation rate than WM during creep. In order to quantitatively describe the heterogeneous creep deformation, a sub-region extensometer method based on the construction of virtual extensometers was proposed to obtain the representative creep strain data of individual regions of weldments. Furthermore, a parameter identification procedure combining a global optimization method (i.e. genetic algorithm) with an initial value determination scheme, was developed to determine the model parameters of BM, WM and HAZ for the hyperbolic-sine creep constitutive model. The results show that the heterogenous creep behavior of the V-mod 2.25Cr1Mo steel weldment can be well characterized by combining the sub-region extensometer method, the hyperbolic-sine creep constitutive model and its genetic algorithm-based parameter identification method.

Experimental mesoscopic investigation of the local cyclic plasticity of a non-oriented electrical steel

Complementary mesoscopic investigations have been carried out on a notched specimen, made of Fe–3%Si steel and submitted to fatigue loading. Load control fatigue testing was conducted to ensure localised cyclic deformation and the resulting displacement fields were measured by means of Digital Image Correlation (DIC). Electron Channelling Contrast Imaging (ECCI) and Electron Back-Scatter Diffraction (EBSD) complete the DIC data by giving a different view of the local plasticity, as they image the dislocation structure and map their related characteristics, such as misorientation.Hence, two misorientation based criteria, namely Grain Reference Orientation Deviation (GROD) and Grain Orientation Spread (GOS) were considered for EBSD analysis. Based on a previous study, a <GOS> − Δεt abacus has been coupled with a <GOS> − DIC abacus in order to evaluate locally the encountered strain field and link this latter to an equivalent total strain variation. The obtained results have been discussed from the evolution of the dislocations structures, as observed by ECCI.This combination of mesoscopic techniques clearly emphasizes the local deformation by means of both qualitative and quantitative measurements. On one hand, DIC and EBSD measurements indicate the presence of strain localisation which can be correlated to a certain level of cyclic strain amplitude. On the other hand, the variation of the strain levels and its distribution when moving away from the notch are confirmed by the dislocation structures evolution seen by ECCI. Such structures vary from cells, vein and channels and entangled dislocations regions as the analysed areas go away from the notch. At a local scale, the DIC measurements behave as numerous virtual extensometers while its combination with EBSD and ECCI data confirms the correlation with the accumulated cyclic strain.