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This study investigated for the first time the corrosion effect of Al 2 O 3 -MgAl 2 O 4 refractory by steel ladle slag using a DIC-coupled Brazilian test at 1200 °C. Three types of alumina-spinel materials were used in the test, namely, original non-infiltrated refractory, slag-infiltrated at 1450 °C as well as postmortem refractory after 69 cycles of work in the sidewalls of steel ladle. Lab infiltration was conducted at 1450 °C using CaO-Al 2 O 3 -SiO 2 -based ladle slag and its analog enriched with manganese (10 % MnO). The tensile strength of postmortem material at 1200 °C was the highest at 10.7 MPa, and it was 52 % and 70 % higher than for reference and MnO-enriched slag, respectively, and 80 % higher than for original refractory. The significantly raised tensile strength of slag-infiltrated materials vs. original non-infiltrated brick was directly related to the densification of microstructure by corrosion products (mainly CA 6 , CA 2 , Fe) which caused the infiltrated materials to be stiffer and with a more brittle nature to fracture. • DIC-coupled Brazilian test at 1200 °C of corroded material was tested for the first time. • Original, lab-infiltrated and post-mortem Al 2 O 3 -MgAl 2 O 4 refractory was tested. • Post-mortem brick had almost 80 % higher tensile strength than the original brick. • Corroded materials were revealed to fracture more brittle than the original brick. [ABSTRACT FROM AUTHOR]

For plain woven SiC/SiC composites used in aerospace thermal-structural applications, not only the pristine material properties but the open-hole performance are of critical concern for the components in service. This study investigated the influence of intrinsic pores induced during SiC matrix preparation and manufactured holes on the macro mechanical properties of plain woven SiC/SiC through experimental and numerical methods. Tensile tests at room temperature were conducted on SiC/SiC specimens with different hole apertures and configurations, and the digital image correlation (DIC) method was employed for full-field strain measurement. Moreover, micro-computed tomography (μ-CT) was utilized to characterize the internal microstructure, original defects, and failure fractures. Based on the reconstructed mesoscale model, the tensile strength and failure mechanisms of pristine and open-hole specimens were predicted and analyzed, with the models validated against the experimental results. The results showed that the inter-tow defects play an important role on the deformation and failure of pristine SiC/SiC specimens during tensile loading. The notch strength results indicated that SiC/SiC exhibits weak notch sensitivity, and the local mesoscopic deformation of the notch is affected by the combination of macroscopic stress gradients and mesoscopic structures. The mesoscale simulation results showed that the position of the hole has a significant impact on the strength of the single layer SiC/SiC composite. The more the notch invades the warp, the greater the decrease in load-bearing capacity, and the relative position of the weft mainly determines the crack propagation path. The failure mode in the simulation results is consistent with the experimental findings, indicating that the simulation model, which considers the weave architecture, can better explain the notch failure behavior of Ceramic Matrix Composites (CMCs). [ABSTRACT FROM AUTHOR]

Neonatal disseminated intravascular coagulation (DIC) is a rare disease with a poor outcome. However, data on the incidence, treatment, and outcome of neonatal DIC are scarce. Thus, this study investigated the status of neonatal DIC in Japan. We sent a retrospective questionnaire-based survey regarding the status of diagnosis and treatment of neonatal DIC from January 1, 2016, to December 31, 2018, to 30 hospitals in Kyushu with a neonatal-perinatal medicine division. The data collected by the questionnaire survey included information about the patients diagnosed with neonatal DIC. Among the 13,582 neonates surveyed, 120 (0.9 %) were diagnosed with DIC. Of them, clinical data were available for 105 cases. There were 11 deaths (mortality rate: 10.4 %), with the most common underlying condition being infection (n = 9), followed by neonatal asphyxia and hematologic disease (both, n = 1). Compared with the survival group, the death group had more infections, as well as a higher rate of bleeding symptoms and organ dysfunction. Neonatal DIC associated with infectious diseases has a poor outcome. Therefore, it is necessary to formulate diagnostic and treatment guidelines for early intervention in such cases. [ABSTRACT FROM AUTHOR]

Tensile response and fracture toughness of the freestanding atmospheric plasma spray 8YSZ coatings was investigated using in situ high resolution optical full-field strain measurement. The elastic properties obtained directly from the tensile experiments were employed in computing the critical mode-I stress intensity factor. Comparison between the fracture toughness values computed from specimen geometry and J-integral via displacement field around the crack tip showed small differences on single edge notched tensile (SENT) specimens to extract their intrinsic mode-I fracture toughness. Two kinds of coatings having different porosity were studied to obtain stress-strain response and compute effect of porosity on mode-I fracture toughness. The samples were fabricated by depositing the coatings on, un-notched and pre-notched substrate templates, and then carefully separating the coatings by acidic dissolution of the substrate. High resolution in situ deformation of the coatings was captured for both tensile and SENT specimens using digital image correlation method combined with an in-house designed microtensile stage. The deformation from the specimen surface was used to obtain elastic material properties under uniaxial tension, which are then used to compute the energy release rate by the path independent J-integral. The critical stress intensity factors calculated from SENT geometry for the low and high porosity coatings were found to be 1.23 ± 0.21 MPa-m0.5 and 0.67 ± 0.12 MPa-m0.5, respectively. In addition, considering the experimental observation of nucleation and propagation of a crack from the notch tip before catastrophic failure, the J-integral based calculation of the critical fracture toughness values were 1.37 ± 0.19 MPa-m0.5 and 0.5 ± 0.1 MPa-m0.5, for the low and high porosity coatings, respectively. As the crack always nucleates from the notch before complete fracture, it can be concluded that the J-integral based method is accurate and suitable for finding the fracture toughness in porous coatings. • Tensile and fracture toughness experiments on APS-8YSZ with two different porosities investigated. • Full field deformation from in situ experiments used to obtain tensile and fracture properties. • The evolution of J-integral was computed using displacement data combined with elastic properties from tensile experiments. • A stable crack growth before catastrophic propagation was observed. • The critical fracture toughness is reliably computed from J-integral and is suggested for porous coatings. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to retrospectively analyze Thrombelastography (TEG) data of severe burn patients to provide a clinical basis for timely diagnosis and treatment of coagulation dysfunction.Methods: The present study comprised burn patients with full thickness TBSA ≥ 60%. The patients included in the study were admitted to the Third Affiliated Hospital of Inner Mongolia Medical University between March 2019 and March 2022 and died within 10 days. Patient demographic and clinical data, including abbreviated burn severity index (ABSI) score, full thickness and overall total surface burn area (TBSA), injury cause, International Society on Thrombosis and Hemostasis (ISTH) score, were retrieved from the electronic medical record system. TEG data (including ACT, K, α, MA and LY30), platelet count (PLT), mean platelet volume (MPV) and platelet distribution width (PDW) data were obtained from the records of included patients for analysis.Results: A total of 9 patients were enrolled. The average burn area was 90.0% TBSA and the full-thickness TBSA was 72.0%. The results showed that α, MA and PLT count values were significantly lower relative to those at obtained throughout admission period (all p < 0.05). PDW and MPV were significantly higher compared with the values at admission (all p < 0.05). ACT time was significantly longer from day 2 after severe burn compared with the ACT time at admission (all p < 0.05). LY30 value from day 3 after severe burn was significantly higher compared with the value at admission (p < 0.05). One patient was diagnosed with diffuse intravascular coagulation (DIC) on admission, whereas eight patients were diagnosed with DIC on the day of death.Conclusion: Coagulation dysfunction after severe burn is mainly characterized by procoagulant disorders and hyperfibrinolysis, which can be timely detected by TEG. Coagulation after severe burn exhibits a gradual aggravation, and can lead to death of patients. [ABSTRACT FROM AUTHOR]

The current study examined the deformation mechanisms, microstructure, and texture evolution in AZX311 Mg alloy sheets subjected to in-plane shear (IPS) deformation. Different levels of shear strains, with values 0.05, 0.10, and 0.15, were applied along the rolling direction (RD) using a specialized in-plane shear testing jig. The strain measurement for the applied shear deformation was conducted utilizing the digital image correlation (DIC) technique. The strain distribution was found to be nearly homogeneous over sufficiently large areas, thereby allowing the microstructural measurements to yield relevant statistical data. A thorough microstructural examination across the thickness using electron back-scattered diffraction (EBSD) revealed that the application of IPS strain led to the formation of a significant number of tensile twins (TTWs) in the sheet. This was evidenced by the emergence of two satellite peaks at the periphery of the pole figures. As the shear strain increased, the proportion of TTWs in the material also increased, encompassing the entire parent grain and leading to the formation of what has been termed as " all-twinned microstructure ". The microstructural and texture investigation after IPS deformation revealed that TTWs were the dominant deformation mechanism that defined the microstructure and texture under IPS deformation, while dislocation slip activity was dominated by prismatic slip, as evidenced by the resolved shear stress analysis in this study. Consequently, this research highlights the effect of IPS deformation on the microstructure and texture evolution throughout the thickness of an Mg alloy sheet and elucidates the underlying mechanisms. [Display omitted] • In-plane shear (IPS) deformation induces significant tensile twins throughout the thickness direction in the shear zone. • Imposing higher shear strains led to a predominantly twinned grain orientation throughout the parent grain. • Shear strain is uniform within the shear zone across varying shear strains and major contributor to the von-Mises strain. • RSS analysis revealed that the initial microstructure supports the activation of tensile twins and prismatic slip. • Tensile twins exerted a more significant influence on the evolution of microstructure/texture during the IPS deformation. [ABSTRACT FROM AUTHOR]

To ensure that the rolled composite plate has excellent processing properties. Annealing is an effective means of modulating organization and mechanical properties. In this study, annealing treatments at different temperatures were applied to the rolled titanium-steel clad plate. The evolution of the interfacial organization was observed using scanning electron microscopy. The strain distribution of the composite plate in the tensile process was investigated using a tensile experiment combined with the DIC method. The results indicate the presence of compounds such as TiC, Fe 2 Ti, and FeTi after hot rolling. As the annealing temperature increases, the thickness of the interlayer diffusion of elements between the two plates increases. The geometric dislocation generated between the grains after hot rolling is significantly improved after annealing treatment, and the geometric dislocation density decreases with the increase in annealing temperature. In the titanium layer, the titanium grains, after annealing at 550 °C and 600 °C, are in the recovery stage, and the amount of recrystallization does not change significantly. However, after annealing at 650 °C, the titanium grains are completely recrystallized, the grains are equiaxed, and the grain-to-grain anisotropy is eliminated. The sample annealed at 550 °C fractures almost simultaneously in the tensile test in the titanium layer and steel layer, with an elongation of 32.3% and a tensile strength of 477.1 MPa, showing the best comprehensive performance. Based on DIC strain curve analysis, The strain curve after annealing at 550 °C is smoother, the necking is relatively consistent, and it reaches a point of relatively consistent local strain instability. • Revealed the existence of compounds such as TiC, Fe 2 Ti, and FeTi in titanium steel composite plates after hot rolling. As the annealing temperature increases, the thickness of the interlayer diffusion of elements between the two plates increases. • In the steel layer, the recrystallized grains increase with increasing annealing temperature. In the titanium layer, the titanium grains, after annealing at 550 °C and 600 °C, are in the recovery stage, and the amount of recrystallization does not change significantly. However, after annealing at 650 °C, the titanium grains are completely recrystallized, the grains are equiaxed, and the grain-to-grain anisotropy is eliminated. • Based on DIC analysis, the strain curve at 550 °C shows smoother fluctuations, relatively consistent necking, and reaches a relatively consistent point of local strain instability. • Combining the strain, displacement DIC analysis, and microstructure analysis of titanium steel composite plates can effectively produce high-performance titanium steel composite plates. [ABSTRACT FROM AUTHOR]

The use of textile reinforced mortar/concrete composites (TRM) in strengthening applications and new constructions necessitates understanding its behavior after exposure to high temperatures. Therefore, in this study, the residual tensile and cracking behavior of carbon based TRMs was studied. A total of 96 TRM samples were tested in the temperature range of 25–450 °C. The main parameters studied were the textile crimp, textile orientation, textile coating, multiple textile layers and hybrid reinforcement. The hybrid TRM was formed with a combination of uncoated and styrene butadiene (SBR) coated textile layers. This study served as one of the first experimental campaigns to use digital image correlation (DIC) for understanding the residual crack opening behavior of TRMs. The results demonstrated that the properties of the TRMs were noticeably influenced by temperature exposure of 450 °C. Unlike the uncoated or hybrid textile TRMs, the SBR coated textile TRMs demonstrated curvature and cracking after 450 °C exposure. The study showed that the load aligned crimped yarn TRMs were always associated with larger deformation irrespective of the exposure temperature. The crack openings also increased significantly after exposure to 450 °C. Whereas the presence of heat formed cracks caused higher initial rate of crack openings. The evolution in the crack spacing with increasing temperature fluctuated due to the possible relative degradation of cracking strength vs interfacial mortar textile bonding. Finally, the proposed empirical equation showed a good fit to the residual average crack opening vs. stress relations. • Heating cooling cycle resulted in curving and/or cracking of the coated textile based TRMs. • Load aligned crimped yarns demonstrated larger strains irrespective of thermal exposure. • The failure mode became severe with increasing temperatures, and was significantly affected after 450 °C exposure. • The residual average crack openings significantly exacerbated after 450 °C exposure. [ABSTRACT FROM AUTHOR]

RFID (Radio Frequency Identification) is commonly used to monitor goods along the supply chain. The feasibility of the application of a RFID tag to monitor CFRP components was demonstrated in a previous work by some of the authors. This work is aimed at evaluating how the integration of a RFID tag inside a CFRP laminate affects the quasi-static strength and the failure mode. Finite element modelling is used to design a specimen with an embedded tag, that may be representative of the tensile state of stress in a larger laminate. Tensile testing is performed both up to failure and by interrupting tests at different load levels in order to inspect the specimen by C-scan. Acoustic Emission (AE) and Digital Image Correlation (DIC) are used as additional non-destructive monitoring techniques. Some interrupted tests were selected to extract micrographic sections that illustrate damage development in the laminate. The extensive destructive and non-destructive characterization allowed to quantify the effect of embedding a RFID tag in the laminate in terms of strength decrease and failure mode. [Display omitted] [ABSTRACT FROM AUTHOR]

CFRP-UHPC panel is an essential type of lightweight concrete structure that can be applied in many cases, such as protective structures, warehouses, and offshore structures. However, further research is needed to achieve the CFRP grid fabrics widely applied in concrete structures. This work proposes a CFRP-UHPC panel with serpentine connectors and conducts three/four-point bending tests, DIC, and finite element methods to reveal its bend behavior. This work also presents the formula for calculating the ultimate moment, considering the stress-strain relationship of UHPC and the interaction of CFRP grid fabrics-UHPC. In summary, this work reveals the failure mechanism of CFRP-UHPC panels with serpentine connectors and proposes a formula for calculating bending capacity. [Display omitted] • Propose a new construction of CFRP-UHPC panel with serpentine spring connectors. • Conduct the three-point/four-point bending tests and demonstrate the failure patterns. • Reveal the stressing state evolution based on the test, DIC test, and FEM results. • Propose bending capacity calculation equations of CFRP-UHPC panels. [ABSTRACT FROM AUTHOR]

This study investigated the fracture properties and FPZ evolution of concrete/rock bi-material interface after low-level fatigue loading. Firstly, the fatigue loading tests were performed under the frequency of 1.0 Hz with respect to two upper limits less than the initial cracking load, i.e. 60 % and 70 % of the peak loads. After 80,000 loading cycles, the quasi-static loading tests were performed to measure the fracture behavior of concrete/rock bi-material interface. Thereafter, the DIC tests were conducted to observe the crack extension process and analyze the FPZ evolution. According to the comparisons of fracture behaviors between the fatigue specimen and control specimen, the effects of the low-level fatigue loading on the fracture properties and FPZ evolution of concrete/rock bi-material interface were discussed. The results indicate that the unloading paths follow the loading paths coincidentally for each loading cycle, and this means that the mechanical response of the concrete/rock bi-material interface under low-level fatigue loading is elastically dominated. After the low-level fatigue loading, the initial cracking load and initial fracture toughness exhibit obvious increasing tendency, whereas the unstable fracture toughness decreases obviously, which is induced by the significant decrease of the critical crack length. In addition, the fully-developed FPZ length and the corresponding crack length of fatigue specimen are less than that of control specimen, indicating that the brittleness of concrete/rock bi-material interface becomes larger after low-level fatigue loading. [ABSTRACT FROM AUTHOR]

• Analysing the bond quality of finger-joints is key for the laminating industry. • Acoustic emission application on finger joints tests for quality control. • New AE parameters are established to correlate DIC and non destructive techniques. The use of Engineered Wood Products (EWPs) for buildings is becoming very popular because they favor decarbonization in the construction sector and improve the performance and mechanical properties of solid timber. Finger joint technology makes it possible to remove the natural defects of timber (knots, splits, decay areas, etc.), providing for clearer timber and the manufacture of larger structural elements. Nowadays, glued laminated timber (GLT) and cross laminated timber (CLT) are the most used products, suitable even for tall buildings. The finger joints —given the adhesive used and the increased friction surface due to their geometry— allow stress to be transferred efficiently between the joined lamellae, making them behave mechanically almost like a single piece of solid timber. The quality control of these products is therefore crucial. In this work, the longitudinal and transverse strain fields in samples with finger joints, measured by means of the Digital Image Correlation (DIC) technique, are compared with the acoustic emission waves released when the sample is subjected to tensile stress. It is shown that there is a very close correlation between the two, meaning that the acoustic emission technique can be considered a promising tool for the quality control of these structural joints. [ABSTRACT FROM AUTHOR]

[Display omitted] • The existence of a textured heterogeneous microstructure at the millimetric scale of a WAAM material is observed via optical observations and Electron BackScatter Diffraction. • The existence of deformation field heterogeneities under uniaxial tension in the plastic domain of a WAAM material is observed via Digital Image Correlation. • The existence of stress field heterogeneities under uniaxial tension in the elastic domain of a WAAM material is observed via Thermoelastic Stress Analysis. • The observed mechanical field heterogeneities are compared and linked to the microstructural heterogeneities. Wire and Arc Additive Manufacturing (WAAM) is particularly well suited to the fabrication of large-scale structural components. Its use for the deposition of Duplex Stainless Steel (DSS) structures is especially sought upon by the naval industry. Although additively manufactured materials usually come with heterogeneous microstructure, residual stresses, internal and surface defects that must not jeopardize the structural integrity of components. In this context, the present study aims to analyse the as-deposited microstructure of a WAAM DSS and its influence on the mechanical behaviour via mechanical field measurement using both Digital Image Correlation (DIC) and Thermoelastic Stress Analysis (TSA). [ABSTRACT FROM AUTHOR]

• Twelve rack-to-spine-bracing shear connections were experimentally investigated. • Comprehensive test data were generated using digital image correlation technique. • A component-based analytical model is established for the shear connections. • Three-dimensional behavior of individual components are analytically determined. • Design and construction recommendations for the shear connections are provided. High-rise steel storage racks are cold-formed thin-walled steel frames, which achieve their lateral strength and stiffness by the use of a spine bracing system in the down-aisle direction commonly located at a short horizontal distance away from the main rack frames. The shear connections between the main rack frame and the spine bracing system play a dominant role in the effectiveness of the spine bracing system. This paper experimentally investigates the behavior of the shear connections used in industrial practice between a steel storage rack and the spine bracing system with posts using four groups of three nominally identical connection specimens. By employing a digital image correlation (DIC) system, the tests generate comprehensive data and establish the real-time deformation fields of individual components of such shear connections. Based on the component-based approach, a linear-elastic analytical model is developed for the type of shear connections under consideration. The proposed analytical model explicitly captures the behavior of the individual connection components, including the three-dimensional flexural bending of endplates, as well as the distortions of the open sections of the upright and the bracing post. Based on the proposed model, this paper quantifies the contribution of each component towards the total deformation of the shear connections. The investigation establishes that the cross-sectional distortion of the bracing post and the out-of-plane bending of the upright web are the most flexible components of such shear connections. Recommendations associated with the shear connections under consideration are proposed for the rack designers and manufacturers. [ABSTRACT FROM AUTHOR]

The personalisation of finite element models is an important problem in the biomechanical fields where subject-specific analyses are fundamental, particularly in studying soft tissue mechanics. The personalisation includes the choice of the constitutive law of the model's material, as well as the choice of the material parameters. In vivo identification of the material properties of soft tissues is challenging considering the complex behaviour of soft tissues that are, among other things, non-linear hyperelastic and heterogeneous. Hybrid experimental-numerical methods combining in vivo indentations and inverse finite element analyses are common to identify these material parameters. Yet, the uniqueness and the uncertainty of the multi-material hyperelastic model have not been evaluated. This study presents a sensitivity analysis performed on synthetic indentation data to investigate the identification uncertainties of the material parameters in a bi-material thigh phantom. Synthetic numerical data, used to replace experimental measurements, considered several measurement modalities: indenter force and displacement, stereo-camera 3D digital image correlation of the indented surface, and ultrasound B-mode images. A finite element model of the indentation was designed with either Ogden-Moerman or Mooney-Rivlin constitutive laws for both materials. The parameters' identifiability (i.e. the possibility of converging to a unique parameter set within an acceptable margin of error) was assessed with various cost functions formulated using the different synthetic data sets. The results underline the need for multiple experimental modalities to reduce the uncertainty of the identified parameters. Additionally, the experimental error can impede the identification of a unique parameter set, and the cost function depends on the constitutive law. This study highlights the need for sensitivity analyses before the design of the experimental protocol. Such studies can also be used to define the acceptable range of errors in the experimental measurement. Eventually, the impact of the evaluated uncertainty of the identified parameters should be further investigated according to the purpose of the finite element modelling. [ABSTRACT FROM AUTHOR]

Mechanical characterization usually relies on standardized sample geometries where homogeneous state of strain and stress are prescribed. Hence, many tests are required to capture the material response over various loading conditions. Using complex geometry allows for exploring wider domain in a single test but would require to have access to local strains and stresses to feed models. In that context, digital image correlation and clustering technique can be used to formulate an inverse problem able to identify fields of stress tensors without a priori constitutive modelling. This study explores the performances of a rate-dependent formulation of such a data-driven stress identification method, for capturing using a single test, the monotonic high strain-rate dependent response of a mild steel alloy. After presenting the problem formulation and resolution framework, a digital twin of a high speed tensile test performed on a notched sample geometry is used to explore identification performances. It allows defining confidence intervals depending on multiple indicators (stress magnitude, multiaxiality) and evaluate the range of strain-rate levels simultaneously captured. The method is eventually applied to a real experiment instrumented with high spatial resolution ultra high speed camera. Stress tensor fields are identified, within a 10 % confidence over the major part of the sample, and its material rate-dependence is retrieved from 20 to 300 s−1 and found in very good agreement with literature. This is the first experimental application of the DDI in a high strain-rate context. The proposed framework may substantially widen the sample design space for mechanical characterization but also allow for probing local stresses during dynamic localization processes where in-situ quantitative data are still missing. • A Rate-dependent formulation of DDI is numerically and experimentally assessed. • Stress fields are identified within 11% error beyond 100 MPa. • The monotonic high strain-rate dependent response of a mild steel is captured. • The yield stress and stress flow rate-dependence is identified up to 300 s-1. [ABSTRACT FROM AUTHOR]

• Designed triply periodic minimal surface (TPMS) lattice gradient cement composite. • TPMS lattice types markedly affect the flexural properties of cementitious mortar. • Gyroid50-30 lattice best improves the flexural toughness of cementitious mortar. Concrete is widely used in construction due to its superior performance but has limited ductility. This investigation aims to enhance ductility by incorporating 3D-printed polymer-reinforced cement composites. We explored functionally graded triply periodic minimal surfaces (TPMS) lattice structures, fabricated using photo-curing 3D printing with ABS-like resins in a cementitious matrix. These lattice structures feature varying relative densities for optimized toughness. Three-point bending tests and digital image correlation (DIC) revealed notable enhancements in flexural properties and crack resistance. The Gyroid50-30 structure increased flexural toughness by 88.6% compared to normal cement mortar. Gyroid60-20 and Gyroid40-40 groups, with different density gradients, showed improvements of 499.2% and 389.8%, respectively. This research suggests that tailoring lattice shape and density gradient can effectively optimize flexural performance. [ABSTRACT FROM AUTHOR]

Steel fiber reinforced 3D printing ultra-high performance concrete (3DP-UHPC) is prepared and experimentally studied. The effects of steel fiber content and various interlayer reinforcing materials on compressive, flexural, and splitting tensile properties are investigated, supplemented by Digital Image Correlation (DIC) technique for crack propagation analysis. Fabricated 3DP-UHPC specimens exhibited compressive strengths exceeding 160 MPa, with a peak at 205.2 MPa. Incremental increases in steel fiber content slightly enhanced compressive strength, whereas the addition of interlayer reinforcing materials, textile/steel wire mesh (SWM), reduced it due to altered interlayer bonding characteristics. The incorporation of textile/SWM significantly improved the flexural performance, enhancing energy absorption capacity and toughness. Specimens reinforced with SWM exhibited excellent flexural performance, with their flexural strength and ultimate deflection reaching 110.9 % and 192.5 % respectively of those before reinforcement. The splitting test revealed typical fractures along the interfaces between printed layers, with higher splitting strength obtained in the bottom layers. In specimens reinforced with carbon textile, glass textile, and SWM, the splitting strengths were more than double those of the subsequent layers. These insights contribute to a deeper understanding of 3DP-UHPC, paving the way for optimized use of reinforcing materials to improve structural integrity and performance. • 3DP-UHPC with compressive strengths exceeding 160 MPa is fabricated. • Increases in steel fiber content enhanced the compressive strength with a peak value of 205.2 MPa. • The addition of textile/steel wire mesh (SWM) significantly improved the flexural performance. • Interlayer delamination and interconnected cracks effectively enhanced the flexural ductility and toughness. [ABSTRACT FROM AUTHOR]

The problem of interface debonding is of fundamental importance in understanding the stress transfer mechanism and behavior of weak interfaces present due to rigid stiffeners. A domain integral method based on Betti's reciprocal theorem was adopted to compute the complex stress intensity factor (SIF) for the completely debonded anti-crack (discontinuity) with mixed boundary conditions. The domain integral approach is based on two admissible mechanical states, which comprise of actual and auxiliary elastic fields. The singular auxiliary fields in terms of angular variations for the completely debonded anticrack were obtained using the full-field solution. The obtained angular variations were compared with the Williams eigenvalue problem for completeness. The displacement and strains were obtained using digital image correlation (DIC) experiments and numerical simulation for parallel and perpendicular orientations of the discontinuity. The obtained DIC strain contours revealed the presence of anti-symmetric and symmetric variation on the bonded side of the anti-crack. The complex SIF is estimated experimentally and numerically based on the domain integral method to seek a better comparison with the analytical estimate. The SIF estimated for the perpendicular orientation is higher than the parallel orientation. [ABSTRACT FROM AUTHOR]

The impact test of red sandstone with different fissure distribution was carried out by Split Hopkinson Pressure Bar (SHPB). The failure process of the specimen in the time dimension was captured by high-speed camera and digital image correlation (DIC). The crushing characteristics of the specimen were discussed from the fractal dimension. Furthermore, the influence of fissure distribution characteristics (quantity and spacing of fissures) on the mechanical properties and fracture behavior of fissured red sandstone was analyzed. The experimental results show that the fissure spacing is negatively correlated with the dynamic compressive strength and peak strain of specimen, while the fissure quantity is negatively correlated with the dynamic compressive strength and positively correlated with the peak strain. Cracks are categorized into five types based on the manner of their initiation and expansion. The crack initiation and propagation are jointly affected by tensile stress and shear stress, but the tensile stress is dominant. With the increase of the fissure quantity, the failure mode changes from tensile failure to tensile-shear mixed failure. The increase of fissure spacing does not change its failure mode, but the formation mode of the main crack changes. The fractal dimension increases with the increase of the fissure quantity, and decreases with the increase of the fissure spacing, i.e., the larger the fissure quantity is, the higher the degree of fragmentation is, and the larger the fissure spacing is, the lower the degree of fragmentation is. The research results can provide a theoretical reference for the study of dynamic failure mechanism of rock mass with non-persistent discontinuities. [ABSTRACT FROM AUTHOR]

• The crack propagation characteristics of coal samples with prefabricated cracks of different sizes were studied. • The size effect of coal tensile fracture and the law of multi-parameter spatial–temporal response are analyzed. • The multi-parameter precursory information of coal samples with different sizes is analyzed. 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. [ABSTRACT FROM AUTHOR]

The paper presents an experimental program on the characterisation of the mechanical behaviour of perforated brick masonry (PBM) under uniaxial compression. The study is aimed to provide a better understanding on the compressive strength and elastic behaviour of a kind of masonry hardly dealt with in the literature. The mechanical response of the investigated masonry shows actually two complexities, linked respectively to the perforated nature of the bricks and the asymmetric cross-section of the units. The latter feature is particularly recurrent in exposed brickwork composed of perforated bricks, whenever one of the face shells has a larger thickness than the other one. For this purpose, an experimental campaign was carried out on units and PBM subjected to uniaxial compressive loading. The mechanical response of PBM is investigated to accurately determine the masonry Young's modulus and the compressive strength. Measurements obtained with conventional sensors are compared with those derived from the Digital Image Correlation (DIC) technique. Lastly, the experimental findings in terms of compressive strength and Young's modulus are cross-referenced with the estimations derived from empirical criteria available in Eurocode 6 and ACI 530.1–02. • Characterisation of the compressive response of Perforated Brick Masonry (PBM). • Derivation of compressive strength and Young's Modulus of asymmetric brick PBM. • Novel concept of co-barycentric area to calculate the compressive strength of PBM. •.DIC technique for the computation of Young's Modulus and Poisson's ratio of PBM • Comparison between experimental results and available empirical formulation. [ABSTRACT FROM AUTHOR]

• Cyclic constitutive of CP-Ti was developed based on the combined hardening model. • Local ratcheting at notch root of CP-Ti specimen was revealed by DIC technology. • Stress filed, local stress ratio, and local hysteresis curve were revealed by FE. • Cyclic characteristics at notch root were summarized though three stress regions. Damage and crack always origin from notch, and it is necessary to understand the local ratcheting and stress relaxation at notch root for commercially pure titanium (CP-Ti). Symmetric strain-controlled cyclic test for smooth CP-Ti specimen is conducted to determine the cyclic constitutive relationship based on the combined hardening model. Asymmetric force-controlled cyclic test combined with Digital Image Correlation (DIC) technology is conducted to reveal local ratcheting strain distribution at notch root of CP-Ti specimen, while the distributions of stress, local stress ratio, and local hysteresis curve at notch root are obtained by finite element (FE) simulation. It is found that plastic zone, local ratcheting and stress relaxation at notch root area change significantly with cyclic load levels. In the low stress amplitude region with the mean nominal stress lower than 87 MPa, the small-scale yield occurs, and the notch root is in a state of plastic shakedown. With the mean nominal stress increasing to 96 MPa in the transition region, the notch root is in a state that exceeds the plastic shakedown limit but the continuous ratcheting progress is not found. In the high stress amplitude region with the mean nominal stress higher than 104 MPa, the plastic zone significantly expends, and the notch root is in a continuous ratcheting progress state, accompanied by stress relaxation. For a specific structural configuration, the local ratcheting at notch root is affected by both the load level and the cyclic deformation characteristics of the material. In the high stress amplitude region, the reverse yield occurs at the notch root during unloading, which promotes continuous ratcheting progress and stress redistribution, resulting in stress relaxation. The higher the load level, the larger the ratcheting strain rate, and the lower the stress relaxation rate. [ABSTRACT FROM AUTHOR]

• The crack propagation process and its strain evolution were captured using the split Hopkinson pressure bar (SHPB) device combined with high-speed digital image processing. • The relationship between dynamic mode Ⅰ fracture toughness and crack propagation velocity of bedding shale with bedding and loading rate was analyzed qualitatively and quantitatively. • Based on the Traction-Separation Law, the method of global cohesive element was used to simulate the dynamic crack propagation and calculate the fracture toughness of bedding shale. The fracture behavior and various of mechanical mechanisms of shale are greatly influenced by the bedding surface. To study the effects of bedding angles on the crack propagation patterns and dynamic fracture properties, the shale notched semi-circular bend (NSCB) specimens were studied by the modified split Hopkinson pressure bar (SHPB) device, three-dimensional digital image correlation (3D-DIC) system with the high-speed (HS) photography and ABAQUS finite element software. The research results showed that at the same impact velocity, the 30°, 45° and 60° beddings played an obvious deflexion effect on the shale crack propagation. However, the 0° and 90° bedding did not deflect the crack propagation. The dynamic fracture toughness of shale NSCB specimens increased with the increase of impact loading rate but the increase magnitude decreased with the higher impact rate. The kinetic energy during specimen fracture was calculated by the extracting displacement data from the 3D-DIC, and it was found that the kinetic energy accounted for less than 6% of the absorbed energy during the dynamic compression of the shale. The crack propagation characteristics of ABAQUS simulation was approximately consistent with the experimental results. It is conducive to the study of shale gas fracturing and the formation of complex seam networks in shale and it is of great research significance for the efficient extraction of shale gas. [ABSTRACT FROM AUTHOR]

2D contractional scaled analogue experiments with composite materials including silica-sand and mica-flakes for overburden and silicone for salt analogue are used to investigate effects of mechanical stratigraphy on the structural evolution and kinematics of salt-detached fold-thrust-belts. Specific parameters tested are mechanical stratigraphy of the overburden and thickness variation of the basal silicone layer. The silicone-detached models in general are characterized by low-taper thrust wedge geometries and non-systematic vergence of folds and thrusts. Strain localization in the undeformed layer occurs as an in-sequence foreland breaking sequence. Strain is nucleating as detachment folds including thrust-bounded and concentric folds. Increased shortening develops break-thrusts in fold limbs. In-sequence frontal thrust interacts with out-of-sequence reactivation of older thrusts in the internal thrust wedge. Syn-kinematic silicone mobilization causes diapirism, allochthonous sheets and source-fed thrust. The specific distribution of discordant and allochthonous silicone structures vary with the mechanical stratigraphy. The impact of the mica-interlayer in the overburden sequence is strain-dependent. It strengthens the undeformed sand-pack compared to initial thrusting while active thrusts with mica-flakes in shear zones are weaker and active for longer than in homogeneous sand-pack. The longevity of thrusts correlates with the transfer of silicone to external domains and hanging-walls of thrusts. The silicone thickness controls the strain nucleation modes whether thrusting-dominated or folding-dominated predating main-thrusting stages. It also governs silicone supply and flow regimes with thick silicone source layers being readily remobilized to source-fed thrust and inflate silicone massifs in the foreland. Insights from the modelling results are that the formation of large-transport source-fed thrusts such as Quele Thrust (China) and Chazuta Thrust (Peru) observed in salt-bearing FTB's is possibly attributed to salt detachment thickness and anisotropic overburden resulting from mechanically layered stratigraphy. • Salt thickness controls deformation nucleation modes and governs viscous material supply and flow regimes. • The impact of mica interlayers is strain-dependent. • Large-transport source-fed thrust can form from salt-cored fold if there's enough salt supply and anisotropic overburden. [ABSTRACT FROM AUTHOR]

In this study, we introduce the integrated deviance information criterion (DIC) for nested and non-nested model selection problems in heteroskedastic spatial autoregressive models. In a Bayesian estimation setting, we assume that the idiosyncratic error terms of our spatial autoregressive model have a scale mixture of normal distributions, where the scale mixture variables are latent variables that induce heteroskedasticity. We first derive the integrated likelihood function by analytically integrating out the scale mixture variables from the complete-data likelihood function. We then use the integrated likelihood function to formulate the integrated DIC measure. We investigate the finite sample performance of the integrated DIC in selecting the true model in a simulation study. The simulation results show that the integrated DIC performs satisfactorily and can be useful for selecting the correct model in specification search exercises. Finally, in a spatially augmented economic growth model, we use the integrated DIC to choose the spatial weights matrix that leads to better predictive accuracy. [ABSTRACT FROM AUTHOR]

To investigate the applicability of recycled sand concrete in high-speed railway ballastless track bed, in this study, the fatigue life, strain evolution curve and calculated stiffness of C40 concrete incorporating 0, 50 % and 100 % recycled sand were explored. Digital image correlation (DIC) and the nanoindentation test were used to explore the influence of recycled sand on the performance of concrete. The results show that the flexural fatigue life of recycled sand concrete conforms to a two-parameter Weibull distribution. The fatigue strain progression and calculated stiffness demonstrate a distinct three-stage trend. Compared to natural aggregate concrete, the first-stage strain contribution of recycled sand concrete decreases by approximately 10 %. With the increase of fatigue cycles, the calculated stiffness decreased significantly, the dissipated energy increases gradually. Compared with recycled sand-free concrete and full recycled sand concrete, the concrete containing 50 % recycled sand possesses the highest elastic modulus and lowest thickness of the interfacial transition zone (ITZ), thus the average fatigue life of recycled sand concrete increased by 4.9 and 10.2 times. • Flexural fatigue performance of concrete is optimal when the replacement ratio of recycled sand is 50 %. • Flexural fatigue strain evolution of recycled sand concrete was monitored by DIC technique. • Flexural fatigue damage evolution mechanism was analyzed by nanoindentation technique. [ABSTRACT FROM AUTHOR]

• Three-point bending tests of notched beams reinforced with a GFRP bar are conducted. • A larger width of the beam was associated with a slightly greater FPZ length. • Cracked hinge model was used to study the GFRP-reinforced beam flexural behavior. • Results of pull-out tests represent an upper bound compared to beam test results. In this study, three-point bending fracture tests of notched beams reinforced with a glass fiber-reinforced polymer bar are conducted. Plain concrete beams are also tested for comparison. Two different widths are considered for the beams. Digital image correlation (DIC) is used on the lateral surface of the beam to study the fracture process zone (FPZ) and neutral axis depths at different load stages. A non-linear analytical model named cracked hinge model and cross-sectional analysis are used to obtain the force in the bar and the interfacial slip between bar and concrete, which are compared to the results from pull-out tests. [ABSTRACT FROM AUTHOR]

The use of High Performance Fibre-Reinforced Concrete (HPFRC with compressive strength up to 100 MPa) has shown to be a competitive alternative to conventional solutions for precast beams. This is justified by its affordable cost, high mechanical performance and enhanced durability. However, the shear response of such elements is still under scientific discussion and most design models provide scattered and highly conservative predictions, discouraging the use of HPFRC. In order to make a step forward in the understanding of such key aspect, this paper presents the results of an experimental investigation on eight full-scale HPFRC beams. The beams were tested with different levels of prestressing and were instrumented with refined optical DIC measurements. Using the experimental data, crack development and kinematics are investigated in detail, as well as the associated contributions of potential shear-transfer actions. The results confirm a significant contribution of the fibres in tension, as well as of the inclination of the compression chord for high levels of prestressing. The outcomes and failure modes of the different specimens are eventually compared and discussed, with the aim of setting the bases for more comprehensive and mechanically-based approaches for shear design of HPFRC. • Shear models for HPFRC yield scattered, conservative predictions. • Eight critical shear prestressed HPFRC beams were tested at full scale. • Prestress level correlates with shear strength in the tested HPFRC elements. • Crack kinematics obtained through DIC were used to obtain the shear contributions. [ABSTRACT FROM AUTHOR]

• Mode II fatigue crack growth is characterized at the steel-to-composite interface. • Displacement and load controlled ENF and 4ENF test methods are compared. • Novel method is proposed to determine crack growth by shear strains from DIC. • Friction and geometrical non-linearity is considered by finite element models. In this paper, mode II fatigue crack growth properties of the composite-to-steel interface are characterised through different test configurations, namely ENF and 4ENF tests. Different loading types including force control and displacement control methods are compared. An innovative shear strain based method is proposed for monitoring the mode II crack growth at the bi-material interface through Digital Image Correlation (DIC). A 3D finite element model with Virtual Crack Closure Technique (VCCT) is built and used for obtaining the strain energy release rate (SERR) to investigate the effect of geometrical nonlinearity, friction at the interface and steel yielding, as well as to verify the mode mixity. The results show that the standard 3-point bending ENF specimen can be unstable under force control and sweeps narrow SERR range by a single test under displacement control. The 4-point bending 4ENF test shows stable crack propagation and clear SERR developing trend. More pronounced geometrical nonlinearity and friction effect exist for 4ENF test which can be considered when interpreting the Paris curves by a nonlinear finite element model. [ABSTRACT FROM AUTHOR]

In the present study, the fracture behavior of additively manufactured (AM) metal parts has been investigated. To this aim, double edge notch tension (DENT) specimens have been printed using AlSi10Mg alloy based on the laser powder bed fusion (PBF) technique. Particularly, DENT specimens have been fabricated with three different ligament lengths and three different printing directions for each ligament length. In this study, we used the concept of essential work of fracture to describe the fracture behavior AMed parts. According to a series of tests under static loading conditions, influences of the ligament length and printing direction on the structural integrity of the DENT specimens have been determined. According to the experimental practices, levels of ductility and size of plastic zone in the ligament region have been documented. Here, we utilized digital image correlation technique to measure strain fields on the surface of the examined samples. Moreover, numerical simulations have been conducted to simulate the stress distribution from DENT specimens. In addition, visual inspection of the fracture surfaces has been conducted using a free-angle observation system. The outcome of this study can be used for future designs of PBF printed parts with a better structural performance. [ABSTRACT FROM AUTHOR]

• The advanced technology of DIC was used. • The characteristics of interlayer damage of ballastless slab laminated structure are revealed. • A model for a ballastless track laminated structure is presented. • The interlayer stress of ballastless slab laminated structure is mainly shear stress. To investigate the issues of transverse through cracks and interlayer damage of the CRTS III slab ballastless track under train loading, the digital image correlation (DIC) technique was employed to reveal the damage mechanisms of the reduced-scale concrete of track slab structural concrete (TSSC) and track slab-filled laminated structural concrete (TSLSC). The results indicate that under train loading, the transverse through cracks of TSLSC exhibit a multi-stage, layer-by-layer cracking characteristic, and there is a risk of cracking in ballastless track when the bottom longitudinal strain exceeds 0.0004. The sudden increase in interlayer longitudinal shear strain difference in the third stage under train loading demonstrates that shear stress is the primary cause of interlayer damage in ballastless track. Tensile damage models based on ultimate stress–strain relationship and yield-fracture strain were established, and a non-contact testing method for the constitutive relationship and energy absorption effect of ballastless track was proposed using DIC technology, aiming to provide reference for the analysis and prediction of ballastless track damage under train loading. [ABSTRACT FROM AUTHOR]

Understanding fuel system behavior during postulated loss-of-coolant accidents is pertinent for continued safe and efficient operation of light water reactors, particularly as higher burnups are being pursued and safety margins re-evaluated. Conventional mechanical models for the incumbent Zr alloys typically rely on the assumption that steady-state creep is the dominant fuel cladding response during transient accident conditions. To investigate this assumption, simulated accident burst testing was performed on Zircaloy-4 claddings with balloon behavior measured in-situ. Two distinct loading conditions were utilized during burst testing: (1) constant-gas-inventory where pressure was allowed to increase with temperature and (2) constant pressure. In-situ strains and strain rates were measured via 2-dimensional digital image correlation techniques and synchronized with temperature to determine deformation dependencies. The temperature dependence of strain rate was characterized by a two segment Arrhenius relationship, with a distinct transition between the high and low temperature/strain regimes. The average activation energy of the lower temperature/strain regime was 328 ± 25 kJ/mol, in agreement with the ∼320 kJ/mol used for conventional LOCA models. However, the higher temperature/strain segment, which encompassed most of ballooning, showed increased activation energies as well as a dependence on whether the burst region was in view. For tests that burst away from the camera view, the average high temperature/strain segment activation energy was 635 ± 150 kJ/mol. For samples where the rupture opening formed in view, the average activation energy was 1015 ± 179 kJ/mol. This observed shift in temperature dependence indicates a transition in deformation mechanism at the end of life, possibly to time independent failure mechanisms, which has not yet been visualized in the literature for Zr alloys. Parameters at the transition points were analyzed to determine thresholds for this change in behavior, which occurred at an average hoop strain of 6.9 ± 2.1 %. [ABSTRACT FROM AUTHOR]

Trabecular bone structure is a complex microstructure consisting of rods and plates, which poses challenges for its mechanical characterization. Digital image correlation (DIC) offers the possibility to characterize the strain response on the surface of trabecular bone. This study employed DIC equipped with a telecentric lens to investigate the strain state of individual trabeculae within their trabecular structure by assessing the longitudinal strain of the trabeculae at both the middle and near the edges of the trabeculae. Due to the high-resolution of the used DIC system, local surface strain of trabeculae was analyzed too. Lastly, the correlation between longitudinal trabecular strain and the orientation and slenderness of the trabeculae was investigated. The results showed that the strain magnification close to the edge of the trabeculae was higher and reached up to 8-folds the strain along the middle of the trabeculae. On the contrary, no strain magnification was found for most of the trabeculae between the longitudinal trabecular strain along the middle of the trabeculae and the globally applied strain. High-resolution full-field strain maps were obtained on the surface of trabeculae showing heterogeneous strain distribution with increasing load. No significant correlation was found between longitudinal trabecular strain and its orientation or slenderness. These findings and the applied methodology can be used to broaden our understanding of the deformation mechanisms of trabeculae within the trabecular network. [Display omitted] • Pure bending states were detected near the edge of single trabeculae. • The strain magnification on the surface of trabeculae was found to be 8 times greater than the average global sample strain. • No significant correlation was found between the longitudinal trabecular strain and its orientation or slenderness. [ABSTRACT FROM AUTHOR]

KIF1A , a gene that encodes a neuron-specific motor protein, plays important roles in cargo transport along neurites. Variants in KIF1A have been described in three different disorders, and neurodegeneration and spasticity with or without cerebellar atrophy or cortical visual impairment syndrome (NESCAVS) is the severest phenotype. A 3-year-old girl was born at term with a birth weight of 2590 g. At five months of age, she visited our hospital due to developmental delay. An EEG showed multiple epileptic discharge, and a nerve conduction study showed severe axonopathy of both motor and sensory nerves. We performed exome sequencing and identified a de novo heterozygous missense variant in KIF1A (NM_001244008.1: c. 757G > A, p.E253K). At six months of age, she developed acute encephalopathy, multiple organ failure and disseminated intravascular coagulation, necessitating intensive care. Her brain CT showed severe brain edema, followed by profound brain atrophy. We diagnosed hemorrhagic shock and encephalopathy syndrome (HSES) according to the clinico-radiological features. Currently, she is bed-ridden, and requires gastrostomy because of dysphagia. The clinical course of our case confirmed that p.E253K is associated with severe neurological features. Severe KIF1A deficiency could cause thermoregulatory dysfunction and may increase the risk of acute encephalopathy including HSES. [ABSTRACT FROM AUTHOR]

Two foods, belonging to different protein sources (dairy vs plant), namely Emmental cheese and tofu, were treated by the instant pressure drop (DIC) process inserted between two drying stages to obtain expanded and crispy snacks. This process consisted of a short heating step (t = 38–52 s) using steam under pressure (p = 0.26–0.62 MPa) and instantaneous pressure drop toward a vacuum. This pressure drop provoked auto-vaporization of the superheated liquid, which resulted in volume expansion, and cooling of the food. The expansion was visualized using a rapid camera at a frequency of 1000 images/s. The pressure and temperature histories were registered simultaneously. Three expansion ratios were evaluated: (i) r the ratio of food volumes after and before DIC process measured using sand pycnometry, (ii) rC calculated from dimensions measured by a caliper, and (iii) rI calculated from dimension reading from images. The shrinkage s = (rI/rC) −1, and the deformation d = (rC/r) −1 of the samples were then evaluated. Using response surface methodology, the optimal processing conditions for maximum expansions r = 2.5 and rC = 4.5 were found for Emmental and tofu, respectively as p = 0.5 and 0.62 MPa, t = 40 and 38 s. The creation of mist, inherent to the pressure drop of steam, made the visual observation impossible at the beginning of pressure drop. The samples were already expanded when the mist disappeared. Taking the mist presence as the upper limit of expansion time, the expansion took dozens of milliseconds at a pressure drop rate of 1.25 MPa/s. The temperature in the reactor decreased at a rate of 750 °C/s. [ABSTRACT FROM AUTHOR]

This paper provides a more realistic representation of the soil-geogrid interface in indirectly activated geogrids. A new testing apparatus is designed using transparent soil that allows an unobstructed observation of the interface to investigate the interaction occurring along the reinforcement. In this investigation, the reinforcement is indirectly activated by the deformations of the surrounding soil. Deformations were determined by digital image correlation (DIC) using a dot pattern attached to the geogrid and a laser speckle plane within the transparent soil. The interaction is derived from relative soil-geogrid displacements, deflections of geogrid transverse members, geogrid strain and force distributions as well as shear stresses acting at the interface. Three zones were identified corresponding to the distinct modes of interaction: pushout, pullout and interlocking, whereby a micro-mechanical conceptual model was validated. The geogrid force reaches its maximum at the intersection of the critical slip plane with the reinforcement. The results indicate that the pushout, pullout and interlocking areas cover 15%, 49% and 36% of the total geogrid length respectively. In this study, a transition area between the pushout and pullout zones was observed where the mobilised interface shear stress increases to a maximum value. • Unobstructed observation of geogrid-soil interface using transparent soil technique. • Identification of interaction mechanisms in indirectly activated geogrids. • Pushout, pullout and interlocking mechanisms occur along reinforcement. • Measurement of soil and geogrid deformations at the interface during mobilisation. • Determination of geogrid tensile force distribution and interface shear stresses. [ABSTRACT FROM AUTHOR]

Grouting is widely used to improve the mechanical properties of fractured rocks, but its impact on the fracture behavior of fractured rocks remains incompletely understood. This research aims to investigate the effects of grouting on the damage and fracture characteristics of fractured rocks under mode I loading. We used epoxy resin and ultrafine cement to grout granite and sandstone centre-cracked Brazilian disc specimens. We conducted Brazilian splitting tests on intact specimens, as well as specimens with and without grouting under mode I loading. Acoustic emission (AE) and digital image correlation (DIC) techniques were utilized to study the effect of grouting on rock fracture behavior. Furthermore, we employed an improved fracture toughness calculation method to evaluate the anti-fracture capacity of grouted specimens. The results show that grouting positively reinforces fractured rocks by increasing the shear crack ratio, mitigating the stress concentration effect at the crack tip, and fostering a more complete and stable development of the fracture process zone (FPZ). Materials with superior strength and bonding properties can effectively improve the mechanical performance of fractured rocks. Notably, epoxy resin significantly boosts the strength, deformation adaptability, and anti-fracture capacity of the specimens, outperforming ultrafine cement in terms of grouting effect. The entropy change of AE energy during the loading process indicates that the rock system undergoes three stages of order-to-disorder-to-order. The second stage and the abrupt changes in entropy value can serve as precursors to rock damage and fracture. This research enriches our understanding of how grouting influences the damage and fracture behavior of fractured rocks, providing valuable insights for risk assessment and disaster prediction in geotechnical grouting engineering. • The splitting failure behavior of rock specimens with and without grouting is studied. • An improved calculation method is employed to assess the anti-fracture capacity of grouted specimens. • Grouting contributes positively to the reinforcement of fractured rocks. • The second stage of entropy evolution based on AE energy can be considered precursors to rock fracture. [ABSTRACT FROM AUTHOR]

• Derived an error generalisation for ICGN-DIC, including interpolation error and random error. • The different correlation criteria do not affect the error in the DIC calculations. • A new method is proposed for analysing the impact of interpolation methods and gradient algorithms. • The computational error corresponding to linear interpolation is smaller than that of Cubic interpolation. • The computational error corresponding to centre difference gradient algorithm is smaller than that of the Barron operator and the Nature operator. The error estimation formula is one of the key points in DIC research. However, most of the correlation criterion used in the research of DIC error is SSD instead of the most commonly used ZNSSD. And the existing error estimation formulas are very complicated, which is not conducive to analyse the relationship between interpolation algorithm, gradient calculation method, image spectrum and error. Therefore, there is a need to derive the error formulae applicable to all SSD class correlation criteria and to find the intermediate variables between the interpolation algorithm, gradient algorithm, image spectrum and error based on the general formulae to facilitate the analysis. This work derives the interpolation error generalization and random error generalization for DIC using SSD class correlation criterion, by using the frequency domain based approach. The Error Coefficient Matrix (ECM) is proposed in order to carry out the analysis of the impact on the computational error of the DIC. The DIC methods using SSD class correlation criterion yield almost identical results and are not limited to the expectation or variance of the error. The low-frequency portion of the EMC has a greater influence on the error than high-frequency portion. Conversely, the high-frequency portion of the image spectrum has a greater influence on the error. Among the commonly used interpolation and gradient algorithms discussed in this work, the smallest RMSE are found in the B-spline and Centre difference algorithms, which are 11% and 83% of the maximum, respectively. The findings of this work help to generalise the existing SSD-based findings to ZNSSD, such as optimal subset size, optimal speckle radius, etc. In addition, the best combination of algorithms used in DIC operations is the combination of B-splines and Centre difference operators. [ABSTRACT FROM AUTHOR]

The through-the-thickness reinforcement of carbon-epoxy composite joints with shape memory alloy (SMA) tufts has shown significant improvement of the mechanical strength, fracture toughness, and delamination resistance. This study explores the thermal-electric properties of SMA filaments tufted in composite T-joints to exhibit multiple functionalities including material-enabled thermographic inspection and structural health monitoring via in-situ strain sensing. Infrared thermography image analysis was performed on both pristine and damaged T-joint specimens subject to pull-off testing. Experimental results showed that the heat generated by SMA tufts measured by an infrared camera provided accurate indication of delamination perpendicular to the tuft direction. SMA tufts were also used as strain sensors embedded within the T-joint. Local changes of the electrical resistance in SMA filaments, both separately and within the joint, were observed during pulling loads. Digital Image Correlation measurements exhibited good correlation between electrical resistance variations and the opening of delamination. These results pave the way for the development of multifunctional composite joining systems combining enhanced through-the-thickness damage tolerance and self-sensing capabilities. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement in zirconium alloys is a highly relevant research topic, important for ensuring the integrity of nuclear fuel clads. While the presence of hydrides in zirconium-based clad is a well-known risk factor due to their brittleness, the effect of the presence of hydrogen in solid solution is unclear. According to the Hydrogen Enhanced Localized Plasticity (HELP) model, hydrogen in solid solution may affect the mechanical performance of a metal by increasing dislocation mobility due to the shielding effect that hydrogen has on the interaction of dislocations with other types of defects. In the presented work, the presence of HELP has been assessed in Zircaloy-4 samples, under conditions relevant to the storage of spent nuclear fuel. Elevated temperature tensile tests were performed on samples containing localized areas of higher hydrogen concentration, as quantified by neutron radiography. Digital Image Correlation (DIC) analysis was performed on the specimen surfaces for quantitative characterization of strain heterogeneity during deformation to identify the regions where the plastic strain localization occurs. These regions could be correlated to elevated amounts of hydrogen in solid solution, that is, in the location immediately adjacent to dissolving hydrides, or in the areas of the samples with local hydrogen concentration close to the expected terminal solid solubility limit (TSS) in the test conditions. The results confirm the presence of localized softening caused by solid solution hydrogen, indicating that the HELP mechanism needs to be taken into account when modeling the mechanical response of zirconium-based nuclear fuel clads at elevated temperatures. [ABSTRACT FROM AUTHOR]

[Display omitted] • The trends of FCR under monotonic loading are contingent on the health of the cement composite. • A novel measurement coefficient (β t) is proposed for monitoring the initiation and propagation of cracks. • DIC and SEM experiments confirm the effectiveness of β t in crack detection. Health and safety are relevant in transportation infrastructures. Most health evaluations are performed by spot measurements using conventional transducers. This study aims to explore a self-sensing composite that can be integrated into a structural layer of a pavement or rail track to continuously evaluate the full layer performance in critical zones and anticipate damage occurrence. For this purpose, a 10 % cement-stabilized standard sand used in conventional structural layers was transformed into a self-sensing composite by synergistic incorporation of 3 % and 4 % multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). In addition, Pluronic F-127 and tributyl phosphate 97 % (TBP) were used for better dispersion of carbon nanomaterials in the mixture, and these materials were compacted at maximum density and optimum moisture conditions. Through a detailed laboratory investigation, including piezoresistivity measurements, digital image correlation (DIC), and microstructure analysis through scanning electron microscopy (SEM), it was possible to propose a novel method to detect the propagation of damage under monotonic loading based on changing the slope of normalized electrical resistance against time. This was supported by a theoretical background able to explain that the emergence and propagation of damage result in increasing electrical resistance and hence fractional changes in resistance (FCR). [ABSTRACT FROM AUTHOR]

• Mode I fracture process is characterized for GFRP-steel bi-material interface. • Double-cantilever beam experiments supplemented by detailed DIC measurement. • Accurate modeling of crack initiation, fiber bridging and propagation by new CZM. • Four-linear traction-separation law derived from DIC measurements and iterative FEA. Debonding is characterized as the governing failure mode in the innovative wrapped composite joints made with glass fiber composite material wrapped around steel hollow sections without welding. The prerequisite for predicting debonding failure of wrapped composite joints is to obtain fracture behavior of the composite-steel bonded interface. The mode I fracture behavior of the bonded interface was experimentally investigated using glass fiber composite-steel double cantilever beam (DCB) specimens. The crack length a and the crack tip opening displacement (CTOD) during the test were accurately measured by analyzing the digital image correlation (DIC) data while the strain energy release rate (SERR) was calculated through the extended global method (EGM). The cohesive zone modeling (CZM) was utilized in the finite element model with the proposal of a four-linear traction-separation law to simulate the mode I fracture process. An approach is introduced to determine the critical stages of the proposed four-linear cohesive law by combining accurate measurements of crack length a and CTOD, along with SERR values. The validity of the four-linear cohesive law and the introduced approach to determine the critical stages were confirmed by good agreement in both global and local behavior between the testing and the FEA results. [ABSTRACT FROM AUTHOR]

Crack-closing and re-centring attributes were observed in cementitious composites utilising segmented pseudoelastic shape memory alloy fibres (S-PSMAFs) developed in this study. S-PSMAFs, produced via laboratory deep drawing, displayed notable strain recovery capacity during detwinning and martensite phases in direct cyclic tensile tests. Cementitious composites incorporating S-PSMAFs at 0.5%, 0.75%, and 1.0% dosages underwent testing in static and cyclic flexure using both unnotched and notched beams. Results were compared with steel fibre (SF) reinforced specimens. Digital image correlation (DIC) provided full-field strain maps and crack propagation data. The cyclic testing allowed assessment of crack-closing and re-centring behaviour at varying deflections post-cracking and at ultimate limit state deflections. S-PSMAF-reinforced composites maintained a crack-closure ratio between 52% and 60% even at larger crack sizes (e.g., 3 mm). Re-centring ratios ranged from 80% to 55%, dependent on the imposed displacement amplitude of cycles. In contrast, SF-reinforced beams lacked effective crack-closing or re-centring behaviour, with both ratios decreasing drastically to about 10% over cycles. Additionally, S-PSMAF-reinforced composites exhibited higher flexural toughness, ductility, force reduction performance factor, greater energy dissipation, and smaller crack sizes compared to their SF-reinforced counterparts. • S-PSMAFs developed in the study showed significant strain recovery. • 0.5%, 0.75%, and 1.0% S-PSMAF dosages were tested in static and cyclic flexure. • DIC method provided detailed strain maps and crack propagation data. • S-PSMAF composites kept a crack-closure ratio of 52% to 60% even at larger crack sizes. • S-PSMAF composites exhibited greater energy dissipation, and smaller crack sizes. [ABSTRACT FROM AUTHOR]

The propagation of cracks on a small scale can result in dynamic disasters, such as rock bursts induced by large-scale fractures in coal seams. To gain insights into the mechanism of fracture-induced disasters in deep coal seams, this study investigates the micro-process and size effect of crack propagation in coal specimens featuring different sizes of center-crack circular discs (CCCD). We conducted Brazilian splitting tests on coal samples with varying dimensions and employed acoustic emission (AE) and digital image correlation (DIC) techniques to quantitatively describe the crack propagation process. Additionally, coal specimens of different diameters were compared for the size effect characteristics of different fracture parameters during the tensile failure process. The results show that as the specimen size increases, quasi-brittle failure characteristics become pronounced, tensile strength gradually decreases and stabilizes, while fracture toughness and fracture process zone length gradually increase and tend to stabilize. The macroscopic cracks in the coal specimens generally extend from the centre of the specimen to both ends along the precracks. Large energy events are mainly concentrated at the lower end of the precracks. As coal specimen size increases, the number of AE events decreases, while the proportion of large energy events gradually increases, and the critical crack opening quantity exhibits a linear increase with specimen size. By conducting the fracture size effect experiment on coal specimens, we extend the relevant mechanical parameters from laboratory-scale tests to field engineering scales. This provides fundamental parameters for the analysis of large-scale fracture process of in-situ coal based on fracture mechanics. [ABSTRACT FROM AUTHOR]

This study investigates the demands generated in the panel zone of welded steel built-up box columns with fillet and complete joint penetration (CJP) groove welds, which are mainly used as columns in steel moment-resisting frames. The motivation for this study stems from the a 360–16 specification for structural steel building, which requires the joining of flange and web plates of box columns with CJP groove welds within a zone extending 12 in. above the upper beam flange and 12 in. below the lower beam flange in special and intermediate steel moment frames. Laboratory experiments have been conducted to examine the strength of these welds under pure shear forces. For this purpose, two laboratory specimens, one with fillet welds and the other with CJP groove welds, have been designed, and the strength of these welds were equal to each other in pure shear force conditions. The fillet weld specimen has resisted up to 1670 kN in the pure shear test, and the CJP groove weld has resisted up to 1520 kN. The entire loading process of each specimen was characterized by employing the digital image correlation (DIC) technique, which enabled the extraction of strain values throughout. Numerical modeling is validated in Abaqus software using experimental results, with comprehensive analyses on force-displacement diagrams and rupture. The outcomes of the tests conducted have shown that the demands generated in the panel zone of the built-up steel box welded sections are satisfactorily tolerated by both fillet and CJP groove welds. The significance of this study can be elaborated in multiple aspects. Firstly, it introduces an innovative test setup meticulously designed to replicate the behavior of welded built-up box columns with corner joints to steel plates. This advanced experimental arrangement not only facilitates the current study, but also serves as a versatile tool for conducting forthcoming experiments, allowing for meaningful comparisons and further exploration of diverse phenomena within the field. Secondly, the deliberate imposition of uniform demands on both types of welds during the study enables a comprehensive examination of their behavioral characteristics. This comprehensive analysis contributes to a more profound comprehension of welds performance under identical conditions, thereby enhancing our knowledge within the field. Finally, the research outcome, which reveals that fillet welds exhibit almost identical load-bearing capacity in comparison to CJP groove welds, bears substantial practical significance for the construction industry. This finding has the potential to instigate more cost-effective and efficient welding practices, which are paramount for maintaining the structural integrity of steel structures. In summary, this study makes a noteworthy contribution to the scientific community by presenting an innovative test setup, deepening the knowledge of weld performance, and suggesting practical enhancements in welding methodologies. These collective contributions serve to elevate the field of structural engineering, promoting advancements in construction practices. • The welded built-up steel box columns can be constructed faster with fillet weld compared to the CJP groove weld. • Two different weld types were investigated for the purpose of welding of the welded built-up box columns. • The digital image correlation (DIC) technique was utilized to validate the experimental results. • The primary observed failure mode of the fillet weld was rupture in the weld line. • The primary observed failure mode of the CJP groove weld was rupture in the steel plate. [ABSTRACT FROM AUTHOR]

Since additive manufacturing (AM) has been utilized for production of functional end-use parts, the mechanical behavior of the additively manufactured parts is a crucial issue. In the present study, compact tension (CT) test is conducted on 3D-printed polymer parts which are fabricated based on the fused deposition modeling (FDM) technique. Considering the influence of the printing parameters on the mechanical performance of the parts, the specimens are fabricated under different printing parameters. In detail, CT specimens are printed with +45°/−45° and 0°/90° filament directions and 0.2 and 0.5 mm layer thicknesses at printing speed of 20 mm/s and 70 mm/s. Based on the CT tests, the fracture behavior of the parts are investigated and their fracture toughness are determined. In addition, digital image correlation technique is used to determine the strain fields on the surface of the CT specimens. Moreover, a series of finite element analysis is performed to study the mechanical behavior of modeled parts. Additionally, scanning electron microscopic investigation is performed for visual examination of the fractured components. According to the results, optimum printing parameters for maximizing the mechanical properties are determined. Due to the wide applications of the FDM 3D-printed parts, the documented results are beneficial for fabrication of parts with a higher mechanical strength. [ABSTRACT FROM AUTHOR]

In this study, a novel three-step method involving liquid casting, hot-rolling, and foaming was employed to fabricate three types of metallurgical bonded aluminum foam sandwich (AFS): AFS with a uniform foam core (UAFS), AFS with a density-graded foam core (GAFS), and AFS with an interlayer plate (IAFS). The bending behaviors of different AFS structures in four cases were investigated using the digital image correlation (DIC) technique to examine the effect of foam core structure, loading direction, and loading temperature. The results showed that the initial peak load (F p), plateau load (F pl) and load oscillation decreased with increasing loading temperature. IAFS demonstrated the low sensitivity to loading temperature, an important reason was the addition of interlayer plate. The deformation mode involved interface separation and foam core detachment occurring in the interface vicinity beneath the indenter at the lower temperatures (≤300 °C) shifted towards well-bonded interface and foam core densification at the higher temperatures (400 °C and 500 °C). Different core structures and loading directions gave rise to four distinct modes of crack initiation and propagation. In addition, as the loading temperature increased, the strain localization effect was diminished, accompanied by hindering in crack formation. The fracture mode of core shear transitioned from brittle to ductile with increasing loading temperature. • Three metallurgical bonded aluminum foam sandwiches with different core structures were obtained. • High-temperature three-point bending behaviors were investigated using the digital image correlation technique. • Core structure and loading direction can change the crack initiation and propagation. • Increasing temperature can hinder the crack formation and change the deformation mode of interface vicinity. [ABSTRACT FROM AUTHOR]

• Shear cracking in predamaged PVA-ECC beam was monitored by using DIC. • The inclusion of coarse aggregate can enhance the shear performance of PVA-ECC beam. • The crack opening and sliding are largely limited due to the coarse aggregate. Normal polyvinyl alcohol-engineered cementitious composites (PVA-ECC) exhibit high mechanical performance but are susceptible to shear cracking. It has been recently found that the shear resistance can be largely improved by including coarse aggregates. However, under complex stress conditions, the mechanism of shear movement and the contribution from coarse aggregate remain unclear. This paper presents an experimental investigation of the shear cracking behavior in pre-damaged PVA-ECC beams with a mixture that includes coarse aggregate. Symmetric and antisymmetric loading tests were carried out to examine the effects of coarse aggregate under different stress rotation fields. To clarify the shear cracking mechanism, digital image correlation (DIC) was applied to observe crack development and strain localization in the shear span of the PVA-ECC beams. The results obtained from DIC and conventional measurements showed good agreement, confirming the reliability of monitoring complex fracture processes using the DIC technique. The shear cracking mechanism of the PVA-ECC beam under complex stress conditions was analyzed. The collaboration of coarse aggregate was observed from the orientation of secondary cracks, which showed less dependence on the presence of precracks. Crack opening and sliding were significantly limited due to the reduced anisotropic effect of the predamage. Therefore, using the DIC technique, the positive effect of coarse aggregates was verified, and the shear cracking mechanism of pre-damaged PVA-ECC beams was revealed through direct observations. [ABSTRACT FROM AUTHOR]

The identification and understanding of fracture processes is a vital component in securing engineering structures. By collecting data through experiments or simulations, the identification of material parameters and the understanding of failure mechanisms can be investigated. In the context of in-laboratory experiments, this is done by provoking fracture process through destructive testing (TD) techniques, while collecting data by non-destructive testing (NDT) techniques and postmortem analysis. While NDT techniques are often used individually, increasing interest is given to collective investigations of source activities. Like this, limitations of one method can be compensated by the next. A multi-modal experimental setup is proposed for holistic understanding of source mechanisms. Combined time resolved AE, DIC and in-volume measurements with post-mortem fracture surface analysis are applied on PMMA tensile cracking experiments for the purpose of AE localization, crack tip detection and determination of crack front complexities and kinematics, respectively. Both high and lower amplitude AE signals were captured and respectively associated to localized dynamic instabilities and stable crack advance. Signals are analyzed individually using localization, waveform analysis, and AE descriptor classification. Crack front velocity heterogeneities are identified as valuable quantity to correlate with fracture induced AE responses. For dynamic instabilities, a linear relationship between AE absolute energy and crack propagation area was found. While identification and analyses of local and global dynamic instabilities has shown to be rather trivial, difficulties arose with respect to quasi-static related AE events. [Display omitted] • Time resolved AE, DIC and in-volume measurements are combined during fracture tests • AE are localized and analyzed in the light of in-volume crack front kinematics • AE signals with high amplitudes are unambiguously connected to dynamic instabilities • Highly correlated AE waveforms cannot be associated to a particular source mechanism [ABSTRACT FROM AUTHOR]