Search Results (64)

This study explores the effectiveness of 3D Digital Image Correlation (DIC) for measuring displacement and strain of a propeller undergoing angular motion. Traditional methods, such as strain gauges, face limitations including physical interference, technical difficulties in sensor connections, and restricted measurement points, leading to inaccuracies in capturing true conditions. To overcome these challenges, this research utilizes non-contact 3D DIC technology, enabling measurement of surface displacements and deformations without interfering with the tested component. Experiments were conducted using the model aircraft propellers mounted on a custom-built test stand for partial angular motion. The 1 Mpx high-speed cameras captured strain and displacement data across the propeller blades during motion. The DIC strain measurements were then compared to strain gauge data to evaluate their accuracy and reliability. The results demonstrate that 3D DIC enables precise displacement measurements, while strain measurements are subject to certain limitations. Displacement measurements were achieved with a noise level of ±10 μm, while strain measurement noise ranged from 26 to 174 µm/m depending on direction. Strain gauge measurements were also performed for verification of the DIC measurements and calibration of the filtering procedure. Two types of non-metallic materials were used in the study: Nylon LGF60 PA6 for the propeller and 3D-printed PC ABS for the cantilever beam used in strain measurement validation. This study underscores the potential of DIC for monitoring rotating components, with a particular focus on measuring strains that are often overlooked in publications addressing similar topics. Additionally, it focuses on comparing DIC strain measurements with strain gauge data on rotating components, addressing a critical gap in existing literature, as strain measurement in rotating structures remains underexplored in current research. Full article

The structural health monitoring (SHM) of existing infrastructure and heritage buildings is essential for their preservation and safety. This is a review paper which focuses on modern three-dimensional (3D) measurement techniques, particularly those that enable the assessment of the structural response to environmental actions and operational conditions. The emphasis is on the detection of fractures and the identification of the crack geometry. While traditional monitoring systems—such as pendula, callipers, and strain gauges—have been widely used in massive, quasi-brittle structures like dams and masonry buildings, advancements in non-contact and computer-vision-based methods are increasingly offering flexible and efficient alternatives. The integration of drone-mounted systems facilitates access to challenging inspection zones, enabling the acquisition of quantitative data from full-field surface measurements. Among the reviewed techniques, digital image correlation (DIC) stands out for its superior displacement accuracy, while photogrammetry and time-of-flight (ToF) technologies offer greater operational flexibility but require additional processing to extract displacement data. The collected information contributes to the calibration of digital twins, supporting predictive simulations and real-time anomaly detection. Emerging tools based on machine learning and digital technologies further enhance damage detection capabilities and inform retrofitting strategies. Overall, vision-based methods show strong potential for outdoor SHM applications, though practical constraints such as drone payload and calibration requirements must be carefully managed. Full article

This study investigates the long-term performance of flexible anti-collision rings after 12 years of service on the Xiangshan Port Highway Bridge. Stepwise loading–unloading tests at multiple loading rates (0.8–80 mm/s) were performed on the anti-collision rings, with full-field strain measurement via digital image correlation (DIC) technology. The results show that: The mechanical response of the anti-collision ring shows significant asymmetric tension–compression, with the tensile peak force being 6.8 times that of compression. A modified Johnson–Cook model was developed to accurately characterize the tension–compression force–displacement behavior across varying strain rates (0.001–0.1 s⁻¹). The DIC full-field strain analysis reveals that the clamping fixture significantly influences the tensile deformation mode of the anti-collision ring by constraining its inner wall movement, thereby altering strain distribution patterns. Despite exhibiting a corrosion gradient from severe underwater degradation to minimal surface weathering, all tested rings demonstrated consistent mechanical performance, verifying the robust protective capability of the rubber coating in marine service conditions. Full article

This study presents a detailed analysis of the influence of hole presence and size on the behavior of CFRP composite plates subjected to axial compression. The plates were manufactured by an autoclave method from eight-ply laminate in a symmetrical fiber arrangement [45°/−45°/90°/0°₂/90°/−45°/45°]. Four central hole plates of 0 mm (reference), 2 mm, 4 mm, and 8 mm in diameter were analyzed. Tests were conducted using a Cometech universal testing machine in combination with the ARAMIS digital image correlation (DIC) system, enabling the non-contact measurement of real-time displacements and local deformations in the region of interest. The novel feature of this work was its dual use of independent measurement methods—machine-based and DIC-based—allowing for the assessment of boundary condition effects and grip slippage on failure load accuracy. The experiments were carried out until complete structural failure, enabling a post-critical analysis of material behavior and failure modes for different geometric configurations. The study investigated load–deflection and load–shortening curves, failure mechanisms, and ultimate loads. The results showed that the presence of a hole leads to localized deformation, a change in the failure mode, and a nonlinear reduction in load-carrying capacity—by approximately 30% for the largest hole. These findings provide complementary data for the design of thin-walled composite components with technological openings and serve as a robust reference for numerical model validation. Full article

This study addresses the constitutive relationship of the welded coarse-grained heat-affected zone (CGHAZ) in 80-mm-thick DH36 marine steel plates. By integrating quasi-static tensile testing, digital image correlation (DIC) technology, and metallographic analysis, we systematically investigated the mechanical property differences and underlying mechanisms between the CGHAZ and base metal (BM). High-precision DIC technology enabled strain field characterization at the microscale in the CGHAZ, while the Ramberg-Osgood model was adopted to establish a dual-material constitutive equation. The results demonstrate that grain coarsening induced by welding thermal cycles significantly influenced the mechanical responses: the CGHAZ exhibited enhanced tensile strength but reduced plastic compatibility due to decreased grain boundary density. Notably, gradient differences in elastic modulus (CGHAZ: 184 GPa vs. BM: 213 GPa) and yield strength (CGHAZ: 363 MPa vs. BM: 373 MPa) between the BM and CGHAZ necessitate strict differentiation in engineering design. This work overcomes the limitations of oversimplified CGHAZ properties in conventional design approaches, providing a novel methodology for strength assessment and lightweight design of marine structures. The findings offer critical theoretical insights and practical guidelines for enhancing the reliability of offshore engineering equipment. Full article

This study examines a triaxial testing system for unsaturated subgrade fillers, utilizing a high-suction tensiometer and photogrammetry to more accurately simulate and analyze their mechanical behavior. Digital image correlation (DIC) technology is combined with non-contact photogrammetry, employing a multi-ray tracing method to reconstruct the 3D model of the sample and monitor its volume changes. Real-time matric suction is measured using a high-suction tensiometer, avoiding traditional suction control methods and enabling a more accurate reproduction of deformation and suction changes in unsaturated soil samples under natural conditions. This study further analyzes key parameters, such as specific volume change, suction change, and shear failure state, under varying moisture content and stress conditions, with parameter calibration for mechanical behavior performed using the BBM model. This system significantly reduces traditional experimental time, offering a new tool for studying the mechanical behavior of unsaturated subgrade fillers, with substantial theoretical value and practical application potential. Full article

Accurate mechanical property parameters constitute an indispensable guarantee for the accuracy of finite element simulations. Traditionally, uniaxial tensile tests are instrumental in acquiring the stress–strain data of materials during elongation, thereby facilitating the determination of the materials’ mechanical property parameters. By capitalizing on the digital image correlation (DIC) non-contact optical measurement technique, the entire test can be comprehensively documented using high-speed cameras. Subsequently, through in-depth analysis and meticulous numerical computations enabled by computer vision technology, the complete strain evolution of the specimen throughout the test can be precisely obtained. In this study, a comparison was made between the application of strain gauges and DIC testing systems for measuring the strain alterations during the tensile testing of 316L stainless steel, which serves as the material for the primary circuit pipelines of pressurized water reactor (PWR) nuclear power plants (NPPs). The data procured from these two methods were utilized as material mechanical parameters for finite element simulations, and a numerical simulation of the uniaxial tensile test was executed. The results reveal that, within the measuring range of the strain gauge, the DIC method generates measurement outcomes that are virtually identical to those obtained by strain gauges. Given its wider measurement range, the DIC method can be effectively adopted in the process of obtaining material mechanical parameters for finite element simulations. Full article

The paper offers an in-depth deformation study of glass fiber-reinforced and carbon composite filaments of 3D printers. During the certification, the authors used DIC (Digital Image Correlation) as a full-field strain measurement technique to explore key material traits as a non-contact optical measurement method. The insights captured through the DIC technology enabled to better understand the localized strain distributions during the loading of these reinforced filaments. The paper analyzes the glass fiber and carbon fiber filaments used in 3D printing that are reinforced with these materials and are subjected to bending and compressive loading. The segment presents how loading affects the performance of reinforced filaments when varying such factors as the deposition patterns, layer orientation, and other process parameters. Different types and combinations of reinforcements and printing variables were tested, and the resulting dependencies of mechanical parameters and failure modes were established for each case. Key conclusions demonstrate that the mechanical behavior of both carbon- and glass fiber-reinforced filaments is strongly affected by the 3D printing parameters, particularly infill density, pattern, and build orientation. The application of Digital Image Correlation (DIC) allowed for a precise, full-field analysis of strain distribution and deformation behavior, offering new insights into the structural performance of fiber-reinforced 3D printed composites. The findings from the study provide guidance for the proper choice of filling material and the optimal parameters for the 3D printing process of models with high-performance indexes and seamless applications in the automotive and industrial manufacturing sectors. Full article

The optimization and evaluation of 3D-printed polylactic acid (PLA) materials for reinforcing concrete elements present a promising avenue for advancing sustainable construction methods. This study addresses the challenges associated with PLA’s dual nature—biodegradable yet mechanically limited for long-term applications—while leveraging its potential to enhance concrete reinforcement. The research identifies gaps in understanding PLA’s mechanical and chemical behavior in alkaline environments, particularly its interactions with concrete matrices. To bridge this gap, four distinct PLA variants (high-impact PLA, engineering PLA, electrical ESD PLA, and gypsum PLA) and ABS (acrylonitrile butadiene styrene) were subjected to dissolution tests in NaOH solutions (pH 12 and 12.55) and mechanical evaluation under three-point bending using digital image correlation (DIC) technology. Test specimens were prepared using optimized 3D printing strategies to ensure structural consistency and were embedded in concrete beams to analyze their reinforcement potential. Force–displacement data and GOM ARAMIS measurements revealed significant differences in mechanical responses, with peak loads ranging from 0.812 kN (high-impact PLA) to 1.021 kN (electrical ESD PLA). Notably, electrical ESD PLA exhibited post-failure load-bearing capacity, highlighting its reinforcement capability. Chemical dissolution tests revealed material-specific degradation patterns, with high-impact and Gypsum PLA showing accelerated surface changes and precipitation phenomena. Observations indicated white crystalline precipitates, likely lime (calcium hydroxide—Ca(OH)₂), residue from the dissolution tests (sodium hydroxide—NaOH), or material-derived residues formed on and near PLA elements, suggesting potential chemical interactions. These findings underline the critical role of material selection and optimization in achieving effective PLA–concrete integration. While PLA’s environmental sustainability aligns with industry goals, its structural reliability under long-term exposure remains a challenge. The study concludes that electrical ESD PLA demonstrates the highest potential for application in reinforced concrete, provided its chemical stability is managed, as its peak value (1.021 kN) showed 25.7% higher load-bearing capacity than high-impact PLA (0.812 kN) and did not lose any of its structural stability in the dissolution tests. This work advances the understanding of PLA as a sustainable alternative in construction, offering insights for future material innovations and applications. Full article

The longevity and safety of concrete precast crane beams significantly impact the operational integrity of industrial infrastructure. Assessment of surface cracks development in concrete structural elements during laboratory tests is performed mainly by applying standard tools such as linear-variable-differential transformers and strain gauges. This paper presents a novel assessment methodology combining deep convolutional neural network for image segmentation with digital image correlation method to evaluate the structural health of precast crane beams after more than fifty years of service. The study first outlines the adaptation of the deep learning U-Net architecture for detecting and segmentation of surface cracks in crane beams. Concurrently, DIC technique is employed to measure surface strains and displacements under load. The integration of these technologies enables a non-destructive, accurate, and detailed analysis, facilitating early detection of deterioration that may compromise structural safety. Initial results from field tests validate the effectiveness of our approach, demonstrating its potential as a tool for predictive maintenance of aging industrial infrastructure. Full article

This study addresses the emerging need for efficient and cost-effective solutions in low-volume production by exploring the mechanical performance and industrial feasibility of cutting tools that are fabricated using stereolithography apparatus (SLA) technology. SLA’s high-resolution capabilities make it suitable for creating precise cutting dies, which were tested on aluminum sheets (Al99.5, 0.3 mm, and AlMg3, 1.0 mm) under a 60-ton hydraulic press. Measurements using digital image correlation (DIC) revealed minimal wear and deformation, with tolerances consistently within IT 0.1 mm. The results demonstrated that SLA-printed tools perform comparably to conventional metal tools in cutting and bending operations, achieving similar surface quality and edge precision while significantly reducing the production time and cost. Despite some limitations in wear resistance, the findings highlight SLA technology’s potential for rapid prototyping and short-run manufacturing in the automotive and electronics sectors. This research fills a critical gap in understanding SLA-based tooling applications, offering insights into process optimization to enhance tool durability and broaden material compatibility. These advancements position SLA technology as a transformative tool-making technology for flexible manufacturing. Full article

This research advocates for the use of basalt fiber-reinforced polymer (BFRP) bars and recycled tire steel fibers to reinforce concrete beams. Six concrete beams were constructed using different volume contents of recycled tire steel fibers (0, 0.5%, 1.0%, 1.5%) and BFRP reinforcement ratios (0.48%, 0.75%, 1.08%). Mechanical properties tests were conducted to investigate the flexural characteristics and failure modes of beams utilizing the non-contact full-field strain displacement measuring technology–digital image (3D-DIC) technology. The recycled tire steel fiber (RTSF) improves flexural performance, which contributes to inhibiting crack propagation, reducing flexural deformation, and improving the first cracking and ultimate loading capacities. Under the same reinforcement ratio, in comparison to ordinary BFRP beams, the cracking load of BFRP-RTSF beams increased by 17.73%, 23.76%, and 42.94%, respectively, and the ultimate bearing capacity increased by 4.03%, 5.85%, and 13.21%, respectively. In addition, a modified calculation model of bearing capacity considering RTSF tensile strength is proposed. The predicted values of BFRP-RTSF beams match well with the experimental values. Full article

Objective: This study investigates the influence of high-temperature treatment on the deformation properties and structural deformation of recycled aggregate concrete (RAC) in response to potential fire hazards in the construction industry. Methods: Standard-cured 28-day RAC specimens were subjected to microwave heating at 300 °C and 600 °C, with subsequent uniaxial compression tests utilizing a WDW-2000 machine and a VIC 3D strain measurement system to analyze strain data through digital image correlation (DIC) technology. Results: After treatment at 300 °C, recycled aggregate concrete (RAC) demonstrated superior mechanical properties to fresh concrete aggregates. This enhancement may be attributed to the more robust siloxane bonds (Si-O-Si) in the recycled materials. Conversely, exposure to 600 °C intensified internal structural damage, notably lowering the material’s elastic modulus and peak stress. DIC analysis highlighted the correlation among temperature, volumetric strain, and crack development patterns, with more extensive cracking at 600 °C. Conclusions: Moderate-temperature treatment enhances RAC’s structure and deformation properties, while high-temperature treatment diminishes its performance. These findings provide valuable insights for assessing building safety post-fire and the application of RAC, emphasizing its suitability at moderate temperatures and risks at high temperatures. Full article

3D digital-image correlation (3D-DIC) is a non-contact optical technique for full-field shape, displacement, and deformation measurement. Given the high experimental hardware costs associated with 3D-DIC, the development of high-fidelity 3D-DIC simulations holds significant value. However, existing research on 3D-DIC simulation was mainly carried out through the generation of random speckle images. This study innovatively proposes a complete 3D-DIC simulation method involving optical simulation and mechanical simulation and integrating 3D-DIC, virtual stereo vision, and image super-resolution reconstruction technology. Virtual stereo vision can reduce hardware costs and eliminate camera-synchronization errors. Image super-resolution reconstruction can compensate for the decrease in precision caused by image-resolution loss. An array of software tools such as ANSYS SPEOS 2024R1, ZEMAX 2024R1, MECHANICAL 2024R1, and MULTIDIC v1.1.0 are used to implement this simulation. Measurement systems based on stereo vision and virtual stereo vision were built and tested for use in 3D-DIC. The results of the simulation experiment show that when the synchronization error of the basic stereo-vision system (BSS) is within ${10}^{-3}$ time steps, the reconstruction error is within 0.005 mm and the accuracy of the virtual stereo-vision system is between the BSS’s synchronization error of ${10}^{-7}$ and ${10}^{-6}$ time steps. In addition, after image super-resolution reconstruction technology is applied, the reconstruction error will be reduced to within 0.002 mm. The simulation method proposed in this study can provide a novel research path for existing researchers in the field while also offering the opportunity for researchers without access to costly hardware to participate in related research. Full article

In this study, the digital image correlation (DIC) method and acoustic emission (AE) technology were combined to study the evolution of rock deformation localization in detail. The second-order spatial–temporal subset DIC (STS-DIC) algorithm was proposed and used for measuring strongly heterogeneous deformation fields of red sandstone specimens under uniaxial compression. The evolution of the deformation field was analyzed with a focus on the deformation localization stage. The length and width of the deformation localization band (DLB) were measured, and the relationships between the relative sliding rate of the DLB, the relative opening rate of the DLB, and the AE counts were identified. Deformation localization was found to result from the rapid evolution of the strain concentration before the peak stress. The complete development of the DLB is an inducing factor for catastrophic rock failure, and the failure modes of the rock specimens were consistent with the final state of the DLB. A good correlation was identified between the AE counts and the relative displacement rate of the DLB, and the sliding rate was found to have a significant influence on the AE counts. Full article