Numerical Simulation Techniques Research Articles

Investigation of Welding-Induced Residual Stresses in a Herringbone Column Using the Blind Hole Technique: An Experimental and Numerical Study

The current research investigates the effect of residual stresses from welding on the stability of steel structures, particularly the herringbone column undulating cross-truss structure in the Zhengzhou New International Exhibition Center project. Residual stresses at 30 key points were measured using the blind hole method, and the temperature and stress fields under thermal coupling were analyzed using numerical simulation techniques. The measured residual stresses of the welded herringbone columns are generally higher than the theoretical calculated values, with the relative error of most measuring points being less than 10% and the minimum difference being 0.98 MPa. It was confirmed that the welding quality meets the design and acceptance standards. Through a combination of experimental measurements and numerical simulations, this study provides valuable reference information for the construction of similar projects. The results indicate that the residual stresses in the herringbone columns are controllable, ensuring the overall safety and reliability of the structure.

Numerical Study on Hydrodynamic Performance and Vortex Dynamics of Multiple Cylinders Under Forced Vibration at Low Reynolds Number

Flow around clustered cylinders is widely encountered in engineering applications such as wind energy systems, pipeline transport, and marine engineering. To investigate the hydrodynamic performance and vortex dynamics of multiple cylinders under forced vibration at low Reynolds numbers, with a focus on understanding the interference characteristics in various configurations, this study is based on a self-developed radial basis function iso-surface ghost cell computing platform, which improves the implicit iso-surface interface representation method to track the moving boundaries of multiple cylinders, and employs a self-constructed CPU/GPU heterogeneous parallel acceleration technique for efficient numerical simulations. This study systematically investigates the interference characteristics of multiple cylinder configurations across various parameter domains, including spacing ratios, geometric arrangements, and oscillation modes. A quantitative analysis of key parameters, such as aerodynamic coefficients, dimensionless frequency characteristics, and vorticity field evolution, is performed. This study reveals that, for a dual-cylinder system, there exists a critical gap ratio between X/D = 2.5 and 3, which leads to an increase in the lift and drag coefficients of both cylinders, a reduction in the vortex shedding periodicity, and a disruption of the wake structure. For a three-cylinder system, the lift and drag coefficients of the two upstream cylinders decrease with increasing spacing. On the other hand, this increased spacing results in a rise in the drag of the downstream cylinder. In the case of a four-cylinder system, the drag coefficients of the cylinders located on either side of the flow direction are relatively high. A significant increase in the lift coefficient occurs when the spacing ratio is less than 2.0, while the drag coefficient of the downstream cylinder is minimized. The findings establish a comprehensive theoretical framework for the optimal configuration design and structural optimization of multicylinder systems, while also providing practical guidelines for engineering applications.

Mechanical characteristics and load-bearing effect of roadway anchorage composite carrier

Bolt support improves the stress state of the surrounding rock and forms an integral bearing structure inside the anchored surrounding rock. Therefore, it is of theoretical significance and practical application value to systematically study the mechanical mechanism and bearing characteristics of the anchorage composite carrier and elucidate the interaction mechanism between the bearing effect of the anchorage composite carrier and the stability of the roadway surrounding rock. In this paper, a mechanical model for the anchorage composite carrier is meticulously constructed through a fusion of theoretical analysis and advanced numerical simulation techniques. An in-depth exploration is conducted to elucidate the factors that significantly impact the bearing characteristics of the anchorage composite carrier. Specifically, the study examines the influence of supporting parameters, including bolt length, bolt diameter, bolt spacing, preload force, and roadway width, on both the effective formation and the thickness of the anchorage composite carrier. Based on the bearing effect of the anchorage composite carrier, aiming at the supporting problem of the cross-layer roadway (III811 interlocking roadway) in Luling Coal Mine of Huaibei Mining Co., LTD., the support technology application based on the bearing effect of the anchorage composite carrier is carried out, the support design scheme is optimized, the supporting effect is evaluated, and the evaluation method of the supporting effect and stability of the roadway is proposed. It is significant to apply support technology based on the bearing effect of anchorage composite carriers.

Thermal, flow and inclusions analysis of clogging mechanism in continuous casting process

The ladle shroud is a vital component in the continuous casting process of steelmaking as it supports the production of a wide range of specialty steels. However, it is plagued by a persistent issue of clogging, which not only diminishes the lifetime of the Alumina-Carbon ladle shroud but also severely disrupts the smooth operation of the continuous casting process. Utilizing a numerical simulation technique, the research adopted the method of particle-liquid two-phases coupling, to probe into the clogging mechanism in the ladle shroud from behavior of heat transfer, flow and inclusions. The study indicated that the temperature distribution and flow behavior have a positive effect on the formation of clogging, especially the inclusions. Various factors synergistically contribute on the inner wall, promoting severe clogging at the outlet of the ladle shroud. Finally, a simulation-based clogging mechanism is concluded coupling above factors.

Quality monitoring of hybrid welding processes: A comprehensive review

Hybrid welding processes have gained significant attention due to their high efficiency and exceptional welding properties. However, there are still significant technological challenges in achieving consistent quality and suppressing welding defects. To overcome this challenge, researchers have focused on the integration of visual analysis techniques, numerical simulation techniques, and advanced technologies such as artificial intelligence/machine learning (AI/ML) and digital twins. This comprehensive review synthesizes current knowledge on quality monitoring in hybrid welding, encompassing an overview of hybrid welding processes, quality assurance, monitoring techniques, key performance indicators, and advancements in monitoring techniques. Furthermore, the review highlights the integration of sensor data with AI/ML algorithms and digital twin technologies, enhancing the capabilities of quality monitoring systems. Notably, the review emphasizes the incorporation of artificial intelligence (AI) and digital twin technologies into quality monitoring frameworks. Artificial intelligence/Machine learning enables real-time analysis of welding parameters and defect detection, while digital twins offer virtual representations of physical welding processes, facilitating predictive maintenance and optimization. The findings underscore the crucial role of sensor technology, AI/ML, and digital twin integration in enhancing defect detection accuracy, improving welded joint quality, and control in hybrid welding. In addition to improving the quality of welded joints, this integration paves the way for further developments in welding technology.

Experimental Study on the Damage Evolution Mechanism of Siltstone by Water Content and Confining Pressure

ABSTRACTProlonged exposure of deep coal mines to erosion from groundwater results in a gradual accumulation of rock mass damage, which can lead to geological hazards such as deformation and instability. These challenges significantly impact the safe operation of deep coal mines. To understand the mechanisms behind siltstone damage progression related to water content and confining pressure, this study explores the influence of these factors on the deformation and damage evolution of siltstone, employing a combination of rock mechanics testing, numerical simulation, and CT scanning techniques. Results demonstrate that increasing water content reduces the compressive strength of rock, leading to more complex failure modes. In contrast, higher confining pressure strengthens the compressive capacity, thereby suppressing the formation and growth of transverse cracks under compression. Using Avizo software, a three‐dimensional model of siltstone was developed to visualize the distribution of fractures in a three‐dimensional field. In the MATLAB platform, a box dimension algorithm based on three‐dimensional digital volume imaging was developed, employing box dimension theory and digital image storage methods. Fractal analysis reveals that the fractal dimension of internal fractures in loaded samples increases linearly with water content, indicating more extensive fracture development and greater specimen damage. Applying the box dimension from three‐dimensional digital volume images as a metric facilitates characterizing the damage evolution in siltstone under different water content conditions. This approach provides a new means to quantitatively evaluate the growth and complexity of internal fractures in siltstone, offering insights into rock damage progression under varying moisture conditions.

Research on Three-Dimensional Resistivity Imaging for Non-Conventional Electrode Arrays in Restricted Exploration Area

The 3D resistivity imaging surveying is adept at identifying structural details at various subsurface depths, and it can acquire valuable underground information even in complex geological environments. This technique has been widely applied in fields such as geological exploration, hydrogeology, and environmental monitoring. Currently, the 3D electrical resistivity surveys in the field are primarily deployed using regular grid and equidistant electrode layouts. However, when the survey area is influenced by obstacles or when the target being investigated is particularly complex, this may hinder the deployment of the electrode array in accordance with a rectangular grid. In some instances, it may even be impossible to position the electrodes directly above the target of investigation. The only viable option is thus to place electrodes around obstacles or special targets. In view of this, this paper studied unconventional electrode arrays and inversion imaging techniques of 3D electrical resistivity surveying in confined areas. It presents the design of three electrode arrays: “□”-shaped, “U”-shaped, and “L”-shaped. Furthermore, the study explores 3D resistivity finite element numerical simulation and inversion imaging techniques based on continuous electrical media. Finally, model experiments were conducted to verify the feasibility of these three special electrode arrays. We have applied the “□”-shaped electrode array to investigate the foundation structure of an ancient pagoda in Zhejiang Province, achieving promising results. This study provides valuable reference for the research and application of special observation in 3D electrical resistivity exploration.

Application Research of a High Turbulence Numerical Simulation Technique in a USBR Type III Stilling Basin

In view of the energy dissipation design of the USBR Type III stilling basin, which is characterized by intense turbulent flow and complex flow patterns, a reliable mathematical model and calculation method is used to track and record the changes of flow parameters during fluid movement. The results of flow movement can be obtained, and the changes to the whole and local parameters of the flow field can be accurately simulated. Using the case of the discharge sluice stilling basin of the flood storage ecological treatment project of Jinchang Industrial Base in Gansu Province, this paper simulates the flow pattern through numerical calculation, thereby saving labor and material costs. The design cycle is also greatly shortened compared with the physical model test, and the technique has good repeatability, controllability, convenient optimization design, and provides technical support and quality assurance for complex energy dissipation problems.

Investigation of Flow Control in an Ultra-Compact Serpentine Inlet with Fluidic Oscillators

For optimal aerodynamic efficiency of specific ultra-compact serpentine intake, fluid oscillators are utilized to regulate airflow. This study employs advanced numerical simulation techniques to examine the effects of various control positions, jet angles, and excitation pressures on flow control efficacy. Control position significantly impacts the flow field structure within the intake, with a lower surface jet configuration outperforming an upper surface scheme. Optimal performance is achieved with the upper and lower surface jet angles set at 20° and 25°, respectively, under an input pressure of 2.5 times the total inlet pressure. This configuration enhances the total pressure recovery coefficient and reduces the steady-state circumferential distortion index and circumferential total pressure distortion coefficient. However, the flow rate ratio coefficient is notably high. While higher excitation pressures for the fluid oscillator do not inherently exhibit greater effectiveness, careful calibration is essential to accommodate varying positions. Optimal excitation pressure is established for the upper surface, while the control effect on the lower surface improves with increasing excitation pressure. Jet angles significantly affect the fluid oscillator’s control mechanism; small-angle jets effectively add energy to the separation zone, mitigating flow separation, whereas larger jet angles introduce excessive disturbances that outweigh their benefits. Overall, smaller jet angles enhance control effectiveness.

Study on the critical velocity for initiation of a covered explosive by fragment impact

Abstract This study examines the critical velocity for initiating a covered explosive via fragment impact, crucial for enhancing ammunition safety and reliability. Using numerical simulation techniques, the initiation threshold and influencing factors under non-normal impact conditions are investigated, which are more relevant to battlefield scenarios. The Jacobs-Roslund formula for NTO based insensitive explosive is calibrated, which is applicable for both flat-nosed and standard conical-nosed fragments. To account for a large range of impact angles, a correction term is introduced, and the predicted values are in good agreement with the simulation results. The effects of fragment pitch, yaw, and charge curvature on the critical velocity are found to be minimal at impact angle not exceeding 25°.

Simulation and multi-dimensional damage evolution analysis of detailed micro-model representing ancient brick masonry compressive behavior

To further investigate the crack propagation and damage evolution mechanisms of ancient masonry under uniaxial compression, this study employs numerical simulation techniques alongside laboratory experiments to characterize and predict both the apparent and internal cracking behaviors of ancient masonry, utilizing a detailed micro-model constructed from the constitutive equations governing brick blocks and mortar. The findings indicate that this comprehensive micro-model effectively replicates the crack development process. The microscopic damage evolution is delineated by distinct stages: initiation, propagation, penetration, and ultimate failure. Furthermore, the mesoscopic fracture degree serves as a quantitative measure for assessing the mesoscopic evolution of ancient masonry during damage events. An internal damage assessment model has been developed to intricately describe the crack propagation process from within to outside. Additionally, recognizing the inherent randomness and complexity associated with crack development, we introduce a fractal dimension index which significantly enhances tracking accuracy throughout all phases of crack progression. Concurrently, in conjunction with a progressive damage model, multi-faceted predictions and evaluations regarding crack development are conducted to provide an effective framework for understanding the damage processes affecting ancient masonry.

In-situ monitoring of clamp-repair-induced displacements in the submarine pipeline using a MEMS accelerometer array: A sea trial

The positioning and displacement monitoring of submarine pipelines is crucial for delivering operational feedback and early warning during its external structural repair processes, particularly in turbid sea areas reliant on diver operations. However, conventional numerical simulation and engineering geophysical techniques are unable to obtain real-time state data amidst repairs. In this study, we develop a monitoring system based on Micro-Electro-Mechanical Systems accelerometer arrays (MEMS-AA) to capture positional and displacement changes in the pipeline. By employing a positioning ring to connect the MEMS-AA with the pipeline, the spatial attitude changes in the MEMS-AA can accurately reflect the displacement of the pipeline. Moreover, a novel method is introduced to reconstruct the spatial attitude of the MEMS-AA, which solves the rotation matrix by the three-axis components of the accelerometer in the gravity field utilizing the greedy search algorithm. Through simulations, we validated the accuracy and effectiveness of the proposed method under the influence of varying ocean noises. The sea trials conducted in Hangzhou Bay demonstrate that our monitoring system can successfully capture real-time pipeline displacement associated with repair operations, providing valuable guidance for engineering operations to ensure the structural integrity of the pipeline.

Analysis of Tensile Failure Behavior of Metal Fiber Laminates Under Different Temperature Environments.

The tensile properties of fiber metal laminates were examined at temperatures ranging from 30 °C to 180 °C in this paper through the integration of numerical simulation techniques, experimental measurements, and digital image correlation techniques. The laminates were initially modeled using finite elements, and the failure behavior of porous basalt-fiber-reinforced aluminum alloy plates was numerically simulated. Consequently, metal fiber laminate stress-strain responses were varied by numerous tensile experiments conducted at varying temperatures. Simultaneously, a scanning electron microscope was used to scan a porous basalt-fiber-reinforced aluminum alloy laminate at different temperatures to determine the tensile mechanical behavior and micro-damage morphology. Lastly, the laminate's dynamic response to the tensile process was observed through digital image correlation technology. The stress distribution was determined to be concentrated around circular openings through analysis. The strain distribution graph exhibited a "band" shape as the number of perforations increased. The findings indicate that fiber metal laminates lose tensile strength as temperatures increase. The ultimate tensile strength of the laminate decreases as the number of perforations increases at the same temperature. Complex damage mechanisms, including matrix debonding, fiber withdrawal, and matrix fracture, can be captured through scanning electron microscopy at varying temperatures. The tensile behavior and damage mechanisms of laminates with hole-containing structures under thermal conditions are examined, and the results can be used to inform the design and utilization of laminate structures.

Numerical Simulation Study on Predicting the Critical Icing Conditions of Aircraft Pitot Tubes.

Aircraft pitot tubes are sophisticated instruments designed to detect airflow pressure and relay this information to onboard computers and flight instruments, enabling the calculation of airspeed through the measurement of total-static pressure differences. The formation of ice on aircraft pitot tubes can compromise the acquisition of airspeed data, misguide pilots, and potentially cause catastrophic flight control failures. This article introduces a predictive methodology for identifying critical conditions that lead to icing on aircraft pitot tubes. Utilizing numerical simulation techniques, the methodology calculates the critical conditions for pitot tube icing across cruise flight regimes and atmospheric conditions, resulting in the generation of a critical condition envelope surface. By comparing these critical conditions against actual sensor data, a predictive danger zone can be established, offering an advanced warning system to ensure flight safety.

Comparative analysis of wellbore electrical heating, low-frequency heating, and steam injection for in-situ conversion in continental shale oil reservoirs

In-situ conversion represents a potential method for developing immature continental shale oil, with efficient heating technology serving as its key component. This study employs coupled thermo-hydraulic-chemical numerical simulation techniques to comprehensively compare the feasibility and efficiency of three methods—wellbore electrical heating, low-frequency electrical heating, and steam injection—during the in-situ conversion process from the perspectives of reservoir heating efficiency, kerogen and heavy oil decomposition, and oil/gas production. The comparison reveals that steam injection, due to the introduction of significant water content, exhibits the poorest heating performance, whereas low-frequency electrical heating demonstrates the most effective results in reservoir heating. When employing electrical heating, particularly low-frequency methods, higher proportions of kerogen and heavy oil decomposition lead to increased overall oil and gas production. Steam heating offers advantages in heavy oil accumulation and production as well as wellbore protection, yet it yields higher water production as a drawback. Through an integrated discussion across five dimensions—heating capacity, wellbore protection, kerogen decomposition, heavy oil decomposition, and fluid production—we find that low-frequency electrical heating performs the best overall. The insights and comparisons discussed in this paper are expected to guide the selection and optimization of heating strategies for in-situ conversion.

A mechanical calculation model for the nonlinear mechanical behavior of the metal rubber clamp in aero engine

As an important pipeline support component, metal rubber clamp is mainly used for pipeline connection, fixation and vibration isolation. At present, the researches on hysteretic and stiffness characteristics of metal rubber clamps in aero engines are still in their infancy. This work aims to develop a nonlinear mechanical calculation model for metal rubber clamps to effectively capture the nonlinear mechanical properties, such as hysteresis characteristics and variable stiffness behavior. The equivalent stiffness model of metal rubber clamps was established by introducing tightening torque and friction between metal wires as control variables, and the mechanical behavior under repeated loads is analyzed by combining the force and deformation relations of typical hysteretic curves. By comparing the measured hysteretic curve and natural frequencies, the proposed equivalent stiffness model of a metal rubber clamp is verified. This also suggests that the proposed model can effectively simulate the dry friction damping characteristics of metal rubber. In addition, the effects of tightening torque and friction coefficient on hysteretic characteristics and stiffness are also analyzed. The aim of this study is to develop mechanical anisotropy tests integrated with equivalent numerical simulation techniques to elucidate the mechanical characteristics of the aero engine clamp. The research can provide theoretical support for the structural design of metal rubber clamps.

A non-contact quantitative risk assessment framework for translational highway landslides: Integration of InSAR, geophysical inversion, and numerical simulation

Landslides frequently disrupt highway networks in mountainous regions globally, presenting a grave threat to the safety of vehicles and pedestrians. A quantitative assessment of landslide risk within the highway network is crucial for the implementation of targeted monitoring, early warning, and engineering interventions. In this study, a non-contact quantitative risk assessment framework for translational landslides is proposed, which integrates Interferometric Synthetic Aperture Radar (InSAR), geophysical inversion, and numerical simulation techniques. The framework can reliably estimate the surface velocity, subsurface geometry, volume, and potential spatial consequences of landslides, and assess the potential damages and losses resulting from the landslide failure. Taking Lashagou L6 landslide in Linxia City, China as a case study, the results demonstrate a robust agreement between the InSAR-derived two-dimensional (2D) displacements and Global Navigation Satellite System (GNSS) observations, which are suitable for the inversion of active landslide thickness. The minimum mean error between the inverted landslide thickness and the observed borehole thickness is 0.8 m. The maximum thickness of the inverted basal sliding surface is 4.1 m, corresponding to a landslide volume of 1.25 × 104 m3. Fully considering the uncertainties within the technical framework, an estimated 1.2–1.7 vehicles are projected to be impacted, resulting in 5.3–7.7 casualties. The proposed non-contact framework demonstrates high reliability and considerable application versatility, particularly beneficial in inaccessible mountainous regions.

Shell engineering afforded dielectric polarization prevails and impedance amelioration toward electromagnetic wave absorption enhancement in nested‐network carbon architecture

3D reduced graphene oxide (rGO) aerogel has exhibited immense potential as electromagnetic (EM) wave absorbing materials (EWAMs) due to its unique structural advantages, but there still remains a challenge to balance the relationship between impedance matching and EM attenuation capability. Herein, a novel shell engineering strategy is proposed to fabricate 3D rGO-based aerogel with nested-network architecture by coating a dense and continuous heterogeneous layer composed of numerous N-doped porous carbon nanocubes (NPCNs). The formation of heterogeneous layer more or less increases the stability of aerogel structure and suppresses the re-stacking of rGO nanosheets. More importantly, NPCNs on the pore walls of rGO aerogel are amorphous, and thus they not only optimize impedance matching of rGO aerogel, but also induce powerful interfacial polarization thanks to the dielectric difference with rGO aerogel. As a result, the final rGO@NPCNs aerogel produces good EM absorption performance, especially for an effective absorption bandwidth (EAB) of 5.1 GHz with a thickness of merely 1.3 mm. The value of EAB can be further extended up to 12.1 GHz by gradient multilayer architecture design. Numerical simulation technique vividly demonstrates that this shell engineering strategy contributes to the penetration of incident EM wave into rGO@NPCNs aerogel as compared with individual rGO aerogels, and facilitates the generation of adequate heterogeneous interfaces to reinforce interfacial polarization loss. Moreover, rGO@NPCNs aerogel also displays good thermal insulation, waterproof functionality, and radar stealth properties, which fully addresses its bright prospects as an excellent candidate for high-performance EWAMs in the future.

Sports biomechanical analysis of knee joint injuries in table tennis players

Table tennis is a fast-paced, explosive sport that puts a lot of strain and stress on players’ lower limbs, particularly their knee joints. This work built a thorough mathematical model to investigate the dynamic and kinematic properties of the knee joint under various motion situations, with the goal of better understanding the biomechanical behavior of the knee joint in table tennis. A model of knee joint motion that takes into account the two degrees of freedom—flexion, extension, and rotation—is put forth based on the concepts of human biomechanics and kinematics theory. This model uses the Newton Euler equation to explain the mechanical behavior of the knee joint and integrates internal forces like muscle forces and external factors like ground reaction forces for torque balance analysis. This study offers a thorough examination of the force distribution and knee joint trajectory in table tennis using numerical simulation techniques. The findings show that the knee joint undergoes considerable compression and shear forces during intense activity, and that the joint’s stress properties vary significantly depending on the kind of movement. This finding is a valuable resource for table tennis players’ knee joint injury prevention and rehabilitation.

Shale Fracture Static Stability Evaluation Method Based on 3D Discrete Fracture Model: A Case Study on the Luzhou Area in Southern Sichuan Basin, SW China

Abstract The stress interference in deep shale may lead to shale fracturing and instability and consequently results in engineering risks such as casing deformation in horizontal wells. Therefore, in the early stages of shale gas exploration and development, it is of great significance to evaluate the stability of shale fractures in advance. The stability evaluation of shale reservoir faults can be mainly divided into two categories at present: quantitative evaluation of single faults and qualitative evaluation of wide-range faults. The quantitative evaluation of single faults primarily relies on numerical simulation techniques, while the qualitative evaluation of wide-range faults primarily employs geophysical methods. Both methods are difficult to meet the needs of shale gas exploration and development. The shale fracture stability evaluation method based on 3D discrete fracture model which is developed in this article can quantitatively evaluate the static stability of wide-range shale fractures in the early stage of exploration and development. In this article, seismic geometric attributes were calculated, and fracture seismic facies was established by means of the Bayesian probabilistic cluster analysis method. Then, 3D discrete fracture modeling under the constraint of fracture seismic facies was performed to establish a discrete fracture model. Finally, according to the Mohr–Coulomb criterion, the shear stress and effective normal stress of discrete fracture were calculated by using the formation pressure data in other exploration and development results and the regional in situ stress obtained through seismic prestack inversion. And thus, the stability evaluation of the fractures in shale reservoirs was eventually completed. In addition, this method was verified by using the casing deformation points in some actual shale-gas horizontal wells, the actual small fault points, and microseismic data. It indicates that the method has higher accuracy and is better applicable to the early shale gas exploration and development.