Crack Propagation Path Research Articles

Dynamic Characteristics of Gear System Under Compound Fault of Tooth Root Crack and Bearing Outer Ring

Research on single faults like tooth root cracks and bearing outer ring failures is well-established. However, existing studies often replace the actual crack propagation path with a simplified linear crack model, neglecting the variation in stress intensity factors. They do not account for the coupling effect between gear teeth when calculating gear mesh stiffness. In practice, gearbox failures are predominantly compound failures involving both gears and bearings. This paper simulates the actual crack propagation path based on Workbench, introduces a dual-tooth meshing zone method to address the tooth-to-tooth coupling effect, and establishes a dynamic model of a system with compound faults of tooth root cracks and bearing outer ring defects. The dynamic response of the system under different levels of deterioration is then investigated. The findings indicate that the crack propagation path exhibits a concave shape, with the curvature of the path increasing as the crack deteriorates. The time-varying mesh stiffness calculated by considering tooth-to-tooth coupling effects aligns more closely with the finite element results. By analyzing the evolution patterns of the impact components and sidebands during the deterioration process, the dynamic evolution trends of the coupling phenomenon between tooth root cracks and bearing outer ring faults are clarified.

Improving interlaminar fracture toughness and compression after impact strength of carbon fiber reinforced epoxy composites by interleaving electrospinning polyethersulfone nanofiber

AbstractThe effect of membrane thickness of electrospinning polyethersulfone (PES) nanofiber membranes on interlayer toughness and impact resistance of carbon fiber reinforced epoxy resin (CF/EP) composites are researched. Intercalation composites with different nanofiber membrane thicknesses, ranging from 10 to 50 μm, are tested at mode I and mode II interlaminar fracture toughness. The impact resistance of nanofiber membranes with different thicknesses is evaluated by the compression after impact (CAI) strength test. Moreover, nanofiber toughening contributions are investigated using the crack path and surface analysis. Results indicate that PES nanofibers increase the toughness of interlayer resin and change the interlaminar crack propagation path of CF/EP composites. The optimum nanofiber membrane thickness for mode I (GI = + 58%) and CAI (CAI strength = + 33%) is 50 μm, while for mode II is 30 μm (GII = + 16.4%). The storage modulus of CF/EP composites increases with the increase of nanofiber membrane thickness. The study also confirms the insertion of a nanofiber membrane slightly improves the tensile strength and interlaminar shear strength (ILSS) of the CF/EP composites.Highlights PES nanofiber membranes of different thicknesses were inserted into the CF/EP. CAI and GI improved by 33% and 58%, respectively of CF/EP composites. The relationship between interlayer fracture toughness and CAI was discussed.

Phase-field modeling of interfacial fracture in quasicrystal composites

Quasicrystals (QCs) have been used as a particle reinforcement phase in polymer or metal matrix composites to enhance the material strength, hardness and wear resistance while maintaining the lightweight advantages of the composites. In this paper, a phase-field fracture model (PFM) is proposed to predict crack propagation and interfacial debonding in QC composites. The phase-field and interface-field variables are introduced to regularize the cracks and interfaces in the composites, respectively. An equivalent critical energy release rate is introduced to characterize the influence of the interface on crack propagation. The present model is numerically implemented in Comsol Multiphysics based on the Weak Form PDE module. Several numerical examples are simulated to demonstrate the ability of the proposed model to predict crack propagation and interfacial failure of QC composites and to analyze the influence of QC reinforcement phase on fracture behaviors of QC composites. Numerical results indicate that the interface significantly influences the crack propagation paths, and the phason elastic field has a remarkable influence on the peak force and failure displacement in the fracture test of QC composites. The developed phase-field model and numeral implementation approach provide a convenient tool for predicting interfacial failure and assessing the safety of QC composites in engineering.

Crack evolution mechanism of stratified rock mass under different strength ratios and soft layer thickness: Insights from DEM modeling

Research on stratified rock masses, which are common geological formations, has primarily focused on their mechanical properties, while studies on crack evolution and microscopic damage mechanisms remain limited. This study addresses this gap by investigating the combined effects of strength ratios and soft layer thicknesses on the microcrack evolution mechanism of stratified rocks using the discrete element method (DEM). Through FISH language programming in the particle flow code (PFC), this study reveals the acoustic emission (AE) characteristics, crack initiation and propagation, damage degree, and final failure characteristics. The key findings are: (1) Higher strength ratios between the hard and soft components of stratified rocks make specimens more sensitive to increases in soft layer thickness. (2) Three types of AE events were identified: continuous active, intermittent active, and silent. (3) Cracks initiate at the interface between components and propagate along the interface into the rock matrix. The strength ratios determine the crack propagation path and the damage extent of the components. (4) The failure of stratified rocks is primarily controlled by the soft component. Crack connections typically form vertical and sub-vertical tensile failure planes in the hard component, and a shear failure surface with a “V”-shaped intersection in the soft component.

Design and control the selection of martensitic variant to simultaneously improve strength and toughness of low-carbon martensitic steel

In this paper, the microstructure evolution and mechanical properties of low carbon steels during direct quenched and rolling followed by water-cooled processes were studied. Two experimental steels, which were directly quenched at 900 °C (Q900) and 1000 °C (Q1000), were compared with steels that were water-cooled after rolling at the same temperatures (R900 and R1000). Microstructural analyses using EBSD and TEM revealed that rolling reduced the size of prior austenite grains (PAGs), resulting in an average width of 3.6 μm, which influenced grain boundary distributions and variant selection. The best combination of strength, ductility and toughness was obtained in R900 steel, including tensile (with the yield strength of 1304 MPa, the total elongation of 22.95 %), Charpy impact (with the impact energy at 20 °C is 182 J), and fracture toughness evaluations (with the J1c is 326.28 KJ/m2), this demonstrates that R900 steel exhibited significantly enhanced strength and ductility compared to Q900 steel. Moreover, EBSD analysis of crack propagation paths highlighted the role of high-angle grain boundaries (HAGBs) in enhancing fracture toughness by deflecting cracks. These findings underscore the critical role of PAGs size in tailoring microstructures to achieve superior mechanical properties in low carbon martensitic steels, offering insights for advanced material design and application in demanding structural and industrial contexts.Keyworks.low-carbon martensitic steel; strength and toughness; martensitic transformation; ductile-to-brittle transition phenomenon; selection of martensitic variants.

Insights into the frost cracking mechanisms of concrete by using the coupled thermo-hydro-mechanical-damage meshless method

Concrete dams in cold regions are prone to frost damage under low temperature conditions. However, there are currently few investigations on the frost cracking mechanisms of concrete by considering the phase change from water to ice in fissures. In the present work, an improved numerical method for modelling frost deterioration of fissured concrete is proposed and validated under the SPH framework. The frost crack propagation of prefabricated fissures is simulated by the present numerical method, and various conditions such as fissure inclinations, aggregate and pore percentages, aggregate sizes are considered. The following conclusions can be drawn: At low temperatures, “main cracks” and “secondary cracks” originate from elliptical fissure surface. “Main crack” propagation is approximately along while the “secondary crack” propagation is approximately perpendicular to the original prefabricated fissure. The inclination angles of prefabricated fissures affect the frost crack morphologies by changing the relative positions of fissure tips, aggregates and pores. The aggregates have an “attracting” effect on frost cracks, and the aggregate percentages and sizes affect the frost crack morphologies by altering the aggregate distributions. The pores are easy to be connected during frost crack propagation, and the pore existence make the frost crack propagation paths more curved. By embedding the thermo-hydro-mechanical-damage model into SPH, this work aims to reveal the frost damage mechanisms in fissured concrete, providing a theoretical basis for the durability design and assessment of concrete structures in cold regions. Meanwhile, it also offers new ideas and methods for optimizing the application of the SPH algorithm in simulating concrete frost cracking, which helps to promote the development of numerical simulation technology in this field.

High-Cycle Fatigue Fracture Behavior and Stress Prediction of Ni-Based Single-Crystal Superalloy with Film Cooling Hole Drilled Using Femtosecond Laser

A high-temperature, high-cycle fatigue test was conducted on a nickel-based single-crystal superalloy with a pore structure. Optical and scanning electron microscopy were utilized to examine the crack propagation paths and fatigue fracture surfaces at the macro and micro scales. The analysis of crack initiation and propagation related to the pore structure facilitated the development of a crack shape factor reflecting these distinct fracture behaviors. Predictions about the high-cycle fatigue stress experienced by the specimen were made, accompanied by an error analysis, providing critical insights for precise stress calculations and structural optimization in engine blade design. The results reveal that high-cycle fatigue cracks originate from corner cracks at pore edges, with the initial propagation displaying smooth crystallographic plane features. Subsequent stages show clear fatigue arc patterns in the propagation zones. The fracture surface exhibits the significant layering of oxide layers, primarily composed of NiO, with traces of CoO displaying columnar growth. AL2O3 is predominantly found at the interfaces between the matrix and oxide layers. Short and straight dislocations near the oxide layers and within the matrix suggest that dislocation multiplication and planar slip dominate the slip mechanisms in this alloy. The orientation of the fracture surface is mainly perpendicular to the load direction, with minor inclined facets in localized areas. Correlations were established between the plastic zone dimensions at the crack tips and the corresponding fatigue stresses. Without grain boundaries in single-crystal alloys, these dimensions are easily derived as parameters for fatigue stress analysis. The selected crack shape factor, “elliptical corner crack at pore edges”, captures the initiation and propagation traits relevant to porous structures. Subsequent calculations, accounting for the impact of oxide layers on stress assessments, indicated an error ratio ranging from 1.00 to 1.21 compared to nominal stress values.

Effect of Thermal Cracking on the Tensile Strength of Granite: Novel Insights into Numerical Simulation and Fractal Dimension

This study investigates the effect of thermal cracking on the tensile strength of granite through a combination of experimental testing and numerical simulations. The primary objective is to understand how thermal stress, induced by heat treatment at various temperatures (25 °C to 600 °C), influences crack initiation, propagation, and tensile strength changes. The granite specimens were subjected to Brazilian splitting tests after heat treatment, and the load–displacement curves and tensile strength variations with heat treatment temperature were analyzed. A grain-based model (GBM) was developed to simulate the complex cracking behavior, incorporating the mineral compositions and thermal expansion properties of the granite. The fractal dimension of the cracks was quantified using the box-counting method, and the relationship between fractal dimension and tensile strength was discussed. The results show that the GBM can effectively simulate the microcracking behavior and tensile fracture properties of heat-treated granite, accounting for mineral composition and thermal expansion. Thermal cracks are mainly intergranular tensile cracks, which increase in number with higher temperatures, while under mechanical loading failure is primarily due to intragranular tensile cracks. Higher heat treatment temperatures lead to denser crack networks with greater fractal complexity, reducing tensile strength and creating more tortuous crack propagation paths.

Experimental investigation on shear performance of RC T-beams strengthened with hybrid bonded CFRP strips

This study presents an experimental investigation on shear performance of strengthened reinforced concrete (RC) beams with hybrid bonded carbon fiber-reinforced polymer (CFRP) strips. Six RC T-beams were prepared including a reference beam, a beam strengthened with externally bonding (EB) method, and four beams strengthened with hybrid bonding (HB) method. Different spacings between steel plate and initial damage of beam were also considered in the test. Failure modes, cracking process, load–deflection curves, and strain development of beam components were discussed in detail. Test results showed that ultimate shear capacity and ductility of RC beams are both improved by HB method and fasteners effectively prevent the FRP debonding failure before shear failure of RC beams. Fasteners changed the propagation path of the critical diagonal cracks which extended towards the steel plate instead of hinge support. Maximum strain of CFRP strip using HB method, which is over 45% of its ultimate tensile strain, is more than twice that using EB method. Modified theoretical models were finally employed to evaluate the shear strength of RC beams increased by HB method. The comparison of theoretical and test results showed that predicted range of load increment agrees well with the test results.

A comparative study of tensile fatigue life in various flexible-oriented three-dimensional woven process structures based on finite element models

To achieve a comparative study of tensile fatigue life in various three-dimensional (3D) structures, 3D orthogonal woven composite (3DOWC), off-axis 3D orthogonal woven composite (OA-3DOWC) and multiaxial 3D woven composite (M3DWC), were designed and manufactured. Tensile and fatigue tests were performed, and microcomputed tomography (Micro-CT) was utilized to observe the mesoscale structural characteristics and the fatigue fracture morphology. Finite element models were established based on the observation. Then a modified power-law fatigue damage model was used for reduction of stiffness and strength during fatigue loading process, and a normalized life model was used to predict the fatigue life at different stress levels. Comparisons were conducted with existing models to analyze their predictive accuracy. Results showed that the tensile strength of M3DWC decreased by 54.6 % compared to 3DOWC, while its fatigue performance of M3DWC was significantly improved. Additionally, OA-3DOWC had the worst tensile strength but slightly improved fatigue performance compared to 3DOWC. And for the maximum error between the prediction and experimental results for the fatigue life is 11.16 %. For the fatigue life at the same stress level, M3DWC > OA-3DOWC > 3DOWC, due to the complex crack propagation paths in the staggered fiber arrangement.

Failure mechanisms of coarse-grained sandstone under pure mode I/II loading: insights from energy evolution and acoustic emission

ABSTRACT Tensile and shear failure are the main damage modes of rocks in geotechnical engineering. To investigate the energy evolution and failure characteristics of coarse-grained sandstone during pure mode I/II loading, loading-unloading tests were performed on cracked straight-through Brazilian discs (CSTBD) with different unloading levels (i), and its acoustic emission (AE) signals and microstructure were monitored. The results show that the AE signals of the CSTBD are negligible before the peak load (Mode I), or appear when the axial load exceeds a stress threshold and then increases significantly before the peak load (Mode II), and the Kaiser effect was observed in the second loading stage. The specimens’ input, elastic and dissipative energies varied quadratically with i. The elastic energy is always greater than the dissipative energy (Mode I), whereas the dissipative energy exceeds the elastic energy at i < 0.5 (Mode II). The crack propagation paths start from the crack tip and extend rapidly and straightly (Mode I) or slowly in the form of wing crack (Mode II) to the loading point. The microstructures of the specimens are mainly intergranular fracture (mode I) and transgranular fracture (mode II). The results provide references for studying energy evolution and failure mechanisms of rocks under mixed modes I+II/I+III loading.

New route for fabricating low-carbon ductile martensite to optimize the stretch-flangeability of dual-phase steel

Traditional cold-rolling dual-phase steel (CR sheet), limited by poor stretch-flangeability as indicated by the hole expansion rate (HER), faces challenges in manufacturing complex automobile parts. To address this, a new type of hot-rolling dual-phase steel with an 800 MPa grade (manufactured by tyipical thin slab continuous casting and rolling process, TSCCR) was designed to replace the traditional one. The TSCCR sheet, with a lower carbon content of 0.047wt.%, compared to 0.093wt.% in the CR sheets, features 40.6% martensite significantly higher than 28.2% in the CR sheet. This increased martensite content, despite being softer and more ductile due to its low hardness, compensates for the tensile strength in the TSCCR sheet. Furthermore, the TSCCR sheet exhibits a unique heterostructure characterized by uneven carbon distribution from the ferrite/austenite interface to other boundaries/interfaces, estimated by the negligible partition local equilibrium (NPLE) model of ferrite transformation. This unique heterostructure diminishes the mechanical disparity between ferrite and martensite, resulting in a higher yield strength of 568 MPa, compared to 456 MPa in the CR sheet. During uniaxial tension, the ferrite and ductile martensite in the TSCCR sheet initiate cooperative plastic deformation earlier than in the CR sheet, despite initially having fewer favorable slip systems in the TSCCR martensite. The low working hardening rate of the TSCCR sheet facilitates the forming layered structure of ferrite and martensite during necking compared to the CR sheet. Consequently, the HER of the TSCCR sheet sharply increased by 144% compared to the CR sheet. This enhancement in HER can be attributed to the crack initiation area, longer crack propagation path, and higher crack propagation resistance facilitated by the ductile martensite, culminating in superior HER.

Initial temperature conduction process and fracture response of rock impacted by ultra-low-temperature fluid: A case study of polymethyl methacrylate

Injecting ultra-low-temperature fluids, such as liquid carbon dioxide (CO2) and liquid nitrogen (LN2), into deep, low-permeability reservoirs for fracturing is an emerging waterless fracturing technology. When these fluids enter the reservoir, they rapidly exchange heat with the fracture walls, triggering intense cold shock, which influences fracture development. Although many scholars have studied the effects of nitrogen freezing and thawing on coal seams, the initial thermal exchange and cold shock process when LN2 first enters the rock mass remains unclear. This paper uses the visualizable material polymethyl methacrylate (PMMA) as the research object, conducting low-temperature impact experiments under different preset temperatures (20 °C, 40 °C, 60 °C, and 80 °C) to investigate the impact of thermal exchange during cold shock on PMMA fracturing. The results show: (1) During LN2 impact, PMMA's temperature changes in three stages: slow cooling (micro-cracks initiation), rapid cooling (formation of long fractures), and temperature recovery (crack formation completion). (2) In prolonged impacts, PMMA temperature decreases linearly, while in short-term cyclic impacts, temperature decreases exponentially with faster recovery, increasing the likelihood of micro-cracks formation. (3) Temperature differences have a dual effect on crack formation and propagation: they significantly enhance internal thermal stress, leading to rapid micro-cracks initiation and expansion, while also causing uneven temperature gradients in the crack propagation region, shifting fracture modes from tensile to complex composite failures and promoting secondary crack formation. However, a significant temperature differential may result in the development of a singular crack propagation path, hindering the formation of complex fracture networks. These findings offer theoretical insights into fracture network formation in waterless fracturing of low-permeability reservoirs.

Cracking and deformation behaviors of overhanging rock: Laboratory tests and optical monitoring

The destabilization of overhanging rock is a dangerous geological problem. In this study, a generalized model of typical overhanging cliffs from the Three Gorges Reservoir area in China with different fracture angles, fracture lengths, and free surface depths is constructed to investigate the cracking and deformation behavior of overhanging rocks. Laboratory tests and deformation field monitoring using the digital image correlation (DIC) method are performed on these specimens to reproduce the destabilization and failure process of overhanging rock under external loading. The influence of peak load is found to be the most sensitive to the fracture length, followed by the free surface depth, and to be the least sensitive to the fracture angle. The DIC-based strain fields reveal that the fracture angle and free surface depth significantly alter the crack propagation paths, whereas the influence of the fracture length is weaker. These parameters also affect the crack initiation time. The relative displacement evolution characteristics indicate that fracture angle, fracture length, and free surface depth affect the shape and size of the rotating block, the rotation center, and the rotation pivot point and degree, respectively. The grayscale characteristic evolution trends are similar for all examined overhanging rock specimens. The evolution of the grayscale indices based on DIC can be divided into high-frequency oscillation, smooth decline (or smooth downward concavity), and stable development stages. Furthermore, the multistage properties of the indices can be used to identify the fracture state of overhanging rocks, providing a theoretical basis for graded early warning of rockfall disasters.

Investigation of the influence of non-uniform strain zone on the crack propagation of PMMA material based on 2D-DIC

Hole defects can lead to non-uniform strain distribution under the impact load, thereby influencing crack propagation behavior. In this paper, 2D-DIC technology was employed to examine the effects of holes of varying sizes and loading rates on crack dynamics in PMMA materials, aiming to elucidate detailed knowledge into the characteristics of crack propagation under complex strain fields. Through DIC analyses, the dynamic evolution of strain fields around the crack tip and hole periphery could be precisely captured, enabling tracking of crack propagation behavior including crack propagation velocity, crack propagation path, and crack deflection angle. It is concluded that the non-uniform strain zones generated by holes exert both inhibitory and attracting effects on crack growth. The influence of non-uniform strain zones on crack propagation increases with the elevation of loading rate and hole size. However, as the loading rate increases, the kinetic energy of the crack itself also increases, necessitating sufficiently large hole sizes to effectively influence crack propagation. Overall, this study provides a detailed experimental explanation of the effects of holes on cracks, which will aid engineers in maximizing the positive impact of holes on material performance and their application in the design of microstructure materials.

High temperature fatigue behavior of coated and uncoated nickel-based single crystal superalloy DD6: Microstructures evolution, damage mechanisms and lifetime prediction

Thermal barrier coatings (TBCs) are widely used to further extend the lifetime of turbine blades by protecting the blades from high temperature corrosion and oxidation. However, the mechanical behavior of turbine blades is obviously affected by the TBCs. In this study, microstructures evolution, damage mechanisms and life prediction of coated and uncoated nickel-based single crystal (NBSX) superalloy DD6 under isothermal fatigue load were investigated at 980 °C. The effects of TBCs on fatigue failure behavior and lifetime of DD6 were addressed. The results showed that the fatigue lifetime reduced with the increase of load. The effect of TBCs on the fatigue lifetime was related to the stress amplitude, as the effect was beneficial at high stress but almost negligible at low stress. Fracture morphologies showed that the cracks more likely initiated and propagated from basal defects for both coated and uncoated DD6, and the microstructure evolution also showed stress amplitude dependence. The crack density of uncoated DD6 increased first and then decreased with the increase of stress amplitude. However, the TBCs reduced the number of cracks that penetrate into the DD6 substrate, and the stress amplitude exerted a significant effect on crack propagation paths. In addition, the rafting behaviors of the DD6 substrate of coated and uncoated samples was compared, and results showed that TBCs could reduce the rafting degree of DD6. Finally, the fatigue lifetime of coated samples was predicted based on the modified Basquin model, and the prediction results fitted well with the experimental results.

Experimental and numerical studies on the propagation paths of gear root cracks

Gear bending fatigue failure has a significant impact on the operational performance of advanced machinery, such as electric vehicles and wind turbines, potentially leading to failures and catastrophic consequences for transmission systems. Several methods are currently used to predict gear crack propagation; however, a comprehensive comparison of their accuracy and efficiency in predicting crack paths is lacking. In this study, the propagation path of root cracks in commonly used automotive gears was investigated using finite element (FE) analysis and experimental testing. Three mixed crack path prediction criteria were integrated to predict the gear root crack propagation using the commercial software ABAQUS by user-defined Python script. The impacts of gear crack parameters, including the gear initial crack length, on gear root crack propagation behaviour were analysed. The simulations were verified by the gear bending fatigue test using a single tooth bending test device. The results indicate that the simulation outcomes align with the experimental tests, demonstrating that all three criteria are effective in predicting gear root crack propagation behaviours.

A data-driven prediction for concrete crack propagation path based on deep learning method

Accurate and efficient prediction of concrete crack propagation path facilitates timely maintenance. To avoid errors arising from assumptions in physical models and parameter measurements, a data-driven prediction method for concrete crack propagation path is proposed. The spatio-temporal prediction approach is presented by unifying the conditional Generative Adversarial Network and Long Short-Term Memory Network (UcGLS-Net). The UcGLS-Net has the advantage of enabling temporal (by Long Short-Term Memory Network, LSTM) and spatial information (by the conditional Generative Adversarial Network, cGAN) in the concrete crack propagation process to be treated simultaneously and distinctly thus improving prediction accuracy. Notably, results demonstrate that UcGLS-Net still works in crack propagation path prediction even with unknown aggregate distribution. Moreover, the effects of historical input quantity and prediction intervals on prediction accuracy of the UcGLS-Net are studied and the network framework is optimized. Due to high efficiency, this study provides a new adaptable and real-time prediction method for concrete crack propagation path, offering support for the design, damage prediction, assessment, and maintenance of concrete structures.

An advanced fast multipole dual boundary element method for analyzing multiple cracks propagation

A new fast multipole dual boundary element method (FMDBEM) is developed to analyze multiple crack propagations. To evaluate accurately the stress fields around the crack tip, a variable-order asymptotic element (VAE) is first proposed to express the singular behavior. This VAE is also suitable for the V-notches with different opening angles, requiring only minor adjustments of stress exponents. Then the VAE is introduced into the FMDBEM framework, where several singularity problems of integrals are solved. Finally, the FMDBEM with VAEs, combined with an adaptive scheme, is used to determine the crack propagation paths. Numerical examples show that the present method is accurate and easy to implement, making it an appealing tool for analyzing large complex structures that include randomly distributed cracks and notches.

Investigating the impact toughness properties and influential factors of titanium alloy joints

Double-sided symmetric MIG welding can significantly enhance welding efficiency for thick titanium alloys and holds promising engineering applications. However, the use of high currents and deposition rates in this process not only boosts welding efficiency but also impacts joint performance, particularly its impact toughness. In this study, the Charpy impact performance of double-sided double-arc MIG welded joints in each region was studied via oscillometric impact tests, and the main factors affecting the impact of joints were revealed. Scanning electron microscope was used to observe the fractures, and the microstructure characteristics and grain orientation of the impact crack propagation path were observed and analysed via metallurgical microscopy and EBSD. In addition, the microstructure of each region of the joint was observed via metallographic microscopy and transmission electron microscopy, which revealed the microstructure characteristics of different regions of the joint and clarified the effects of microstructure and grain orientation in different regions of the welded joint on the impact performance of each region of the double-sided, double-arc MIG welded joint. The results show that the crack initiation energy across different regions of joints typically ranges between 18 and 20 J, with minimal variations. Crack propagation plays a pivotal role in determining impact toughness, which is influenced both by microstructural features and orientation. This provides guidance for subsequent adjustments and improvements to the impact performance of the joint.