Local Stress Concentration Research Articles

Hydrogen-Induced Ductility Loss of GH625 Superalloy Under Thermal Hydrogen Charging

The effect of thermal hydrogen charging on the tensile properties of GH625 superalloy was investigated. The results reveal that hydrogen significantly reduces the ductility of the GH625, leading to a shift from microvoid coalescence (MVC)-induced ductile fracture to intergranular (IG) brittle fracture. Random grain boundaries (GBs) are the primary sites for crack initiation. Hydrogen reduces the critical fracture stress of the δ phase at grain boundaries, causing cracking of the δ phase. Under the influence of hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced decohesion (HEDE), the δ/γ interface debonds, forming microcracks that propagate along the fractured δ phase, leading to intergranular cracking. Annealing twin boundaries (TBs) serve as secondary sites for crack initiation. Hydrogen-induced local stress concentration promotes twin boundary sliding and hydrogen segregation reduces twin boundary cohesion strength, which is the primary cause of TB crack formation.

Compressive behavior of improved star-shaped honeycomb multi-cell structures: Experiments and simulations

Honeycomb materials are considered ultra-light materials with excellent mechanical properties due to their unique cellular structure. Their high strength, low density, and excellent energy-absorbing abilities have led to their widespread application in various fields. The star cellular structure is a classical cellular structure proposed by many scholars, exhibiting a negative Poisson’s ratio effect. However, due to the susceptibility of the star-shaped units and the vertical supporting rods at the joints to local instability and stress concentration under compressive loads, the buckling of the supporting rods can induce lateral displacement, thereby compromising the overall structural integrity and performance. To address this phenomenon, this study eliminates the supporting rods from the star-shaped structure, specimens of the Improved Star-Shaped Honeycomb (ISSH) were fabricated using Selective Laser Sintering (SLS) technology, followed by uniaxial quasi-static compression experiments and finite element simulations, followed by uniaxial quasi-static compression experiments and finite element simulations. The study investigates whether changes in geometric parameters can enhance the tunability of the structure for different application scenarios. The results reveal that the rod-free star-shaped structure exhibits higher stiffness and strength, and variations in wall thickness and angular parameters significantly influence the structural performance and deformation failure mechanisms. This study enriches the research on star-shaped honeycomb structures.

Using the appropriate modulus of elasticity of periodontal ligament matters in stress analysis of human first premolar tooth and periodontium structures

Although the modulus of elasticity of the human periodontal ligament (EPDL) values used in dentistry widely ranged from 0.01 to 175 MPa, the exact EPDL value has not been determined. This study aimed to verify whether and how EPDL values affect the stress distribution over the tooth and periodontium structures, and to determine the appropriate EPDL range. A 3D multi-component human first premolar model was created based on a cone-beam computed tomography dataset. Finite element analysis was performed to analyze stress distribution and deformation of the structures under an average Asian occlusal force with different EPDL values (0.0689–68.9 MPa). The low EPDL caused excessive PDL deformation, contributing to a non-uniform stress distribution and localized stress concentration, especially in the cementum, enamel, and dentin. With the low EPDL value, the stress magnitude was overestimated by 1,195%, potentially leading to erroneous conclusions regarding material failure and tooth movement. The EPDL value significantly affects the stress magnitude and distribution over the tooth and periodontium. The appropriate EPDL range of 0.964 ± 0.276 MPa is suggested for human first premolars to ensure accurate and reliable FEA simulations and help avoid misinterpretation of the stress results, which could compromise orthodontic planning and restoration design.

Visualizing fiber end geometry effects on stress distribution in composites using mechanophores.

Localized stress concentrations at fiber ends in short fiber-reinforced polymer composites (SFRCs) significantly affect their mechanical properties. Our research targets these stress concentrations by embedding nitro-spiropyran (SPN) mechanophores into the polymer matrix. SPN mechanophores change color under mechanical stress, allowing us to visualize and quantify stress distributions at the fiber ends. We utilize glass fibers as the reinforcing material and employ confocal fluorescence microscopy to detect color changes in the SPN mechanophores, providing real-time insights into the stress distribution. By combining this mechanophore-based stress sensing with finite element analysis (FEA), we evaluate localized stresses that develop during a single fiber pull-out test near different fiber end geometries-flat, cone, round, and sharp. This method precisely quantifies stress distributions for each fiber end geometry. The mechanophore activation intensity varies with fiber end geometry and pull-out displacement. Our results indicate that round fiber ends exhibit more gradual stress transfer into the matrix, promoting effective stress distribution. Also, different fiber end geometries lead to distinct failure mechanisms. These findings demonstrate that fiber end geometry plays a crucial role in stress distribution management, critical for optimizing composite design and enhancing the reliability of SFRCs in practical applications. By integrating mechanophores for real-time stress visualization, we can accurately map quantified stress distributions that arise during loading and identify failure mechanisms in polymer composites, offering a comprehensive approach to enhancing their durability and performance.

Study on the Stress Accumulation Characteristics of a Rotating Metal Hydride Reactor

The reactor is the core device used in guaranteeing the alloy's stable high-level reversible hydrogen storage. This work investigates a rotating reactor as new structure to alleviate stress accumulation using inertial force and counterforce, compared to typical statics reactors. The rotating reactor’s strain and response exhibited notable differences in the whole five stages at the 8th absorption/desorption cycle. In the cycle of vertical reactor, plastic deformation began by the 4th cycle, followed by a rapid linear increase in strain values leading swiftly to failure in the 19th cycle. When inverted, plastic deformation began by the 17th cycle and fracture occurred after 29th cycles, and for rotating reactor at 1.39 rpm, the curve of stress accumulation changed gently, sudden fracture occurred after 36th cycles. Particle size distribution of rotating reactor was skewed toward the large size as a herald of more strong anti-pulverization. Meanwhile, the expansion area was located in lower part, and the bulging notably shifted upwards compared to vertical reactor. This was attributed to the fact that the dynamic inertial force and counterforce effect improved the uniformity of alloy filling and prevented the formation of high-density areas at the representative bottom obviously alleviating local stress concentration phenomena.

Mechanical response characteristics and cushioning of sealed airbags under different length–diameter ratios

In the event of a mine fire, rapidly constructing blast-resistant seals is one of the most effective measures to contain the disaster. This study conducted blast cushioning experiments on sealed airbags and numerical simulations by analysis system/Livermore software-dynamics (ANSYS/LS-DYNA), an explicit simulation software, to analyze the mechanical response characteristics and cushioning effectiveness of sealed airbags under different length-to-diameter ratios. The research results indicate that airbags with different length-to-diameter ratios all exhibit cushioning effects, and the airbag can recover its deformation after pressure release. As airbag length increases, vertical deformation along the pipeline appears, forming a radial compression failure mode. Stress concentrations are mostly located at the edges of the airbag, while arched structures can reduce the concentrated stress. Excessively long or short airbags significantly increase localized stress concentrations. The total energy absorbed by the airbag during cushioning shows a linear relationship with its length, and an energy absorption model for single-chamber airbags with varying length-to-diameter ratios was established. Under full-scale simulation conditions, the optimal length-to-diameter ratio range is 0.75:1. The reflected energy of shockwave encountering airbag is independent of airbag length and remains a fixed value when inflation pressure remains constant. These findings provide theoretical support for the design and application of explosion-resistant airbag.

Enhancing metallurgical and mechanical properties of friction stir lap welding of aluminum alloys by microstructure reconstruction

Friction stir processing (FSP) is successfully employed to alleviate their hook defects of friction stir lap welding (FSLW) of aluminum alloys. The mechanical properties and microstructural characteristics are compared and analyzed between the FSLW&FSP joint fabricated by FSLW and FSP and the FSLW joint. The microstructural analysis shows that the hook defect zone at the advancing side of the FSLW joint is changed into the overlap zone (OZ) of the FSLW&FSP joint due to microstructure reconstruction caused by performing the FSP. The heterogeneous and coarse grains at the hook defect zone of the FSLW joint are transformed into refined and equiaxed grains at the OZ of the FSLW&FSP joint as a result of dynamic recrystallization. The results of tensile tests show that tensile strength and fracture toughness of the FSLW&FSP joint are 85.7% and 220% higher compared to those of the FSLW joint, respectively. The cross sections of broken lap joints reveal that their failure location is shifted from the hook defect at AS of the FSLW joint to the thermo-mechanically affected zone of the FSP zone of FSLW&FSP joint. The combined action of effective sheet thickness increasement, microstructure uniformity, grain refinement, and local stress concentration reduction act as the strengthening mechanism of the lap joint of aluminum alloys.

Anti-Seismic Performance Research of Complicated Nodes Involved in Ultra-Limited Steel Structures Subjected to Rare Occurrence Earthquakes

This study focuses on the seismic performance of complicated nodes in the ultra-limited steel structure under rare occurrence earthquakes. The Xi’an Urban Exhibition Center (Chang’an Cloud) is chosen as the engineering background, and the ANSYS (18.0) analysis software is employed. Based on the overall importance and the extent of post-damage impacts, the critical nodes are selected for structural design. The research aims to develop simplified and reliable structural forms that can withstand the most adverse conditions at both the overall nodes and local component levels. Stress distribution under the most unfavorable scenarios is calculated to achieve the seismic design objectives of the overall structure. The research results indicate that localized stress concentration areas can reach or exceed the yield strength of the steel, which enters the plastic phase. The Von Mises stresses in the remaining nodes are lower than the yield strength of the steel. The overall performance is excellent without significant plastic deformation. Thus, the design requirements for non-yielding performance under rare seismic events are met. The conclusions can provide reliable references for the critical structural techniques and seismic design of complicated nodes.

Study on the mechanical properties of gradient grains based on molecular dynamics

ABSTRACT This study used molecular dynamics simulations to investigate the plastic deformation mechanisms of gradient nano-grained (GNG) copper. The results show that GNG structures have higher yield stress compared to uniform nanocrystalline structures, with the g = 0.30 model exhibiting a significant increase in flow stress. GNG structures can effectively distribute atomic stress, transferring it from coarse grains to fine grains and reducing local stress concentration. Coarse grains undergo severe shear deformation, while grain boundary (GB) activities transition from migration in coarse grains to rotation in fine grains. GNG structures enhance the ability to coordinate deformation through GB motion, suppress dislocation formation, and facilitate interactions between dislocations and GBs, thereby improving strength and toughness.

Study on the parameters of steel plate reinforcement rib-deck crack considering local stress disturbances

Local reinforcement will change the local stiffness distribution of the component, causing perturbation effects on the local stress of the fatigue detail. Only considering the reinforcement effect may lead to excessive strengthening and induce new fatigue-prone points. For the fatigue detail of the rib-deck weld, steel plate reinforcement test and numerical simulations were conducted. The stress changes of the deck weld toe and weld root before and after reinforcement were analyzed. The influence of parameters such as steel plate length, thickness, and width on the reinforcement effect of the weld toe crack and local stress disturbance was discussed, and reasonable parameters were recommended. The results show that after the cracking of the weld toe, the stress concentration locations at the weld toe and weld root of the deck shift from the center of the specimen to the crack tip. Steel plate reinforcement can effectively restrain the crack propagation, but can lead to an increase in the stress at the deck weld root within the reinforced area. A good reinforcement effect can be achieved while the steel plate covers the crack, and further increasing the steel plate length has limited improvement on the reinforcement effect but reduces the adverse effect of steel plate reinforcement on the stress of the deck weld root. Increasing the steel plate width will increase the adverse effect of steel plate reinforcement on the deck weld root stress, and it is recommended to use steel plates with a length greater than 120 mm and a length-to-width ratio greater than 4 for reinforcement. Increasing the width of the steel plate has a relatively small effect on the reinforcement effect and the stress at the deck weld root, and steel plates with the same thickness as the deck are recommended.

Multi-scale topology optimisation design and mechanical property analysis of porous interbody fusion cage

Background Titanium (Ti) and polyether ether ketone (PEEK) interbody fusion cages cause postoperative stress shielding problems. The porous cage design is one of the solutions advanced to mitigate this problem. Objective Exploring the mitigation of stress shielding with a porous interbody fusion cage after surgery for idiopathic scoliosis. Methods The porous interbody fusion cage was constructed based on the multiscale topology optimisation method, and the postoperative lumbar spine models implanted with it. The porous Ti and PEEK fusion cages were evaluated under physiological conditions to investigate their mechanical properties. Results The volume of the porous fusion cage was reduced by 52.57%, and the stress was increased by 242.76% and 252.46% compared with the Ti and PEEK fusion cage; the modulus of elasticity of the porous fusion cage was reduced by 76.85%, and the strain was increased by 131.40%∼686.51% compared with the Ti cage; the porous fusion cage increased L3 cortical bone stress by 13.36% and 13.52% and cancellous bone by 82.93% and 76.72%, respectively, compared with the original interbody fusion cages. Conclusion The porous interbody fusion cage has a much more lightweight design which facilitates growth of bone tissue. However, a frame structure should be constructed to minimize issues with stress peaks and localised stress concentrations. It also has a significantly lower stiffness which helps alleviate vertebral stress shielding, further fostering bone growth. The porous fusion cage thus meets the clinical requirements for better fusion outcomes.

Research on the material removal mechanism of vibration-assisted nano-scratch on single-crystal GaN by molecular dynamics.

Single-crystal gallium nitride (GaN) is a semiconductor material known for its hardness and brittleness. This research aims to reveal the differences in the micro-mechanisms of material removal during traditional grinding and ultrasonic vibration-assisted grinding and to provide guidance for the high-efficiency, high-quality planarization processing of single-crystal GaN. To achieve this purpose, molecular dynamics (MD) simulation methods were used to establish a model (30nm × 40nm × 15nm) of single-crystal GaN being scratched by a single abrasive grain with and without ultrasonic vibration assistance. The differences in the surface morphology and subsurface damage formation mechanisms of single-crystal GaN under conditions with and without ultrasonic assistance were compared. The results indicate that, compared to traditional grinding, the periodic ultrasonic vibrations reduce the normal force and result in a more uniform distribution of stress and temperature, thereby mitigating local stress concentration and thermal accumulation effects. Ultrasonic vibration alters the motion of the abrasive grain, expanding the material removal range from 7.384 to 10.315nm, decreasing the number of residual atoms in the machining area, and lowering the chip pileup height at the leading edge of the abrasive grain from 2.063 to 1.528nm. Additionally, the micro-shear deformation induced by ultrasonic vibrations helps to suppress brittle fracturing caused by excessive local stress, thus reducing the thickness of the damaged subsurface. At a scratch depth of 2nm, the total length of dislocation lines in the ultrasonic-assisted scratch is reduced from 185.256 to 33.315 nm compared to traditional scratching. These findings offer new insights into the microscopic mechanisms of material removal in high-efficiency, high-quality grinding processes of single-crystal GaN. This study adopts LAMMPS software for MD simulations to investigate the physical behavior of GaN during the grinding process. The simulation results are then visualized and analyzed using OVITO software to elucidate microstructural changes in the material. During the simulation, the temperature of the Newtonian layer is calculated based on the statistical analysis of atomic velocities under the NVE ensemble. The grinding force applied to the GaN workpiece is determined by differentiating the atomic potential energy. Von Mises stress analysis is adopted to ascertain the stress distribution during the scratching process. Finally, the changes in the crystal structure during scratching are identified and classified using analysis of identified defect structures.

The ultrastructure of the starfish skeleton is correlated with mechanical stress.

Echinoderms and vertebrates both possess mesodermal endoskeletons. In vertebrates, the response to mechanical loads and the capacity to remodel the ultrastructure of the skeletal system are fundamental attributes of their endoskeleton. To determine whether these characteristics are also inherent in Echinoderms, we conducted a comprehensive biomechanical and morphological study on the endoskeleton of Asterias rubens, a representative model organism for Echinoderm skeletons. Our analysis involved high-resolution X-ray CT scans of entire individual ossicles, covering the full stereom distribution along with the attached muscles. Leveraging this data, we conducted finite element analysis to explore the correlation between mechanical loads acting on an ossicle and its corresponding stereom structure. To understand the effects of localized stress concentration, we examined stereom regions subjected to high mechanical stress and compared them to areas with lower mechanical stress. Our results show that the stereom microstructure, both in terms of thickness and orientation, corresponds closely to the mechanical loading experienced by the ossicles. Additionally, by comparing the stereom structures of ossicles in various developmental stages, we assessed the general remodeling capacity of these ossicles. Our findings suggest that the ability to adapt to mechanical loads is a common feature of mesoderm endoskeletons within the Deuterostomia taxonomic group. However, the material remodelling may be a specific trait unique to vertebrate endoskeletons. STATEMENT OF SIGNIFICANCE: This study shows a correlation between the ultrastructure and the mechanical stress in the starfish endoskeleton, suggesting that this fundamental structure-function relationship may be an ancestral feature of not only vertebrate endoskeletons. However, unlike vertebrate skeletons, not all starfish ossicles remodel in response to changing stress, indicating a potential divergence in skeletal adaptation mechanisms. Our methodological approach combines morphometrics and finite element modeling and thus provides a powerful tool to investigate biomechanics in complex skeletal structures.

Ultrasonic-assisted MoS2/GO/TiO2 ceramic coatings: Enhancing anti-friction performance through dual-interface optimization

Ceramic coatings containing two-dimensional materials (2D materials) provide effective protection for light alloys during wear, significantly improving their anti-friction performance. MoS2 has proven highly effective in enhancing the anti-friction performance of ceramic coatings, particularly when synthesized via plasma electrolytic oxidation (PEO). However, dislocation pinning due to the incoherent interfaces in MoS2/TiO2 coatings tends to cause localized stress concentrations and brittle fracture, requiring effectively improve nanomechanical properties by optimizing interface design. To address these issues, this study used ultrasonic-assisted PEO to disperse graphene oxide (GO), which provided more possibility for in-situ synthesis MoS2, ultimately resulting in MoS2 with modified interlayer spacing. The change in interlayer spacing induced dislocation evolution at incoherent interface, leading to dual interface formation. At MoS2 (0.534 nm)/TiO2 interface: dislocation dipoles evolve to create considerable distortion, facilitating releasing shear stresses and inhibiting crack propagations. This process is followed by dislocation annihilation, keeping to stable interfacial bonding. Additionally, the others form strong dislocation pinning to obstruct dislocation slip and enhancing deformation resistance at MoS2 (0.227 nm)/TiO2 interface. The combined effects of dual interfacial enhancements resulted in a 90.0 % reduction in friction coefficients of the MoS2/GO/TiO2 coating compared to the traditional ceramic coating. This facile technique provides a new strategy to fabricate self-lubricating ceramic coatings on light alloys, while the introduction of ultrasound during PEO offers valuable guidance for applying ultrasound in the synthesis of 2D materials.

Soft interface instability and gas flow channeling in low-permeability deformable media

Understanding gas percolation through a clay layer or a shale formation is of great importance for the development of a geologic repository for nuclear waste disposal, a subsurface system for gas storage, and an engineering approach for hydrocarbon extraction from unconventional reservoirs. Gas injection experiments have revealed complex dynamic behaviours of gas percolation through water saturated compacted bentonite, characterized by a high breakthrough pressure, rapid breakthrough, a pressure/stress decay after the breakthrough, a relatively high migration rate, high-frequency periodic/nonperiodic variations in flow rate, stepwise rate reductions during relaxation, and low gas saturation over the whole process, all indicating channelling nature of the processes. Using linear stability analyses, we show that this channelling can autonomously emerge from the instability of the deformable interface between the injected gas and the compacted bentonite matrix driven by local stress concentration, pore dilation, and hydrologic gradient. Channel patterns formed would possess a fractal geometry. We further show that, once a percolating channel is established, the gas injected would percolate through the channel in a chain of gas bubbles, also due to the interface instability, resulting in periodic/chaotic variations in gas flow rate. Our work provides a unified explanation for key features observed for gas percolation in low-permeability deformable media. The work also suggests a possibility of designing an engineered barrier system for a nuclear waste repository that can have controllable gas release while limit water transport.

Development of Intimate Contact Technology for High Performance All-Solid-State Batteries

The widespread adoption of electric vehicles (EVs) as alternatives to fossil fuels to facilitate a greener and more sustainable future is the most remarkable technological development of recent years. Nevertheless, the exponential increase in energy demand has given rise to significant concerns regarding the safety of batteries, which necessitate urgent consideration. While conventional lithium-ion batteries (LIBs) employ flammable liquid electrolytes, they have demonstrated susceptibility to thermal runaway incidents, which present significant safety hazards and necessitate a fundamental transformation in energy storage technologies. All-solid-state batteries (ASSBs) have emerged as a promising alternative that is able to revolutionize the energy storage industry.One of the primary obstacles that greatly hampers the performance of ASSBs is the issue of point contact between the solid electrolytes and the active materials. This problem stems from poor interfacial adhesion and restricted intimate contact between the two components, impeding effective charge transfer and ion diffusion. The presence of non-conductive interfaces, voids, or delamination zones hinders the efficient diffusion of lithium ions, resulting in increased interfacial resistance and restricted usage of active materials within the electrodes. Furthermore, the issue of solid contact contributes to the localized stress concentration and mechanical strain that occurs during charge-discharge cycles. In this presentation, the concepts of intimate contact in both the anode and cathode will be discussed.

Vibration responses and stability assessment of anchored extremely fractured rock mass based on modal analysis

This study is devoted to revealing the vibration responses of anchored fractured rock structure subjected to external excitation disturbances. By utilizing a self-constructed vibration testing platform, a series of vibration tests were conducted regarding various anchoring parameters (bolt spacing D, pre-tightening torque Pt and types of bottom support) and lateral forces Fl. Modal analysis was employed to propose modal parameters including natural frequency ωr and damping ratio ξr, extracted from the vibration signals, as sensitive indicators for assessing structural stability. The test results reveal that a smaller D and higher Pt can effectively enhance the reinforcement effect provided by bolts, as indicated by an increase in ωr and a decrease in ξr in self-stabilized state of the anchored structure. As Fl increases, the restraining effect supported by constrained frame intensifies, the increasing ωr and decreasing ξr can be observed during lateral loading. When the anchored structure is subjected to a large Fl, the weak support areas between adjacent steel belts are susceptible to concentrate as zones of rock collapse, resulting in the formation of circular cavities and a corresponding sharp reduction in Fl, alongside a pronounced decrease in ωr and a significant increase in ξr. Compared to the steel belts, the steel mesh acting as bottom support structure has more advantages in providing effective restraint to achieve self-stability of the anchored structure, as the steel mesh is able to distribute the internal stress more uniformly and reduce localized stress concentrations between rock blocks. As the mining face advances, the stress concentration and redistribution caused by mining activities lead to an increase in fragmentation degree of the roadway roof and a decrease in ωr. The findings of this study provide a scientific basis for understanding the relationship between vibration signals and the stability of anchored fractured surrounding rocks in roadway.

Assessment of inter- and intra-granular fracture behaviors of polycrystalline LiNixCoyMn1-x-yO2 particles during a charging process

LiNixCoyMn1-x-yO2 (NCM) particles have been used as cathode materials for lithium-ion batteries because of their augmented energy density and elevated operational voltage. However, polycrystalline NCM (PC-NCM) particles exhibit intergranular, intragranular, or hybrid inter/intragranular fractures during electrochemical cycling. In this study, a chemical–mechanical coupling model, an embedded cohesive zone model damage unit, is developed to simulate the fracture evolution of randomly aggregated PC-NCM particles. A damage index is proposed to characterize crack evolution by including the comprehensive influence of crack number, length, and area. The influence of variations in fracture toughness, C-rates, and primary particle size on inter/intragranular fracture evolution is discussed in detail. The coexistent intergranular and intragranular fracture phenomena are successfully simulated and agree well with existing experimental observations. The simulation results indicate that local stress concentration leads to inter- and intra-granular fractures. Increasing the intragranular fracture toughness effectively prevents intragranular fractures but exacerbates intergranular fractures. Higher C-rates worsen intergranular fractures and increase the PC-NCM particle damage value. The effects of the primary particle size on particle damage vary with C-rate and fracture toughness ratio. This study enhances the understanding of the fracture mechanism of PC-NCM particles and offers valuable insights into their design.

Effect of multi‐angle lamination on mechanical properties and damages behavior of carbon fiber reinforced resin matrix composites

AbstractCarbon fiber reinforced resin matrix composites, when subjected to multi‐angle delamination during vacuum hot pressing, suffered from defects such as uneven fiber distribution, resin‐rich zones, and voids. These defects caused varied damage and failure behaviors in the composites, seriously affecting their mechanical properties. In this paper, the defect distribution, tensile and flexural properties, and damage behaviors of multi‐angle lay‐up specimens prepared in an autoclave were studied. The results indicated that irregularly shaped voids in laminates with a 0° angle difference primarily led to local stress concentration. Elliptical and elongated voids in laminates with a 90° angle difference were mainly susceptible to delamination. The [0/90]8 layer exhibited the best overall mechanical properties. The proportion of 0° laminates had a direct impact on the mechanical properties, with 0° contact laminates on the bending‐compression side capable of withstanding higher bending loads. The [+45/−45]8 plyer demonstrated pseudo‐delayed behavior, enabling the laminate to show better toughness under load. Variations in damage due to the proportions and positions of the laminates influenced the mechanical properties and damages behavior of multi‐angle laminates.Highlights Angular differences were observed to affect void and resin distribution. The best overall mechanical properties were attributed to [0/90]8 laminates. Pseudo‐delay behavior was exhibited by [+45/−45]8 laminates. Proportion of 0° layers impacted mechanical properties. Greater bending loads were withstood by the 0° contact layer.

In-situ investigation on tensile deformation behavior of hybrid hot-rolled wire arc additive manufactured Al-Mg alloys

Hybrid hot rolling and wire arc additive manufacturing (HR-WAAM) are becoming an effective way for enhancing both tensile strength and plasticity in Al-Mg alloys. This work systematically studies the microstructural evolution and strengthening mechanisms of HRAM Al-Mg alloys during the stretching process. The results show that interlayer hot rolling can effectively refine grains, reduce defects, and promote uniform precipitation of second phases. Within a lower strain range, uniformly distributed fine grains help prevent the formation of high geometrically necessary dislocation (GND) density in localized areas, thereby reducing local stress concentration. With a higher strain range, this microstructure can promote coordinated grain transformation towards softer orientations, reduce local microstructure work hardening, and allow GND to develop within a broader range of plastic deformation, thereby exhibiting excellent strain coordination ability. These factors collectively contribute to the improved strength and ductility of the material. Compared with traditional WAAM samples, the yield strength, tensile strength, and elongation of HRAM samples have increased by 18 MPa, 92 MPa, and 11 %, respectively. Consequently, this study provides new insights and a theoretical foundation for advancing additive manufacturing technology in the production of high-performance Al-Mg alloys.