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Graphite–carbon fiber composite structural electrodes are regarded as a novel class of multifunctional materials in which electrochemical energy storage and mechanical load-bearing capabilities are integrated, offering broad application prospects in structural batteries and composite energy storage systems. However, under electrochemical–mechanical coupling, significant volumetric deformation and stress concentration are frequently induced during the discharge process, leading to material degradation and compromising structural integrity and service performance. In this study, a two-dimensional multilayer multiphysics simulation model was developed. Stiffness and diffusion coefficient degradation were imposed on the graphite active layer, while a phase-field damage model was employed to characterize mechanical deterioration within the carbon fiber substrate. In this manner, performance degradation of the composite materials under multiphysical coupling conditions was effectively captured. It was observed that an increased thickness ratio resulted in intensified volumetric shrinkage of the active layer, which, when constrained by the substrate, led to amplified interfacial stress and stress localization. Elevated discharge rates were found to increase lithium concentration gradients, thereby significantly raising the normal stress at the interface. Moreover, temperature increases were shown to accelerate lithium-ion diffusion, which in turn intensified non-uniform volumetric strains and enhanced the magnitude of interfacial mechanical responses.

The interface of carbon nanotube (CNTs)/alumina ceramic composites has a very important effect on their mechanical properties. In this study, an appropriate theoretical cell model was established to study the interfacial stress transmission in CNT/alumina composites. The stress transfer equation is derived as follows: The tensile stress of the CNTs and interfacial shear stress were simulated under an axial tension load, and the relationship between the stress transmission and the effective length of the CNTs was analyzed. The theoretical results were compared with the finite element method (FEM) results, and the results were found to be in good agreement. This study can provide a theoretical basis for adjusting the appropriate length of CNTs and interfacial interactions under different tension loads.

In this paper, we examine the development of the estimation models of bond strength and effective bond length for a double strap joint between carbon fiber reinforced polymer (CFRP) plate and corroded steel plate. The experimental study on the bond behavior between CFRP plate and corroded steel plate is summarized first and the analytical interfacial bond–slip model for CFRP plate externally bonded to corroded steel plate is proposed. Based on the theoretical stress analysis for the CFRP plate–corroded steel plate double-lap joint, the piecewise expressions of the interfacial shear stress and the normal peel stress of the interface between CFRP plate and corroded steel plate were established. The estimation models of the bond strength and the effective bond length for the double strap joint between the CFRP plate and the corroded steel plate were consequently developed on the basis of interfacial stress distribution equations and the stress boundary conditions. The comparison between the predicted and experimental results indicated that the proposed models could be adopted to predict the bond strength and effective bond length for the CFRP plates externally bonded to corroded steel substrates with reasonable accuracy. The proposed estimation models are expected to provide meaningful references and essential data for the reliable application of CFRP strengthening system to the performance improvement of corroded steel structures.

Asphalt concrete impervious facings, widely adopted as the impervious structures for rockfill dams and upper reservoirs in pumped storage power stations, typically have a multilayer structure with a thin sealing layer, a thick impervious layer, and a thick leveling bonding layer. The properties of the interfaces between these layers are crucial for the overall performance of the facings. This paper develops a model to investigate the complex interface damage behavior of the facing under static water pressure and gravity. The model considers two damage origins: one is the interface adhesion–decohesion damage, which is described by the cohesive zone model (CZM) combined with the Weibull-type random interface strength distribution, and the other is the bulk damage of each layer, described by Mazars’ model. Primarily, a comparison between numerical simulation and indoor direct shear tests validates the reliability of the CZM for the asphalt concrete layer interface. Then, the damage distribution of the two interfaces is simulated, and the characteristics of the interface stress are analyzed in detail. The interface shear stresses of the ogee sections, which have different curvatures, all show an interesting oscillation between the thin sealing layer and the impervious layer, and the interface damage at this interface exhibits high heterogeneity. Furthermore, tension stress exists in the local zones of the ogee section, and the damage in this section is significantly greater than in other parts of the facings.

Tungsten trioxide (WO3) exhibits complementary optical and electrical responses toward hydrogen, yet the interplay between interfacial stress, crystal phase stabilization, and gasochromic/chemiresistive performance remains insufficiently understood. In this work, WO3 films were grown on four single-crystal oxide substrates to systematically tune interfacial stress and thereby modulate the resulting crystal phase, microstructure, and exposed facets. θ–2θ diffraction revealed that WO3 adopts a monoclinic phase on YAlO3 and SrLaAlO4, whereas a high-temperature orthorhombic phase is stabilized on LaAlO3 (LAO) and SrTiO3 due to stronger interfacial constraint. Compared with the amorphous quartz reference, the single-crystal substrates significantly enhanced both gasochromic and chemiresistive responses. In particular, the orthorhombic WO3/LAO film exhibited an electrical response of 1.97 × 104 (Rair/RH2), an optical transmittance changed of 12.7%, and an electrical response time of 1 s toward 2% H2 at 80 °C, far exceeding the monoclinic and amorphous counterparts. The combined effects of stress-induced phase stabilization, film orientation, and hydrogen diffusion pathways are shown to govern the non-monotonic sensing trends among different substrates. These findings elucidate the structural origin of hydrogen sensitivity in WO3 and provide guidance for stress-engineered design of high-performance gasochromic and chemiresistive sensors.

Background Screw loosening is a frequently reported complication following pedicle screw fixation, resulting in various adverse outcomes. The primary trigger for screw loosening is biomechanical deterioration. Iatrogenic injury to the pedicle is a commonly observed scenario. This alteration can lead to an increased risk of pedicle screw loosening. Bilateral pedicle screws distribute load during the patient's daily activities and can be regarded as an integrated structure from a biomechanical perspective. Consequently, biomechanical interactions are prevalent between the two sides of the pedicle screws. This study aimed to determine whether unilateral pedicle injury influences contralateral screw loosening by deteriorating the local biomechanical environment. Methods The numerical model of the L5 vertebral body, developed in our previous studies, was employed in this investigation. Bilateral pedicle screws were inserted following the standard trajectory. Simulations of both half and complete ventral and dorsal side pedicle injuries were performed on the right‐side pedicle. Stress and strain values of the screw trajectory, along with screw displacement values on the contralateral side, were recorded to assess the potential risk of screw loosening. Results Compared to the model without pedicle injury, models with pedicle injuries exhibited higher interfacial stress and strain, as well as greater screw displacement. This effect was particularly pronounced when the pedicle on the side of torque restriction (e.g., caudal side pedicle injury under the flexion loading condition) was considered. Furthermore, unilateral iatrogenic injury to the pedicle can trigger multi‐degree‐of‐freedom coupled motion under a single‐direction torque. Conclusions Single‐side iatrogenic pedicle injury can lead to multi‐degree‐of‐freedom coupled motion of the screw‐fixed vertebral body, and biomechanical deterioration of the contralateral screw trajectory, thereby increasing the risk of contralateral pedicle screw loosening.

Strength assessment for thermal barrier coatings (TBCs) is vital in the safety design of hot-section components in engines. However, several crucial factors, including thermally grown oxide (TGO) growth and creep–plasticity interaction, have been less considered in thermo-mechanical analyses for TBCs near air holes. In this study, a unified viscoplastic constitutive model incorporating TGO growth is developed and integrated into a finite element framework. The model considers multiple factors, including TGO growth, creep–plasticity interaction, interface undulation, and temperature gradient. Additionally, an analytical solution for the non-uniform temperature field of a TBC is derived. The model is then applied to calculate interfacial stresses and accumulated strain energies in the TBC near an air hole, which promote interface debonding. The obtained results can be utilized to investigate the mechanisms of hole edge delamination in TBCs, considering the combined effects of multiple complex factors. A competition for the potential failure initiation location is revealed between the first oxide layer and the evolving TGO/bond coat interface. The developed viscoplasticity model demonstrates effective capability in modelling a range of dynamic behaviors that collectively contribute to hole edge delamination failure.

Compared with the previous model, a simplified mapping model of CRTS II slab ballastless track between pier settlement and the vertical deformation of rail was proposed based on Timoshenko’s beam theory. A cooperative finite element analysis model was established for verification purpose and the analysis of interlaminar stress. The results showed that the emergence of pier settlement causes the appearance of the void of the sliding layer between the base plate and the box girder above the piers, and the shear cogging reduces the void length to a certain extent. It was also observed that the rail is deformed cambered at the side pier (the pier with no settlement on both sides of the middle pier) and downwards at the middle pier (the pier with settlement). Moreover, the comparison between the theoretical value of the rail deformation and the finite element result demonstrated that the proposed mapping model can precisely characterize the relevant relationship. A conclusion also can be drawn that the pier settlement is attributed to the additional stress on the interface between the track slab and cement and asphalt mortar (CA mortar), and the interfacial stress is increased due to the effect of shear cogging.

Interfacial stress between layers of thermal barrier coatings near free edges is a critical factor that may cause turbine blades to fail. This paper uses simulation methods to reveal the effects of variations in geometric and material parameters on the stress of thermal barrier coatings. The stress distributions of a disk-shaped coating–substrate system undergoing thermal mismatch are calculated by an analytical method and the finite element method. The analytical solution reveals that the coefficient of thermal expansion, elasticity modulus, Poisson’s ratio, and thickness of each layer affect interfacial stress between coatings and substrate. The simulation results exhibit significant concentrations of the normal and shear stresses, which make the coating system prone to cracking and spalling from the free edge. The parametric analysis highlights that the thermal mismatch strain affects the stress magnitude. The region affected by free edges becomes larger with increasing thickness, elasticity modulus, and Poisson’s ratio of the topcoat. Finally, two integral parameters are proposed to represent the stress state near the free edge related to mode I and II fracture, respectively. The parameters, not sensitive to the grid density, are validated by experiments.

A prestressed concrete cylinder pipe (PCCP) consists of a concrete core, a steel cylinder, prestressing wires, and a mortar coating. Most PCCP failures are related to the breakage of prestressing wires. It is thus expected that the load-bearing capacity of PCCP is significantly affected by the length of the prestress loss zone and the stress distribution in the broken wire. Based on a tri-linear bond-slip model, the length of prestress loss zone and the stress transfer mechanism between a broken wire and a mortar coating are analysed in this paper. During the breaking (unloading) process of a prestressing wire, the interfacial bondline exhibits the following three stages: elastic stage, elastic-softening stage, and elastic-softening-debonding stage. The closed-form solutions for the interfacial slip, the interfacial shear stress, and the axial stress in the broken wire are derived for each stage. The solutions are verified by the finite element predictions. A parametric study is presented to investigate the effects of the size of the prestressing wires, the prestressing level, the interfacial shear strength, and the residual interfacial shear strength on the interfacial stress transfer. For an example PCCP with an inner diameter of 4 m, the length of prestress loss zone increases from 500 mm to 3300 mm as the radius of prestressing wire increases from 1 mm to 7 mm. It increases from 2700 mm to 7700 mm when the interfacial shear strength reduces from 3.94 MPa to 0.62 MPa and reduces from 13,200 mm to 7300 mm as the residual interfacial shear stress factor increases from 0.1 to 0.9.