Search Results (4,634)

Metal additive manufacturing (MAM) enables the fabrication of geometrically complex and high-performance components but is accompanied by steep thermal gradients, repeated thermal cycling, phase transformation, residual stress, and deformation. These effects can reduce dimensional accuracy, manufacturing stability, fatigue resistance, and service reliability. This review systematically examines residual-stress and deformation behavior in MAM from the perspectives of formation mechanisms, influencing factors, measurement and prediction methods, mitigation strategies, and service-related consequences. The temperature gradient, mechanical constraint, and phase transition mechanisms are discussed as quantitatively coupled rather than independent processes. Comparative attention is given to process-specific differences, alloy-dependent thermophysical and metallurgical behavior, multi-track and multi-material interactions, and complex geometries. Destructive and non-destructive measurement techniques are compared in terms of penetration depth, spatial resolution, uncertainty, and cross-validation. Thermo-mechanical finite element, inherent strain, analytical, reduced-order, machine-learning, physics-informed, and digital-twin approaches are evaluated according to accuracy, efficiency, transferability, and applicability. Mitigation strategies are further compared considering residual-stress reduction, deformation control, manufacturing cost, and mechanical-property retention. Finally, challenges associated with uncertainty quantification, service environments, post-machining stress redistribution, and closed-loop control are identified. This review provides an integrated framework for selecting measurement, prediction, and mitigation approaches for reliable and high-precision MAM. Full article

In the construction process of a super-long-span short-distance continuous variable cross-section tunnel, multiple geometric mutations along the alignment induce significant discontinuity and asymmetry in the mechanical response of the surrounding rock-support system, which differs significantly from that of conventional single-variable-section tunnels. This aggravates local asymmetric stress concentration and sudden deformation surges, posing severe construction risks. To reveal the influence of different excavation methods on the mechanical response of the surrounding rock-support system during the construction of this type of tunnel, the Tangshan Road Interchange and Connection Line Project was added based on the Qingdao Qingyin Expressway. The large-span continuous variable cross-section sections of A, B, and C in the north line of the Tangshan Road Tunnel were selected as the research objects, and a three-dimensional finite element numerical model was established and rigorously validated against field monitoring data from three representative cross-sections. Three typical construction methods—the Distributed Bench Excavation Method (DBM), Double Sidewall Drift Method (DSM), and Distributed Double Sidewall Drift Method (DDSM)—were systematically compared and studied. The results indicate that the section transition zones (A → B and B → C) are the most sensitive key control areas. Compared with DBM, DDSM significantly reduced the vault initial support stress in Section A by 38.1% (from 6.51 to 4.03 MPa), the left and right spandrel stresses by 17.9% and 26.9%, respectively, and peak bolt axial forces by over 20%. Although DSM achieves maximum lateral convergence reduction (reducing haunch convergence by 32.8% in Section C), DDSM delivers the optimal comprehensive control by effectively restricting vault settlement and balancing support stress distribution. The field monitoring trend was highly consistent with the numerical simulation results, which confirms the accuracy of the established model. The research results can provide a reference for the selection of construction methods and deformation control of large-span continuous variable cross-section tunnels. Full article

The mechanical compatibility between dental restorative materials and the natural tooth structure is a relevant factor for long-term clinical performance. Although zirconia (yttria-stabilized tetragonal zirconia polycrystal, Y-TZP) and lithium disilicate are widely used for full-coverage crowns, their biomechanical interaction with the underlying dentin and pulp under functional loading remains insufficiently characterized. This study reports a comparative finite element analysis (FEA) of a mandibular first molar under vertical (200 N, axial) and oblique (200 N, 30°) loading, evaluating three configurations: an intact healthy tooth, a zirconia Y-TZP full-coverage crown, and a lithium disilicate full-coverage crown. The three-dimensional geometry was obtained from a cone-beam computed tomography (CBCT) study of a caries-free mandibular first molar, previously described and verified by the present group, and was analyzed in ANSYS Workbench (Static Structural). Von Mises equivalent stress, maximum principal stress and total deformation were obtained for enamel or restoration, dentin, and pulp in each configuration. Zirconia produced the highest stress concentrations in the coronal restoration (88.4 MPa vertical; 174.5 MPa oblique), exceeding the healthy enamel baseline by 57.6% and 89.7%, respectively. Both restorative materials reduced dentin stress relative to the healthy tooth, consistent with the stress-shielding effect driven by elastic-modulus mismatch. Under oblique loading, the maximum principal stress in healthy enamel reached 61.7 MPa, approaching or exceeding the upper bound of the reported tensile strength range (~10–40 MPa) and identifying oblique loading as the more demanding of the two conditions analyzed. Within the limitations of the present finite element model, lithium disilicate demonstrated a more favorable stress distribution, with dentin stress values closer to the intact-tooth baseline. The model does not include a luting cement layer, a periodontal ligament, the dentin–enamel junction, anisotropic tissue behavior or cyclic loading, and no experimental validation was performed; the results are therefore presented as a controlled numerical comparison between three configurations under the specific conditions simulated, and not as direct clinical selection criteria. Full article

Accidental web openings caused by impact, corrosion, or conflict-related damage can substantially reduce the strength, stiffness, and stability of steel bridge girders. Although numerous studies have examined beams containing intentionally designed web openings, limited experimental research has systematically compared practical rehabilitation methods for accidental openings in slender-web plate girders. This study experimentally and numerically evaluates several rehabilitation configurations incorporating welded patch plates and transverse stiffeners. Ten slender-web steel girder specimens, each 1800 mm long, 800 mm deep, and 300 mm wide, were tested under monotonic concentrated loading at mid-span. Nonlinear finite element models were also developed to qualitatively examine the principal deformation and instability trends. Relative to the control specimen, the untreated web opening reduced the ultimate load by approximately 43% and exhibited approximately 10% greater deflection at its respective ultimate load. One-sided and two-sided welded patch plates increased the ultimate load of the damaged specimen by approximately 22% and 26%, respectively. Transverse stiffeners increased the ultimate load by approximately 73% while exhibiting substantially lower ultimate-load deflections. The combined use of patch plates and transverse stiffeners provided the greatest improvement, increasing the ultimate load by approximately 101–123% relative to the untreated damaged specimen and substantially reducing lateral instability. The findings demonstrate that effective rehabilitation of slender-web girders requires not only restoration of the interrupted load path but also restraint of web instability. Full article

The benefits of additive manufacturing (AM, i.e., 3D printing) have made it one of the most widely used and favored production techniques across a variety of industries. In the current study, the influence of geometry and thermal aging on the mechanical strength of AMed parts has been investigated. In this context, specimens based on fused deposition modeling were printed using polylactic acid material. The specimens with three distinct geometries were created and analyzed since the geometry of AMed parts affects their mechanical performance. In this study, tensile tests were conducted under static loading circumstances, specifically on dumbbell-shaped, smooth, and V-notched test coupons. Furthermore, we conducted accelerated thermal aging between $-5 °$C and 35 °C, which is below the glass temperature of the material under investigation, to assess the impact of the thermal environment. In addition, a series of finite element models were developed to study the stress distribution and deformation in the examined components. According to the results, for unaged specimens, smooth samples demonstrated the highest fracture load at 1980.5 N, while dumbbell-shaped samples recorded the lowest at 1173.9 N. Moreover, the V-notched specimens sustained higher fracture loads compared to dumbbell-shaped samples across both aged and unaged conditions. This study’s findings demonstrate that in designing 3D-printed parts, consideration must be given to their geometric appearance and environmental operating circumstances. Full article

Distortion-induced fatigue is an important failure mechanism in steel plate girder bridges. Existing studies have advanced the understanding of local stress responses and damage identification of distortion-sensitive details; however, the mechanism by which traffic lane distribution affects distortion-induced fatigue characteristics and governs fatigue damage accumulation remains insufficiently understood. To address this issue, a global–local finite element model was established using ABAQUS 2016 to investigate deformation transfer behavior and fatigue stress responses in a steel plate girder bridge. Longitudinal and transverse load position analyses were conducted to quantify the spatial characteristics of fatigue responses. Furthermore, a lane-distribution-based fatigue damage assessment framework was developed and verified. The results demonstrated that distortion-induced fatigue response is governed by deformation incompatibility, with web gap welds identified as the critical fatigue details under different structural configurations. The transverse displacement at the stiffener end showed a strong correlation with fatigue stress (Spearman coefficients > 0.8). The transverse influence range extended across almost the entire region between the two main girders, indicating that adjacent-lane loads contribute to fatigue damage accumulation. Compared with the single-lane critical load method, the proposed framework better represents fatigue damage evolution under actual lane distributions and captures asymmetric damage between the two girders, with the maximum difference reaching 46.7%. This study provides new insights into distortion-induced fatigue evolution from the perspective of traffic lane characteristics and offers a refined approach for fatigue assessment of existing steel plate girder bridges. Full article

This study develops a finite element analysis (FEA) framework to quantify hydrostatic consolidation of ultra-high-molecular-weight polyethylene (UHMWPE) fibril arrays containing interstitial voids. Hexagonal and stochastic representative volume elements (RVEs) were constructed from experimentally measured fibril diameters and embedded in a nearly incompressible Mooney–Rivlin medium to transfer hydrostatic pressure to irregular fibril surfaces. Molecular dynamics (MD)-derived fibril properties at 300 K and 400 K were used to evaluate the effects of temperature, elastic–plastic deformation, and stochastic microstructure on void collapse and effective fiber properties. The 300 K elastic model required pressures approaching 1.3 GPa to reach approximately 1–2% void content, whereas the combined effects of elevated temperature, elastic–plastic fibril behavior, and stochastic fibril packing reduced the corresponding pressure to approximately 160 MPa. The stochastic RVE exhibited a higher initial void content, earlier plastic dissipation, lower initial effective stiffness, and nonuniform fibril–fibril contact evolution compared to the idealized hexagonal RVE. As void content decreased, both models converged toward the dense fibril response. The framework establishes a processing–microstructure–property relationship linking consolidation pressure to the evolving void morphology, fibril shape and contact development, and the resulting effective plane-strain bulk modulus and the transverse compressive stress–strain response, including the Young’s modulus and Poisson’s ratio, of UHMWPE fibers. Full article

Classical continuum descriptions based on homogenized parameters, such as modulus and relative density, become inadequate when performance is governed by deliberately engineered multiscale architecture rather than by composition, as in hierarchical and fractal-inspired mechanical metamaterials. In these materials, geometry couples deformation across length scales in ways that single-scale models cannot capture. This review synthesizes theoretical, numerical, and experimental literature published mainly over the last two decades, with emphasis on the last five years. It draws preferentially on peer-reviewed journal articles and highly cited studies; strictly periodic single-scale metamaterials and general electromagnetic–metamaterial literature are cited only where needed to establish historical context and are not otherwise within the scope of this review. The specific contribution of this review is threefold: (i) a mechanics-oriented classification of hierarchical and fractal-inspired architectures according to the deformation mechanism they activate (bending-, stretching-, membrane-, or buckling-dominated), rather than by geometric appearance alone; (ii) an explicit structure-mechanism-property-function framework linking multiscale geometry to strength, failure evolution, and energy absorption, tested against automotive crashworthiness as an application case study; and (iii) a critical account of when fractal–mathematical descriptors (scale invariance, similarity ratio, iteration depth, and fractal dimension) are mechanically meaningful, since many finite hierarchical lattices are fractal-inspired rather than fractal in the strict mathematical sense. The synthesis shows that relative density alone is an insufficient performance descriptor: outcomes depend on whether deformation is bending-, stretching-, membrane-, or buckling-dominated, and hierarchy or fractal-inspired recursion improves performance only when each structural level is assigned a distinct mechanical role rather than repeating geometry without function. The crashworthiness case study confirms that no single architecture is universally optimal once force efficiency, intrusion control, and manufacturability are considered alongside energy absorption. Future progress requires integrated structure-mechanism-property-function frameworks that combine theoretical modeling, high-resolution simulation, data-driven design, and experimental validation, with complexity justified only when it is mechanically purposeful, validated, and manufacturable at scale. Full article

This study presents a parametric optimization model for the friction disc of a combined friction face milling cutter operating under intensive contact friction, high clamping forces, and cyclic thermomechanical loading. The computational framework integrates ANSYS Workbench, the Static Structural module, Design of Experiments (DOE), Kriging surrogate modeling, and Multi-Objective Genetic Algorithm (MOGA) optimization. The friction disc geometry is defined by two design variables: the radial depth of the relief groove, a (3–6 mm), and its axial width, b (3–8 mm). Structural performance is evaluated using the von Mises equivalent stress and axial displacement of the cutting zone. Heat-treated 65G spring steel, with a yield strength of 640 MPa, is selected as the material. Using a safety factor of four, the allowable stress is limited to 160 MPa, while the permissible axial displacement is 0.05 mm to satisfy axial runout requirements for face milling cutters. Finite element analysis and response surface modeling show that parameter a predominantly affects axial deformation, whereas the combined influence of a and b governs the acceptable stress region. Multi-Objective Genetic Algorithm (MOGA) optimization identifies design solutions satisfying both strength and stiffness constraints. The proposed approach enables the determination of the minimum admissible values of the geometric parameters a and b while satisfying the prescribed strength, stiffness, and axial displacement constraints. Full article

Modeling choice is key to modal analysis of rib-reinforced vibration test fixtures; however, systematic criteria for selecting shell or solid finite element (FE) models remain limited. This study proposes a decision framework that translates comparisons between shell and solid models into selection criteria. Five headlamp vibration test fixtures were modeled using shell and solid elements under identical material properties, boundary conditions, bonded contacts, and mounted point mass conditions. Natural frequency differences ranged from 1.81% to 11.21% for the first three modes, averaging 6.52%. The shell models reproduced the overall lower mode deformation trends of the solid models, particularly global bending and torsional modes. The dominant effective mass direction was consistent in most individual mode comparisons. Shell models required fewer nodes and elements, with analysis times of only 3.99% to 11.97% of those for solid models. Shell models are suitable for preliminary and iterative modal assessment, whereas solid models are recommended when the margin for resonance avoidance is small, dominant effective mass directions differ, or the representation of local three-dimensional stiffness is important. These results indicate that the proposed framework provides practical criteria for selecting shell or solid FE models for individual modes according to the analysis objective and design stage. Full article

Developing Cu-based composites with excellent electrical and mechanical properties under multiphysics-coupled service conditions remains challenging. Novel Cu-Nb-Gr composites were fabricated by high-energy ball milling and High-pressure Multi-field Assisted Rapid Sintering. Experiments combined with computational fluid dynamics (CFD) and finite element method (FEM) simulations were used to investigate how Gr regulates material performance. The incorporation of 3 vol.% Gr promoted the formation of a semi-continuous Gr-rich structure coupled with an Nb-rich load-bearing structure. Under arc erosion, the semi-continuous Gr-rich structure provided efficient heat-conduction pathways, reducing the peak temperature and metal-vapor recoil force, while the Nb-rich load-bearing structure suppressed liquid–metal spattering and stabilized the molten pool. Simultaneously, Gr dynamically spread to form a continuous solid-lubricating film during sliding friction, significantly reducing the coefficient of friction and interfacial shear stress. Furthermore, under compressive loading, the semi-continuous Gr-rich structure coupled with the Nb-rich load-bearing structure alleviated interfacial elastic–modulus mismatch and extreme stress concentration, limiting macroscopic plastic deformation of the matrix. Consequently, Cu-Nb-3Gr achieved a favorable balance of arc-erosion resistance, wear resistance, and compressive performance, providing a new strategy for improving conventional Cu-based composites. Full article

A Nomex aramid paper honeycomb sandwich structure is the core material of the main load-bearing structures in aviation. Macroscopic full-scale refined modeling faces the problems of large mesh quantity and high calculation cost. Homogenization equivalence is the core path to achieve its efficient simulation design. Most of the existing mature equivalent models are based on the ideal assumption that the honeycomb always remains macroscopically straight, without considering the equivalent performance changes caused by the morphological distortion of micro-cells under bending conditions. Therefore, it is difficult to support a high-precision simulation of large-curvature special-shaped honeycomb sandwich structures. This paper takes the over-stretched rectangular lattice aramid honeycomb as the research object. The mechanical parameters of the matrix are calibrated through experiments, and the reliability of the fine shell finite element model is verified (the maximum error of the end-face strain characteristics between simulation and the DIC test is less than 10%). A customized finite element sample matrix for compression bending is designed, and the angle distribution laws of honeycomb cells under different thicknesses and different bending curvatures are extracted. It is found that the cell angle shows a linear change trend along the wall-thickness direction, which is only strongly correlated with the initial geometric parameters and the bending radius. Finally, a semi-empirical model that can quickly predict the morphology of bent honeycomb cells is obtained through fitting. Verified by the glass compression-molding visualization experiment, the maximum relative error of the predicted cell angle is only 5.05%. This research establishes a rapid characterization method for the deformation of honeycomb cells under bending deformation, providing theoretical support for the microscopic homogenization equivalent modeling of curved honeycomb sandwich structures. Full article

Footwear geometry plays an important role in determining mechanical performance, plantar load distribution, comfort, and foot stability during gait. Understanding how constructive design parameters influence foot biomechanics is essential for developing footwear that improves comfort while reducing excessive mechanical loading. Although various finite element studies have investigated insole and outsole design, midsole materials, and plantar pressure redistribution, comparatively little attention has been paid to the influence of upper construction parameters, particularly vamp opening configuration, on the biomechanical behaviour of feet and footwear. This study investigates how the opening amplitude of the vamp affects the biomechanical response of three constructive variants—medium (M1), wide (M2), and narrow (M3) vamp openings—developed on a common shoe last derived from anthropometric data. Finite element analysis was conducted using ANSYS 17.2, with 3D models built in Delcam Crispin ShoeMaker Pro 2015 R2 for the three loading scenarios. Total deformation and von Mises stress were extracted as primary output parameters for both the foot and footwear. The results indicate that wider vamp openings increase structural flexibility, with M2 recording the highest total deformation across multiple scenarios, whereas narrower openings generate elevated stress concentrations, particularly in loading scenario 2. The medium vamp opening (M1) demonstrated the most favourable stress distribution overall, with a maximum stress of 1.838 Megapascals (MPa). Validation against experimental plantar pressure data confirmed that loading scenario 3 follows the same plantar pressure distribution trend as in the biomechanical study. The results confirm finite element analysis as an effective computational tool for footwear design evaluation and indicate that vamp amplitude should be considered alongside material selection and geometry as a key variable influencing comfort, fit, and structural performance. Full article

This study investigates the structural behavior of steel I-beams containing corrosion-induced section loss and web openings, along with the effectiveness of fiber-reinforced polymer (FRP) strengthening as a retrofit strategy. Although previous studies have investigated the effects of corrosion, web openings, and FRP strengthening in steel beams, limited attention has been given to comparing the structural response of slender and deep steel beams under these deterioration scenarios and assessing strengthening strategies according to their distinct failure mechanisms. The analysis considers two structural response regimes: slender beams governed predominantly by flexural behavior and deep beams where shear deformation plays a significant role. Three-dimensional (3D) nonlinear solid finite element (FE) models are developed to evaluate the influence of corrosion location, web opening position, and FRP-strengthening schemes on load-carrying capacity and failure behavior. The results indicate that corrosion-induced flange thinning significantly reduces flexural capacity in slender beams, while web degradation has a comparatively smaller effect. FRP strengthening of the tension flange is found to be the most effective strategy for restoring flexural performance in slender beam configurations. In contrast, deep beams exhibit higher sensitivity to shear-related damage, where web openings located in shear transfer regions lead to substantial reductions in load capacity. Strengthening of the web region using FRP significantly improves shear resistance and overall structural performance. Overall, the study highlights distinct differences in damage sensitivity and strengthening effectiveness between slender and deep beam responses under corrosion and web opening effects, providing practical guidance for condition assessment and retrofit design of deteriorated steel I-beams. Full article

Liquefaction is one of the most destructive geotechnical hazards affecting foundations and earth structures during earthquakes. Although geosynthetic-encased stone columns (GESCs) have demonstrated promising performance in mitigating liquefaction, their behavior has primarily been investigated at the single-column level, while the seismic response of finite GESC groups remains insufficiently understood. This study evaluates the seismic performance of stone column (SC) and GESC groups arranged in square patterns using a three-dimensional coupled hydro-mechanical finite-element model developed in OpenSeesSP. A comprehensive parametric study was conducted to investigate the effects of column-group configuration (1 × 1, 3 × 3, 5 × 5, and 7 × 7), geosynthetic encasement thickness, stone column permeability, geosynthetic permeability, and column spacing under the 1940 El Centro earthquake excitation. The results show that GESC groups substantially improve liquefaction mitigation by accelerating pore-water pressure dissipation and reducing earthquake-induced ground deformation. Compared with untreated ground, GESC groups arranged in 3 × 3, 5 × 5, and 7 × 7 configurations reduce lateral ground displacement by up to 70%. Furthermore, increasing the group size from a single encased column (1 × 1) to a 7 × 7 GESC group decreases lateral deformation at the model by approximately 40%, highlighting the importance of column-group configuration in controlling seismic ground response. Overall, the proposed numerical framework provides practical guidance for optimizing GESC design and improving the seismic performance of liquefaction-prone ground. Full article