Stress Distribution Research Articles (Page 1)

ABSTRACT The primary objective of this study is to investigate the feasibility of fully replacing aluminium trihydrate (ATH) with glass fibre reinforced plastic (GFRP) waste dust in resin-based composite formulations while ensuring mechanical integrity, fire performance, and impact resilience. For the first time, ATH was substituted with GFRP waste, and the composites were comprehensively assessed. Viscosity increased due to the heterogeneous and complex particle size distribution of GFRP waste, as confirmed by scanning electron microscopy and particle size analysis. Despite this, the optimised formulation R2 100 retained properties very close to the control (R0), with a tensile strength of 118.56 MPa (95% retention), a cross-breaking strength of 188.04 MPa (98% retention), and an interfacial shear strength of 32 MPa (91% retention). Fire testing confirmed compliance with industrial safety benchmarks, achieving a Limiting Oxygen Index (LOI) of 29, a smoke density of 260 Ds, and a toxicity index of 5. Finite element analysis of laminate was carried in accordance with ASTM D7136 boundary conditions, revealed comparable stress distributions and dent depths for both ATH- and GFRP-based formulations. This unique substitution underscores the industrial viability of GFRP waste as a sustainable alternative filler, aligning with circular economy principles.

In deep mining engineering, high-stress roadways frequently experience severe damage, thereby compromising the stability of the surrounding rock. This study investigates the stress-energy evolution in the 31,402 material roadway in Hongqinghe Coal Mine through numerical simulation and field measurement. The study focuses on three critical stages of its whole life cycle: facing the excavation roadway, gob-side entry driving, and mining of the working face. The mechanical behavior of each stage shows significant differences. The results show that while facing the excavation roadway, the primary areas of stress concentration and energy dissipation were observed to be approximately 4m from the goaf driving heading. As the gob-side entry progresses, the stress distribution within the coal pillar transitions to a bimodal pattern, with most energy dissipation occurring on the gob side. When mining the 31,402 working face, the stress distribution across the coal pillar approaches equilibrium, and the energy dissipation pattern evolves into a bimodal form. A partition control strategy for different stages of roadway surrounding rock is proposed, and the support parameters are determined. Engineering practice demonstrates that this technology can effectively control the deformation of the surrounding rock in roadways.

Progressive deepening of coal extraction has directed attention to the objective transmission of floor stresses beneath inclined remnant pillars. Physical analogue experiments, three-dimensional finite-difference analyses (FLAC3D) and a semi-space elastic solution were jointly employed to quantify stress redistribution after panel extraction. The results reveal a bilateral arch-shaped failure zone within the roof strata and identify two characteristic floor-stress patterns that are governed by seam dip. For inclinations of 15-30°, near-floor stress exhibits quadratic decay from approximately 70MPa to 25-30MPa; for dips of 30-60° the decay is effectively linear, declining from 45 to 50MPa to 15-20MPa. The compiled data furnish a quantitative framework for panel layout and laminated-roof control in deep inclined seams.

Purpose This study aimed to analyze the biomechanical effects of two bone cement injection techniques by establishing a finite element model of osteoporotic vertebral compression fractures. Methods CT data from a healthy male volunteer were used to construct a three-dimensional finite element model of the L1–L3 vertebrae. A simulated vertebral compression fracture was created at L2, followed by virtual vertebroplasty using two cement distribution patterns: the vertical group (VG) and the inclined group (IG). Stress distribution, maximum von Mises stress in the vertebrae and intervertebral discs, and the maximum displacement of L2 were compared between the two groups. Results In the L2 vertebra, the maximum stress in the VG is reduced under all six loading conditions. VG showed reduced maximum stress in the L1 vertebra during extension, left bending, and left/right rotation. For the L3 vertebra, VG achieved the lowest maximum stress under all loading conditions. In the L1–L2 intervertebral disc, VG resulted in lower maximum stress than IG during flexion, extension, and lateral bending. while in the L2–L3 disc, VG produced the lowest maximum stress under all six conditions. Furthermore, under flexion and extension, the maximum displacement of L2 was smaller in VG compared with IG. Conclusions The vertical cement distribution pattern effectively reduces vertebral and intervertebral disc stress and provides greater stability of the fractured vertebra compared with the inclined distribution pattern.

To address the challenge of simulating shear failure in anchor bolts within FLAC3D, a shear failure criterion, Fs(i) ≥ Fsmax(i), is proposed based on the PILE structural element. Through secondary development using the FISH programming language, a modified mechanical model of the PILE element is established and integrated into the FLAC3D-FISH framework. Comparative analyses are conducted on shear tests of bolt shafts and on anchor bolt support performance under coal–rock interface slip conditions, using both the original PILE model and the modified mechanical model. The results demonstrate that the shear load–displacement curve of the modified PILE model clearly reflects shear failure characteristics, satisfying a quantitative shear failure criterion. Upon failure, both the shear force and axial force of the structural element at the failure point drop abruptly to zero, enabling effective simulation of shear failure in anchor bolts within the FLAC3D environment. Using the modified model, the distribution of principal stress differences in the surrounding rock after roadway excavation is analyzed. Based on this, the concept of a stress-bearing ring in the surrounding rock is introduced. The reinforcing effects of bolt length, spacing, and ultimate load capacity on the stress-bearing ring in weak and fractured surrounding rock are investigated. The findings reveal that: (1) shear failure initiates in bolt shafts near the coal–rock interfaces, occurring earlier near the coal–floor interface than near the coal–roof interface; (2) the stress-bearing ring in weak and fractured surrounding rock shows a discontinuous and uneven distribution. However, with support improvements—such as increasing bolt length, reducing spacing, and enhancing failure load—the surrounding rock gradually forms a continuous stress-bearing ring with more uniform thickness and stress distribution, migrating inward toward the roadway surface.

Traumatic brain injury (TBI) is a significant public health concern and its rising prevalence in road traffic accidents underscores the need for deeper understanding and tailored investigation. This study explores the feasibility of employing the female finite element head model (FeFEHM) to analyse biomechanical responses in two distinct road traffic accident scenarios, focusing on strain and stress distribution in critical brain structures. Two collision scenarios from the German In-Depth Accident Study (GIDAS) were reconstructed using validated Total Human Model for Safety (THUMS) simulations. The extracted skull kinematics were applied to the FeFEHM in ABAQUS to compute maximum principal strain, von Mises stress, and intracranial pressure across key brain regions, including the corpus callosum and pituitary gland. Simulations revealed strain concentrations in the parietal and temporal lobes, while the mid-body region was the most affected in the corpus callosum. Pituitary gland deformation was minimal under both loading conditions. Our findings align qualitatively with reported injury sites and injury risk was consistent with those observed in the real-world crashes. The findings highlight the potential of integrating sex-specific biomechanical models into crash biomechanics workflows. Future work should extend this approach across larger datasets and impact scenarios to support its implementation in regulatory and engineering contexts, since the actual sample size prevents conclusions regarding sex-specific biomechanics.

Technology for reducing track vibrations is a key approach to limiting the propagation of vibrations during train operation, yet existing damping tracks still have room for improvement. Derived from the existing sleeper-damping track (ESDT) and the sleeper-damping track with elastic side-supporting pads (SDTESSP) structures, a new sleeper-damping track with elastic composite-supporting pads (SDTECSP) was developed in this paper. To evaluate the dynamic performance of SDTECSP, finite element models (FEMs) and dynamic models were established for different damping tracks. First, under the same load and support stiffness, the stress distribution characteristics of floating-slab track (FST), ESDT, SDTESSP, and SDTECSP were compared and analyzed. And the stress concentration areas of the rail, sleeper, and track bed were identified. Then, the accuracy of the SDTECSP model was verified by the impact test of drop hammer. Finally, the dynamic performance of the track subsystem and the vehicle subsystem for four damping tracks was effectively evaluated by the combination of field test and simulation. The influence of different vehicle speeds on the track subsystem was analyzed. The results show that compared to FST, ESDT, SDTESSP, and SDTECSP exhibit superior performance in vibration damping capability, structural stability, and structural optimization design.

The bogie serves as a critical structural component in high-speed trains, subjected to dynamic loads throughout its operational lifecycle. Enhancing the fatigue life of the bogie necessitates not only ensuring welding quality but also effectively managing welding residual stresses during the manufacturing process. In this study, an efficient and simplified thermal–elastoplastic finite element method was developed based on the ABAQUS software platform, and its reliability and applicability were validated through comparison with measured data. The computational approach was employed to investigate the distribution characteristics of welding residual stresses in a weathering steel bogie beam, with particular emphasis on the influence of different welding sequences on residual stress distribution. Simulated results demonstrate that the welding sequence significantly influences the residual stress distribution and magnitude within the beam. The numerical simulation methodology developed in this study offers a powerful tool for optimizing welding sequences to regulate residual stresses during the fabrication of bogie structures.

Background and Objectives: This study aimed to evaluate the biomechanical behavior of three-unit implant-supported prostheses with different bridge configurations (mesial cantilever, distal cantilever, and pontic) and two types of retention in the atrophic posterior maxilla, through three-dimensional finite element analysis (3D FEA). The focus was on stress distribution in short implants used in pontic and mesial cantilever designs. Materials and Methods: Six 3D finite element models were developed to represent various prosthetic designs and retention mechanisms in a maxillary segment including the first premolar, second premolar, and first molar regions. Type III bone with 8 mm vertical height simulated an atrophic maxilla. Standard implants were placed in premolar areas and short implants in molar regions. A 100 N oblique load at 45° was applied to each unit to simulate masticatory function. Stress distribution was assessed using von Mises and principal stress criteria. Results: The highest implant and crown stress occurred in the cement-retained distal cantilever (100.14 MPa and 329.95 MPa, respectively), while the lowest values were found in the screw-retained pontic model (44.74 MPa and 81.23 MPa). Mesial cantilevers showed intermediate stress levels. Screw-retained designs generally generated lower stresses within implants than cement-retained ones. In cortical bone, stress ranged from 10.25 MPa in the cement-retained distal cantilever to 4.22 MPa in the screw-retained pontic, while trabecular bone showed maximum stress of 1.69 MPa and 0.82 MPa, respectively. Conclusions: Prosthetic design and retention type significantly influenced biomechanical performance. Screw-retained pontic prostheses with short implants in the molar region provided the most favorable stress distribution. When cantilevers are required, mesial extensions are biomechanically more advantageous than distal ones. Short implants can thus be safely used in the posterior maxilla when accompanied by proper prosthetic design and retention type.

As the core component of new energy vehicles, the performance of the steering axle will directly affect the overall maneuverability, stability, and safety of vehicle driving. The structural performance indexes of the steering axle of the pure electric vehicle are analyzed by the finite element method, and a reasonable improvement plan is given according to its shortcomings. Firstly, the 3D model of the steering axle is established by SolidWorks (SOLIDWORKS 2023), and the details are simplified appropriately and then imported into the ANSYS (ANSYS2020R2 software) platform for static force analysis and modal analysis. Then, the stress distribution, deformation, and the first six orders of intrinsic frequency values of the steering axle are calculated and analyzed by using four working conditions, such as regular driving, emergency braking, lateral slip, and uneven road excitation, and it is concluded that the maximum stress of the original structure under each working condition is less than the requirement of the ultimate stress value. However, from the results, the maximum stress value is concentrated in the emergency braking condition and appears in the intermediate beam corner and the steering knuckle journal, which is also the most dangerous condition. In the modal analysis, it is concluded that the intrinsic frequency of this symmetry structure is much larger than the excitation frequency, and it can produce better dynamic effects under the working conditions, and the dynamic performance is better. Based on this, combined with the results of the static analysis of the proposed new increase in the thickness of the intermediate beam to improve the structural strength of the improvement measures, for this symmetry structure, through the re-simulation of the effect of the most critical conditions (emergency braking), the maximum deformation of the steering axle has been greatly reduced. In addition, the overall stiffness of the symmetry structure has been greatly improved, while the maximum stress is still less than the value of the permissible stress range, and the modal characteristics of the structure has not been affected. The finite element analysis software can effectively evaluate the performance and improve the optimization of the steering axle, which has certain theoretical significance and engineering reference value.

Background/Aim: Immature permanent teeth with necrotic pulps present thin dentinal walls and open apices, making them highly susceptible to cervical fractures even after apexification. This study aimed to compare stress distribution patterns produced by different coronal base materials following mineral trioxide aggregate (MTA) apexification using three-dimensional finite element analysis (FEA). Materials and Methods: A CBCT-based model of a maxillary immature incisor was reconstructed and modified to simulate six restorative scenarios: control (sound tooth), MTA + conventional glass ionomer cement (GIC), MTA + resin-modified glass ionomer cement (RMGIC), MTA + bulk-fill flowable composite, MTA + conventional composite resin, and MTA + flowable composite resin. A 100 N oblique load (45°) was applied, and von Mises stress, displacement, and periodontal ligament strain were analyzed. Inter-model comparisons were performed using one-way ANOVA with Tukey post hoc tests (p < 0.05). Results: All models exhibited maximum stress concentration in the cervical third of the root. Bulk-fill flowable composite and RMGIC generated lower cervical stress and more homogeneous distribution compared with GIC or conventional composite resin. Conventional composite resin produced the highest stress concentration due to its higher stiffness. Derived biomechanical metrics confirmed statistically significant differences between groups (p < 0.05). Conclusions: The coronal base material strongly affects the biomechanical behavior of immature incisors restored after MTA apexification. Selecting low-modulus, stress-dissipating materials such as bulk-fill flowable composites or RMGICs may minimize cervical stress and potentially reduce fracture risk. These computational findings warrant validation through in vitro and clinical studies.

This study investigates the influence of different finite element material modeling approaches on the mechanical response of a femoral bone segment under three-point bending. Four material variants, ranging from homogeneous isotropic to heterogeneous isotropic models, were analyzed to assess their impact on displacement and stress distribution. Results demonstrate that material heterogeneity significantly affects displacement magnitudes, with homogeneous models underestimating deformation compared to heterogeneous ones that more realistically represent cortical and cancellous bone properties. Stress distribution patterns were primarily governed by geometry and boundary conditions, though stress concentrations near supports were identified as potential numerical artifacts. These findings underscore the importance of incorporating bone heterogeneity and anisotropy in FEM for accurate biomechanical simulations. Future research should focus on advanced anisotropic modeling, nonlinear behavior, and physiologically relevant loading conditions to enhance predictive capabilities, particularly for clinical applications such as implant design and surgical planning.

To investigate the dynamic performance and seismic response of Ming dynasty masonry pagodas in the Jiangnan region of China, the Great Wenfeng Pagoda in Taizhou, Zhejiang Province, was selected as the study object. Based on on-site inspection and maintenance records, the in situ compressive strength of masonry at each level was measured using a rebound hammer, considering that the pagoda was immovable and no destructive testing was permitted. A numerical model of the pagoda was established using the finite element software ABAQUS 2016 with a hierarchical modeling approach. The seismic response of the pagoda was computed by applying the El Centro wave, Taft wave, and artificial Ludian wave, and the seismic damage mechanism, the distribution of principal tensile stress, and seismic weak zones were analyzed. The results showed that the horizontal acceleration increased progressively along the height of the pagoda. Under minor earthquakes, the pagoda remained largely elastic, whereas under moderate and strong earthquakes, the acceleration at the top and bottom and the story drifts increased markedly, with the effects being most pronounced under the Taft wave. The damage was primarily concentrated in the first and second stories at the lower part of the pagoda and around the doorway. Tensile stress analysis indicated that the masonry blocks in the first and second stories were at risk of tensile failure under strong seismic action, whereas the lower-level stone blocks in the first story remained relatively safe due to their higher material strength. This study not only reveals the seismic weak points of Ming dynasty masonry pagodas in the Jiangnan region but also provides a scientific basis for seismic performance assessment, retrofitting design, and sustainable preservation of traditional historic buildings.

This study examines the fracture toughness of Al6061 alloy-based hybrid composites reinforced with silicon carbide particles and cenosphere microspheres. Aluminum alloy Al6061 is widely utilized in structural applications due to its balanced mechanical properties, and its hybridization with SiC and cenosphere reinforcements enhances its performance under critical loading conditions. The effect of specimen thickness on fracture toughness was examined by fabricating compact tension specimens in accordance with ASTM E399 standards, with thickness-to-width ratios ranging from 0.2 to 0.7. Controlled fatigue cracks were introduced, and both experimental testing and finite element simulations were conducted to assess the critical stress intensity factor and crack propagation behaviour across different thicknesses. Results show that the fracture toughness is constant after the B/W ratio of 0.5 and above, states as plane strain fracture toughness. The 3wt% SiC and 6wt% cenosphere in Al6061 shows the highest fracture toughness up to 15.56 MPa√m, due to the effective stress distribution and interfacial bonding. The fractography using the scanning electron microscopy reveals that particle debonding is major failure mechanism, with microcracking in 3wt% cenosphere composites and crack deflection and stress transfer at high reinforcement contents. Experimental results were well matched with the simulation model with ±10% differences, proving its validity.

The objective of this study is to assess, through numerical simulation, the effect of CFRP sheet strengthening on the structural behavior of prestressed hollow - core slabs (HCS), using the ABAQUS 6.13 software suite. Extensive research over the past decade has identified externally bonded CFRP as an effective solution for strengthening prestressed concrete elements, including HCS with non - circular voids. The numerical simulation of CFRP - strengthened hollow - core slabs is inherently complex, influenced by factors such as construction methodology, loading scenarios, and nonlinear material properties. Several modeling approaches have been proposed in the literature, each aiming to address specific aspects of these complexities. The retrofitting technique in this study involved applying CFRP sheets to the internal end regions of the slab voids, over a length of 300 mm, using one and two layers, respectively. To simulate the CFRP material, two modeling approaches were examined. The first involved skin reinforcement, which consists of applying a bonded layer to a part’s surface and incorporating defined material and structural properties. The second modeling approach involved contact interaction with cohesive behavior, aiming to capture potential debonding effects. The developed finite element models were validated by comparison with test results from an extensive experimental investigation. The Concrete Damage Plasticity (CDP) model was adopted for concrete behavior, while the Mises yield surface was used for modeling isotropic metal plasticity. For the CFRP material, the simulation process included two stages. First, orthotropic elasticity in plane stress (lamina) was defined using ABAQUS 6.13. In the second stage, Hashin’s failure criteria for unidirectional fiber composites were applied to evaluate the failure response of the CFRP sheets. Results are presented in terms of the load – deflection relationship, crack patterns, and von Mises stress distribution. In addition, a parametric investigation was carried out to analyze the influence of CFRP strengthening length and thickness on the load - bearing capacity and stiffness of the specimens.

This study presents a numerical investigation into the structural behavior of a pile-in-pile (PIP) slip joint utilizing square hollow section (SHS) members, with a comparative assessment against conventional circular hollow sections (CHSs). A comprehensive finite element model was developed and validated against published CHS experimental results to evaluate key performance indicators, including stress distribution, buckling behavior, and load-carrying capacity under pure bending, axial compression, and diagonal lateral loads. The analysis revealed that SHS joints demonstrated distinct stress concentration patterns and higher capacity under axial compression, whereas CHS joints provided superior performance under bending due to their geometric symmetry. However, SHS corners were more vulnerable under diagonal loading, exhibiting localized buckling at relatively lower loads. These structural weaknesses can be mitigated through design improvements, such as increased wall thickness or corner strengthening. The findings highlight that while SHSs introduce certain vulnerabilities compared to CHSs, they also offer advantages in axial load resistance, supporting their potential as a viable alternative for offshore wind foundation connections.

This paper presents a hybrid methodology for predicting rock mass deformation and roadway loads induced by longwall mining. The approach combines the classical Budryk–Knothe influence function model with numerical simulations in the FLAC3D finite difference environment. Instead of explicitly reproducing large-scale excavation and caving, the impact of mining is introduced through analytically derived displacement boundary conditions applied to the numerical model. This allows detailed analyses of the rock mass deformation state while significantly reducing computational effort compared with conventional geomechanical models. The methodology involves deriving displacement components from the Budryk–Knothe influence function, implementing them through Python 3.6.1 scripts in FLAC3D 7.00, and performing stepwise simulations of longwall advance. Results show that the proposed approach reduces the number of finite difference zones by nearly an order of magnitude, achieving more than a tenfold decrease in computation time. At the same time, the displacement and stress distributions obtained remain consistent with both the analytical Budryk–Knothe solution and those from the classical numerical model. The study demonstrates that this methodology provides a reliable and efficient tool for assessing stress redistribution and deformation around roadway excavations influenced by mining. Its application enhances the accuracy of deformation predictions, supports support system design, and improves safety and efficiency in underground mining operations.

AimsThe management of Paprosky IIIB acetabular bone defect is challenging in revision total hip arthroplasty. Custom-made acetabular components (CMAC) have been increasingly used in recent years. However, the iliac fixed flange of CMAC is still a mechanically weak area, where nonuniform stress distribution and micromotion may cause prosthesis failure. This study aimed to enhance the iliac fixation effect by enhancing the structure of the iliac flange or using a quadri-flange CMAC. The biomechanical performance was compared to provide a theoretical basis for clinical application.MethodsThe inhomogeneous finite element analysis (FEA) model was reconstructed according to the Paprosky IIIB acetabular defect. The biomechanical performance of enhanced triflanged and quadri-flange CMAC was evaluated according to the peak stress and the Von Mises stress distribution under routine conditions. The relative micromotion between the pelvis and prosthesis was analyzed to assess the stability of the implant.ResultsThe peak stresses of the enhanced triflanged and quadri-flange CMAC were 126.90 and 140.70 MPa under gait cycle, respectively. The stress distribution in the enhanced triflanged CMAC was more uniform. In contrast, nonuniform stress distribution and larger high-stress concentration regions were found in the quadri-flange CMAC, especially in the screw contact sites between the screw and superolateral bone of the ilium. The results of micromotion showed that there was a larger proportion of units with > 28 μm in the quadri-flange CMAC (15%), while the enhanced triflanged CMAC structure had a smaller ratio (8%).ConclusionThe enhanced triflanged CMAC has better stress, stress distribution, and micromotion than quadri-flange CMAC in this model. In cases where both prostheses are suitable for use, the enhanced triflanged CMAC is more highly recommended.Cite this article: Bone Joint Res 2025;14(11):941–952.

Abstract Shale is a heterogeneous material at the mesoscale composed of multiple mineral constituents, and its macroscopic mechanical properties are strongly influenced by the proportion, spatial distribution, and mechanical characteristics of each component. Traditional finite element methods for investigating the effective modulus of shale require high-resolution models, leading to substantial computational cost. To overcome this challenge, this study proposes two prediction models based on the Fourier neural operator (FNO) for rapid estimation of the effective modulus of mesoscale shale samples. The first model directly maps shale scanning electron microscopy (SEM) images to effective modulus values, while the second model, a physics-informed FNO (PI-FNO), predicts the internal stress field of shale samples and derives the effective modulus by incorporating physical constraints such as equilibrium equations. Both models are trained and tested on 5000 mesoscale shale volume elements, with 1000 additional real SEM samples used for validation. Results show that the direct FNO model achieves a mean prediction error of only 0.27%, while the PI-FNO model yields 0.94% error but provides additional insights into internal stress distributions. Furthermore, the inference time per sample is about 17 ms for the FNO and 24 ms for the PI-FNO, demonstrating their potential for large-scale applications. These findings indicate that the proposed methodology not only ensures accurate and efficient prediction of the effective modulus of shale but also offers a generalizable framework for evaluating the effective mechanical parameters of other heterogeneous material systems.

Uniaxial compression testing provides essential mechanical property characterization for intact rock specimens. The accuracy of specimen preparation critically affects compression test results through end-surface geometry deviations: parallelism, perpendicularity, and diameter tolerance. Specimen end-surface parallelism is affected by surface irregularities (e.g., protrusions, warping), whereas perpendicularity deviations indicate angular misalignment of the specimen with the loading axis. This study develops a 3D uniaxial compression model using RFPA3D, with rigid loading plates to simulate realistic boundary conditions. Three typical end-surface defects are modeled: protrusions (central/eccentric), grooves, and unilateral warping. Specimens with varying tilt angles are generated to evaluate perpendicularity deviations. Simulation results reveal that central end-surface protrusions induce: (1) localized stress concentration, which forms a dense core, and (2) pronounced wedging failure when protrusion height exceeds critical thresholds. Eccentric protrusions trigger characteristic shear failure modes, while unilateral warping causes localized failure through stress concentration at the deformed region. Importantly, end-surface grooves substantially alter stress distributions, generating bilateral stress concentration zones when groove width exceeds critical dimensions.