Changes In Stress Distribution Research Articles

Effects of Hypergravity on Phase Evolution, Synthesis, Structures, and Properties of Materials: A Review

In a hypergravity environment, the complex stress conditions and the change in gravity field intensity will significantly affect the interaction force inside solid- and liquid-phase materials. In particular, the driving force for the relative motion of the phase material, the interphase contact interaction, and the stress gradient are enhanced, which creates a nonlinear effect on the movement mode of the phase material, resulting in a change in the material’s behavior. These changes include increased stress and contact interactions; accelerated phase separation; changes in stress distribution; shear force and phase interface renewal; enhanced interphase mass transfer and molecular mixing; and increased volume mass transfer and heat transfer coefficients. These phenomena have significant effects on the synthesis, structural evolution, and properties of materials in different phases. In this paper, the basic concepts of hypergravity and the general rules of the effects of hypergravity on the synthesis, microstructure evolution, and properties of materials are reviewed. Based on the development of hypergravity equipment and characterization methods, this review is expected to broaden the theoretical framework of material synthesis and mechanical property control under hypergravity. It provides theoretical reference for the development of high-performance materials under extreme conditions, as well as new insights and methods for research and application in related fields.

Corneal Stress Distribution Using the Procedure of Goldmann Applanation Tonometry, as Tested on a Human Cornea Model.

To assess the effect of corneal thinning and changes in intraocular pressure (IOP) on the distribution of corneal stress induced by Goldmann applanation tonometry (GAT). A 2D model of a human cornea was created using a computer-aided design and finite element analysis software, employing previously reported corneal biomechanical properties. The GAT procedure was simulated, and the magnitude and distribution of stress in the corneal stroma were obtained for several corneal thicknesses, stiffnesses, and IOP. A significant increase in stress was found in the outer and inner layers of the central cornea and in the inner layers of the surrounding central region. The maximal stress value was observed in the central outer layers when the stiffness was doubled, as in our theoretical baseline cornea (125.16 kPa). Minimal stress was observed in the central inner layers for a central corneal thickness of 300 µm (28.17 kPa). The thickness and stiffness of the cornea significantly influenced the magnitude of the stress, whereas the stress distribution in the cornea did not show significant changes. The change in IOP did not induce significant changes in either stress magnitude or stress distribution. The changes and distribution of corneal stress when a GAT procedure is performed support the idea that variations in corneal thickness and stiffness induce changes in corneal biomechanics that may be relevant for IOP readings. These findings are relevant for assessing IOP in corneas that have undergone surgical procedures or have diseases that alter their layers.

Incremental closure method to estimate changes in contact stress distributions for partially closed fatigue cracks in mode I loading

Incremental closure method to estimate changes in contact stress distributions for partially closed fatigue cracks in mode I loading

Surrogate-based positioning optimization of hip prostheses for minimal stress shielding

The stress shielding phenomenon causes undesirable changes in stress distribution in the bones in which implants are implanted. This phenomenon leads to a gradual decrease in bone density in the vicinity of the implant and ultimately loosening. To improve the endurance of the prosthesis and postpone the revision surgery the prosthesis should be designed and positioned in such a way that the post-implant stress distribution within the bones is as close to the natural distribution as possible.We formulate the problem of achieving a near-normal stress distribution as a constrained optimization problem in which the difference between pre- and post-implant stress distributions constitutes the loss function and five positional and dimensional parameters, including Femoral Anteversion, Neck Shaft Angle, Femoral Head Offset, Cup Version, and Cup Inclination comprise the set of design variables. Finite Elements (FE) analysis is used to obtain the stress distribution in bones before and after the implantation. To create a FE model, first a three-dimensional model of the patient's hip is created using CT images. The model is then subjected to the loads obtained from the patient's gait analysis, and the Stress Shielding Index (SSI) is calculated at critical points of the bones before and after the implantation. The difference between pre- and post-implant SSI values defines the cost function. To reduce the computational cost of numerous cost function evaluations a surrogate model (a 5 × 1 MLP neural network) is employed to predict the value of the cost function. Design Of Experiments (DOE) is used to sample the hyperspace of the design variables and generate training, test and validation data. The optimization problem is solved using Genetic Algorithms and the results are compared with with the results of the best set of initial samples.Results from the proposed approach show a significant reduction in the difference between pre- and post-implant stress distributions and a 12% reduction in the Stress Shielding Index.

Modulated Mechanical Properties of Epoxy-Based Hybrid Composites via Layer-by-Layer Assembly: An Experimental and Numerical Study.

In this study, epoxy-based composites were fabricated using a layer-by-layer assembly technique, and their mechanical properties were systematically evaluated. The inclusion of cellulose nanocrystals led to variations in the mechanical properties of the composites. These modified properties were assessed through tensile and flexural tests, with each layer cast to enhance strength. Due to the inherent characteristics of epoxy, a single specimen was fabricated through chemical bonding, even post-curing. This approach demonstrated that a three-layer structure, developed using the layer-by-layer method, exhibited improved elastic and flexural moduli compared to a single-layer composite. This improvement aligns with theoretical predictions, which suggest that stiffness increases when stiffer materials are positioned farther from the neutral axis in a layered structure. Furthermore, numerical analysis validated changes in stress distribution across each layer. Consequently, this method enables the production of composites with superior mechanical properties while minimizing the quantity of cellulose nanocrystals required.

Influence of mining depth and panel length in longwall underground coal mining on the distribution of principal stresses along the barrier pillars

Abstract The production increase in longwall underground coal mining is in line with the dimension changes of the mining panel that subsequently affect changes in stress distribution and disrupts roadway stability. This paper studies the effect of panel dimensions on stress distribution around the roadway using the finite element method to model the panel conditions numerically, drawing height and shape of the goaf from empirical data. In this study, the length of the panels made varied between 500 and 1500 meters and the depth of the panels varied between 200 and 1000 meters from the surface. Based on the modelling results, stress changes due to differences in panel size occurred at the depth of 800 and 1000 meters, the longer the panel, the greater the stress that occurs. The further from the surface, the greater the pressure on the barrier pillar, at a depth of 200 meters the main pressure is 3.4 times the vertical pressure at the end of the excavation, while at a depth of 1000 meters the pressure increases to 5 times the vertical pressure.

Effects of Implemented Residual Stresses on Mechanical Responses and Behavior of the Full-Layered Murine Aortic Medial Ring: A Parametric Finite Element Study.

It is known that elastic laminae (ELs) in the aortic wall, especially the inner layers, are structurally buckled due to residual stresses under unpressurized conditions. Herein, we aimed to develop a realistic computational model, replicating the mechanical behavior of an aortic ring from no-load to physiological conditions by considering inherent residual stresses, which has not been widely included in conventional modeling studies. We determined specific conditions to reproduce EL buckling with a "preferable" residual stress distribution under no-load conditions by combining the design of experiments and multiobjective optimization. Subsequently, we applied these conditions to two ring models with distinct wall structures comprised ELs and smooth muscle layers (SMLs), and compared their mechanical responses to assess the effect of implemented residual stresses by tracking changes in stress distribution in the aortic wall and corresponding EL waviness under no-load and pressurized conditions. We successfully reproduced EL buckling with a steady upward residual stress distribution that was considered "preferable" under no-load conditions. Furthermore, we replicated radially cut ring models that spontaneously opened in vitro, and confirmed that an SML circumferential stress distribution approached a uniform state under pressurized conditions, effectively mediating stress concentrations induced at the inner layers. We established a ready-to-use scheme to implement intrinsic residual stresses in the aortic wall. Our computational model of the aortic ring, reproducing realistic mechanical responses and behavior, represents a valuable tool that offers essential insights for hypertension prevention and potential new clinical applications.

Alterations in Adipose Tissue and Adipokines in Heterozygous APE1/Ref-1 Deficient Mice.

The role of apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) in adipose tissue remains poorly understood. This study investigates adipose tissue dysfunction in heterozygous APE1/Ref-1 deficiency (APE1/Ref-1+/-) mice, focusing on changes in adipocyte physiology, oxidative stress, adipokine regulation, and adipose tissue distribution. APE1/Ref-1 mRNA and protein levels in white adipose tissue (WAT) were measured in APE1/Ref-1+/- mice, compared to their wild-type (APE1/Ref-1+/+) controls. Oxidative stress was assessed by evaluating reactive oxygen species (ROS) levels. Histological and immunohistochemical analyses were conducted to observe adipocyte size and macrophage infiltration of WAT. Adipokine expression was measured, and micro-magnetic resonance imaging (MRI) was used to quantify abdominal fat volumes. APE1/Ref-1+/- mice exhibited significant reductions in APE1/Ref-1 mRNA and protein levels in WAT and liver tissue. These mice also showed elevated ROS levels, suggesting a regulatory role for APE1/Ref-1 in oxidative stress in WAT and liver. Histological and immunohistochemical analyses revealed hypertrophic adipocytes and macrophage infiltration in WAT, while Oil Red O staining demonstrated enhanced ectopic fat deposition in the liver of APE1/Ref-1+/- mice. These mice also displayed altered adipokine expression, with decreased adiponectin and increased leptin levels in the WAT, along with corresponding alterations in plasma levels. Despite no significant changes in overall body weight, microMRI assessments demonstrated a significant increase in visceral and subcutaneous abdominal fat volumes in APE1/Ref-1+/- mice. APE1/Ref-1 is crucial in adipokine regulation and mitigating oxidative stress. These findings suggest its involvement in adipose tissue dysfunction, highlighting its potential impact on abdominal fat distribution and its implications for obesity and oxidative stress-related conditions.

Effect of plantar fascia stiffness on plantar windlass mechanism and arch: Finite element method and dual fluoroscopic imaging system verification

This study explored the relationship between the foot arch stiffness and windlass mechanism, focusing on the contribution of the posterior transverse arch. Understanding the changing characteristics of foot stiffness is critical for providing a scientific basis for treating foot-related diseases. Based on a healthy male's computed tomography, kinematic, and dynamics data, a foot musculoskeletal finite element model with a dorsiflexion angle of 30°of metatarsophalangeal joint was established. Analyze the changes in stress distribution of the plantar fascia, metatarsophalangeal joint angle, arch height, and length during barefoot walking as the stiffness of the plantar fascia varies from 25 % to 200 %. For validation, the simulated arch parameters were compared with the dual fluorescence imaging system measurements. The width of transverse arch, height, and length of longitudinal arch measured by the dual fluorescence imaging system were 45.14 ± 1.63 mm, 29.29 ± 1.57 mm, and 155.16 ± 2.69 mm, respectively. The results of the simulation were 46.51 mm, 29.96 mm, and 156.71 mm, respectively. With the increase of plantar fascia stiffness, the effect of the windlass mechanism increased, the flexion angle of the metatarsophalangeal joint decreased, the distal stress of plantar fascia decreased gradually, while the proximal and middle stress increased, the transverse arch angle increased, but when the plantar fascia stiffness exceeds 150 %, the transverse arch angle decreases. The increase of plantar fascia stiffness will increase the effect of the windlass mechanism but decrease the flexion angle of the metatarsophalangeal joint. The stiffness of the plantar fascia influences the behavior of the plantar fascia. The plantar fascia stiffness affects the distal tension of the plantar fascia by affecting the flexion of the metatarsophalangeal joint in the plantar windlass mechanism. It affects the stiffness of the transverse arch of the foot together with the ground reaction force acting on the distal metatarsal.

How does turbulence intensity affect the fatigue life of composite airfoils based on existing CFD and experimental data?

This research investigates the effect of airflow turbulence intensity on the fatigue life of composite airfoil structures in aerospace engineering. Using advanced Computational Fluid Dynamics (CFD) simulations, this study provides a comprehensive analysis of how varying levels of turbulence intensity—ranging from mild (5%) to severe (30%)—impact the mechanical degradation and fatigue performance of carbon-fiber-reinforced polymers (CFRPs) used in airfoil designs. The research quantifies the relationship between turbulence levels and changes in stress distribution, highlighting critical points of fatigue crack initiation and subsequent propagation. The study includes detailed comparisons of CFD results to experimental data to validate the predictive models and discusses how localized stress fluctuations under high-intensity turbulence accelerate the onset of fatigue failure. We present significant findings that demonstrate a non-linear relationship between turbulence intensity and the reduction in fatigue life, suggesting optimal design modifications for enhanced durability. Furthermore, this paper explores current challenges in merging CFD data with real-world fatigue testing and proposes advanced techniques such as adaptive mesh refinement and hybrid simulation models to improve predictive accuracy and computational efficiency in future research.

Multiscale study of interfacial properties of carbon fiber reinforced polyphthalazine ether sulfone ketone resin matrix composites

In view of the limitations of traditional research tools on interfacial failure mechanisms in fiber/PPESK composites, this work proposes a multiscale research tool to carry out an in-depth study of the interfacial behavior between fibers and matrix. Based on microdroplet debonding tests, at the mesoscopic scale, the influence of residual thermal stress on the interface damage mode is explored through finite element (FEM) simulations. The evolution mechanism of composite material interfaces in spatial and temporal dimensions is examined based on changes in interfacial stress distribution, energy dissipation, and damage morphology during the debonding process, which can be summarized as follows: accompanied by elastic-plastic deformation and friction effects, the progressive process from localized to complete failure presents a dominant Type II damage mode at the interface. To further explore the interface failure mechanism at the molecular level, an interface model of CF/PPESK composite materials was established using molecular dynamics (MD) method. By monitoring the atom movement trend, the “fiber-matrix displacement synergistic effect" in the interfacial shear damage process was revealed, thereby establishing a multiscale mapping relationship of composite material interface. Based on this, the combination of FEM and MD was utilized to investigate the interface damage process of composite materials under different service conditions and to reasonably predict the initiation and expansion of microcracks. This study provides a pioneering perspective on interface damage research in composite materials with a “top-down” multiscale approach.

Stress Distribution Patterns of the Femorotibial Joint After Medial Closing-Wedge Distal Femoral Varus Osteotomy: An Evaluation Using Computed Tomography Osteoabsorptiometry

Background: Distal femoral varus osteotomy (DFVO) is an established surgical procedure for addressing valgus malalignment across various knee conditions. However, the effect of DFVO on stress distribution within the femorotibial joint has not been explored through in vivo studies. Purpose: To (1) explore the distribution pattern of subchondral bone density across the proximal tibia in nonarthritic knees without arthritis and in those of patients with valgus knees, (2) assess changes in the pattern of bone density distribution in patients with valgus knees before and after medial closing-wedge (MCW) DFVO, and (3) determine the correlation between leg alignment and changes in bone density distribution. Study Design: Cohort study; Level of evidence, 3. Methods: The authors retrospectively analyzed clinical and radiographic data from 14 patients (14 knees; mean age, 44 years; 3 men, 11 women) treated with MCW-DFVO for lateral compartment osteoarthritis (OA) due to valgus malalignment, alongside a control group of 18 patients (18 knees; mean age, 21 years; 4 men, 14 women) without OA. The distribution patterns of subchondral bone density distribution on the femorotibial articular surface of the tibia were examined both preoperatively and >1 year postoperatively using computed tomography osteoabsorptiometry. Quantitative analyses were conducted on the locations and percentages of the high-density areas (HDAs) on the articular surface. The mean time between surgery and the postoperative radiograph and computed tomography absorptiometry imaging was 13.6 months (range, 11-19 months). The mean length of clinical follow-up was 28.7 months (range, 14-62 months) after surgery. Results: The mean proportion of HDA in the lateral compartment relative to the total HDA (lateral ratio) was significantly greater in the preoperative OA group (58.8%) compared with the control group (41.1%) (P < .001). After MCW-DFVO, the mean lateral ratio in the OA group notably declined to 45.3% (P < .001). The lateral ratio exhibited a significant correlation with the hip-knee-ankle angle in both the control (r = 0.630; P = .011) and OA (r = 0.537; P = .047) groups. Moreover, the alteration in the lateral ratio after MCW-DFVO showed a significant relationship with changes in the hip-knee-ankle angle (r = 0.742; P = .002) and the mechanical lateral distal femoral angle (r = −0.752; P = .002). Within the lateral compartment, HDAs in the 3 lateral regions of the 4 lateral subregions diminished after MCW-DFVO, whereas in the medial compartment, HDAs in the 3 lateral subregions saw an increase. Conclusion: The mean lateral ratio was significantly greater in the preoperative OA group compared with the control group. MCW-DFVO resulted in a redistribution of HDA from the lateral to the medial compartment of the proximal tibial articular surface. The extent of alignment correction after MCW-DFVO was closely linked to the shifts in HDA distribution, reflecting changes in stress distribution.

The strength of an adhesive contact in the presence of interfacial defects

Adhesive contacts which possess a dominant stress concentration, such as at the contact edge in spherical junctions or at the detachment front in a peeling film, are well studied. More complex adhesive junction geometries, such as mushroom-shaped fibrils in bioinspired micropatterned dry adhesives, have exhibited a complex dependence of adhesive strength on the presence of interfacial defects within the contact. This has led to the emergence of statistical variation of the local behavior among micropatterned sub-contacts. In order to examine the interplay between geometry and interfacial defect character in control of the adhesive strength, the model system of a stiff cylindrical probe on an elastic layer is examined. Both experiments (glass on PDMS) and cohesive zone finite element simulations are performed, with analytical asymptotic limits also considered. The thickness of the elastic layer is varied to alter the interfacial stress distribution, with thinner layers having a reduced edge stress concentration at the expense of increased stress at the contact center. The size and position of manufactured interfacial defects is varied. It is observed that for the thickest substrates the edge stress concentration is dominant, with detachment propagating from this region regardless of the presence of an interfacial defect within the contact. Only very large center defects, with radius greater than half of that of the contact influence the adhesive strength. This transition is in agreement with analytical asymptotic limits. As the substrate is made thinner and the stress distribution changes, a strong decay in adhesive strength with increasing center defect radius emerges. For the thinnest substrate the flaw-insensitive upper bound is approached, suggesting that this decay is dominated by a reduction in the contact area. For penny-shaped defects at increasing radial positions, the adhesive strength for the thinnest substrates becomes non-monotonic. This confirms an intricate interplay between the geometry-controlled interfacial stress distribution and the size and position of interfacial defects in adhesive contacts, which will lead to statistical variation in strength when defects form due to surface roughness, fabrication imperfections, or contaminant particles.

Направления обеспечения качества гипсоизвестковых вяжущих при реставрации

Purpose: to consider issues related to the standard definition of the strength characteristics of an air binder and a cement binder. To show a technological solution to the problem of regulating the strength of an air binder stone by stabilizing care during setting and hardening. Methods: during the research, GOST 23789- 2018 “Gypsum binders. Test methods”. Results: a distinctive feature of restoration plaster solutions is that structure formation and strength gain occur only in an air-dry environment. As a result, the availability of approved and applied standards for the manufacture and use of restoration plaster solutions does not fully guarantee the creation of a reliable and safe environment for the life of an architectural heritage monument. It has been established that the mechanical characteristics (compressive and bending strength limits), as well as elastic parameters should be the same or lower in historical and restoration solutions in order to avoid changes in stress distribution. Practical significance: developed taking into account the comprehensive care of hardening stone, gypsum-lime binders can have a wide range of applications. They can be used as mortars for the preservation of architectural heritage and in the reconstruction of modern buildings, self-supporting partitions, fire protection elements or drywall (in places where a higher mechanical load is expected).

Experimental study on the stability of noncohesive landslide dams based on seepage effect

Landslide dams composed of unconsolidated, noncohesive soil are easily affected by seepage. As seepage develops, the dam's characteristics change dynamically, indirectly affecting its stability. However, previous studies on dam failure have mostly assumed that the dam characteristics remain constant before failure, often overlooking these changes and their effects on stability. In this study, 48 sets of flume experiments were conducted to quantify the impact of seepage under varying upstream inflow rates, dam heights, downstream slope angles, and particle size distributions. During the storage phase, the rise rate of the water level is closely linked to the seepage's diversion capacity. The diversion rate of inflow reached as high as 0.747 in this study, but decreased to 0.230 as inflow increased. Furthermore, changes in the internal stress distribution within the dam, driven by seepage, contributed to dam settlement and the sliding of the downstream slope. Notably, dam settlement exhibited both non-uniform spatial distribution and temporal stage development. The maximum settlement ratio between the point in the upstream breach and the point in the downstream breach reached as high as 2.79. Regarding the soil changes within the dam, after the seepage channel became connected, the primary soil loss involved silt particles ranging from 10 to 20 μm in size. This result reflects the increasing non-uniformity within the dam caused by seepage. Finally, Considering the changes in dam characteristics under the influence of seepage, in this study, a logistic regression model was established to assess dam stability. Overall, this study enhances the understanding of how seepage affects dam stability by examining various dam properties and presenting a model for stability assessment.

Effect of weld-line position on springback behavior in advanced high-strength steel tailor-welded blanks on hat-shaped bending application

In this study, both experiments and finite-element analysis are performed to elucidate the effect of weld-line position on the springback behavior of advanced high-strength steel tailor-welded blanks (AHSS-TWBs). AHSS-TWBs are fabricated from grade 590Y high-strength steel and 980Y advanced high-strength steel, each with a thickness of 1.2 mm. Gas tungsten arc welding is performed to obtain autogenous butt-weld joints. Three distinct weld-line position patterns are systematically analyzed to investigate the springback phenomenon via hat-shaped draw bending. Experiments on the AHSS-TWBs show that the weld-line position affects springback. The stress distribution changes with the weld-line position, thereby initiating variations in both the components of the bending moment and the corresponding springback angle. Depending on the weld-line position, different springback behaviors and bending moments are resulted on the components.

Dynamic Evolution Law of Production Stress Field in Fractured Tight Sandstone Horizontal Wells Considering Stress Sensitivity of Multiple Media

Inter-well frac-hit has become an important challenge in the development of unconventional oil and gas resources such as fractured tight sandstone. Due to the presence of hydraulic fracturing fractures, secondary induced fractures, natural fractures, and other seepage media in real formations, the acquisition of stress fields requires the coupling effect of seepage and stress. In this process, there is also stress sensitivity, which leads to unclear dynamic evolution laws of stress fields and increases the difficulty of the staged multi-cluster fracturing of horizontal wells. The use of a multi-stage stress-sensitive horizontal well production stress field prediction model is an effective means of analyzing the influence of natural fracture parameters, main fracture parameters, and multi-stage stress sensitivity coefficients on the stress field. This article considers multi-stage stress sensitivity and, based on fractured sandstone reservoir parameters, establishes a numerical model for the dynamic evolution of the production stress field in horizontal wells with matrix self-supporting fracture-supported fracture–seepage–stress coupling. The influence of various factors on the production stress field is analyzed. The results show that under constant pressure production, for low-permeability reservoirs, multi-stage stress sensitivity has a relatively low impact on reservoir stress, and the amplitude of principal stress change in the entire fracture length direction is only within the range of 0.27%, with no significant change in stress distribution; The parameters of the main fracture have a significant impact on the stress field, with a variation amplitude of within 2.85%. The ability of stress to diffuse from the fracture tip to the surrounding areas is stronger, and the stress concentration area spreads from an elliptical distribution to a semi-circular distribution. The random natural fracture parameters have a significant impact on pore pressure. As the density and angle of the fractures increase, the pore pressure changes within the range of 3.32%, and the diffusion area of pore pressure significantly increases, making it easy to communicate with the reservoir on both sides of the fractures.

Wear-resistant enhanced composite coatings on TC4: Combining halide-activated pack cementation and plasma electrolytic oxidation

Enhancing the wear resistance is crucial to broadening titanium alloy application potential. In this study, we discovered that preparing a boron-infiltrated prefabricated coating using halide-activated pack cementation (HAPC) before plasma electrolytic oxidation (PEO) can significantly improve the wear resistance of TC4. The composite coatings (HAPC/PEO) produced through this method exhibit effective boron (B) penetration, with the main phase being H3BO3. We investigated the properties of HAPC/PEO and compared the wear resistance to a single PEO coating. Our results show that the hardness and modulus of elasticity of HAPC/PEO are enhanced, while its resistance to plastic deformation is increased and the coating is not easily damaged during friction. HAPC/PEO shows a 55 % decrease in the coefficient of friction and a 47 % reduction in wear rate compared to PEO coating, indicating superior wear resistance. We analyzed the stress distribution and displacement changes during friction between the PEO coating and HAPC/PEO using ABAQUS. The influence of the main phases' structure on the two coatings' wear resistance is also discussed, and the significant role of the laminated structure of H3BO3 in enhancing the wear resistance of HAPC/PEO was discovered.

A global springback compensation method for manufacturing metallic seal ring with complex cross-section and submillimeter precision

The fabrication of complex thin-walled components with irregular cross-sectional geometries often necessitates multi-pass forming processes. The springback phenomena at the microscale level contribute significantly difficulty to the precise control of geometrical accuracy for such components. To achieve submillimeter precision control of micro features in metal seal rings, this research proposed a global springback compensation method to facilitate the attainment of the optimized surfaces of dies. Through the analysis of changes in cross-sectional shape, stress distribution and bending moment in the multiple stages, several partition points were set up to divide the cross-section into four zones. For a partitional control of the manufactured surface, the compensation magnitudes for each segment are determined by iteratively refining the compensation factors using the secant method. The iteration of compensation factors is based on the deviation of dimensions measured by finite element simulation, which greatly saves experimental costs. The experimental results indicate that the predictive dimensional alterations by the global compensation agree with the experimental ones exhibiting a maximum error of less than 3 %. Furthermore, the springback behavior during the unloading and trimming stages coupling caused a dimensional error of 14.9 % for the wave width and 8.3 % for the peak width. Following the application of coupled compensation through two iterations, a distinct decrease in the relative average errors of springback values for both part width and peak width, achieving reductions to 2.4 % and 0.6 %, respectively. Compared to the traditional single springback compensation technique, the global compensation strategy effectively mitigates the out-of-tolerance issues induced by the trimming process.

Applications of Finite Element Analysis in Endodontics: A Systematic Review and Meta-Analysis

ABSTRACT Background: Endodontics increasingly uses finite element analysis (FEA) to evaluate stress distribution, fracture resistance, and temperature changes in treated teeth. FEA’s endodontic uses, benefits, and drawbacks are examined in this systematic review and meta-analysis. Methods: A PubMed systematic search found relevant studies published up to January 2022. Original endodontic research articles utilizing FEA to quantify stress distribution, fracture resistance, or temperature changes in treated teeth were eligible. The systematic review comprised 30 publications, 15 of which were meta-analyzed. Data were extracted using a standard form, and the “Newcastle-Ottawa Scale (NOS)” for observational studies and the Cochrane risk of bias tool for randomized controlled trials assessed quality. Random-effects models calculated pooled effect sizes and 95% confidence intervals in RevMan 5.4 meta-analysis. Results: Meta-analysis shows FEA-guided endodontic treatment improves stress distribution (P &lt; 0.001) and fracture resistance (P &lt; 0.05) compared to conventional treatments. The temperature did not vary significantly (P = 0.12). Stress distribution had an effect size of 0.75 (95% CI: 0.65–0.85), fracture resistance 0.42 (95%: 0.12–0.72), and temperature variations -0.18. Conclusion: In conclusion, FEA is a valuable technique in endodontics for stress distribution study and fracture resistance testing. FEA models’ accuracy, dependability, and clinical applicability were questioned, underlining the need for more research and development to maximize their endodontics clinical use.