Stress Analysis Research Articles

Machine learning based analysis of entropy production and wall shear stress in blood flow through stenosed artery

The building up of cholesterol and various substances on the inner boundary of arterial walls forms a plaque (stenosis), which results in the narrowing of walls of arteries, and this exerts additional stress on the walls. Shear stress at the wall of arteries may cause the formation of plaque, plaque growth, and expansive arterial remodeling, and it may also result in an increased risk of plaque rupture. The purpose of this research work is to use machine learning approaches to analyze the wall shear stress and entropy generation through irreversible processes of blood flow in a porous stenosed artery within the context of magnetohydrodynamic consideration. As a way of illustrating blood’s non-Newtonian behavior, the Casson fluid model is used. A blood flow model in the context of mild stenosis has been developed, and it has subsequently been computationally addressed using an explicit finite difference method. The velocity, temperature, entropy generation, Bejan number, and wall shear stress are visualized for different values of pertinent variables. The result reflects the increased velocity in the stenosed region. A hybrid machine learning method using artificial neural network and particle swarm optimization is implemented to optimize the entropy generation and wall shear stress. The network is trained using Stochastic gradient–descent training procedure as well as Levenberg–Marquardt training procedure, and the outcomes of both training procedures are compared. Using this machine learning process, the minimum entropy production has been found for specific values of the Hartmann number, dimensionless temperature difference, and pulsatile component of pressure gradient. This machine learning-based optimization approach enhances the ability to forecast quantitative changes in affecting parameters, which will contribute to minimized damage to the arterial wall, improved blood flow efficiency and the delivery of necessary components to tissues.

Overexpression of BnaA10.WRKY75 Decreases Cadmium and Salt Tolerance via Increasing ROS Accumulation in Arabidopsis and Brassica napus L.

Soil is indispensable for agricultural production but has been seriously polluted by cadmium and salt in recent years. Many crops are suffering from this, including rapeseed, the third largest global oilseed crop. However, genes simultaneously related to both cadmium and salt stress have not been extensively reported yet. In this study, BnaA10.WRKY75 was screened from previous RNA-seq data related to cadmium and salt stress and further analyses including sequence comparison, GUS staining, transformation and qRT-PCR were conducted to confirm its function. GUS staining and qRT-PCR results indicated BnaA10.WRKY75 was induced by CdCl2 and NaCl treatment. Sequence analysis suggested BnaA10.WRKY75 belongs to Group IIc of the WRKY gene family and transient expression assay showed it was a nuclear localized transcription factor. BnaA10.WRKY75-overexpressing Arabidopsis and rapeseed plants accumulated more H2O2 and O2- and were more sensitive to CdCl2 and NaCl treatment compared with untransformed plants, which may be caused by the downregulation of BnaC03.CAT2. Our study reported that BnaA10.WRKY75 increases sensitivity to cadmium and salt stress by disrupting the balance of reactive oxygen species both in Arabidopsis and rapeseed. The results support the further understanding of the mechanisms underlying cadmium and salt tolerance and provide BnaA10.WRKY75 as a valuable gene for rapeseed abiotic stress breeding.

Temperature calibration of sample rods for neutron diffraction apparatus in the range of 6–473 K

Abstract Internal stresses play a crucial part in determining a material’s properties, which emphasizes the significance of accurate stress measurement and analysis. Neutron diffraction technology is a very promising approach to studying the complex microstructural properties of many materials, especially with the growing demand for cryogenic studies. This new device has a robust load capacity of 50 kN and works smoothly in a wide temperature range of 6 K–473 K. Furthermore, the diffraction angle is 47 degrees broader. Regardless of the samples, we observed that a thermal balance point existed close to 180 K. Importantly, thermal resistance was eliminated by the use of an analytical method, which has an extraordinarily small error of 2%. Using this exact calibration methodology ensures that the sample temperature is accurate during the experiments. This work presents a crucial apparatus for investigating the complexity of internal stresses in materials and offers an effective method for estimating and managing sample temperatures while doing research.

Transcriptome-Wide Identification of m6A Writers, Erasers and Readers and Their Expression Profiles under Various Biotic and Abiotic Stresses in Pinus massoniana Lamb.

N6-methyladenosine (m6A) RNA modification is the most prevalent form of RNA methylation and plays a crucial role in plant development. However, our understanding of m6A modification in Masson pine (Pinus massoniana Lamb.) remains limited. In this study, a complete analysis of m6A writers, erasers, and readers in Masson pine was performed, and 22 m6A regulatory genes were identified in total, including 7 m6A writers, 7 m6A erases, and 8 readers. Phylogenetic analysis revealed that all m6A regulators involved in Masson pine could be classified into three distinct groups based on their domains and motifs. The tissue expression analysis revealed that the m6A regulatory gene may exert a significant influence on the development of reproductive organs and leaves in Masson pine. Moreover, the results from stress and hormone expression analysis indicated that the m6A regulatory gene in Masson pine might be involved in drought stress response, ABA-signaling-pathway activation, as well as resistance to Monochamus alternatus. This study provided valuable and anticipated insights into the regulatory genes of m6A modification and their potential epigenetic regulatory mechanisms in Masson pine.

Influence of sequential machining process on the surface topography of dies

Near net-shape manufacturing of components is a trend that aims to significantly reduce machining times and material waste, trading the machining efficiency for smaller lead times. Cold forging of gear-shaped components is one such operation that generates a component with superior geometrical accuracy and precision, however, the machined cavity is often subject to high mechanical loads and fatigue failures. The usual manufacturing chain involves hard machining, die-sinking electro-discharge machining, and mechanical polishing with abrasive media. Without proper knowledge of the resulting surface roughness and morphology, the tribological aspects of the surface can be neglected. Therefore, this study aims to investigate the manufacturing chain of gear-shaped cavities in terms of surface roughness, surface morphology, and surface residual stresses generated after die-sinking electro-discharge machining (roughing and finishing regimes), as well as mechanical polishing. The surface of the gear tooth was evaluated in three distinct regions: flank, top, and bottom. The results showcased that, even though the surface roughness/texture of the different regions of interest illustrates similar magnitudes, the surface morphology presented completely adverse features, highlighting the importance of a thorough analysis of the machined surface. Residual stress analysis indicated that the mechanical polishing operation was not enough to remove the high-magnitude tensile residual stresses.

Residual stress evaluation in innovative layer-level continuous functionally graded materials produced by Powder Bed Fusion-Laser Beam

The main objective of this study is to evaluate residual stresses in AISI 316L and 18Ni Maraging 300 functionally graded materials with continuous variation of composition within a single layer using the contour method. The manufacture of this kind of layer-level continuous functionally graded materials by employing a Powder Bed Fusion-Laser Beam system utilizing a blade/roller-based powder spreading technique has only been recently devised and a proper residual stress analysis is still required. In fact, as the mechanical properties of additively manufactured samples are significantly influenced by the direction of construction, the same holds true for the direction along which the compositional variation is made. Furthermore, in this study, the impact of solution annealing and aging heat treatment, which are necessary for enhancing the mechanical properties of martensitic steel, on residual stresses was explored. Additionally, the effect of adopting material-differentiated process parameters was investigated. The results indicated that each specimen displayed areas of tensile stress concentration on the upper and lower surfaces, balanced by compression in the center. The application of heat treatment led to a decrease in the maximum tensile stress of 8% and provided a uniform and significant stress reduction within the maraging steel. Finally, the implementation of material-specific process parameters for the three composition zones in conjunction with the heat treatment resulted in a reduction in the maximum residual stress of 35% and also a significantly lower residual stress field throughout the specimen.

Comparative Study of Analytical and Numerical Methods for Stress Analysis in Screw Thread Fillets

Comparative Study of Analytical and Numerical Methods for Stress Analysis in Screw Thread Fillets

Numerical analysis of stresses on angular contact ball bearing under the static loading with respect to race thickness and housing stiffness

A 3-dimensional model of the angular contact ball bearing (ACBB) was modeled using Abaqus/standard (Dassault systems- version 2017) to investigate the influence of race thickness on the bearing performance. It was found that the ability to support higher contact stress increased with race thickness. However, large deformations were found to occur on outer race with thickness of 3.3 mm and only small deformations were observed on outer race with a thickness of 9.9 mm. The large deformations induce higher shear stresses on thin races than on thick races. These stresses cause spall growth in bearings and propagate into a network of cracks. As a result of these findings, thin races are prone to failure compared with thick races.

Development of 3D-printed universal adapter in enhancing retinal imaging accessibility

BackgroundThe revolutionary technology of smartphone-based retinal imaging has been consistently improving over the years. Smartphone-based retinal image acquisition devices are designed to be portable, easy to use, and cost-efficient, which enables eye care to be more widely accessible especially in geographically remote areas. This enables early disease detection for those who are in low- and middle- income population or just in general has very limited access to eye care. This study investigates the limitation of smartphone compatibility of existing smartphone-based retinal image acquisition devices. Additionally, this study aims to propose a universal adapter design that is usable with an existing smartphone-based retinal image acquisition device known as the PanOptic ophthalmoscope. This study also aims to simulate the reliability, validity, and performance overall of the developed prototype.MethodsA literature review has been conducted that identifies the limitation of smartphone compatibility among existing smartphone-based retinal image acquisition devices. Designing and modeling of proposed adapter were performed using the software AutoCAD 3D. For the proposed performance evaluation, finite element analysis (FEA) in the software Autodesk Inventor and 5-point scale method were demonstrated.ResultsPublished studies demonstrate that most of the existing smartphone-based retinal imaging devices have compatibility limited to specific older smartphone models. This highlights the benefit of a universal adapter in broadening the usability of existing smartphone-based retinal image acquisition devices. A functional universal adapter design has been developed that demonstrates its compatibility with a variety of smartphones regardless of the smartphone dimension or the position of the smartphone’s camera lens. The proposed performance evaluation method generates an efficient stress analysis of the proposed adapter design. The end-user survey results show a positive overall performance of the developed universal adapter. However, a significant difference between the expert's views on the developed adapter and the quality of images is observed.ConclusionThe compatibility of existing smartphone-based retinal imaging devices is still mostly limited to specific smartphone models. Besides this, the concept of a universal and suitable adapter for retinal imaging using the PanOptic ophthalmoscope was presented and validated in this paper. This work provides a platform for future development of smartphone-based ophthalmoscope that is universal.

Damage Mechanism Analysis of the Connecting Screw of Turbine Disk-Drum Assembly

The turbine disk-drum is one of the key components of an aero-engine and its assembly is connected with high-strength refined screws. But due to the uncoordinated rotation and deformation, the screws have abnormal wear damage. Through detailed contact stress analysis of screw body and component level using the finite element method, combined with experimental observation, the mechanism of wear damage of screw surface in screws is determined. It mainly includes the following: Firstly, the finite element method is used to calculate the deformation and stress distribution of the connecting screw of the turbine disk-drum assembly. Then, after the overspeed test, the morphology of the screws disassembled from the disk-drum assembly is evaluated. It was found that the wear degree in the circumferential direction and axial direction of the screw was quite different, that is, the screw wear experiment was consistent with the finite element analysis results. Finally, the influence of different rotation states and screw tightening states on screw wear was compared and analyzed. Conclusions obtained in this paper will be helpful to improve the assembly reliability of turbine drum.

Coulomb Stress Analysis in Nemrut Caldera (East Anatolia, Türkiye)

In volcanic areas, seismic events with low energy occur before seismic activity or due to the movement observed in the magma. These earthquakes, which are caused by the expansion-contraction movement that has been revealed in different studies and is mostly observed in the magma chamber, can be recorded with continuous observations. On the other hand, it is not easy to distinguish between tectonic and volcanic origins of earthquakes occurring in volcanic areas. In this study, Coulomb stress analysis was carried out using earthquakes in the Nemrut Stratovolcano, which is located in the eastern Türkiye and is at the westernmost end of a volcano arc, and it was concluded that the stress is related to the Nemrut Caldera, therefore the positive stress caused by the expansion of the magma chamber of the Nemrut Volcano creates tremors.

Conceptual design of coolant circuits and thermal stress analysis for JA-DEMO divertor

Engineering design of the JA-DEMO divertor concept, i.e. double-coolant circuits of 200°C coolant (5MPa) for high heat load targets (CuCrZr-pipe) and 290°C coolant (15MPa) for high neutron load Plasma Facing Units (F82H-pipe) and cassette body (CB), has been developed. Computational fluid dynamics (CFD) calculation of the coolant distributions to targets, baffles, reflectors, dome and to CB was performed in order to determine the feasibility of the key concepts. (i) All PFU support designs for the coolant distribution to PFUs were optimized to reduce variation of the flow velocity (Vcool) at the inlet of PFUs less than 5 – 6 %. Parallel coolant circuit design for the dome and reflectors was also developed, and mass flows were adjusted by orifices and the main mass flow rate. (ii) A new cooling concept with two layers of puddles and fins at the side routes was proposed for CB. The design provided Vcool = 0.55 – 1.27 m⋅s−1 and average Vcool = 1.04 m⋅s−1 with the fin transparent ratio of 0.1. It was enough to exhaust the nuclear heat, and the design issues were identified under the coolant condition. (iii) Heat exhaust on fish-scale surface target and stress-strain of the CuCrZr pipe were investigated under assuming a DEMO divertor condition. Steady-state heat load at wet region by plasma (qtwet) was restricted below 13.5 MWm−2 to avoid W-recrystallization. In the stress-strain cycle of higher qtwet ∼15.3 MWm−2, maximum tensile σ (120 – 200 MPa) and total change in strain during the heat load cycle (Δε ∼0.25 %) were relatively small. These evaluations suggested that such high heat load cycle may not be a critical lifetime issue, but reduction in Tcool is preferable to handle ITER-like slow transients such as 15 – 20 MWm−2.

Macauba palm endocarps under compression forces considering the different treatments: A study about physical and mechanical properties for seed extraction

Macauba (Acrocomia aculeata) is a palm tree native to the tropical forests of North America and Brazil, with fruits that hold significant potential across agricultural and industrial sectors, including cosmetics, pharmaceuticals, food, and biofuels. The spherical, drupe-like fruit consists of a fibrous peel (epicarp), pulp (mesocarp), endocarp, and seed. The endocarp, housing the seeds, is a dense, mechanically robust triaxial spheroid with high caloric value. To harness macauba potential on an industrial scale, strategies incorporating high-performance machinery are necessary, replacing rudimentary extraction methods with more rational approaches to crop development. Understanding the physical and mechanical properties of such crops is crucial for designing machines and processes for agricultural product cultivation. This study focuses on the mechanical behavior of the macauba palm endocarp for seed extraction, evaluating its geometric and mechanical properties through compressive stress analysis. Geometric properties such as endocarp characteristics, circularity, sphericity, eccentricity, and surface area were examined, alongside the influence of different endocarp treatments on rupture strengths. Compression tests on macauba fruit endocarps revealed treatment methods (control, 24, 48, and 72-h water immersion, and 10-day sun exposure) influence on mechanical properties at various strain rates (100–600 mm.min-1).Results show the macauba palm endocarp behaves as a spheroid. Immersing macauba endocarps in water increased their rupture strength during compression. However, sun exposure for 10 days rendered the fruit more fragile and less tenacious, reducing rupture force by over 40 % compared to control samples. The Deformity Modulus of macauba fruit endocarp ranged from 30.1 GPa to 53.2 GPa depending on the treatment applied.

Multiscale modeling and thermal conductivity evaluation of nano-reinforced composite materials with pore defect

The performance of resin-based composite materials often exhibits diversity due to the designability of various components. Thermal conductivity, an important thermal parameter of the composite, plays a significant role in thermal-chemical reactions, thermal stress analysis, temperature conduction, etc. However, it is relatively difficult to experimentally explore the thermal conduction mechanism of hybrid composite materials, mainly due to the relatively difficult control of various components. Therefore, this paper proposes a sequentially coupled cross-scale numerical method to characterize the thermal conductivity of nano-reinforced composite materials with pores by a multiscale periodic Representative Volume Element model generated by an improved Random Sequential Absorption algorithm. Firstly, periodic temperature boundary conditions are described, and the thermal conductivity performances of nano-reinforced matrix and composite with pores are investigated based on the finite element homogenization theory. Then, the proposed modes are validated and grid sensitivity analysis is conducted, indicating that the optimal grid sizes for the RVE models are 1.9 nm for the nano-reinforced matrix and 0.14 μm for the composite with pores based on a comprehensive comparison of four pore characterization methods, respectively. Furthermore, the study explored the effect of multiple parameters including nanoparticle content, pore content, and pore shape on thermal conductivity. Numerical findings reveal that the thermal conductivity of the nanocomposite matrix exhibits a linear increase with higher particle content. Specifically, compared to 0 % particle content, the thermal conductivity rises by 141.92 % at 12 % particle content. While the composite material's transverse thermal conductivity is sensitive to porosity content, it is less influenced by pore shape. The method proposed in this paper provides an effective approach for studying the thermal conduction of nano-reinforced composite materials with pores, and the research findings also offer theoretical guidance for process engineers.

Research on the Stress Analysis and Performance Optimization of Lounge Bridge— A Case Study of Xuezhai Bridge

Research on the Stress Analysis and Performance Optimization of Lounge Bridge— A Case Study of Xuezhai Bridge

Finite element analysis of stresses on the skull base caused by trauma during sinus lift with mallet and osteotome

Finite element analysis of stresses on the skull base caused by trauma during sinus lift with mallet and osteotome

Assessing Work Stress and Its Impact On Job Satisfaction and Performance of Employees in Banks

The Banking industry is known for its fast-paced, high–pressure environment, which can lead to significant work-related stress for employees. Factors such as long work hours, tight deadlines, heavy workloads, and complex customer interactions can all contribute to elevated stress levels. Additionally, the constant need to adapt to changes in regulations, technology, and, market conditions adds to the challenges faced by banking professionals. Studies have shown that work stress can have a profound impact on the physical and mental well-being of employees, leading to issues such as burnout, anxiety, and depression. This, in turn negatively affects job satisfaction, employee engagement, and overall performance within the organization. The paper aims to provide a comprehensive analysis of work stress and its effects on job satisfaction and employee performance within the banking industry. It t examines the key factors contributing to work-related stress, the impact on job satisfaction, and strategies for mitigating the negative consequences. The information presented in the paper can help HR professionals and managers in the banking sector to develop effective stress management programs and improve overall employee well-being and productivity.

Finite element simulation of treatment with locking plate for distal fibula fractures.

An improved Finite Element Model(FEM) is applied to compare the biomechanical stability of plates with three different options in the treatment of distal fibula fractures in this study. The Computed Tomography(CT) scan of the knee to ankle segment of a volunteer was performed. A 3D fibula FEM was reconstructed based on the CT data. Three different loads (uni-pedal standing, torsion, and twisting) were applied, the same as in the experiments in the literature. The stresses and strains of the three options were compared under the same loads, using a 4-hole locking plate (Option A), a 5-hole locking plate (Option B), and a 6-hole locking plate (Option C) in a standard plate for lateral internal fixation. The simulation results show that all three options showed a stress masking effect. Option C had the best overall biomechanical performance and could effectively distribute the transferred weight. This is because option C has greater torsional stiffness and better biomechanical stability than options A and B, and therefore, option C is the recommended internal fixation method for distal fibula fractures. The Finite Element Analysis(FEA) method developed in this work applies to the stress analysis of fracture treatment options in other body parts.

Investigation into the impact of charging rates on the stress development within silicon composite electrodes.

Silicon, renowned for its remarkable energy density, has emerged as a focal point in the pursuit of high-energy storage solutions for the next generation. Nevertheless, silicon electrodes are known to undergo significant volume expansion during the insertion of lithium ions, leading to structural deformation and the development of internal stresses, and causing a rapid decline in battery capacity and overall lifespan. To gain deeper insights into the intricacies of charge rate effects, this study employs a combination of in situ measurements and computational modeling to elucidate the cyclic performance of composite silicon electrodes. The findings derived from the established model and curvature measurement system unveil the substantial alterations in stress and deformation as a consequence of varying charge rates. Notably, the active layer experiences compressive forces that diminish as the charge rate decreases. At a charge rate of 0.2, the active layer endures a maximum stress of 89.145 MPa, providing a comprehensive explanation for the observed deterioration in cycling performance at higher charge rates. This study not only establishes a fundamental basis for subsequent stress analyses of silicon electrodes but also lays a solid foundation for further exploration of the impact of charge rates on composite silicon electrodes.

Computational modeling of neuronal nitric oxide synthase biochemical pathway: A mechanistic analysis of tetrahydrobiopterin and oxidative stress

Neuronal cell dysfunction plays an important role in neurodegenerative diseases. Oxidative stress can disrupt the redox balance within neuronal cells and may cause neuronal nitric oxide synthase (nNOS) to uncouple, contributing to the neurodegenerative processes. Experimental studies and clinical trials using nNOS cofactor tetrahydrobiopterin (BH4) and antioxidants in neuronal cell dysfunction have shown inconsistent results. A better mechanistic understanding of complex interactions of nNOS activity and oxidative stress in neuronal cell dysfunction is needed. In this study, we developed a computational model of neuronal cell using nNOS biochemical pathways to explore several key mechanisms that are known to influence neuronal cell redox homeostasis. We studied the effects of oxidative stress and BH4 synthesis on nNOS nitric oxide production and biopterin ratio (BH4/total biopterin). Results showed that nNOS remained coupled and maintained nitric oxide production for oxidative stress levels less than 230 nM/s. The results showed that neuronal oxidative stress above 230 nM/s increased the degree of nNOS uncoupling and introduced instability in the nitric oxide production. The nitric oxide production did not change irrespective of initial biopterin ratio of 0.05–0.99 for a given oxidative stress. Oxidative stress resulted in significant reduction in BH4 levels even when nitric oxide production was not affected. Enhancing BH4 synthesis or supplementation improved nNOS coupling, however the degree of improvement was determined by the levels of oxidative stress and BH4 synthesis. The results of our mechanistic analysis indicate that there is a potential for significant improvement in neuronal dysfunction by simultaneously increasing BH4 levels and reducing cellular oxidative stress.