Stress analysis

In this paper, we have put forward a system which will detect workload of brain. Different classification algorithms will evaluate the real time workload of a person. User will perform certain task at the same time frequency from the brain will be gathered. On the basis of trained data and classification algorithm will help system to determine the workload of the person. A 2d brain image will be final hard copy report of the person. System will help various individual and organization to know the work related load of a person and to reduce the stress level thereby increasing productivity. IndexTerms EEG machine, Neural networks, Brain image

This paper presents elastic stress distributions near a cracktip in a continuous fiber composite. The material heterogeneity is explicitly accounted for by using the finite element method and a new Mesh Superposition Technique. This new technique superposes a fine mesh with heterogeneous material properties over a coarse mesh with homogeneous ones. The results indicate that the load transferred by fibers near a cracktip may be well described by the homogeneous orthotropic elastic K~ field. A technique to postprocess the K~ field to accurately obtain the detailed stress distributions within the fiber and matrix is also presented.

This report summarizes a parametric analysis performed to determine the effect of varying the percent on-cell reformation (OCR) of methane on the thermal, electrical, and mechanical performance for a generic, planar solid oxide fuel cell (SOFC) stack design. OCR of methane can be beneficial to an SOFC stack because the reaction (steam-methane reformation) is endothermic and can remove excess heat generated by the electrochemical reactions directly from the cell. The heat removed is proportional to the amount of methane reformed on the cell. Rapid reaction kinetics provided by the high-temperature SOFC operation and excess steam over the nickel-based anode catalyst ensure complete methane conversion. Thus, the thermal load varies with methane concentration entering the stack. The endotherm due to the fast reformation reaction can cause a temperature depression on the anode near the fuel inlet, resulting in large thermal stresses. This effect depends on factors that include inflowing methane concentration, local temperature, and stack geometry. The analysis assumed the fuel would be partially to fully pre-reformed in an external reformer such that the desired fuel compositions would be delivered to the stack, where the remaining percentage of the reformation reaction would be completed on-cell. Simulations were performed using an SOFC stack modeling tool developed at PNNL and validated for the prediction of fuel use, on-cell methane reforming, and distribution of temperature. The study was performed using three-dimensional stack model geometries. Cross-flow, co-flow, and counter-flow configuration stacks of 10x10-and 20x20-cm cell sizes were examined. Thermal performance was evaluated based on the predicted maximum temperature difference on the anode. Electrical performance was based on the predicted power output. Mechanical performance was based on the maximum principal stress on the anode. Fuel utilization was established at 75%. The effect of cathode air cooling was included in the study by examination of 30% and 15% air utilizations.

The focus of this paper is the description and numerical validation of a computational method where stress analysis can be performed directly from computer-aided design data without mesh generation. The clear benefit of the approach is that no mesh needs to be generated prior to running the analysis. This is achieved by utilising the isogeometric concept whereby computer-aided design data are used to construct not only the geometry discretisation but also the displacement and traction approximations. In this manner, significant savings can be made in the engineering design and analysis process. This paper also demonstrates that, compared with a standard boundary-element method implementation using quadratic Lagrangian shape functions, superior accuracy is achieved using the present approach for the same number of degrees of freedom. It further illustrates practical applications of the method, comparing against results obtained with a standard boundary-element method and finite-eleme...

Chers collègues, j'ai beaucoup de respect pour votre savoir, votre savoir-faire ainsi que pour votre sens aigu de la communication. Moi-même, je suis prestataire de telles connaissances, et je compte parmi mes amis, nombre de dispensateurs de tels savoirs, c'est vous dire combien le domaine m'est familier. De temps à autre, pendant que vous exercez vos habiletés, il vous traverse peut-être l'esprit cette question de savoir et de comprendre ce qu'il se trame, physiologiquement, au sein de votre cerveau et dans ceux de vos apprenants, mais, probablement, sans aller au-delà de cet instant de légitime curiosité. La question me semble, sans nul doute, fondée au vu de certaines recettes pédagogiques, particulièrement à caractère injonctif, habituellement et rituellement employées par certains formateurs pour diffuser et inculquer leurs enseignements. En effet, afin qu'un auditoire quelconque puisse s'imprégner positivement de savoirs en la matière, il ne faudrait pas que ces enseignements revêtent des formes pressantes ou d'obligation. Il faut garder à l'esprit que nos neurones, ainsi que toutes les autres composantes de notre cerveau (système limbique, cortex frontal, etc.) ne font qu'exécuter, fidèlement, les missives reçues de la part de nos cinq sens : Vue, ouïe, odorat, goût, toucher.

**Abstract**

This study investigates the mechanical behavior of a centrifugal pump shaft under static loading conditions using finite element analysis (FEA). The research focuses on the "SCANPUMP NB 100/80-16" model, a centrifugal pump commonly used in oil field operations. The primary objective is to evaluate the shaft's stress distribution, deformation, and safety factors to ensure operational reliability and performance.

A multi-methodological approach is employed, combining traditional analytical calculations, numerical analysis via MATLAB, educational software (MIT Shaft Calculator), and advanced simulation using SolidWorks. The shaft is modeled and discretized into finite elements, and static structural analysis is conducted considering gravitational loads from the shaft, impeller, and coupling, supported by two bearings.

Results indicate that the maximum von Mises stress (1.177 MPa), deformation (4.582×10⁻³ mm), and displacement values remain within acceptable limits, confirming the shaft's structural integrity under given conditions. The finite element method provides more precise and distributed results compared to conventional methods, highlighting its effectiveness in predicting mechanical behavior.

This work demonstrates the successful application of FEA in optimizing centrifugal pump design, reducing reliance on physical prototypes, and enhancing predictive maintenance strategies. It contributes to the field by validating computational tools for mechanical analysis and supporting the design of more efficient and durable pumping systems in industrial applications.

**Keywords:** Centrifugal Pump, Shaft, Finite Element Analysis, Static Analysis, SolidWorks, MATLAB, Von Mises Stress, Structural Integrity.

Lining cracks are one of the most common diseases in highway tunnels, and the existence of lining cracks directly affects the overall stability and durability of tunnels, which has an important impact on the safe operation of tunnels, and it is necessary to analyze and study the characteristics of tunnel lining cracks. Combining with the detection data of multiple highway tunnels in the field, the different types of tunnel cracks are divided, and the classification numerical statistics method is used to obtain that the number and length of annular cracks in highway tunnel cracks are significantly higher than those of the other two kinds of cracks, and the longitudinal cracks in tunnel crack cracking degree are greater than the circumferential cracks and the inclinded cracks. The influence degree of cracks on the safety of tunnel structure longitudinal cracks are relatively the largest, the inclinded cracks are second only to longitudinal cracks, and the influence of cyclic cracks is relatively small. It provides reference for tunnel engineering design, construction, operation management and comprehensive improvement work.

The gas permeability is an important indicator to assess the material's ability to prevent the ingress of aggressive chemical species. The pre senc of aggressive fluids and their transport is by far the most important factor controlling the du rability of cement based composites. This paper presents an experimental study of gas permeability of ordinary concrete according to its saturation, because the hydric state of concrete conditions the transfer parameters such as permeability. Thus the world of aggressive penetration varies signific antly depending on moisture content and its evolution over time. The experimental results conce r ing the measurement of gas permeability of concrete samples with different sizes and that of t he degree of saturation by weighing and therefore mass loss measurements were performed. The analysis highlights the effect of saturation on the variation of the relative gas permeability of concr ete stressing the specific attention to sample size (scale ...

Fixed Mask 1 (FM1) and Photon Shutter 2 (PS2) are two of the critical elements on the front end of the beamlines at the Advanced Photon Source (APS) now under construction at Argonne National Laboratory (ANL). FM1 and PS2 use an enhanced heat transfer tube developed at ANL. Due to a high localized thermal gradient on these components, inclined geometry is used in their design to spread the footprint of the x-ray beam. Complete closed form solutions for steady state conditions have been developed for the analyses of the thermal and thermGmechanica1 behavior of FM1 and PS2. A modified Manson-CofEn fatigue relation is propused to predict the predict the thermal fatigue. The maximum temperatures and maximurneffective stresses have been parametrically studied. Fatigue-failure l i e predictions are presented for the FM1 and PS2 designs.

The supporting pressure value of excavation face directly determines the stable state of excavation face, and its value will directly lead to instability of excavation face if the value is too small. When the shield is underneath the existing tunnel, special attention should be paid to the support pressure setting of the shield working face. When setting support pressure, the rigidity constraint of existing tunnel on surrounding soil should be fully considered. In this paper, we used ABAQUS software to analyse the failure mode of the soil around the existing tunnel due to the instability of the excavation surface caused by the small pressure setting of the excavation face, which is caused by the small pressure setting of the excavation face. By using the method of theoretical analysis, we optimized the prism in the traditional wedge model to chamfer platform with different opening angles to make it closer to the actual situation, and calculated the critical support pressure of shield tunnel face when it passes through the built tunnel. The research results can provide a reference for the effective value of support force of shield excavation face when the shield tunnel passes under the existing tunnel at a short distance.

The paper deals with the possibilities of diagnostics of the moral reasoning of children and adults, focused on the use of the Test of moral reasoning. The tool is a modification of the original Test of moral maturity of personality, which authors are J. Kotásková and I. Vajda. The modified test distinguishes between passive, constructive and destructive approaches of conflicts among pupils (children). In the first part of the article we offer an overview of selected ours and foreign diagnostic tools that can examine the moral reasoning of children and adults. In the next section we present the partial results of research of moral reasoning, involving 408 respondents, including 283 children (pupils) aged 10-13 years, 84 elementary school teachers and 41 parents. Our goal was to compare the moral reasoning of children and adults, children of elementary schools and children of special educational institutions. We were interested in differences between teachers and parents, where we assumed that teachers will suggest more often constructive approaches of conflicts than parents. The results show the highest incidence of passive approaches of conflicts from the perspective of children and adults.

Synchrotron radiation XRD was used to study the residual stress field in two different ceramic coatings: polycrystalline diamond (-5 pm) on WC-Co and Y,O,-partially-stabilised-zirconia (-300 pm) on Al substrates. In both cases, the use of synchrotron radiation, and the possibility of changing wavelength in particular, permitted to study the residual stress trend inside the ceramic layers. For the diamond coated component, the stress analysis was extended also to the WC substrate, in the interface region with the coating.

By Gerard Feller In our hectic society many people feel that the pressure of work, family and social expectations are getting heavier and heavier. This Biblical article about 'stress management' provides guidance on the issue, where it comes from, how it affects you and how to manage it better. This timely and far-reaching topic explains how stress manifests itself; from achievement drive to mental exhaustion. It also emphasizes the crucial role of faith and the restoration. As the author Gerard Feller explains, stress is, more often than we think, an issue of spirit, soul and body, and it calls for an 'all-around' approach. Besides prayer and prayer support, the article pleads for the testing against Biblical values in regular treatment methods. In this way a pastoral approach is created that is both practical and profound. Discover in this article inspiring guidance not only to fight stress, but to really deal with it-supported by your faith in the power of God.

The method of caustics was used to investigate the dynamic problem of interaction of two collinear edge cracks in plane PM~A specimens. By varying the externally applied strain rate and the initial crack lengths, useful conclusions were derived on the instability of interacting cracks, their paths of propagation, the variation of the crack propagation velocities and the stress intensity factors.

En el presente trabajo se abordan las experiencias en la utilización de la modelación matemática y la realización de pruebas de carga no destructivas en cimentaciones sobre pilotes para evaluar su capacidad de carga. Para ello se exponen los resultados obtenidos en pruebas de carga de más de 2000 kN, y la distribución de cargas en una estructura portuaria, evaluando su capacidad resistente. Se establecen comparaciones entre los métodos teóricos de cálculo de la capacidad de carga del pilote aislado y modelos matemáticos basados en el Método de los Elementos Finitos. Finalmente se comprueba la coincidencia entre el modelo numérico y los resultados de la prueba de carga a escala real demostrado que el muelle tiene continuidad estructural lo que permite un trabajo espacial del mismo que garantiza una mejor redistribución de las cargas que sobre él actúan.

Presently work some practical recommendations are approached for the use of programs with base in the Method of the Finite Elements (MEF) that frequently are used for the modeling of problems tension deformation, plastic deformations and fail in deep foundations that are obviated throwing results far from the reality in many cases. For they are exposed it approaches of great use in the international bibliography and the author's experiences in their application for the case of piles. It is exemplified through comparisons the results obtained through the modeling with other formulations being proven validates it of the proposed pattern.

Nakakatulog ka ba kahit stressed ka? This study delves into the relationship between sleep quality and stress levels, alongside other variables like occupation and daily steps, using multiple linear regression analysis. Multiple linear regression was the data mining method used, enabling the examination of how various independent variables influence the dependent variable of sleep quality. The primary focus on stress stems from its well-established influence on sleep patterns, which will be further narrated in the literature review. Stress lang ba, o iba pa? Despite existing research, gaps persist due to methodological inconsistencies and inadequate consideration of individual differences. This research aims to predict not only stress but also other environmental factors that may also affect sleep quality. The clean and integrated Sleep Health and Lifestyle Dataset by Laksika Tharmalingam underwent thorough further pre-processing, including data cleaning, transformation, normalization, and splitting into training and testing sets, to ensure accuracy and reliability for analysis. The evaluation involved analysing a scatter plot comparing actual versus predicted sleep quality values and the coefficients of features depicting each variable's impact magnitude. While the scatter plot revealed some divergence suggesting potential model inaccuracies, it also demonstrated a strong positive relationship overall. The results and discussion highlights stress and physical activity levels as significant negative influences of sleep quality, and provides conclusions and recommendations for stress management.

Keywords: Sleep, Sleep Quality Stress, Stress Levels, Data, Data Analysis, Data Normalization, Data Splitting, Data Mining, Scatter plot, Multiple Linear Regression

Background: Spermatogenesis can progress only normally in a tightly regulated redox environment under the fine regulation of testosterone and other hormones. This process is particularly vulnerable to stress, which can disturb the gut microbiome—an important factor in testicular function. However, it is not known if supplementation with probiotics can mitigate the effects of psychological stress on sperm production. This study aimed to investigate the effect of gut probiotics on testicular function of rats during psychological stress.
Methods: Thirty-five adult male rats were randomly assigned into seven groups with five rats each. The research was divided into two phases: one week and two weeks' administration, in which the rats were subjected to probiotics only, stress only, and probiotics plus stress. Data were analyzed using one-way ANOVA and student Newman-Keuls post hoc test for multiple comparisons at p <0.05
Results: Chronically stressed reduced testicular weight and testicular relative organ weight, the same as acutely stressed rats. However, treatment with probiotics resulted in statistically significant differences as a mitigating effect.
Conclusion: Gut probiotics have a generally beneficial impact on the testes when evaluating biochemically and morphological parameters.

Aircraft is a complex mechanical structure that must be designed with a very high structural safety. Aircraft will rarely fail due to a static overload during its service life. As the aircraft continues its operation, fatigue cracks initiate and propagate due to fluctuating service loads. Normally fatigue cracks will initiate from stress concentration locations, and the stress is more in the area of cutout. Here in this work, a beacon light hole on the fuselage of an aircraft is considered. The main objective of this study is to find the maximum stress during fatigue load testing. Finite Element Method (FEM) is used for analysis. Here, Finite Element Analysis (FEA) software used is MSC/NASTRAN V 7.0.

Surface deformation of a ferroelectric (111)-oriented thin film of La-modified PbTiO3 is induced by contact with the tip of a scanning force microscope (SFM). The deformation is accompanied by switching of the out-of-plane polarization of ferroelectric domains revealed by simultaneous piezoresponse force microscopy. The effect shows up in topographic SFM images as strokes in the fast scan direction due to surface deformation occurring below the scanning tip, and is critically dependent on the contact force for which a threshold value is deduced that allows proper SFM characterization of such thin films. At higher force, SFM might be used as a nanoscale tool for investigating fundamental properties like phase transitions under applied stress in such systems.

Gears are one of the most basic components of any machine or mechanism. Spur gear is the most common means of transmitting power in the modern mechanical engineering world. The main objective of this research paper is to analyze the bending stresses occur on the gear tooth profile when subjected to loading condition with the help of FEM and Photo-elastic technique. Photo elastic stress analysis is a technique that provides stress distribution over an entire object/structural member of interest it is based on the property of some transparent material to exhibit colorful pattern when viewed with polarized light. These patterns occur as the result of alternation of the polarized light by the internal stresses into two waves travel at different velocities. In this work root radius are taken gear parameters, how stress redistribution are taken place by varying this parameter studied. The stresses are calculated with the help of the FEA this result are compared with the stresses calculate...

Deep induction hardening has been performed on two batches of smooth cylindrical specimens with a hardening depth respectively around 2 mm and 3 mm. The distributions of axial and circumferential residual stresses are analysed for the two specimen batches by X-ray diffraction technique. The radial normal stress field is estimated through the use of the well known Moore and Evans correction. Finally, the experimental residual stresses are compared with those obtained from a multiphysic finite element modelling of the whole induction treatment process, including electromagnetic, thermal, metallurgical and mechanical phenomena. The simulated residual stress field is in good agreement with X-ray analysis especially at depths lower than one-tenth the specimen diameter. At deeper depths, a correction of the experimental X-ray analysis has been done to obtain realistic values.

A finite element stress analysis for a hypothetical nuclear graphite moderator brick has been carried out, considering dimensional and other property changes due to fast neutron irradiation. The stresses and deformations of the brick during operation and at shutdown have been examined. The results indicate a possible relationship between the turnarounds in the stresses and the dimensional change rate of the material. A theoretical solution is also presented for a hollow cylinder with similar dimensions, which is in good agreement with the finite element results for the graphite brick. Further analytical results are presented using different dimensional change rates. The results confirm that the turnaround in the hoop stress has a close relationship with the dimensional change rate of the material.

Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor jximary lithium loop and the Space Stirling Power Convertor(SSPC)was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design woii: focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled ccxicept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refiractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems.

An analytical solution is performed using stress function approach for multi-layered filament-wound composite cylinders subjected to combined internal pressure and thermal loading. It is assumed that there is a liquid or gas of various temperatures in the cylinders. The effects of the wind angle variation through the radial section of the cylinders are also investigated. Thus, the layers are oriented symmetrically and antisymmetrically for (0°/90°), (30°/-30°), (45°/-45°) and (60°/-60°) orientations. A computer program is developed to conduct stress and deformation analyses of composite cylinder with different winding angle. All the integration constants are found from the radial stress and displacement in the normal direction of layers.

The singular stress, electric fields and magnetic fields in a rectangular magnetoelectroelastic body containing a moving crack under longitudinal shear are obtained. Fourier transforms and Fourier sine series are used to reduce the mixed boundary value problems of the crack, which is assumed to be permeable or impermeable, to dual integral equations, and then expressed in terms of Fredholm integral equations of the second kind. Results show that the stress intensity factors are influenced by the material constants, the geometry size ratio and the velocity of the crack, and the propagation of the crack possibly brings about branching phenomena.

The singular stress, electric fields and magnetic fields in a rectangular magnetoelectroelastic body containing a moving crack under longitudinal shear are obtained. Fourier transforms and Fourier sine series are used to reduce the mixed boundary value problems of the crack, which is assumed to be permeable or impermeable, to dual integral equations, and then expressed in terms of Fredholm integral equations of the second kind. Results show that the stress intensity factors are influenced by the material constants, the geometry size ratio and the velocity of the crack, and the propagation of the crack possibly brings about branching phenomena.

En este trabajo se presentan resultados de asentamientos obtenidos de mediciones y modelación numérica de cimentaciones en Balsas Combinadas con Pilotes BCP (losas de fundación con pilotes) en una estructura industrial con cargas significativas. Con el objetivo de evaluar los asentamientos ocurridos en la balsa debido a los años de explotación, se lleva a cabo un análisis del comportamiento de la cimentación ante diversas combinaciones de cargas. Además, se verifica la validez del modelo utilizado mediante la comparación con mediciones reales de desplazamientos en la base de la cimentación.

A steel bridge was subjected to loads which are over its capacity load. Strengthening works were done to allow passing of the required load. To ensure that the strengthened works gained enough increase in flexure stiffness, a dynamic test using controlled traffic technique was performed. The bridge dynamic characteristics before and after strengthening work and just after passing of load were determined. Experimental studies were carried out on two spans for a multiple simple spans bridge using a certain vehicle passing over the bridge. The bridge acceleration response was measured and the bridge fundamental frequency was determined for each span before and after strengthening and after passing of load. The results were used to evaluate the bridge flexure stiffness.

In recent decades, studies in the field of psychobiology have broadened and deepened our understanding of issues related to psychosomatic medicine. In particular, numerous biological functions sensitive to psychosocial and emotional stimuli have been identified. The development of the concept of stress and its subsequent modifications, as well as the emergence of specific fields of interest such as psychoneuroendocrinoimmunology (PNEI), have certainly contributed to these changes.

One of the main drawbacks of Element Free Galerkin (EFG) method is its dependence on moving least square shape functions which don't satisfy the Kronecker Delta property, so in this method it's not possible to apply Dirichlet boundary conditions directly. The aim of the present paper is to discuss different aspects of three widely used methods of applying Dirichlet boundary conditions in EFG method, called Lagrange multipliers, penalty method, and coupling with finite element method. Numerical simulations are presented to compare the results of these methods form the perspective of accuracy, convergence and computational expense. These methods have been implemented in an object oriented programing environment, called IN-SANE, and the results are presented and compared with the analytical solutions.

One of the main drawbacks of Element Free Galerkin (EFG) method is its dependence on moving least square shape functions which don't satisfy the Kronecker Delta property, so in this method it's not possible to apply Dirichlet boundary conditions directly. The aim of the present paper is to discuss different aspects of three widely used methods of applying Dirichlet boundary conditions in EFG method, called Lagrange multipliers, penalty method, and coupling with finite element method. Numerical simulations are presented to compare the results of these methods form the perspective of accuracy, convergence and computational expense. These methods have been implemented in an object oriented programing environment, called IN-SANE, and the results are presented and compared with the analytical solutions.

Simultaneous excitation of a turbulent mixing layer by two frequencies, a fundamental and a subharmonic, was investigated experimentally. Plane perturbations were introduced to the flow at its origin by a small oscillating flap. The results describe two experiments that differ only in the amplitudes of the imposed perturbations and both are compared to the data acquired while the mixing layer was forced at a single frequency. Conventional statistical quantities such as: mean velocity profiles, widths of the flow, turbulent intensities, spectra, phase-locked velocity and vorticity fields, as well as streak-lines were computed. The rate of spread of the flow under concomitant excitation at the two frequencies was much greater than under a single frequency although it remained dominated by two-dimensional eddies. The Reynolds stresses and turbulence production are associated with the deformation and orientation of the large coherent vortices. When the major axis of the coherent vortices starts leaning forward on the high velocity side of the flow, the production of turbulent energy changes sign (i.e. becomes negative) and it results in thinning the flow in the direction of streaming. It also indicates that energy is extracted from the turbulence to the mean motion Resonance phenomena play an important role in the evolution of the flow. A vorticity budget showed that the change in mean vorticity was mainly caused by the nonlinear interaction between coherent voracities. Nevertheless the locally dominant frequency scales the mean growth rate, the inclination and distortion of the mean velocity profiles as well as the phaselocked vorticity contours.

The determination of residual stresses is an important issue when it comes to material failure analysis. The variation of global indentation properties, due to the presence of residual stresses, can serve as a guideline for the size and direction of such stresses. One of these global indentation properties, the material hardness, is unfortunately invariant of residual stresses when metals and alloys are at issue. In this situation, one has to rely on the size of the indentation contact area for residual stress determination. For other materials such as ceramics and polymers, where elastic deformations are of greater importance at indentation, such invariance is no longer present. Here, this variation is investigated based on finite element simulations. The aim is then to determine how the indentation hardness is influenced by the principal residual stress ratio and also discuss if such an influence is sufficient in order to determine the size and direction of such stresses in an exp...

The influence from residual surface stresses on global indentation properties, i.e., hardness and size of the contact area, have been studied quite frequently in recent years. A fundamental assumption when evaluating such tests is that the material hardness is independent of any residual stresses. This assumption has been verified in the case of cone indentation of classical Mises elastoplastic materials. However, a detailed investigation of this feature in the case of three-dimensional indentation, i.e., Vickers and Berkovic indentation, has not been presented previously. It is therefore the aim of the present study to remedy this shortcoming using finite element methods. The numerical results pertinent to Vickers indentation clearly show that the material hardness is independent of residual (or applied) stresses (also in case of three-dimensional indentation problems). The limitations of the validity of hardness invariance are also discussed in some detail.

The gravitational water vortex power plant is an emerging technology of power generation from water vortex in a small amount. It can generate electricity in a low head of range (0.7-2m). This system is very simple and requires less keep-up. This research aims to develop the propeller type runner which gives optimum efficiency and cylindrical basin suitable for this propeller runner in GWVPP. The research has been conducted by developing a new propeller runner and cylindrical basin considering the top surface open as the atmosphere. Blade angle, discharge hole diameter of the basin, the position of runner, and rpm are optimized on CFD-based optimization. After the CFD analysis, the optimum blade angle was 43º, exit hole diameter of this basin was found 175 mm which is 20% of the basin diameter. The optimum height was found 785mm which is 65.42% of the total height. And the efficiency of the optimized system was 23.639 % at 40 rpm.

The effects of variation in humidity coupled with long-term loading give rise to dimensional changes and creep effects in wooden elements. Many wooden products such as cross-laminated timber (CLT) plates as well as many common structural details used in timber engineering are vulnerable to variations in moisture content (MC) as well as to creep effects. This paper addresses the long-term effects in the material modelling of timber by the finite element method (FEM), also considering the viscoelastic and mechanosorptive effects in wood. The model was calibrated using both relaxation tests and creep tests. The results from both long-term compression perpendicular- to-grain tests (relaxation and creep) performed on glulam (GL30c) from Norway spruce (Picea abies) with moisture control are presented in this paper. The material model considers the effect of loading and moisture changes. For realistic comparison, the pith location of each lamella was specified in the numerical analyses. Ul...

This paper describes the fatigue life computation and comparisons of welded structures made up of high strength steels. Fatigue life of a T-joint two side fillet welded component is computed with four different methods. The methods used for investigation are nominal stress method, effective notch method, structural stress method and simple fracture mechanics method. To investigate the problem using structural stress and effective notch method, a fillet welded plate is modeled in ANSYS software and two-dimensional linear elastic analysis is performed. The fatigue lives obtained with these methods are reported and compared with the results obtained from nominal stress and simple fracture mechanics approach.

This paper presents the investigation of residual stresses on the corners of cold formed high strength structural steel members. In order to achieve magnitude of residual stresses at inside corner of cold bent section, two-dimensional nonlinear finite element analyses (FEA) have been performed by simulating the press-braking process in Ansys software. These simulations were performed by defining material properties of two types of structural steels i.e. S355 and S650 while plate thickness of 5 mm and 10 mm has been used. During the analyses, ro/t ratio of 4, 5, 6 and 7 for 5 mm plate thickness and ro/t ratio of 6, 7 and 8 for 10 mm plate thickness with bent angle of 1100, 1000, 900, 800 and 700 have been maintained. As a result of theses analyses, the tension residual stresses obtained on the middle of the inside surface of the bend range from 60% to 92% of the yield strength of the material. These FE-simulations do not only provide the magnitude of residual stresses but also give a...

The Rajendran-Grove (RG) ceramic damage model is a three-dimensional internal variable based constitutive model for ceramic materials, with the considerations of micro-crack extension and void collapse. In the present paper, the RG ceramic model is implemented into the newly developed computational framework based on the Meshless Local Petrov-Galerkin (MLPG) method, for solving high-speed impact and penetration problems. The ability of the RG model to describe the internal damage evolution and the effective material response is investigated. Several numerical examples are presented, including the rod-on-rod impact, plate-on-plate impact, and ballistic penetration. The computational results are compared with available experiments, as well as those obtained by the popular finite element code (Dyna3D).

The unloading process of an elastic-plastic spherical contact under stick contact condition is analyzed for various material properties. The evolution of normal and shear stress distribution at the contact area as well as the residual profile of the sphere and residual von Mises stresses inside the sphere are presented. Empirical expressions for the residual interference and for the evolution of the interference and contact area during the unloading are provided. Good agreement with experimental results is shown.

We present a detailed theoretical and experimental analysis of Engineered Swift Equilibration (ESE) protocols applied to two hydrodynamically coupled colloids in optical traps. The second particle disturbs slightly (10\%10% at most) the response to an ESE compression applied to a single particle. This effect is quantitatively explained by a model of hydrodynamic coupling. Then we design a coupled ESE protocol for the two particles, allowing the perfect control of one target particle while the second is enslaved to the first. The calibration errors and the limitations of the model are finally discussed in detail.

Progressive and general collapse of structures are extremely able to cause great casualties and financial losses. Accordingly, evaluation the performance of structures after losing primary elements is of great importance to prevent the structural collapse. This paper presents the progressive collapse assessment of RC moment frames with concrete shear wall system according to different span lengths. First, story column was destroyed by removing its reaction in different scenarios. Then, performance of the structure was evaluated under this circumstance to assess the different span length effects in RC moment frames with concrete shear wall. The results indicated that the shear wall has a positive effect on preventing progressive collapse and reduces the maximum vertical displacement by 30%. It was also observed that maximum Dynamic Amplification Factor (DAF) in the building occurs with the shear wall and the minimum length of the span. However, the maximum Demand Capacity Ratio (DCR)...

Background: This study investigated how cumulative lifetime stress, as measured by the Stress and Adversity Inventory (STRAIN) scale, relates to salivary cortisol levels in temporomandibular disorders (TMD) patients compared to controls. Furthermore, to determine which specific lifetime stress domains are the strongest predictors of TMD. Methods: The study was conducted with 110 participants (55 TMDs patients, 55 controls). Lifetime stress was assessed using the STRAIN questionnaire, and salivary cortisol levels were measured at two time points (7 AM and 10 AM) using Enzyme-Linked Immunosorbent Assay (ELISA). Statistical analyses included t-tests, Analysis of variance (ANOVA) and multiple regression to identify significant stress predictors for TMD. Results: The TMDs patients had significantly higher stress scores (11.10 ± 3.26) compared to the controls (1.43 ± 0.99) (p = 0.001). Myalgia showed highest stress levels (11.69 ± 3.72), while patients with myofascial pain had the lowest (8.80 ± 1.14) (p = 0.043). Cortisol levels were highest in the of disc displacement without reduction with limited mouth opening (DDWoR with LO) group (82.49 ± 124.34) and lowest in myalgia patients (4.69 ± 3.90) (p = 0.001). Significant stress predictors for TMDs included relationship stress (p = 0.04), humiliation (p = 0.02), marital/partner stress (p < 0.001) and death-related stress (p = 0.01). Conclusions: TMDs patients experience significantly higher lifetime stress and cortisol levels than controls. Myalgia patients showed a complex psychological and physiological stress link, whereas the DDWoR with LO subgroup exhibited a distinct physiological stress response. Specific life stressors, particularly relationship-and partner-related stress, are key predictors of TMDs. These findings reinforce the importance of a biopsychosocial approach in understanding and managing TMDs. Future research should focus on longitudinal and interventional studies to further elucidate causal mechanisms and effective therapeutic strategies.

In the modern digital age, platforms like Reddit have ascended as pivotal spaces where individuals candidly express their experiences and emotions, especially surrounding stress. The traditional methodologies employed to categorize stress, which predominantly hinge on manual surveys or expansive keyword searches, present inherent limitations. They often provide only a superficial granularity and grapple with the ever-evolving, voluminous data pouring in from platforms like Reddit. Notably, these prevailing systems conspicuously lack the computational sophistication required to deeply comprehend and categorize the intricate expressions of stress embedded in large-scale online dialogues. Such methods frequently misconstrue context, overlook linguistic subtleties, or overgeneralize diverse stressors into overarching, broad categories. In terms of assessment, this research stands out in its originality and novelty, pioneering the application of BERT for discerning stress categories on Reddit. The methodology is delineated with crystal-clear precision and thoroughness, ensuring a replicable blueprint for future endeavors. Given the burgeoning prevalence of online stress dialogues, the research's societal relevance and significance are undeniable. By adroitly bridging a crucial void in stress categorization and proffering a refined, scalable solution, this study solidifies its position as a seminal contribution to the field of online stress analytics.

This paper examines the impact of a multilayered gradient coating, applied via plasmaactivated chemical vapor deposition (PACVD), on the structural and mechanical attributes of nanostructured WC-Co cemented carbides. WC-Co samples containing 5 and 15 wt.% Co were synthesized through a hot isostatic pressing (HIP) process using nanoparticle powders and coated with two distinct multilayer coatings: titanium nitride (TiN) and titanium carbonitride (TiCN). Nanosized grain formation without microstructural defects of the substrates, prior to coating, was confirmed by magnetic saturation and coercivity testing, microstructural analysis, and field emission scanning electron microscope (FESEM). Nanoindentation, fracture toughness and hardness testing were conducted for uncoated samples. After coatings deposition, characterizations including microscopy, surface roughness determination, adhesion testing, coating thickness measurement, and microhardness examination were conducted. The impact of deposited coatings on wear resistance of produced hardmetals was analyzed via scratch test and dry sliding wear test. Samples with higher Co content exhibited improved adhesion, facilitating surface cleaning and activation before coating. TiN and TiCN coatings demonstrated similar roughness on substrates of identical composition, suggesting Co content's minimal influence on layer growth. Results of the mechanical tests showed higher microhardness, higher elastic modulus, better adhesion, and overall superior tribological properties of the TiCN coating.