stress

The bending of sandwich plates made of functionally graded material (FGM) that are supported by variable two-parameter elastic foundations under hygro-thermo-mechanical loads is covered in this paper. This study's methodology was based on refined trigonometric shear deformable plate theory (RTSDT) and four-variable refined plate theory. The governing equation was then obtained by introducing the virtual work principle and solving it using a Navier solution. We evaluated our intriguing results with several models found in the literature after we had obtained them. Lastly, we talked about the influence of the elastic foundation parameters, the plate aspect ratio, the power-law index, temperature and moisture differential, and the layer thickness ratio on symmetrical and asymmetrical plates, with or without a middle core.

With the invention of internal combustion engines in the late 19th century, a tremendous transformation in the field of transportation occurred, paving the way for acceleration in all human endeavors. Consequently, internal combustion engines have continuously advanced, with industry players competing and innovating in this sector. Various industries have shown a noticeable interest in creative approaches to design and improve the quality and performance of these engines. Internal combustion engines can be broadly categorized into gasoline and diesel engines. Marine diesel engines, like gasoline engines, are internal combustion or internal ignition engines that convert chemical energy from fuel into thermal energy inside the cylinder and then convert thermal energy into the mechanical energy required for ignition generation. The importance and necessity of using diesel engines in various industries, especially in maritime applications, are undeniable, as the focus of this research. The field of diesel engines is considered one of the crucial components of a country's industrial and scientific self-reliance and ignition, with the measurement of a nation's capacity and ignition in various sectors, from politics and economics to defense and military, being dependent on the knowledge, analysis, design, and production of equipment and tools that are internationally competitive. Key parameters that play a significant role in selecting engines include size, ignition, and how they perform in various applications. An engine's ignition level and appropriate performance are directly related to optimal design and understanding the forces and stresses applied to the engine components during operation. The primary objective of this project is to perform a mechanical analysis of the piston, connecting rod, and crankshaft in a 150-horse-ignition marine diesel engine, to improve thermal performance and enhance engine efficiency. To achieve this, an in-depth study will be conducted, using available diagrams to analyze these components, and the results obtained will be used to evaluate strategies for reducing thermal stresses and increasing efficiency. Ultimately, based on the research data, it can be concluded that the quenching process on the piston crown with a ceramic material reduces the maximum stress by an average of 40% for the critical element in four phases: compression, combustion, and exhaust. As a result, it increases the reliability coefficient by 23% for the critical element in the ignition phase.

In this paper, the creep analysis in a thick-walled cylinder subjected to internal pressure and heat flux at the inner and outer surfaces has been investigated. The displacement field is obtained based on the first-order shear deformation theory and the thermal field is assumed two-dimensional through the thickness and along cylinder whose in radial direction the thermal field is considered linear. The equilibrium equations of the mechanical and thermal fields were derived using the energy method and the principle of virtual work for mechanical loading and heat flux. The creep behavior is described by Bailey-Norton’s time-dependent creep law. Analytical solutions with iteration methods have been used to obtain the stresses, strains, and displacement. The relationship between the temperature and the creep deformation was investigated by examining changes in the radial displacement by increasing the temperature by two to three times at a specific point. The effects of parameters such as pressure, heat flux and radial displacement at different temperatures on stress distribution were discussed. It was shown the circumferential stress accounts for the most changes caused by creep behavior. The presented method provides a semi-analytical solution to investigate the creep behavior of the thick-walled cylinders, which can be used for purposes such as designing and their optimization and parametric study under real temperature loading conditions.

In the present work, a displacement-based high-order shear deformation theory is introduced for the static response of functionally graded plates. The present theory is variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. By dividing the transverse displacement into the bending and shear parts and making further assumptions, the number of unknowns and equations of motion of the present theory is reduced a and hence makes them simple to use. The material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of material constituents. The equilibrium equations of a functionally graded plate are given based on the higher order shear deformation theory. The numerical results presented in the paper are demonstrated by comparing the results with solutions derived from other higher-order models found in the literature and the present numerical results of Finite Element Analysis (FEA). In the numerical results, the effects of the grading materials, lay-up scheme and aspect ratio on the normal stress, shear stress and static deflections of the functionally graded sandwich plates are presented and discussed. It can be concluded that the proposed theory is accurate, elegant and simple in solving the problem of the bending behavior of functionally graded plates.

The mechanical properties of a polycarbonate matrix composite with glass fiber reinforcements used for the manufacture of a multistage centrifugal pump impeller are researched in this article. The material properties are modelled using DIGIMAT (The Material Modelling Platform) to determine the strain resistance of the composite with different proportions of reinforcements. The Tsai–Hill failure criterion is used to determine the strength in all cases. The results have been verified by physical testing to determine the influence of the shape and mass proportion of reinforcements on its mechanical properties. The strength of the manufactured part is correlated to technological factors using the MARC MENTAT solver, and the most and the least favorable combinations of these factors are determined.

The present paper aims to study the effects of different mass fractions of silica nanoparticles on the tensile, compressive, and flexural mechanical properties of polymer composites via experimental methods and non-linear damage model. Epoxy polymers consist of two parts: the first part has a low viscosity, ML-506, as the epoxy base, and the second part contains a polyamide as a hardener, HA-11. Spherical silica nanoparticles with four different mass fractions of 0, 0.2, 0.5 and 1 % are dispersed into the epoxy polymer system under two different ultrasonic times. The tensile and flexural mechanical properties of the prepared samples are determined using standard tests. Experimental measurements show that the mechanical properties of polymer composites improve with increasing mass fraction of nanoparticles. In addition, increasing the ultrasonic time from half-an-hour to one hour is further improves the mechanical properties of polymer composites. A non-linear damage model based on the Weibull theory is used to interpret the flexural stress–strain relationships of the tested materials. The parameters in this model are tensile modulus E, Weibull scale parameter σ0 and Weibull shape parameter β. A good agreement is seen between the results of the stress-strain curve obtained from the above mentioned model and experimental results.

Incremental forming process, as one of the methods used for forming complex parts in rapid prototyping, has various applications in the automotive and aerospace industries. The incremental forming process can be used to flange a metal sheet that, compared to conventional flanging, not only increases the formability but also does not require expensive dedicated dies. The deformation and damage mechanisms in the incremental forming process are completely different from conventional forming processes and need exact and thorough investigation. The present study is aimed at evaluating the damage and deformation mechanics in the hole-flanging process by single-stage and multistage incremental forming on AA6061-T6 sheets, considering several parameters affecting damage and fracture, including equivalent plastic strain, stress triaxiality, and lode angle parameter. These important parameters can reveal the stress and strain states as well as the deformation mechanism, which have been less addressed in the hole-flanging by incremental forming. The results indicated that the stress and strain states varied in different regions of the flange wall, such that the strain state was as plane strain at the bottom of the wall in contact with the unformed part of the sheet, biaxial tensile state at the middle of the wall, and uniaxial tensile state at the top of the wall on flange edge. The highest damage was observed at the flange edges, and the fracture occurred at low values of stress triaxiality in this area, indicating the shear fracture in the hole-flanging of AA6061-T6 sheets during the incremental forming. Finally, a slight increase was observed in the forming limit by forming with a multistage strategy instead of the single-stage one, although the equivalent plastic strain increased significantly.

The aim of this study is to evaluate the effect of the alveolar bone quality on von Mises stress at the bone-implant interface during occlusal loading. Four (3D) finite element models of fully osteointegrated 3-mm diameter × 11.5-mm length dental implant indifferent alveolar bone with different cortical bone thickness are created, using SolidWorks computer aided design software. The alveolar bone cortical-spongy bone ratio modelled includes I) 90%-10%, II) 60%-40%, III) 40%-60%, and IV) 10%-90%. These models are then exported to ABAQUS software and stress analyses are run under an occlusal load of 70 N acting on the platform face of the dental implant. Results of this study show that the implants are subjected to similar stress distributions in all models; maximum stress values are confined in the outer cervical plate of the cortical bone around the neck. This could explain bone loss and implant de-osseointegration. Peak stresses are lowest in the model with 90% cortical bone (14.2 MPa) and almost doubled in the model with 10% cortical bone (26.6 MPa). The stress values gradually reduce towards the apical area, demonstrating masticatory force transfer from implant to bone. Furthermore, both cortical and spongy bone structures exhibit highest stress values in the model with thinnest cortical layer. The high interfacial stress concentration near the implant-cortical bone junction could lead to bone failure or implant instability induced by fatigue or overload risk. Results of our study could be a first step towards the development of a clinical pre-operative planning tool for dental implantolgy.

An elastic finite element analysis was conducted to evaluate the stress distribution in the initiation zone of the adhesive rupture during the 3-point bending test. This test is used to measure the adherence between a polyepoxy adhesive and aluminum alloy with different surface treatments. The purpose is to compare, in the high stress concentration areas, the stress fields calculated using finite element method with the experimental data obtained in different configurations. Focusing on the load level at crack initiation, on the localization and the size of adhesive failure initiation, a local criterion for adhesive fracture is proposed based on the value of the stress normal to the interface.

This paper presents two-dimensional stress and strain behavior of a FG rotating cylindrical shell subjected to internal-external pressure, surface shear stresses due to friction, an external torque, and constant temperature field. A power law distribution was considered for thermomechanical material properties. First order shear deformation theory (FSDT) was used to define the displacement and deformation field. Energy method and Euler equation were employed to derive constitutive differential equations of the rotating shell. Systems of Six differential equations were achieved. Eigenvalue and eigenvector methods were used to solve these equations. It was found that the material grading index has a significant effect on stresses and strains of a rotating functionally graded material cylindrical shell in radial and longitudinal directions.

In the present study, investigation of mechanical behaviour of the fuel cladding material for a nuclear superheat Boiling Water Reactor with annular fuel rods, is carried out. In this design, each annular fuel element is cooled internally by steam and externally by water. For the fuel cladding material, radiation embitterment and irradiation-assisted stress corrosion cracking (IASCC) are the most important issues that have to be taken into account. Hence, for cladding, two materials are considered. Preliminary thermal expansion and stress analysis have been done for a fresh (begin of cycle) ASBWR (Annular-fuelled Superheat Boiling Water Reactor) fuel element. The purpose of these analysis is to investigate the stress distribution and thermal expansion of the cladding in the initial phase of operation. The results show that there is a noticeable difference in the axial expansion between the inner and outer claddings. For T91 (modified 9Cr-1Mo steel) cladding, the maximum axial thermal growth of the inner cladding is 22.12 mm, which is about 9.7 mm more than the outer cladding. For Inconel 718 cladding, the results are 27.8 mm and 13.4 mm, respectively.

the amount of rotten tooth that is come out of teeth is an important issue in dental filling because of its effects on strength of teeth. The main goal of this study is to determine a criterion for the amount of rotten tooth which can be brought out. To do so, first, a three-dimensional finite element model of the complex shape of Right First Molar Mandibular has been established. Then, cylindrical holes with different values of height and diameter (diameter of holes from 3 mm to 8 mm and height of 3 mm to 5.9 mm) is created on the cusp of the tooth. A uniform pressure (from 10 Pa to 10 kPa) is applied around the tooth resembling the belt which is utilized in reality. According to the obtained displacement and stress contours, the diameter of tooth hole can be increased up to 7 mm for pressures under 10 Pa while for higher pressures, the diameter of tooth hole can just be increased up to 6 mm. In addition, due to sudden increase in stress at a pressure of 10 kPa, increasing the value of pressure to higher values is not recommended.

This study aims to analyze the linear elastic behavior of an aluminum matrixnanocomposite reinforced with SiC nanoparticles. Once, a representative volume element was consideredfor the nanocomposite with a cuboidal inclusion. The elastic moduli of the matrix and the inclusion werethe same, but it contained eigenstrain. The stress and the strain fields were obtained for the inclusionand the aluminum by Galerkin vector method. The stress and the strain fields in the inclusion problemwere in a good agreement with the results in the literature. A similar representative volume element wasconsidered for the nanocomposite with a cuboidal inhomogeneity. The elastic moduli of the matrix andthe inhomogeneity were different, but it did not have any eigenstrain. For the calculation of the Eshelbytensor and the elastic fields for the inhomogeneity problem, the equivalent inclusion method (EIM) wasapplied. In the EIM, the uniform and equivalent eigenstrain were considered. The stress and the strainfields within the inhomogeneity and the matrix were obtained. Results showed that the stress and thestrain in the cuboidal inclusion were less than the cuboidal inhomogeneity due to the difference betweenthe matrix and the reinforcement materials.

In this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive model is defined by the Θ projection concept, based on the experimental results existing in the literature. Loading applied is due to the inertial body force caused by the rotation and a constant temperature field throughout the disk. To achieve history of stresses and displacements, a numerical procedure using finite difference and Prandtl-Reuss relations is used. Stress and deformation histories are calculated using successive elastic solution method. In order to verify the solution approach, both composite and aluminum rotating disks were taken into account and the thermo-elastic and time-dependent creep behaviours for composite as well as the former for aluminum were obtained. Results from the current study were found to be in very good agreement with those available from literature in the area. It was shown that convex thickness profile disks display the least creep displacement, creep effective and circumferential stresses. Additionally, constant and concave thickness profiles were positively correlated with time while for linear and convex ones, it was found to have an inverse trend.