Effect Of Initial Stress Research Articles

On the three-dimensional dynamics of microtubule by considering initially stress

To design anticancer drug Taxol working more efficiently, looking at details of microtubules' dynamic behavior has become more important for researchers worldwide. According to this issue, dynamic stability analysis of microtubule-associated proteins (MAPs) using the state-space technique based on three-dimension elasticity theory is presented. Besides, the MAPs structure is under various body pressure. The state-space technique is applied along the radial direction, and the differential quadrature method (DQM) along the axial direction in the case of another end supports. The novelty of the current study considers the various boundary conditions for MAPs structure and body pressure, which is implemented on the proposed model using the theory of Three-dimension (3D) elasticity. The validity of applied solutions is examined by comparing results with those of available literature, experimental data, and molecular dynamic (MD) simulation outcomes. A thorough parametric investigation is conducted on the effect of initial stress, boundary conditions, and geometry of the shell (such as mid-radius to thickness and length to mid-radius ratios) on the dynamic stability of the MAPs structures under initial stress.

Thermal conductivity changes of photo-elastic semiconductor excited in gravitational field with hydrostatic initial stress and internal heat source

In this work, the effect of hydrostatic initial stress is studied with the exited semiconductor material. Electrons are exited at the free surface of the elastic semiconductor medium using the photo-thermal-elastic theory during the transport (diffusion) process. The thermal memories are due to the dual-phase-lag (DPL) relaxation times of the heat conduction equation with a novel model. In this model, the thermal conductivity is chosen as a linear dependent function of the thermal temperature impact which is variable. The effect of gravitational field is taken into account during the two-dimensional (2D) elastic deformation under the impact of an internal heat source. The Kirchhoff transformation mapping is used. The harmonic wave (normal mode) method is applied for the 2D governing equations to obtain the main physical fields analytically. Some thermal and mechanical forces are applied with other elastic-plasma conditions at the free surface of the semiconductor material to get the complete solutions. Some comparisons used a novel parameters which depend on the DPL model and the differences in the thermal conductivity parameters and they are illustrated graphically and discussed.

Elasticity Solution for Bending and Frequency Behavior of Sandwich Cylindrical Shell with FG-CNTRC Face-Sheets and Polymer Core Under Initial Stresses

This paper explores the high-accuracy analysis of bending and frequency response of the sandwich cylindrical shell with functionally graded (FG) carbon nanotubes reinforced composite (FG-CNTRC) face-sheets and polymeric core under the effect of initial axial stress and various mechanical loading based upon the three-dimensional theory of elasticity for various sets of boundary conditions. The sandwich structure is composed of multilayers with uniformly dispersed carbon nanotubes (CNT) in each fictitious layer of face-sheets, but its weight fraction changes layer-by-layer along the thickness direction. With the aid of compatibility conditions, the sandwich structure with three layers is modeled. Analytical bending and frequency solutions are obtained for simply supported shells. Also, the state-space based differential quadrature method (SS-DQM) is employed to determine the bending and frequency response of the sandwich cylindrical shell by considering various boundary conditions. The bending response of the sandwich cylindrical shell is obtained under the impact of various mechanical loadings. The influences of several parameters, such as initial stress and various mechanical loadings are investigated on the bending and frequency of the structures. The results of the presented study can be served as benchmarks to assess the validity of the conventional two-dimensional theory.

Torsional vibration of irregular single-walled carbon nanotube incorporating compressive initial stress effects

Abstract This study is an attempt to show the impacts of surface irregularity and compressive initial stresses on the torsional vibration of a single-walled carbon nanotube (SWCNT). The governing equation and corresponding closed-form solutions were derived with the aid of Hamilton's principle. Then, the natural frequencies were obtained analytically and the influences of surface irregularity and compressive initial stresses on the torsional vibration were studied in detail. Numerical results analyzing the torsional vibration incorporating compressive initial stress effects were discussed and presented graphically. The effects of surface irregularity on the natural frequency of torsional vibrations of nanomaterials, especially for SWCNTs, have not been investigated before, and most of the previous research works have been carried for a regular carbon nanotube. Therefore, it must be emphasized that the torsional vibrations of irregular SWCNTs are novel and applicable for the design of nano-oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element. The analytical solutions and numerical results revealed that the surface irregularity and compressive initial stress have notable effects on the natural frequency of torsional vibrations. It has been observed that, as the surface irregularity and compressive initial stress parameters increase, the torsional natural frequency of vibrations of SWCNTs also increases. Since SWCNTs have very small size, they are always subject to initial stresses from different resources; therefore, understanding the influences of compressive initial stresses on the torsional frequency of nanotubes helps the engineers and researchers to design proper nanodevices for different applications with irregular shapes.

Dispersive characterization of Rayleigh surface waves in a liquid medium with inhomogeneity coefficients

The primary purpose of this paper is to examine the role of initial stress, magnetic field, coefficient of heat transfer, and inhomogeneity coefficients on the Rayleigh wave propagation. A liquid medium with an inhomogeneity coefficient associated with the density in the form of a trigonometric and linear function of depth has been considered. It is laid over an orthotropic rotating magneto-thermo-elastic medium under gravity and initial stress. By employing suitable mathematical treatment, displacements have been found in the form of and functions. The frequency equation has been achieved analytically with the help of natural boundary conditions. Numerical calculations and discussions have been performed with the help of graphical presentation, justifying the impact of inhomogeneity coefficients. As an outcome, a significant effect of initial stress and magnetic field on Rayleigh wave propagation has also been observed, which finds its application towards geophysical prospecting, wave mechanics, civil engineering, and mechanical engineering.

Responses of multilayered two-dimensional decagonal quasicrystal circular nanoplates with initial stresses and nanoscale interactions

Mechanical behaviors in multilayered two-dimensional decagonal quasicrystal (QC) circular nanoplates with initial stresses and nanoscale interactions including electrostatic and Casimir forces are investigated using the state space approach. A uniform static initial biasing field with the initial stresses and related electric displacement for the piezoelectric phase is considered in this research. The external voltage and no voltage between the nanoplate and substrate is respectively applied to the model with QC/crystal/QC structure. The electromechanical coupling characteristics of the model are numerically calculated for different nonlocal scale parameters, initial gaps, initial stresses, and nanoscale interactions. Results indicate that all responses in the phonon, phason, and electric fields are positively influenced by the attraction between the substrate and nanoplate under the Casimir force. The effect from Casimir force is more significant than the effect produced by the electrostatic force under the applied external voltage. The initial compressive stress can reduce displacement and increase electric displacement and Casimir force. Besides, the effect of initial compressive stress is not as evident as the Casimir effect, which determines loading conditions.

A rotational gravitational stressed and voids effect on an electromagnetic photothermal semiconductor medium under three models of thermoelasticity

In the current article, the main aim is to investigate a new model on a volume fraction, photothermal, initial stress, electromagnetic field, gravity, and rotation effect on an isotropic homogeneous semiconducting generalized thermoelasticity solid under three thermoelastic models viz: classical dynamical (CD), Lord–Shulman (LS), and dual-phase-lags (DPL). The basic governing equations of the problem are presented considering voids, electromagnetic field, photothermal, initial stress, gravitational, rotation, and semiconducting in the context of the model of generalized thermoelasticity. The normal mode analysis method has been applied for solving the partial differential equations to this phenomenon under the assumption boundary conditions. The obtained results see that the photothermal, rotation, electromagnetic field, voids, the process of semiconductor, initial stress, gravity, and thermal relaxation time took a significant role on the phenomenon. The physical quantities with some comparisons are introduced analytically and presented by figures to clear the impact of the external parameters and agreement with the previous and practical results.

Dual-phase-lag model on thermo-microstretch elastic solid Under the effect of initial stress and temperature-dependent

The present paper attempts to investigate the propagation of plane waves in an isotropic elastic medium under the effect of initial stress and temperature-dependent properties. The modulus of elasticity is taken as a linear function of the reference temperature. The formulation is applied under the thermoelasticity theory with dual-phase-lag; the normal mode analysis is used to obtain the expressions for the displacement components, the temperature, the stress, and the strain components. Numerical results for the field quantities are given in the physical domain and illustrated graphically. Comparisons are made with the results predicted by different theories (Lord–Shulman theory, the classical coupled theory of thermoelasticity and the dual-phase-lag model) in the absence and presence of the initial stress as well as the case where the modulus of elasticity is independent of temperature.

Vibration Analysis of Nanoplate with the Effects of Surface Irregularity and Initial Stresses

Based on Kirchhoff plate theory, the vibration behavior of irregular nanoplate with consideration of initial compressive stress effects is investigated. The equations of motion are derived and the closed form solutions for the natural frequency of the nanoplate are obtained. The analytical solutions reveal that, the natural frequency of the nanoplate, are found to be significantly dependent on the irregularity and compressive initial stresses present in the nanoplate. Numerical results show that, the natural frequency of nanoplates increases with increase of surface irregularity and initial stress parameters. To the author best knowledge, the effects of surface irregularity and initial stresses on the vibration behaviour of nanoplates have not yet been studied, and the present work is an attempt to find out this effectiveness. The results of this work is expected to be useful to design and analyze the vibration properties of nanostructures and Devices in NEMS.

S-waves propagation in a magneto-elastic half-space of non-homogeneous anisotropic material under couple stress and rotation

The effect of magnetic field parameter H ¯ , rotation parameter Ω ¯ and couple stress parameter R on propagation of shear waves in an anisotropic, thinly layered laminated medium is explored. The frequency equation for the problem has been derived to determine the velocity of the shear waves using linear inhomogeneties. The numerical computation for different values of rigidity parameter A, density parameter C, anisotropic factor N ¯ , initial stress parameter P ¯ , magnetic field parameter H ¯ couple stress parameter R and wave number has been made and the results are shown graphically using MATLAB. The results indicate that the effects of initial stress, magnetic field, anisotropy, couple stress and rotation are very pronounced.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ КОНТАКТНОЇ ВЗАЄМОДІЇ ПОПЕРЕДНЬО НАПРУЖЕНОГО КІЛЬЦЕВОГО ШТАМПА ТА ПРУЖНОГО ПІВПРОСТОРУ З ПОЧАТКОВИМИ НАПРУЖЕНЯМИ

Стаття присвячена математичному моделюванню контактної взаємодії попередньо напруженого кільцевого штампа та пружного півпростору з початковими (залишковими) напруженнями. Представлено розв’язок для кільцевого пружного штампа, що враховує вплив початкових напружень. Задачу розв’язано у випадку рівних коренів визначального рівняння. Дослідження представлено в загальному вигляді для теорії великих початкових деформацій і двох варіантів теорії малих початкових деформацій у рамках лінеаризованої теорії пружності при довільній структурі пружного потенціалу. Припускається, що початкові стани пружного кільцевого штампа та пружного півпростору однорідні та рівні. Дослідження проводиться в координатах початкового деформованого стану, які пов'язані з лагранжевими координатами (природного стану). Крім того, вплив кільцевого штампа викликає невеликі збурення відповідних величин основного напружено-деформованого стану. Також передбачається, що пружний кільцевий штамп та пружний півпростір виготовлені з різних ізотропних, трансверсально-ізотропних або композиційних матеріалів. Наведені загальні розв’язки основних диференціальних рівнянь лінеаризованої теорії пружності у випадку осесиметричної деформації для скінченної кільцевої області. У результаті, розв’язки поставленої задачі представлені у вигляді нескінченних рядів, коефіцієнти яких визначаються з нескінченної системи алгебраїчних рівнянь. Проведено дослідження впливу початкових (залишкових) напружень у півпросторі та кільцевому штампі на розподіл контактних характеристик в області контакту. У випадку рівних коренів та потенціалу Бартенєва-Хазановича наведено результати чисельного аналізу, що подані у вигляді графіків, які ілюструють достатньо значний вплив початкових напружень. Отже, вплив початкових напружень на напружено-деформований стан пружного кільцевого штампа, що втискається у пружний півпростір, полягає у тому, що: у випадку стиснення початкові напруження в півпросторі призводять до зменшення напружень у пружному штампі, а у випадку розтягу – до їх збільшення, а для переміщень – навпаки.

Electromagnetic field and initial stress on a porothermoelastic medium

In this study, the porothermoelastic problem with the effect of the magnetic field and initial stress was investigated. We applied normal mode analysis to solve the resulting non-dimensional coupled equations. Numerical results for the displacements, temperature distribution, pore pressure, stresses, induced electric field and induced magnetic field distributions are presented graphically and discussed. The medium deformed because of thermal shock and due to the application of the magnetic field, there result an induced magnetic and an induced electric field in the medium. Numerical analyses are given graphically on the square (2D) and cubic (3D) domains to illustrate the effects of the porosity parameter, magnetic field and initial stress parameter on the physical variables.

Study on the Effect of Isotropic Initial Stress on the Anchoring Performance of Self‐Expanding Bolts

In order to study the anchoring performance of a new type of self‐expanding, high‐strength, precompression anchoring technology with a large amount of expansion agent (ω ≥ 5) cement slurry as anchoring solids under confined surrounding rock conditions, a rock mass anchoring device and methods that simulate in situ stress are developed, and real‐time monitoring of expansion stress and anchor pull‐out tests are carried out. The results show that the internal interface stress has a loss effect over time, and the stress loss value shows a linear increase trend with the dosage, but the loss rate shows a linear decreasing relationship with the dosage. This paper defines the coordinated additional stress and obtains its temporal and spatial evolution law in the rock mass. It is pointed out that there is a lag time difference between the peak of internal interface stress and the peak of coordinated additional stress, explaining its mechanical mechanism from the perspective of stress transfer. The strong restraint of the sealing section of the anchor hole causes the anchor solid to form a “shuttle‐shaped” microexpanded head with thin ends and a middle drum under the expansion stress. During the drawing process, the microexpanded head is “stuck” in the anchor hole and moves upward to form the unique “load platform effect” of the anchoring system. And the mechanical mechanism diagram of this effect is obtained. It is pointed out that this effect can greatly improve the ductility of the anchoring system and the ultimate energy consumption value of damage. A prediction model for the ultimate pull‐out force of self‐expanding bolts is established. It is pointed out that the initial confining stress value has an exponential effect on the ultimate pull‐out force. It shows that the surrounding rock with strong confinement constraints can greatly increase the ultimate pull‐out resistance of the bolt. The self‐expanding strengthening coefficient λ and the surrounding rock stress influence coefficient k are introduced, the bolt interface mechanics formula and energy equation of the self‐expanding anchor system are established, and the feasibility of the formula is verified by the calculation example. It is concluded that the ultimate pull‐out resistance of the anchorage with ω = 30 is increased by 3.38 times compared with the ordinary anchorage under the initial confining stress condition of 0.7 MPa, the prepeak displacement of the bolt is increased by 2.08 times, and the prepeak energy consumption of the anchoring system is increased by 7.34 times. The cost only increased by 0.023% based on the literature example.

Influence of gravity and initial stress on Rayleigh wave propagation in magneto-thermoelastic medium

The main aim of present study is to show the effect of gravity, initial stress and magnetic field on the Rayleigh waves propagation in homogeneous orthotropic magneto-thermoelastic medium in the context of Three Phase Lag (TPL) model at two temperature. The governing equations of thermoelasticity have been solved by normal mode technique to deduce the frequency equation for Rayleigh wave with relevant boundary conditions. Special cases have been derived for isothermal and thermally insulated surfaces. Computer simulation is used for numerical discussion to show the effects of various parameters on phase velocity of Rayleigh waves. The variation in phase velocity corresponding to wave number has been demonstrated graphically in the presence of gravity, initial stress and magnetic field.

Vibrational analysis of an irregular single-walled carbon nanotube incorporating initial stress effects

AbstractIn this work, an attempt is done to apply the eigenvalue approach as well as Donnell thin-shell theory to find out the vibrational analyses of an irregular single-walled carbon (ISWCNT) incorporating initial stress effects. The effects of surface irregularity and initial stresses on natural frequency of vibration of nano materials, especially for single-walled carbon nanotubes (SWCNTs), have not been investigated before, and most of the previous research have been carried for a regular and initial stress-free CNTs. Therefore, it must be emphasized that the vibrations of prestressed irregular SWCNT are novel and applicable for the design of nano oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element. The surface irregularity is assumed in the parabolic form at the surface of SWCNT. A novel equation of motion and frequency equation is derived. The obtained numerical results provide a better representation of the vibration behavior of prestressed ISWCNTs. It has been observed that the presence of either surface irregularity or initial stress has notable effects on the natural frequency of vibration, particularly in the short-length SWCNTs. Numerical results show that the natural frequency of SWCNT decreases with increase in surface irregularity and initial stress parameters. To the authors’ best knowledge, the effect of surface irregularity and initial stresses on the vibration behavior of SWCNTs has not yet been studied, and the present work is an attempt to find out this effectiveness. In addition, the results of the present analysis may serve as useful references for the application and the design of nano oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element.

Effect of initial deviatoric stress on anisotropy of marine clay during principal stress rotation

The effect of the initial deviatoric stress direction and magnitude of deviatoric stress q on the strain components and non-coaxial behavior of soft marine clay during principal stress rotation was experimentally examined. The strain components and pore water pressure depended considerably on the deviatoric stress direction and q. Through polar diagrams, a notable non-coaxiality was observed between the orientations of the major principal strain increment and major principal stress, and the non-coaxial angle fluctuated with variations in the initial deviatoric stress direction and q. The results can provide an experimental basis for constitutive modeling of continuous major principal stress axes for ocean engineering.

Surface waves in hygrothermoelastic half-space with hydrostatic initial stress

The present research article deals with the study of surface wave propagation in hygrothermoelastic medium with hydrostatic initial stress. The coupled wave equations in terms of displacement, temperature and moisture concentration are solved analytically. The values of the penetration depth of different waves are obtained and depicted graphically against frequency. To explore some interesting results, the authors have also discussed deformation in the medium caused due to a mechanical force along the free surface of hygrothermoelastic solid with hydrostatic initial stress. The components of displacement, mechanical stresses, moisture concentration and temperature distribution in the medium are obtained and presented analytically. The graphical results of the variations of these quantities are presented graphically to show the effect of hydrostatic initial stress.

Nonlinear Buckling Strength of Steel H-Beam under Localized Fire and Pure Bending

This paper presents a numerical simulation to assess lateral-torsional buckling (LTB) behavior of steel H-beams exposed to localized fire. The nonlinear buckling analysis was conducted using a finite element program, ABAQUS, to assess LTB of the beams. The steel beams were subjected to pure bending and localized fire. The location of the localized fire was applied below at a one-eighth point, a quarter-point and a half of the beam from the support. The combined effects of initial geometric imperfection and residual stress were also considered. The buckling strength of the beam under localized fire and ISO-834 standard fire were generated and compared. The results showed that the LTB strength degradation of the beam under localized fire was slower than that in ISO-834 standard fire. The fire source location and the length-to-height ratio of the beam have a significant effect on the LTB strength of the beam. The LTB capacity of beams using Eurocode 3 with the uniform heating assumption can give over-conservative results when the real fire scenario is localized fire. The buckling strength of steel beams using Eurocode 3 can give unconservative results when the fire scenario is ISO-834 standard fire.

Influence of several fields on Rayleigh waves propagation in a fiber-reinforced orthotropic half-space material under four thermoelastic models

The objective of this paper is to investigate the fiber-reinforced with effect of rotation, initial stress, heat flux, and gravity field on Rayleigh waves in electro-magnetoelastic homogeneous orthotropic material half-space under four models of generalized thermoelasticity: (i) classical and dynamical coupled model (CD), (ii) the Lord–Shulman model (LS), (iii) the Green–Lindsay model (GL), and (iv) the Green–Naghdi model (GN of type II) is devoted to study the problem. Lame’s potentials are used to obtain the frequency equation, which determines the velocity of Rayleigh waves (real part) and the attenuation coefficient (imaginary part) of the determinant under rotation, magnetic field, electric field, heat flux, initial stress, and gravity field. The numerical results have been obtained and illustrated graphically for each case. A comparison of the results was obtained with the previous theories of thermoelasticity in the absence of fiber-reinforced. The results obtained indicated the significant effect of the fiber-reinforced on the propagation of surface waves that has good contributions to industries, engineering, structures, and other topics related to the phenomenon.

Effects of initial stress state on the subsurface stress distribution after ultrasonic impact treatment on thick specimens

Thick welded specimens with different initial stress states were prepared and treated with the ultrasonic impact treatment (UIT). The subsurface stresses before and after UIT were measured by the X-ray diffraction (XRD) method combined with layer removal. The measured results were corrected based on the finite element correction method. The effects of initial high tensile stress and low compressive stress on the in-depth after-UIT stress distributions were investigated. The results show that initial stress has no effects on the stresses induced by the UIT within 1 mm depth and within that depth, UIT can induce almost the same longitudinal and transverse stress curves beneath the surface with a peak compressive stress close to the material yield strength at the depth of near 0.6 mm and 0.8 mm. UIT induces almost the same longitudinal and transverse stresses along with the measured depth under initial low compressive stress state. While under the initial high tensile stress state, the initial stress dominates the final stress distribution over 1 mm depth. Initial high tensile stress (welding residual stress) can reduce the depth of the after-UIT compressive stresses to 62.5% to 75% of that under the initial low-compressive stress state.