initial stress
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Author(s):  
Ahmed E. Abouelregal ◽  
Kadry Zakaria ◽  
Magdy A. Sirwah ◽  
Hijaz Ahmad ◽  
Ali F. Rashid

This work aims to assess the response of viscoelastic Kelvin–Voigt microscale beams under initial stress. The microbeam is photostimulated by the light emitted by an intense picosecond pulsed laser. The photothermal elasticity model with dual-phase lags, the plasma wave equation and Euler–Bernoulli beam theory are utilized to construct the system equations governing the thermoelastic vibrations of microbeams. Using the Laplace transform technique, the problem is solved analytically and expressions are provided for the distributions of photothermal fields. Taking aluminum as a numerical example, the effect of the pulsed laser duration coefficient, viscoelasticity constants and initial stress on photothermal vibrations has been studied. In addition, a comparison has been made between different models of photo-thermoelasticity to validate the results of the current model. Photo-microdynamic systems might be monolithically integrated on aluminum microbeams using microsurface processing technology as a result of this research.


2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Jiangchao Liu ◽  
Wenxue Gao ◽  
Shenghui Zhang ◽  
Yu Hu
Keyword(s):  

2022 ◽  
Vol 51 ◽  
pp. 101472
Author(s):  
Jun Yan ◽  
Qi Zhang ◽  
Qi Xu ◽  
Zhirui Fan ◽  
Haijiang Li ◽  
...  

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3243
Author(s):  
Ambreen Afsar Khan ◽  
Anum Dilshad ◽  
Mohammad Rahimi-Gorji ◽  
Mohammad Mahtab Alam

Considering the propagation of an SH wave at a corrugated interface between a monoclinic layer and heterogeneous half-space in the presence of initial stress. The inhomogeneity in the half-space is the causation of an exponential function of depth. Whittaker’s function is employed to find the half-space solution. The dispersion relation has been established in closed form. The special cases are discussed, and the classical Love wave equation is one of the special cases. The influence of nonhomogeneity parameter, coupling parameter, and depth of irregularity on the phase velocity was studied.


2021 ◽  
Vol 9 ◽  
Author(s):  
Guojun Liu ◽  
Yuan Zhao ◽  
Yugang Cheng

This paper examines the fracture propagation problems of supercritical carbon fracturing in low permeability shale. Acoustic emission monitoring and computerized tomography (CT) scanning methods were used to study the influence of initial stress ratios on crack initiation and propagation crack in fracturing experiments. The results show that crack initiation pressure and crack morphology are very different under different stress conditions. Under the condition of constant confining pressure, when the initial stress ratio λ = 1, cracks are mainly in a horizontal direction; while for an initial stress ratio of λ < 1, cracks are mainly in a vertical direction. With the decrease of λ, crack initiation pressure, reopening pressure, and fracturing liquid volume also decrease, and crack propagation is not as obvious. According to CT scanning results, the crack propagation direction is the same as the maximum principal stress, and fewer cracks are initiated with a smaller initial stress ratio. Based on the acoustic emission characteristics, the fracturing process (including crack initiation, propagation, and closure), can be divided into three stages: 1) the pressure accumulation in the wellbore, 2) Pump Closure; and 3) crack reopening. This study provides the basis for a reasonable selection of shale gas fracturing formation and geo-sequestration of greenhouse gas CO2.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Latha Madhuri Poonem ◽  
Rajitha Gurijala ◽  
Sindhuja Ala ◽  
Malla Reddy Perati

PurposeThe purpose of this paper is to investigate the effect of initial stress and heterogeneity on the propagation of torsional waves in dissipative medium. The problem consists of dry sand poroelastic half-space embedded between heterogeneous self-reinforced half-space and poroelastic medium. The frequency equation is derived in the framework of Biot's theory with some variants.Design/methodology/approachTorsional wave propagation in dry sand poroelastic half-space embedded between self-reinforced half-space and poroelastic medium. All the constituents here are assumed to be dissipative, heterogeneous and initial stressed.FindingsPhase velocity and attenuation are computed against wavenumber for various values of self-reinforcement parameter, inhomogeneity parameter and initial stress. Particular cases are discussed in absence of dissipation. The numerical results are presented graphically.Originality/valueInitial stress and heterogeneity effects on torsional waves in dry sand half-space between reinforced half-space and poroelastic medium are investigated. The frequency equation is derived, and which intern gives the phase velocity and attenuation coefficient for various values of initial stress, self-reinforcement parameter and heterogeneity parameter. From the numerical results, it is clear that as wavenumber varies phase velocity and attenuation are periodic in nature for all the cases. Particular cases are discussed in absence of dissipation. This kind of analysis can be extended to any elastic solid by taking magnetic, thermo and piezoelectric effects into account.


Neurosurgery ◽  
2021 ◽  
Vol 90 (1) ◽  
pp. 66-71
Author(s):  
Gregory J. Cannarsa ◽  
Aaron P. Wessell ◽  
Timothy Chryssikos ◽  
Jesse A. Stokum ◽  
Kevin Kim ◽  
...  

2021 ◽  
Author(s):  
Xinnan Liu ◽  
Yuan Tian ◽  
Yihe Wang ◽  
Yiqiang Ren ◽  
Xiaoruan Song

In this paper, global sensitivity analyses of attenuation zones of 2D periodic foundations are conducted. Global sensitivity analyses of upper bound frequency and lower bound frequency of the 1st attenuation zone of 2D periodic foundation are conducted considering four input parameters, i.e., initial stress ratio, filling ratio of core, filling ratio of resonator and periodic constant. Interactions and relative importance of input parameters are calculated.


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