The buckling load parameters of the graded nanotube sandwich structure reported in this article under the influence of uniform thermal loading. The corresponding properties of the graded nanotube ...sandwich evaluated via the extended rule of mixture including temperature dependent properties of each constituent. The nanotube structural model derived mathematically using a higher-order polynomial displacement to maintain the required shear stress continuity and thermal distortion via Green-Lagrange strain. Further, the variational technique is adopted to obtain the governing equilibrium equation of the sandwich structural panel and the subsequent algebraic form achieved using the isoparametric displacement finite element steps. The computational buckling load parameter predicted using the own MATLAB code with the help of the current mathematical model. The model accuracy and the consistency are established through simultaneous convergence and validity study with available published results. Finally, the detail applicability of the current higher-order model is highlighted through a series of numerical examples and corresponding inferences.
The present research reported the large geometrical deformation-induced deformation and stress analysis of the bidirectional (2D) functionally graded material (FGM) shell panel under variable ...mechanical loading (static and dynamic). The responses of graded structures are obtained numerically through an in-house finite element model using the higher-order displacement functions. Additionally, a few experiments are performed first time using layerwise deposited polymeric composite reinforced with luffa-fibre (variation of fibre considered through the thickness) to verify the necessity of the current Green-Lagrange nonlinear strain (GLNST) kinematic model for the graded structure. The numerical effective FG panel properties are computed with the help of Voigt’s micromechanical model, including different grading laws, i.e. power-law (POL), sigmoid (SGM) and exponential (EPL). Also, the model has been prepared considering the porosity (even porosity, EVP and uneven porosity, UEP) variations through the panel thickness to achieve realistic conditions.
Abstract
Asteroseismology is a powerful tool that may be applied to shed light on stellar interiors and stellar evolution. Mixed modes, behaving like acoustic waves in the envelope and buoyancy modes ...in the core, are remarkable because they allow for probing the radiative cores and evanescent zones of red giant stars. Here, we have developed a neural network that can accurately infer the coupling strength, a parameter related to the size of the evanescent zone, of solar-like stars in ∼5 ms. In comparison with existing methods, we found that only ∼43% of inferences were in agreement with a difference less than 0.03 in a sample of ∼1700 Kepler red giants. To understand the origin of these differences, we analyzed a few of these stars using independent techniques such as the Monte Carlo Markov Chain method and echelle diagrams. Through our analysis, we discovered that these alternate techniques are supportive of the neural-net inferences. We also demonstrate that the network can be used to yield estimates of coupling strength and period spacing in stars with structural discontinuities. Our findings suggest that the rate of decline in the coupling strength in the red giant branch is greater than previously believed. These results are in closer agreement with calculations of stellar-evolution models than prior estimates, further underscoring the remarkable success of stellar evolution theory and computation. Additionally, we show that the uncertainty in measuring period spacing increases rapidly with diminishing coupling strength.
The adhesively bonded single-lap joint strength is computed numerically and verified with the experiment. An ABAQUS model is prepared to analyze by adding the primary information, i.e., geometry, ...material properties, element, and solution type, including the boundary conditions. The model accuracy has been verified through two-step comparisons with published numerical deflection data and in-house experiments. The validated model is used to compute the energy-absorbing capacity better to understand lap joint strength. Further, the statistical analysis (variance-based sensitivity analysis) is conducted to measure the model output variability with the model input parameter. Additionally, the influences of geometry and property-dependent design parameters (layup schemes, loading position, adherend thickness ratio (L/t), and adhesive thickness ratio: (a/h), including the overlapping length (25, 30, 35, and 40 mm) are examined through several examples. The conclusions on the overlap length in bonded joints are that an increase in intact/lap length improves the joint stiffness and decreases the deflection. Similarly, a few insights on layer sequence (angle-ply) and shear stress thickness ratio are discussed in detail.
Abstract
Asteroseismology is a powerful tool to probe stellar structure. Spaceborne instruments like CoRoT, Kepler, and TESS have observed the oscillations of numerous stars, among which
δ
Scutis are ...particularly interesting, owing to their fast rotation and complex pulsation mechanisms. In this work, we inferred model-dependent masses, metallicities, and ages of 60
δ
Scuti stars from photometric, spectroscopic, and asteroseismic observations using least-squares minimization. These statistics have the potential to explain why only a tiny fraction of
δ
Scuti stars pulsate in a very clean manner. We find most of these stars with masses around 1.6
M
⊙
and metallicities below
Z
= 0.010. We observed a bimodality in age for these stars, with more than half the sample younger than 30 Myr, while the remaining ones were inferred to be older, i.e., hundreds of Myrs. This work emphasizes the importance of the large-frequency separation (Δ
ν
) in studies of
δ
Scutis. We also designed three machine-learning (ML) models that hold the potential for inferring these parameters at lower computational cost and much more rapidly. These models further revealed that constraining dipole modes can help in significantly improving age estimation and that radial modes succinctly encode information regarding luminosity and temperature. Using the ML models, we also gained qualitative insight into the importance of stellar observables in estimating mass, metallicity, and age. The effective temperature
T
eff
strongly affects the inference of all structure parameters, and the asteroseismic offset parameter
ϵ
plays an essential role in the inference of age.
The natural fiber (Luffa cylindrica fiber) reinforced epoxy composite has been fabricated and their structural responses (frequency and deflection) have been computed experimentally and numerically ...first time using the corresponding experimental elastic properties. The numerical responses are obtained with the help of an in-house MATLAB code developed based on the higher order finite element (FE) model. The completeness of the model has been examined by comparing the current FE solutions (frequency and the central deflection) with the reference as well as in-house experimental data. The effect of fiber volume fractions on the elastic properties is verified for four different weight percentage of treated Luffa fiber (0%, 3.2%, 6.4%, and 9.6%). Finally, the inclusive behavior of the current higher order FE model and the corresponding influence of the significant design parameter of Luffa fiber-reinforced composite structure have been debated by solving different numerical examples.
Abstract Free vibration responses of shear deformable functionally graded single/doubly curved panels under uniform, linear and nonlinear temperature fields are investigated in the present article. ...The micromechanical material model of functionally graded material is computed using Voigt model in conjunction with the power-law distribution to achieve the continuous gradation. The material properties are assumed to be the function of temperatures. The mid-plane kinematics of panel geometry is derived using the higher order shear deformation theory. The governing equation of the vibrated panel is obtained using Hamilton's principle. The desired solutions of free vibrated functionally graded shells are computed numerically using the suitable finite element steps. The convergence behaviour of the numerical results has been checked and validated by comparing the responses with that to available published literatura. The applicability of the proposed model has been highlighted by solving various numerical examples for different material and geometrical parameters and temperature fields.
The finite element (FE) solutions of the smart (SMA: shape memory alloy fibre bonded) composite with and without crack are computed in this research. The structural model is derived mathematically ...considering the shear deformation effect, and the proposed functions maintain the necessary continuity of stresses. The numerical solutions are obtained via the computer code considering the blocking/recovery stress phenomenon (via marching technique) due to the inclusion of SMA fibre. The necessary correctness and the numerical results sensitivities are verified as priori. The solutions are showing an improvement of structural stiffness (decrease in deflections around 22–27% and 14–22% for the prestrain values 3–5% and 10–30% volume fraction of shape memory alloy fibre, SMA) due to the activation of SMA (under elevated temperature) fibres. Finally, the influences of all different structural design (aspect ratio, thickness ratio, boundary conditions, load intensities and crack dimension), material (SMA relevant data), environment and damage effects on the static flexural deflections are examined through a series of examples.
In the present article, the linear and the nonlinear deformation behaviour of functionally graded （FG） spherical shell panel are examined under thermomechanical load. The temperature- dependent ...effective material properties of FG shell panel are evaluated using Voigt＇s micro-mechanical rule in conjunction with power-law distribution. The nonlinear mathematical model of the FG shell panel is developed based on higher-order shear deformation theory and Green-Lagrange type geometrical nonlinearity. The desired nonlinear governing equation of the FG shell panel is computed using the variational principle. The model is discretised through suitable nonlinear finite element steps and solved using direct iterative method. The convergence and the val- idation behaviour of the present numerical model are performed to show the efficacy of the model. The effect of different parameters on the nonlinear deformation behaviour of FG spherical shell panel is highlighted by solving numerous examples.
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