Probabilistic micromechanical spatial variability quantification in laminated composites

SN and SS are grateful for the support provided through the Lloyd’s Register Foundation Centre. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research.Peer reviewedPostprin

On quantifying the effect of noise in surrogate based stochastic free vibration analysis of laminated composite shallow shells

This paper presents the effect of noise on surrogate based stochastic natural frequency analysis of composite laminates. Surrogate based uncertainty quantification has gained immense popularity in recent years due to its computational efficiency. On the other hand, noise is an inevitable factor in every real-life design process and structural response monitoring for any practical system. In this study, a novel algorithm is developed to explore the effect of noise in surrogate based uncertainty quantification approaches. Representative results have been presented for stochastic frequency analysis of spherical composite shallow shells considering Kriging based surrogate model. The finite element formulation for laminated composite shells has been developed based on Mindlin’s theory considering transverse shear deformation. The proposed approach for quantifying the effect of noise is general in nature and therefore, it can be extended to explore other surrogates under the influence of noise

Stochastic natural frequency analysis of damaged thin-walled laminated composite beams with uncertainty in micromechanical properties

This paper presents a stochastic approach to study the natural frequencies of thin-walled laminated composite beams with spatially varying matrix cracking damage in a multi-scale framework. A novel concept of stochastic representative volume element (SRVE) is introduced for this purpose. An efficient radial basis function (RBF) based uncertainty quantification algorithm is developed to quantify the probabilistic variability in free vibration responses of the structure due to spatially random stochasticity in the micro-mechanical and geometric properties. The convergence of the proposed algorithm for stochastic natural frequency analysis of damaged thin-walled composite beam is verified and validated with original finite element method (FEM) along with traditional Monte Carlo simulation (MCS). Sensitivity analysis is carried out to ascertain the relative influence of different stochastic input parameters on the natural frequencies. Subsequently the influence of noise is investigated on radial basis function based uncertainty quantification algorithm to account for the inevitable variability for practical field applications. The study reveals that stochasticity/ system irregularity in structural and material attributes affects the system performance significantly. To ensure robustness, safety and sustainability of the structure, it is very crucial to consider such forms of uncertainties during the analysis

Type I singularities and the Phantom Menace

We consider the future dynamics of a transient phantom dominated phase of the universe in LQC and in the RS braneworld, which both have a non-standard Friedmann equation. We find that for a certain class of potentials, the Hubble parameter oscillates with simple harmonic motion in the LQC case and therefore avoids any future singularity. For more general potentials we find that damping effects eventually lead to the Hubble parameter becoming constant. On the other hand in the braneworld case we find that although the type I singularity can be avoided, the scale factor still diverges at late times.Comment: More references added. Final PRD versio

Probing the Stochastic Dynamics of Coronaviruses: Machine Learning Assisted Deep Computational Insights with Exploitable Dimensions

A machine learning assisted efficient, yet comprehensive characterization ofthe dynamics of coronaviruses, in conjunction with finite element (FE)approach, is presented. Without affecting the accuracy of prediction inlow-frequency vibration analysis, an equivalent model for the FE analysis isproposed, based on which the natural frequencies corresponding to first threenon-rigid modes are analyzed. To quantify the inherent system-uncertaintyefficiently, Monte Carlo simulation is proposed in conjunction with themachine learning based FE computational framework for obtaining completeprobabilistic descriptions considering both individual and compound effect ofstochasticity. A variance based sensitivity analysis is carried out to enumeratethe relative significance of different material parameters corresponding tovarious constituting parts of the coronavirus structure. Using the modalcharacteristics like natural frequencies and mode shapes of the virus structureincluding their stochastic bounds, it is possible to readily identifycoronaviruses by comparing the experimentally measured dynamic responsesin terms of the peaks of frequency response function. Results from this first ofits kind study on coronaviruses along with the proposed generic machinelearning based approach will accelerate the detection of viruses and createefficient pathways toward future inventions leading to cure and containmentin the field of virology

Development and characterizations ofultra-highmolecular weightEPDM/PPbasedTPVnanocomposites for automotive applications

This research article reports, the preparation of thermoplastic vulcanizates (TPVs) and TPV nanocomposites (TPVNs) based on EPDM and polypropylene (PP). New generation ultra-high molecular weight EPDM (UHMW-EPDM) and PP with nano-fillers (nano-clay and nano-silica) and has been studied and characterized extensively typically for automotive applications. This special type of UHM-EPDM-based TPVs exhibit superior physico-mechanical properties over conventional EPDM-based TPVs and in the presence of nano-fillers, they show even better physical properties. The TPVNs were prepared with a fixed EPDM: PP ratio and the nano fillers were varied at different concentrations. The influence of nano-fillers, especially hectorite nano-clay and nano-silica has been first explored through physico-mechanical properties. Tensile strength, elongation at break, and modulus at various strain are improved for nano-filler filled TPVNs. We have observed that due to the incorporation of nano-fillers into the TPV matrix, swelling has been decreased. From morphology (AFM, SEM) study, it is observed that the fillers are well dispersed in the TPV matrix and nano-silica fillers are well dispersed than nano-clay (hectorite). Furthermore, small-angle X-ray scattering (SAXS) studies have also been pursued to get a better insight into the TPV system. These newly developed TPVs can be used as potential candidates for application in the automotive sector

Cosmological evolution of interacting phantom (quintessence) model in Loop Quantum Gravity

The dynamics of interacting dark energy model in loop quantum cosmology (LQC) is studied in this paper. The dark energy has a constant equation of state $w_x$ and interacts with dark matter through a form $3cH(\rho_x+\rho_m)$. We find for quintessence model ($w_x>-1$) the cosmological evolution in LQC is the same as that in classical Einstein cosmology; whereas for phantom dark energy ($w_x<-1$), although there are the same critical points in LQC and classical Einstein cosmology, loop quantum effect reduces significantly the parameter spacetime ($c, w_x$) required by stability. If parameters $c$ and $w_x$ satisfy the conditions that the critical points are existent and stable, the universe will enter an era dominated by dark energy and dark matter with a constant energy ratio between them, and accelerate forever; otherwise it will enter an oscillatory regime. Comparing our results with the observations we find at $1\sigma$ confidence level the universe will accelerate forever.Comment: 15 pages, 8 figures, to appear in JCA

Scalar field exact solutions for non-flat FLRW cosmology: A technique from non-linear Schr\"odinger-type formulation

We report a method of solving for canonical scalar field exact solution in a non-flat FLRW universe with barotropic fluid using non-linear Schr\"{o}dinger (NLS)-type formulation in comparison to the method in the standard Friedmann framework. We consider phantom and non-phantom scalar field cases with exponential and power-law accelerating expansion. Analysis on effective equation of state to both cases of expansion is also performed. We speculate and comment on some advantage and disadvantage of using the NLS formulation in solving for the exact solution.Comment: 12 pages, GERG format, Reference added. accepted by Gen. Relativ. and Gra