Natural Frequency based delamination estimation in GFRP beams using RSM and ANN

The importance of delamination detection can be understood from aircraft components like Vertical Stabilizer, which is subjected to heavy vibration during the flight movement and it may lead to delamination and finally even flight crash can happen because of that. Any solid structure's vibration behaviour discloses specific dynamic characteristics and property parameters of that structure. This research investigates the detection of delamination in composites using a method based on vibration signals.  The composite material's flexural stiffness and strength are reduced as a result of delaminations, and vibration properties such as natural frequency responses are altered. In inverse problems involving vibration response, the response signals such as natural frequencies are utilized to find the location and magnitude of delaminations. For different delaminated beams with varying position and size, inverse approaches such as Response Surface Methodology (RSM) and Artificial Neural Network (ANN) are utilized to address the inverse problem, which aids in the prediction of delamination size and location

Artificial neural network based delamination prediction in composite plates using vibration signals

Dynamic loading on composite components may induce damages such as cracks, delaminations, etc. and development of an early damage detection technique for delaminations is one of the most important aspects in ensuring the integrity and safety of composite components. The presence of damages such as delaminations on the composites reduces its stiffness and further changes the dynamic behaviour of the structures. As the loss in stiffness leads to changes in the natural frequencies, mode shapes, and other aspects of the structure, vibration analysis may be the ideal technique to employ in this case. In this research work, the supervised feed-forward multilayer back-propagation Artificial Neural Network (ANN) is used to determine the position and area of delaminations in GFRP plates using changes in natural frequencies as inputs. The natural frequencies were obtained by finite element analysis and results are validated by experimentation. The findings show that the suggested technique can satisfactorily estimate the location and extent of delaminations in composite plates

FABRICATION OF DRUG DELIVERY SYSTEM FOR CONTROLLED RELEASE OF CURCUMIN, INTERCALATED WITH MAGNETITE NANOPARTICLES THROUGH SODIUM ALGINATE/POLYVINYLPYRROLIDONE-CO-VINYL ACETATE SEMI IPN MICROBEADS

Objective: The aim of the present work is to fabricate curcumin (CUR) encapsulated microbeads in the polymer matrix of sodium alginate (SA)/poly(vinylpyrrolidone)-co-vinyl acetate (PVP-co-VAc) intercalated with magnetite nanoparticles (MNPs) using glutaraldehyde (GA)/calcium chloride CaCl2 as the crosslinker. Methods: Magnetite nanoparticles (MNPs) were synthesized by a modified co-precipitation method. Curcumin encapsulated SA/PVP-co-VAc microbeads, intercalated with MNPs were prepared by simple ionotropic gelation technique. The formation of microbeads and uniform distribution of curcumin were characterized using spectroscopic methods. In addition, swelling and drug release kinetic studies of the microbeads were performed in simulated intestinal fluid (pH 7.4) and simulated gastric fluid (pH 1.2) at 37 °C. Results: Microbeads formation was confirmed by Fourier Transform Infrared (FTIR). Differential Scanning Calorimetry (DSC) studies reveal that the peak at 181 °C of CUR was not observed in CUR loaded microbeads, which confirms that CUR was encapsulated at the molecular level in the polymer matrix. The X-Ray diffraction (X-RD) diffractograms of CUR shows 2Ө peaks between 12-28 °, which indicated the crystalline nature of CUR, these peaks are not found in CUR loaded microbeads, suggesting that the drug has been molecularly dispersed in the polymer matrix. The X-RD 2Ө peaks of MNPs are observed in the MNPs loaded microbeads, which confirms that MNPs are successfully loaded in the microbeads. The swelling studies and in vitro release studies were performed at pH 1.2 and 7.4. The results reveal that at pH 7.4 highest swelling and release was observed, which confirms that the developed microbeads are pH sensitive and are suitable for intestinal drug delivery. The drug release kinetics fit into the Korsmeyer-Peppas equation, indicating non-Fickian diffusion. Conclusion: The results concluded that the present system as dependent on pH of the test medium and hence suggest suitability for intestinal drug delivery

Artificial neural network based delamination prediction in composite plates using vibration signals

Dynamic loading on composite components may induce damages such as cracks, delaminations, etc. and development of an early damage detection technique for delamination prediction is one of the most important aspects in ensuring the integrity and safety of such components. The presence of damages such as delaminations on the composites reduces its stiffness and changes the dynamic behaviour of the structures. As the loss in stiffness leads to changes in the natural frequencies, mode shapes, and other aspects of the structure, vibration analysis may be the ideal technique for delamination prediction. In this research work, the supervised feed-forward multilayer back-propagation Artificial Neural Network is used to determine the position and area of delaminations in glass fiber-reinforced polymer (GFRP) plates using changes in natural frequencies as inputs. The natural frequencies were obtained by finite element analysis and results are validated experimentally. The findings show that the suggested technique can satisfactorily estimate the location and extent of delaminations in composite plates

Bulk viscosity in hyperonic star and r-mode instability

We consider a rotating neutron star with the presence of hyperons in its core, using an equation of state in an effective chiral model within the relativistic mean field approximation. We calculate the hyperonic bulk viscosity coefficient due to nonleptonic weak interactions. By estimating the damping timescales of the dissipative processes, we investigate its role in the suppression of gravitationally driven instabilities in the $r$-mode. We observe that $r$-mode instability remains very much significant for hyperon core temperature of around $10^8$K, resulting in a comparatively larger instability window. We find that such instability can reduce the angular velocity of the rapidly rotating star considerably upto $\sim0.04 \Omega_K$, with $\Omega_K$ as the Keplerian angular velocity.Comment: 10 pages including 7 figure

SODIUM ALGINATE/GELATIN MICROBEADS-INTERCALATED WITH KAOLIN NANOCLAY FOR EMERGING DRUG DELIVERY IN WILSON’S DISEASE

Objective: The aim of the present study was to fabricate and evaluate the drug release studies using Sodium Alginate (SA) and Gelatin (GE) microbeads intercalated with Kaolin (KA) nanoclay for sustained release of D-Penicillamine (D-PA). Methods: Sodium alginate/gelatin/Kaolin blend microbeads were prepared by an extrusion method by using glutaraldehyde (GA) as a crosslinker. The obtained microbeads were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X–ray diffraction (XRD). Drug release kinetics of the microbeads was investigated in simulated intestinal fluid (pH 7.4) at 37 °C. Results: Microbeads formation was confirmed by FTIR spectroscopy. X-RD reveals that the KA should be intercalated with the drug and also it confirms the molecular level dispersion of D-Penicillamine into microbeads. Scanning Electron Microscopy (SEM) studies reveal that the beads were in spherical shape with some wrinkled depressions on the surface. The in vitro release study indicates the D-Penicillamine released in a controlled manner. The in vitro release kinetics was assessed by Korsmeyer-Peppas equation and the ‘n’ value lies in between 0.557-0.693 indicates Non-Fickian diffusion process. Conclusion: The results suggest that the developed KA intercalated microbeads are good potential drug carrier for the controlled release of D-PA