vibrational characteristics
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2022 ◽  
pp. 088532822110649
Author(s):  
Juliana C Rosa ◽  
Jean J Bonvent ◽  
Arnaldo R Santos

The rotary jet spinning technique permits the production of biomaterials that can be used as devices that come into contact with biological systems (including biological fluids) for diagnostic or surgical applications. These materials are composed of synthetic or natural compounds and allow the incorporation of drugs for therapeutic purposes. Two solutions containing 50% poly(lactic acid) (PLA) and 50% poly(ε-caprolactone) (PCL) diluted in three different solvents were prepared for rotary jet spinning (RJS) process. Vancomycin, an antibiotic indicated for the treatment of severe staphylococcal infections in patients with penicillin allergy, was added in the polymer solutions, to obtain drug-loaded fibrous mats. Morphological surface characterization by scanning electron microscopy revealed heterogeneous pores in the microfibers. Vancomycin loading interfered with the morphology of all samples in terms of fiber size, leading to smaller diameter fibers. Attenuated total reflectance/Fourier transform infrared spectroscopy was used for identification of the samples. The vibrational characteristics of PCL/PLA and vancomycin were consistent with expectations. Vero cell culture assays by the extract dilution and direct contact methods revealed the absence of cytotoxicity, except for the sample prepared with 50% of PCL and of a 9/2 (V/V) vancomycin content, with the growth of confluent and evenly spread cells on the fibrous mats surface. Microbiological analysis, performed on Staphylococcus aureus by the halo inhibition test and by the broth dilution method, showed that the antibacterial activity of vancomycin was maintained by the loading process in the polymer fibers. The results showed that rotary jet spinning produces satisfactory amounts of Vancomycin-loaded fibers, as potential web dressing for wound repair


Author(s):  
Somkiat Seesanong ◽  
Chaowared Seangarun ◽  
Banjong Boonchom ◽  
Chuchai Sronsri ◽  
Nongnuch Laohavisuti ◽  
...  

Calcium dihydrogen phosphate monohydrate [Ca(H2PO4)2·H2O] (a fertilizer) was successfully synthesized by the recrystallization process by using a prepared triple superphosphate (TSP) that derived from oyster shell waste as starting material. This bio-green, eco-friendly process to produce an important fertilizer can promote a sustainable society. The shell-waste-derived TSP was dissolved in distilled water and kept at 30, 50, and 80 °C. Non-soluble powder and TSP solution were obtained. The TSP solution fraction were then dried and the recrystallized products (RCP30, RCP50, and RCP80) were obtained and confirmed as Ca(H2PO4)2·H2O. Whereas the non-soluble products (NSP30, NSP50, and NSP80) were observed as calcium hydrogen phosphate dihydrate (CaHPO4·2H2O). The recrystallized yields of RCP30, RCP50, and RCP80 were found to be 51.0%, 49.6%, and 46.3%, whereas the soluble percentages were 98.72%, 99.16%, and 96.63%, respectively. RCP30 shows different morphological plate sizes, while RCP50 and RCP80 present the coagulate crystal plates. X-ray diffractograms confirm the formation of both the NSP and RCP. The infrared adsorption spectra confirmed the vibrational characteristics of HPO42‒, H2PO4‒ and H2O existed in CaHPO4·2H2O and Ca(H2PO4)2·H2O. Three thermal dehydration steps of Ca(H2PO4)2·H2O (physisorbed water, polycondensation, and re-polycondensation) were observed. Ca(H2PO4)2 and CaH2P2O7 are the thermodecomposed products from the first and second steps, whereas the final product is CaP2O6.


Author(s):  
Abhyuday Parihar

Abstract: Conventional leaf spring made up of conventional materials like plain carbon steel are heavy and add weight to vehicle which reduces mileage. This necessitates new material which is light in weight and could provide adequate strength to leaf spring along with higher strain energy absorption to absorb shocks. The current research is intended to study the structural and vibrational characteristics of leaf spring made of P100/6061 Al, P100/AZ 91C Mg and structural steel materials. The investigation is carried out using ANSYS FEA software. The FEA results have shown that P100/AZ/ 91C generated lower stresses as compared to P100/6061 Al and structural steel material. The modal analysis of leaf spring aided to determine mass participation factor and mode shapes corresponding to each frequency. Keywords: Leaf Spring, Energy Absorption, Structural Steel Materials, ANSYS FEA, Frequency.


2021 ◽  
Vol 169 ◽  
pp. 108287
Author(s):  
Ali Reza Damercheloo ◽  
Ahmad Reza Khorshidvand ◽  
S. Mahdi Khorsandijou ◽  
Mohsen Jabbari

2021 ◽  
Vol 9 ◽  
Author(s):  
Muhammad Usman Bashir ◽  
◽  
Anees Ur Rehman ◽  
Aashir Waleed ◽  
Umar Siddique Virk ◽  
...  

Turbomachinery has a vital role in the industrial engineering and the bladed disks such as; compressor, impeller pumps, turbine generator and jet engines are the critical components of turbomachinery. This work is focused on the “mistuning effect” of bladed disks of a turbine, which creates the lack of symmetry and ultimately damages the turbine blade. In order to completely understand the severity of the damage caused by the mistuning effect on the turbine disk, the study and analysis of the model parameters is very important. This work provides an insight to the various effects caused by the presence of crack and mistuning levels, in the mistuned turbine blisk, by using smeared material properties and modal assurance criterion (MAC) techniques. Moreover, a mistuned blisk model with four cracks (at various locations and different depth levels) has been developed and compared with the tuned blisk model, in order to determine the severity of damage occurred. The MAC results indicate that the severity of damage may vary depending on the location and depth of the crack and mistuning may alter the dynamic and vibrational characteristics of the structure.


2021 ◽  
Author(s):  
ALFONSO PAGANI ◽  
MARCO ENEA ◽  
ERASMO CARRERA

In the aerospace industry, machine learning techniques are becoming more and more important for Structural Health Monitoring (SHM). In fact, they could be useful in giving a precise and complete mapping of damage distribution in a structure, including low-intensities or local defects, which cannot be detected via traditional tests. In this work, feedforward artificial neural networks (ANN) are employed for vibration-based damage detection in composite laminates. In the framework of Carrera Unified formulation (CUF), one-dimensional refined models in conjunction with layer-wise (LW) theory are adopted. CUF-based Monte Carlo simulations have been used for the creation of a dataset of damage scenarios for the training of the ANN. Therefore, the latter is fed with the vibrational characteristics of these structures. The trained ANN, given these dynamic parameters, is able to predict location and intensity of all damages in the laminated composite structures.


BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7101-7111
Author(s):  
Wengang Hu ◽  
Shuang Li ◽  
Yan Liu

The effects of the moisture content, density, and striking direction of a hammer on the vibrational characteristics, i.e., the fundamental frequency and dynamic modulus of elasticity, of four wood species, i.e., poplar (Populus tomentosa), mahogany (Swietenia mahagoni), beech (Fagus orientalis), and ash (Fraxinus excelsior), commonly used in wood products were investigated, aiming to provide basic evidence for the nondestructive testing of wood materials. The results showed that the effect of the wood species on the fundamental frequency, dynamic modulus of elasticity, and static modulus of elasticity was statistically significant. The dynamic moduli of elasticity of the four wood species were higher than the corresponding static moduli of elasticity. The effect of the striking direction on the dynamic modulus of elasticity was not significant, indicating that no matter where the hammer struck, i.e., radial and tangential surfaces, the fundamental frequency was essentially constant. Negative relationships were found between the fundamental frequency and the density and moisture when the data of the four wood species were viewed as a population sample. The vibrational characteristics of each wood species varied, which can be applied to the nondestructive testing of wood.


2021 ◽  
Vol 32 (19) ◽  
pp. 24041-24049
Author(s):  
Long Wang ◽  
Jiqing Lv ◽  
Feng Shi ◽  
Kaixin Song ◽  
Wen Lei ◽  
...  

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