Forced vibration characteristics of embedded graphene oxide powder reinforced metal foam nanocomposite plate in thermal environment

Abstract Dynamic behavior of a new class of nanocomposites consisted of metal foam as matrix and graphene oxide powders as reinforcement is presented in this study in the framework of forced vibration. Graphene oxide powders are dispersed through the thickness of a plate made from metal foam material according to four various functionally graded patterns on the basis of the Halpin-Tsai micromechanical homogenization method. Also, three kinds of porosity distributions including two symmetric and one uniform patterns are considered for the metal foam matrix. As external effects, the plate is rested on the Winkler-Pasternak substrate and under uniform thermal and transverse dynamic loadings. By an incorporation of the refined higher order plate theory and Hamilton's principle, the governing equations of the dynamically loaded graphene oxide powder reinforced metal foam nanocomposite plate are derived and then solved with Galerkin exact solution method to achieve the resonance frequencies and dynamic deflections of the structure. Moreover, the influence of different boundary conditions is taken into account. The results indicate that the forced vibrational response of the graphene oxide powder strengthened metal foam nanocomposite plate is dramatically dependent on various parameters such as graphene oxide powders' weight fraction, different boundary conditions, various porosity distributions, foundation parameters and temperature change of uniform thermal loading

Experimental study of corrugated metal-composite tubes under axial loading

In this study, crushing behavior of corrugated metal-composite tube was examined experimentally under axial loading condition. Six types of specimens, classified into two groups of metal and metal-composite, were tested under quasi static axial loading. The failure mechanism and failure history of the specimens were presented and discussed. The experimental result showed that corrugated metal composite tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load-displacement diagram, reduction of initial peak load and controlling failure mechanism. Moreover, it was also found that adding filament wound layer of composite on the surface of metallic corrugated tube compensated weakness of corrugated metal tubes, which is low energy absorption capacity. Metal-composite corrugated showed high energy absorption capacity as well as preferable crushing characteristic under the axial loading

The Effect of Number of Corrugation on Crashworthiness of Aluminum Corrugated Tube under Lateral Loading

Thin-walled tubes have been developed and are growing in use as new energy absorber structures. The objective of this study is to investigate the energy absorption and crushing characteristics of corrugated tubes with different number of corrugation in a specific length exposed to lateral loading. At the first step, experimental tests were carried out on a corrugated tube with three con\u27ugations (two inner and one outer) and a tube without corrugation. After that, a finite element model was developed by means of ABAQUS software in order to study the effect of corrugation number on crushing properties of thin-walled tubes. The results show that tubes with corrugations have a higher mean crushing force which is directly proportional to the number of corrugations. Moreover, the plateau region in load-displacement curve decreases by increasing the number of corrugations and therefore the tube reaches its densification point earlier. Plastic strain variation pattern along the tubes were investigated as well

ESDA2010-24782 EXPERIMENTAL STUDY OF CORRUGATED TUBES UNDER LATERAL LOADING

ABSTRACT The protection of structures under impact loading often necessitates the need for energy absorbers; devices designed to absorb the impact energy in a controlled manner and hence, protect the structure under consideration. Thinwalled tubes are widely used as energy absorbers in various vehicles and moving parts. The objective of the present study is to investigate the energy absorption characteristic of tubes with corrugations in different geometries, in lateral direction. In order to produce corrugations, an innovative solution is introduced. Corrugations can be very easily generated on the surface of cylindrical aluminum tubes by stamping method. Corrugations with different wavelengths and amplitudes can be produced by this method. Experimental tests are conducted to study the effect of changing corrugation geometry (type and amplitude). Quasi-static tests are carried out whose results for lateral compression show that tubes with corrugation have a higher mean crushing force and this force is directly proportional to number of corrugations and their amplitude. Moreover, it is observed that corrugated tubes can absorb approximately four times more energy than tubes without corrugations, in the same size and weight. Finally, considering the experimental tests, corrugated tubes are shown to be more effective in lateral direction as an energy absorber, and they also exhibit desirable force-deflection responses which are important in the design of energy absorbing devices

Forced vibration characteristics of embedded graphene oxide powder reinforced metal foam nanocomposite plate in thermal environment

Dynamic behavior of a new class of nanocomposites consisted of metal foam as matrix and graphene oxide powders as reinforcement is presented in this study in the framework of forced vibration. Graphene oxide powders are dispersed through the thickness of a plate made from metal foam material according to four various functionally graded patterns on the basis of the Halpin-Tsai micromechanical homogenization method. Also, three kinds of porosity distributions including two symmetric and one uniform patterns are considered for the metal foam matrix. As external effects, the plate is rested on the Winkler-Pasternak substrate and under uniform thermal and transverse dynamic loadings. By an incorporation of the refined higher order plate theory and Hamilton's principle, the governing equations of the dynamically loaded graphene oxide powder reinforced metal foam nanocomposite plate are derived and then solved with Galerkin exact solution method to achieve the resonance frequencies and dynamic deflections of the structure. Moreover, the influence of different boundary conditions is taken into account. The results indicate that the forced vibrational response of the graphene oxide powder strengthened metal foam nanocomposite plate is dramatically dependent on various parameters such as graphene oxide powders' weight fraction, different boundary conditions, various porosity distributions, foundation parameters and temperature change of uniform thermal loading.This research is financially supported by the Ministry of Science and Technology of China (Grant No. 2019YFE0112400), National Science Foundation of China (Grant No. 52078310), the Taishan Scholar Priority Discipline Talent Group program funded by the Shan Dong Province, and the first-class discipline project funded by the Education Department of Shandong Province. The publication of this article was funded by Qatar National Library.Scopu

On the dynamics of FG-GPLRC sandwich cylinders based on an unconstrained higher-order theory

In the present paper, a novel unconstrained higher-order theory (UCHOT) is applied to analyse the free vibration of cylindrical sandwich shells with nanocomposite face sheets reinforced with graphene platelets. UCHOT considers the shear and thickness deformations. It is assumed that the cylinder includes a soft core which embedded between functionally graded graphene platelets reinforced composites (FG-GPLRC). FG-GPLRC face sheet consists of several laminas that the GPL weight fraction is modified layer to layer based on the various functionally graded (FG) patterns. The Winkler-Pasternak elastic foundation is located at the inner surface of the shell. Highly coupled motion equations are solved by a semi-analytical approach. This approach is blended of the generalized differential quadrature and trigonometric expansion (TE-GDQ) methods. Solving the obtained eigenvalue problem, corresponding frequencies to the cylindrical sandwich shell are achieved. In the results part, comparison studies are carried out to indicate the validity and performance of the selected theory and solution method. Afterward, some parametric results are demonstrated to investigate the impacts of shell theory order, geometrical parameters, FG model, elastic foundation parameters, and boundary conditions on the frequency response of the mentioned structure

Mathematical Model for Thin-walled Corrugated Tube under Axial Compression

In this research, theoretical investigation of corrugated aluminum tubes is performed to predicting the energy absorption characteristics. Aim to deform plastic tubes in predetermined intervals, corrugations are introduced on its surface. Theoretical relations are presented for predicting the energy absorption and mean crushing load of corrugated tubes. Other than that, corrugation helps to control the failure mode

Experimental study of corrugated metal-composite tubes under axial loading

In this study, crushing behavior of corrugated metal-composite tube was examined experimentally under axial loading condition. Six types of specimens, classified into two groups of metal and metal-composite, were tested under quasi static axial loading. The failure mechanism and failure history of the specimens were presented and discussed. The experimental result showed that corrugated metal composite tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load-displacement diagram, reduction of initial peak load and controlling failure mechanism. Moreover, it was also found that adding filament wound layer of composite on the surface of metallic corrugated tube compensated weakness of corrugated metal tubes, which is low energy absorption capacity. Metal-composite corrugated showed high energy absorption capacity as well as preferable crushing characteristic under the axial loading

Evacetrapib: Another CETP Inhibitor for Dyslipidemia With No Clinical Benefit

Evacetrapib is a cholesteryl ester transfer protein (CETP) inhibitor that has been recently studied as a cholesterol modifying agent to reduce cardiovascular risk and mortality in high risk cardiovascular disease patients. Evacetrapib acts to decrease lipid exchange through CETP inhibition. CETP acts to transfer cholesteryl esters from high-density lipoprotein-cholesterol (HDL-C) to low-density lipoprotein cholesterol (LDL-C) and very-low-density lipoprotein (VLDL-C). HDL-C is involved in reverse cholesterol transport and its blood levels have been shown to be inversely correlated with cardiovascular risk. Thus, a pharmacologic agent that can elevate HDL-C has been seen as an exciting area of research. In recent studies, evacetrapib was shown to be safe and efficacious. It produced an increase in HDL-C up to 128% and a 35% decrease in LDL-C, in comparison to placebo. In addition, evacetrapib was also shown to be more potent than previous CETP inhibitors. HDL-C particles treated with evacetrapib remained functional and had improved cholesterol efflux. A previously studied CETP inhibitor, torcetrapib, exhibited side effects of hyperaldosteronism, manifesting in electrolyte disturbances, and hypertension. These detrimental effects were not seen with evacetrapib. Recently, the results of evacetrapib\u27s phase III ACCELERATE trial showed no significant reduction in major adverse cardiovascular events or mortality, and the drug will not be marketed. Although beneficial cholesterol effects were seen with this drug, more needs to be known to understand what role, if any, evacetrapib has in the reduction of cardiovascular risk

Experimental and theoretical studies on axially crushed corrugated metal tubes

In this paper, crushing behaviors of tube with shallow and deep corrugation are experimentally and theoretically examined under axial loading condition. Three types of specimens were tested under quasi static axial loading. Their failure mechanism and failure history are presented and discussed. The experimental result showed that corrugated metal tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load displacement diagram, reduction of initial peak load and controlling failure mechanism. The theoretical solution based on experiment and modified simplified super folding element (MSSFE) theory is proposed that depends on the number of plastic hinge line, wall thickness, length of structure and flow stress of material. The comparison between theoretical solution and experiment shows a good agreement with acceptable errors. 2018 Elsevier LtdThis publication was made possible by GSRA grant GSRA2-1-0611-14034 from Qatar National Research Fund (a member of Qatar Foundation). The finding achieved herein are solely the responsibility of author