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

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

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

Collapse behavior of thin-walled corrugated tapered tubes

Thin-walled structures have been widely used in energy absorption and safety applications such as automotive, due to their lightweight and progressive folding modes. This work studies the collapse behavior and energy absorption of corrugated tapered tubes (CTT) under axial crushing numerically. The tested tubular structures were impacted axially with a striker's mass that is restricted to translational motion along the structures' axes. The effect of CTT's geometric features on different performance indicators, namely the initial peak force (PF), mean crushing force (MF), energy absorption (EA) and specific energy absorption (SEA) was studied. The results showed that the amplitude of corrugation is the most influential factor on the force-displacement characteristics of CTTs. Moreover, three deformation modes were found for CTTs, and the development of a mode was mainly influenced by the corrugation's amplitude and wavelength. In addition, for the tested range of geometric features, the initial peak force was found to be reduced when corrugation is adopted, especially for longer corrugation's amplitudes and wavelengths. On the other hand, the energy absorption (EA) and specific energy absorption (SEA) were found to be reduced when corrugation is adopted. Finally, it was found that the two most influential geometric factors on the performance indicators of CTT were the corrugation's amplitude and wall thickness. 1 2017 Elsevier LtdScopu

A novel axially half corrugated thin-walled tube for energy absorption under Axial loading

In this paper, tubes with different axial corrugations were studied under axial loading. Accordingly, a new axially half-corrugated thin-walled tube was developed to improve the energy absorption characteristics. The forming process of the corrugations on the tubes has also been described. Comprehensive experimental and numerical analysis have been conducted in order to investigate the effects of various geometrical parameters on crushing behavior of the structure. It has been shown that by the use of the new axially half corrugated tube, there is much more efficient crushing via a more uniform force-displacement result as well as a considerable improvement in other crashworthiness characteristics. Subsequently, a numerical study has been conducted on the same tubes to both have the numerical results validated and assure the repeatability and reliability of the experimental results. An efficient model in axial loading has been obtained which is offering a perfect concertina form. The obtained model deforms through an inversion mode causing an extra frictional force between the inverted part and the tube itself, resulting in a considerable increase in SEA, mean force, and consequently CFE. - 2019 Elsevier LtdScopu

Numerical and experimental investigation on corrugation geometry for metallic tubes under lateral loading

Energy absorption devices are being used to protect structures from severe damages and reduce injury to occupants during accidents. The integrated characteristics of crash absorption devices can be classified as high energy absorption capacity, light-weight, and cost-effective. One of the thin-walled structures which has drawn the attention of scientists is corrugated tube structure. In this paper, the effect of corrugation geometry on the crushing parameters of an aluminum corrugated tube is investigated. In this regard, different elliptical corrugation shapes were deemed and the compression response was numerically evaluated under lateral quasi-static loading. Finally, the crashworthiness parameters were extracted and compared to determine the influence of corrugation shape on the crashworthy response. Our results showed that using vertical elliptical corrugation decrease the densification point. Moreover, there is a gradual enhancement of mean crushing load by moving from the horizontal elliptical corrugations to the vertical ones. Also, by modifying of corrugation shape, the stress variation pattern changes, significantly.This 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.Scopu

Crushing analysis and multi-objective optimization of different length bi-thin walled cylindrical structures under axial impact loading

This article attempts to increase the crashworthiness characteristics of energy absorbers. It is found that the effect of the bi-tubular arrangement on the energy absorption and peak force is nonlinear. This nonlinearity is somewhat related to friction but is mostly related to the changing of buckling modes. Therefore, it is possible to reach higher Specific Absorbed Energy (SAE) in the bi-tubular case than with two tubes since the weight is the same in both arrangements while the energy absorption is higher in the bi-tubular case. To exploit this, multi-objective optimization of bi-thin walled cylindrical aluminium tubes under axial impact loading is performed. The absorbed energy and the SAE are considered as the objective functions while the maximum crush load is regarded as a constraint. Finally, the optimal dimensions of tubes are found in order to maximize the SAE and energy absorption for a specified maximum crushing force. - 2019, - 2019 Informa UK Limited, trading as Taylor & Francis Group.Scopu

Magneto-electro-elastic vibration analysis of modified couple stress-based three-layered micro rectangular plates exposed to multi-physical fields considering the flexoelectricity effects

In this paper, based on the CPT, motion equations for a sandwich plate containing a core and two integrated face-sheets have derived. The structure rests on the Visco-Pasternak foundation, which includes normal and shear modules. The piezo-magnetic core is made of CoFe2O4 and also is subjected to 3D magnetic potential. Two face sheets at top and bottom of the core are under electrical fields. Also, in order to obtain more accuracy, the effect of flexoelectricity has took into account at face sheets’ relations in this work. Flexoelectricity is a property of all insulators whereby they polarize when subject to an inhomogeneous deformation. This property plays a crucial role in small-scale rather than macro scale. Employing CPT, Hamilton’s principle, flexoelectricity considerations, the governing equations are derived and then solved analytically. By present work a detailed numerical study is obtained based on Piezoelectricity, Flexoelectricity and modified couple stress theories to indicate the significant effect of length scale parameter, shear correction factor, aspect and thickness ratios and boundary conditions on natural frequency of sandwich plates. Also, the figures show that there is an excellent agreement between present study and previous researches. These finding can be used for automotive industries, aircrafts, marine vessels and building industries