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A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： s.sAUrABH r.KIrAN D.sINGH r.VAIsH V.s.CHAUHAN school of Mechanical and Materials Engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHsDT) of plates is employed to characterize the displacement field, with the incorporation of Green-Lagrange nonlinearity. The problem is modeled using the C0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(Hr), helicoidal exponential(HE), helicoidal semi-circular(Hs), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

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Nonlinear primary resonance analysis of nanoshells including vibrational mode interactions based on the surface elasticity theory

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Applied Mathematics and Mechanics(English Edition) 2020年第2期41卷 233-260页

作者： A.sArAFrAZ s.sAHMANI M.M.aghdam Mechanical Engineering Department Amirkabir University of TechnologyTehran 15875-4413Iran school of science and Technology The University of GeorgiaTbilisi 0171Georgia

The deviation from the classical elastic characteristics induced by the free surface energy can be considerable for nanostructures due to the high surface to volume ratio. Consequently, this type of size dependency should be accounted for in the mechanical behaviors of nanoscale structures. In the current investigation, the influence of free surface energy on the nonlinear primary resonance of silicon nanoshells under soft harmonic external excitation is studied. In order to obtain more accurate results,the interaction between the first, third, and fifth symmetric vibration modes with the main oscillation mode is taken into consideration. Through the implementation of the Gurtin-Murdoch theory of elasticity into the classical shell theory, a size-dependent shell model is developed incorporating the effect of surface free energy. With the aid of the variational approach, the governing differential equations of motion including both of the cubic and quadratic nonlinearities are derived. Thereafter, the multi-time-scale method is used to achieve an analytical solution for the nonlinear size-dependent problem. The frequency-response and amplitude-response of the soft harmonic excited nanoshells are presented corresponding to different values of shell thickness and surface elastic constants as well as various vibration mode interactions. It is depicted that through consideration of the interaction between the higher symmetric vibration modes and the main oscillation mode, the hardening response of nanoshell changes to the softening one. This pattern is observed corresponding to both of the positive and negative values of the surface elastic constants and the surface residual stress.

关键词： nanostructure nonlinear dynamics surface stress mode interaction multi-time-scale method

Characterization of MCrAlY/nano-Al_(2)O_(3) nanocomposite powder produced by high-energy mechanical milling as feedstock for high-velocity oxygen fuel spraying deposition

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International Journal of Minerals,Metallurgy and Materials 2021年第9期28卷 1534-1543页

作者： F.Ghadami A.sabour rouh aghdam s.Ghadami Department of Materials Engineering Tarbiat Modares UniversityP.O.Box 14115-143TehranIran

Al_(2)O_(3) nanoparticles and MCrAlY/nano-Al_(2)O_(3) nanocomposite powder(M=Ni,Co,or NiCo)were produced using high-energy ball *** MCrAlY/nano-Al_(2)O_(3) coating was deposited by selecting an optimum nanocomposite powder as feedstock for high-velocity oxy-gen fuel thermal *** morphological and microstructural examinations of the Al_(2)O_(3) nanoparticles and the commercial MCrAlY and MCrAlY/nano-Al_(2)O_(3) nanocomposite powders were investigated using X-ray diffraction analysis,field-emission scanning electron microscopy coupled with electron dispersed spectroscopy,and transmission electron *** structural investigations and Williamson-Hall res-ults demonstrated that the ball-milled Al_(2)O_(3) powder after 48 h has the smallest crystallite size and the highest amount of lattice strain among the as-received and ball-milled Al_(2)O_(3) owing to its optimal nanocrystalline *** the case of developing MCrAlY/nano-Al_(2)O_(3) nanocompos-ite powder,the particle size of the nanocomposite powders decreased with increasing mechanical-milling duration of the powder mixture.

关键词： MCrAlY Nanocomposite powder High-energy mechanical milling Williamson-Hall analysis HVOF coating

Numerical and experimental analysis of the closed-cell aluminium foam under low velocity impact using computerized tomography technique

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Acta Mechanica sinica 2019年第1期35卷 144-155,I0005页

作者： s.Talebi M.sadighi M.M.aghdam Department of Mechanical Engineering Amirkabir University of TechnologyTehranIran

In the present work, the response of closed-cell aluminum foams under low-velocity impact has been studied numerically and experimentally. Computerized tomography is employed to access three-dimensional (3D) microstructure of the closed-cell aluminum foam. Effective parameters including foam density and the velocity of impactor on foam dynamic behavior are investigated. In order to show the validity and accuracy of results, some static experiments and low-velocity impact tests have been conducted. results in dicate a remarkable agree me nt between the simulation and experimental data. Moreover, the results show that by increasing the density of foam samples, the highest difference between numerical and experimenidi results for peak stress and absorbed energy are 35.9% and 6.9%, respectively, which is related to the highest density. For impact velocities ranging from 3.1 to 4.2 m/s, the maximum discrepancy in peak stress and absorbed energy occur at an inipact velocity of 3.1 m/s in which corresponding errors are 33.3% and 6.6%, respectively. For the impact velocity of 40 m/s, the highest increase in peak stress and absorbed energy are 667.9% and 370.3% associated with the density of 0.5 and 0.3 g/cm^3, respectively.

关键词： Finite element analysis Impact Aluminum foam Experimental analysis Energy absorption

Nonlinear buckling and postbuckling behavior of cylindrical shear deformable nanoshells subjected to radial compression including surface free energy effects

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Acta Mechanica solida sinica 2017年第2期30卷 209-222页

作者： s.sahmani M.M.aghdam M.Bahrami Department of Mechanical Engineering Amirkabir University of Technology P.O. Box 15875-4413 Tehran Iran

The objective of the present investigation is to predict the nonlinear buckling and postbuckling characteristics of cylindrical shear deformable nanoshells with and without initial imperfection under hydrostatic pressure load in the presence of surface free energy *** this end, Gurtin-Murdoch elasticity theory is implemented into the irst-order shear deformation shell theory to develop a size-dependent shell model which has an excellent capability to take surface free energy effects into account. A linear variation through the shell thickness is assumed for the normal stress component of the bulk to satisfy the equilibrium conditions on the surfaces of nanoshell. On the basis of variational approach and using von Karman-Donnell-type of kinematic nonlinearity, the non-classical governing differential equations are derived. Then a boundary layer theory of shell buckling is employed incorporating the effects of surface free energy in conjunction with nonlinear prebuckling deformations, large delections in the postbuckling domain and initial geometric imperfection. Finally, an eficient solution methodology based on a two-stepped singular perturbation technique is put into use in order to obtain the critical buckling loads and postbuckling equilibrium paths corresponding to various geometric parameters. It is demonstrated that the surface free energy effects cause increases in both the critical buckling pressure and critical end-shortening of a nanoshell made of silicon.

关键词： Nanoscale structures size effect Nonlinear buckling surface free energy Boundary layer theory

Free vibration and transient response of double curved beams connected by intermediate straight beams

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 37-62页

作者： r.A.JAFArI-TALOOKOLAEI H.GHANDVAr E.JUMAEV s.KHATIr T.CUONG-LE school of Mechanical Engineering Babol Noshirvani University of Technology Department of Mechanical Engineering Faculty of Engineering New Uzbekistan University University of Business and science Center for Engineering Application and Technology solutions Ho Chi Minh City Open University

This paper investigates the free vibration and transient response of interconnected structures including double curved beams and intermediate straight beams,which are all constructed from functionally graded porous(FGP) materials. The strain potential and kinetic energies of each beam along with the work done by the external force are calculated. Additionally, a higher-order beam element is introduced to derive stiffness and mass matrices, along with the force vector. The curved and straight beams are discretized, and their assembled stiffness, mass matrices, and force vectors, are *** conditions at the joints are used to derive the total matrices of the entire structure. subsequently, the natural frequencies and transient response of the system are determined. The accuracy of the mathematical model and the self-developed computer program is validated through the comparison of the obtained results with those of the existing literature and commercial software ANsYs, demonstrating excellent ***, a comprehensive study is conducted to investigate the effects of various parameters on the free vibration and transient response of the considered structure.

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simple separation method of Zn(Ⅱ) and Cd(Ⅱ) from brine solution of zinc plant residue and synthetic chloride media using solvent extraction

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Chinese Journal of Chemical Engineering 2020年第4期28卷 1055-1061页

作者： Ali Asghar Balesini aghdam Hossein Yoozbashizadeh Javad Moghaddam Department of Materials Engineering Science and Research BranchIslamic Azad UniversityTehranIran Materials and Metallurgical Engineering Department University of ZanjanZanjanIran

In this work,the possibility of separation of Zn^2+and Cd^2+metal ions from chloride(brine)solutions was *** this purpose,simple solvent extraction(sX)experiments by di-2-ethylhexyl phosphoric acid(D2EHPA)in kerosene as a diluent was performed on synthetic and industrial chloride solution obtained from brine leaching of zinc filter cakes(by-product of zinc hydrometallurgical processing).The optimal conditions for separation were *** zinc extraction efficiency was 99%with negligible co-extraction of ***,a highΔpH0.5 value for Zn(Ⅱ)and Cd(Ⅱ)was ***-Ir and slope analysis indicated that ZnClA·3HA and CdClA·3HA species were probably extracted.

关键词： solvent extraction Brine media Leaching filter cakes Zinc Cadmium

Getting physical with medical education:Exercise based virtual anatomy review classes for medical students

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World Journal of Methodology 2025年第1期15卷 20-25页

作者： Nadeesha r samarasinghe Taniya s Nagpal Michele L Barbeau Charys M Martin Division of General surgery Faculty of MedicineUniversity of British ColumbiaVancouver V6T 1Z3BCCanada Faculty of Kinesiology Sport and RecreationUniversity of AlbertaEdmonton T6G 2R3ABCanada Anatomy and Cell Biology University of Western OntarioLondon N6A 3K7ONCanada Department of Anatomy and Cell Biology Schulich School of Medicine and DentistryThe University of Western OntarioLondon N6A 3K7ONCanada

The benefits of regular physical activity are well ***,few studies have examined the effectiveness of integrating physical activity(PA)into curricula within a post-secondary *** investigate the incorporation of PA into medical curriculum,we developed a series of optional exercise-based review sessions designed to reinforce musculoskeletal(MsK)anatomy course *** synchronous sessions were co-taught by a group fitness instructor and an anatomy *** fitness instructor would lead students through both strength and yoga style exercises,while the anatomy instructor asked questions about relevant anatomical structures related to course material previously *** the sessions,participants were asked to evaluate the classes on their self-reported exam preparedness in improving MsK anatomy knowledge,PA levels,and mental *** participants completed surveys;a majority agreed that the classes increased understanding of MsK concepts(90.0%)and activity levels(97.7%).Many(70.0%)felt that the classes helped reduce *** majority of respondents(90.0%)agreed that the classes contributed to increased feelings of social ***,medical students saw benefit in PA based interventions to supplement MsK course *** with increasing activity levels and promoting health behaviours,integrating PA into medical curriculum may improve comprehension of learning material,alleviate stress and foster social connectivity among medical students.

关键词： Medical education Musculoskeletal Anatomy Exercise Online learning

studying the effect of surfactant assisted low-salinity water flooding on clay-rich sandstones

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Petroleum 2024年第2期10卷 306-318页

作者： saeed Khezerloo-ye aghdam Alireza Kazemi Mohammad Ahmadi Department of Petroleum Engineering Amirkabir University of Technology(AUT)TehranIran Department of Petroleum and Chemical Engineering College of EngineeringSultan Qaboos UniversityMuscatOman

sandstone reservoirs often contain clay particles that can cause damage and reduce permeability during low-salinity water *** this study,the effect of surfactants on fine migration in clay-rich sandstones and its impact on oil recovery was ***,the impact of surfactants on interparticle forces in fine-matrix,fine-fine,and oil-matrix systems was *** results showed that both CTAB(cetyltrimethyl ammonium bromide)and Qs(quillaja saponin)cause EDL compaction,weakening the repulsive ***,sDs(sodium dodecyl sulfate)and TX(triton X-100)do not affect the ***,the effect of surfactants on IFT reduction and wettability alteration was experimentally *** surfactants reduced IFT due to the surface excessive concentration *** wettability alteration experiment illustrated that although Qs and CTAB compact EDL around oil and matrix particles leading to attraction force augmentation,they both alter wettability through adsorption on matrix and carboxylic groups present in crude oil,*** aqueous solutions were then injected into various clay-rich sandstone sanpacks,which resulted in increased oil ***,the mechanisms leading to enhanced oil recovery variedby surfactant *** increased recovery by 10%through IFT reduction and wettability alteration,while sDs and TX increased recovery by 12%and 9%,respectively,through wettability alteration and extreme fine *** contrast,partial fine migration in the Qs flooding experiment reached a recovery increase of 18%.Permeability trends through experiments were also *** CTAB injection,permeability did not reduce,while Qs aqueous solution reduced rock permeability to 5 m *** and TX reduced the magnitude of permeability to 2 m *** conclusion,this study demonstrates that surfactants can effectively improve oil recovery in clay-rich sandstones by altering the interparticle forces,reducing IFT,and changing *** results

关键词： surfactant flooding smart water Fine migration recovery factor