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Full-Text Articles in Engineering
Editorial: Advances In The Dynamics Of Granular Materials, Florin Bobaru, J. S. Chen, Joseph A. Turner
Editorial: Advances In The Dynamics Of Granular Materials, Florin Bobaru, J. S. Chen, Joseph A. Turner
Department of Engineering Mechanics: Faculty Publications
Granular materials exhibit a complex array of phenomena which makes the prediction of their behavior extremely difficult. Granular materials are strongly dissipative and show collective (heap formation, jamming) and size segregation phenomena, and can propagate surface waves. They display fluidization and convective motion, and under certain vibration regimes, they tend to mix when they would otherwise segregate, and segregate when they might otherwise mix. The wide range of behaviors that granular materials can display has been one of the main factors for which the development of predictive models has continued to remain an open problem.
The papers in this Special …
Force Chains And Resonant Behavior In Bending Of A Granular Layer On An Elastic Support, Kitti Rattanadit, Florin Bobaru, Konlayut Promratana, Joseph A. Turner
Force Chains And Resonant Behavior In Bending Of A Granular Layer On An Elastic Support, Kitti Rattanadit, Florin Bobaru, Konlayut Promratana, Joseph A. Turner
Department of Engineering Mechanics: Faculty Publications
In this paper we investigate the interaction between a granular layer and an elastic foundation using a coupled Discrete Element Method-Finite Element Method (DEM–FEM) computational model. We use this dynamics code to simulate quasi-static bending of the granular layer and we observe the changes taking place in the structure of the force chains for two cases: with and without rolling resistance. A reversal of the arches formed in the force chains leads to a bending resistance similar to that observed in dynamic experiments on resonant behavior under bending of a layer of sand in a container with an elastic bottom. …
A Model For Predicting The Multiscale Crack Growth Due To An Impact In Heterogeneous Viscoelastic Solids, Flavio V. Souza, David H. Allen
A Model For Predicting The Multiscale Crack Growth Due To An Impact In Heterogeneous Viscoelastic Solids, Flavio V. Souza, David H. Allen
Department of Engineering Mechanics: Faculty Publications
A two-scale model for predicting the multiple crack growth in viscoelastic solids due to an impact is presented. The cracks are considered only at the local scale through the use of a micromechanical viscoelastic cohesive zone model. The multiscale model has been implemented in a finite-element code. In order to minimize the computation time, the local finite-element meshes are solved in parallel by multiple processors. An example problem is given in order to demonstrate the capabilities of the model.
The Magnetoelectric Effects In Multiferroic Composite Nanofibers, C. L. Zhang, W. Q. Chen, S. H. Xie, J. S. Yang, Jiangyu Li
The Magnetoelectric Effects In Multiferroic Composite Nanofibers, C. L. Zhang, W. Q. Chen, S. H. Xie, J. S. Yang, Jiangyu Li
Department of Engineering Mechanics: Faculty Publications
In this letter, we analyze the quasistatic and dynamic magnetoelectric responses of multiferroic composite nanofibers consisting of both ferroelectric and ferromagnetic phases and demonstrate that the nanofibers exhibit magnetoelectric responses orders of magnitude higher than multiferroic composite thin films of similar compositions. The analysis suggests that the multiferroic nanofibers are promising for magnetoelectric applications.
Reduction Of Surface Acoustic Wave Resonator Normal Acceleration Sensitivity Using Piezoelectric Actuators, X. Y. Shan, Y. T. Hu, J. S. Yang
Reduction Of Surface Acoustic Wave Resonator Normal Acceleration Sensitivity Using Piezoelectric Actuators, X. Y. Shan, Y. T. Hu, J. S. Yang
Department of Engineering Mechanics: Faculty Publications
We attach a piezoelectric actuator to a surface acoustic wave resonator under normal acceleration to reduce its acceleration sensitivity. It is shown theoretically that under a given acceleration, the acceleration induced frequency shift in the resonator can be reduced or even completely eliminated when a proper electric field is applied to the piezoelectric actuator.
Harvesting Magnetic Energy Using Extensional Vibration Of Laminated Magnetoelectric Plates, C. L. Zhang, J. S Yang, W. Q. Chen
Harvesting Magnetic Energy Using Extensional Vibration Of Laminated Magnetoelectric Plates, C. L. Zhang, J. S Yang, W. Q. Chen
Department of Engineering Mechanics: Faculty Publications
Magnetically forced extensional vibrations of laminated plates with piezoelectric and piezomagnetic layers are analyzed theoretically. It is shown that such a structure can be used to harvest magnetic energy and convert it to electric energy. The output power and the energy conversion efficiency are calculated. The load dependence of the magnetoelectric coupling coefficient is also obtained.
Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.
Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.
Department of Engineering Mechanics: Faculty Publications
We introduce here adaptive refinement algorithms for the non-local method peridynamics, which was proposed (in J. Mech. Phys. Solids 2000; 48:175–209) as a reformulation of classical elasticity for discontinuities and long-range forces. We use scaling of the micromodulus and horizon and discuss the particular features of adaptivity in peridynamics for which multiscale modeling and grid refinement are closely connected. We discuss three types of numerical convergence for peridynamics and obtain uniform convergence to the classical solutions of static and dynamic elasticity problems in 1D in the limit of the horizon going to zero. Continuous micromoduli lead to optimal rates of …
Evaporation Induced Two-Dimensional Buckling Within Liquid Droplet, Ziguang Chen, Maozi Liu, Gang-Yu Liu, Li Tan
Evaporation Induced Two-Dimensional Buckling Within Liquid Droplet, Ziguang Chen, Maozi Liu, Gang-Yu Liu, Li Tan
Department of Engineering Mechanics: Faculty Publications
Evaporation of a liquid droplet containing a thin layer of surfactants atop could generate two-dimensional buckling on surfaces. Herringbone features were produced via embedded nanoparticle beds. We assign transient surface tension as the driving force for such a phenomenon. Considering the surfactant layer as a thin elastic film, a continuum model is employed to calculate the mechanical properties of the layer. Particularly, we estimated an elastic modulus of 4 GPa for the surfactant layer, indicating rather strong mechanical properties of these small molecules when they are close packed to form supramolecules via noncovalent binding.
Optimal Electrode Shape And Size For Shear Mode Thin Film Acoustic Wave Resonators, L. M. Xu, B. B. Tang, Y. T. Hu, H. Fan, J. S. Yang
Optimal Electrode Shape And Size For Shear Mode Thin Film Acoustic Wave Resonators, L. M. Xu, B. B. Tang, Y. T. Hu, H. Fan, J. S. Yang
Department of Engineering Mechanics: Faculty Publications
We study electrode shape and size for plates of hexagonal crystals or polarized ceramics with the sixfold axis or the poling direction parallel to the plate surfaces so that they can be excited into thickness-shear vibration by an electric field in the plate thickness direction. Electrode size and shape optimal in the sense that they satisfy the criterion of Bechmann’s number in every direction are determined.
Connected Vibrating Piezoelectric Bimorph Beams As A Wide-Band Piezoelectric Power Harvester, Zengtao Yang, Jiashi Yang
Connected Vibrating Piezoelectric Bimorph Beams As A Wide-Band Piezoelectric Power Harvester, Zengtao Yang, Jiashi Yang
Department of Engineering Mechanics: Faculty Publications
We analyze coupled flexural vibration of two elastically and electrically connected piezoelectric beams near resonance for converting mechanical vibration energy to electrical energy. Each beam is a so-called piezoelectric bimorph with two layers of piezoelectrics. The 1D equations for bending of piezoelectric beams are used for a theoretical analysis. An exact analytical solution to the beam equations is obtained. Numerical results based on the solution show that the two resonances of individual beams can be tuned as close as desired by design when they are connected to yield a wide-band electrical output. Therefore, the structure can be used as a …
Tem Study Of Lizardite-1t Particles In Toluene Solvent, J. Yan, Xingzhong Li, J. Y. Jiang, L. Tan
Tem Study Of Lizardite-1t Particles In Toluene Solvent, J. Yan, Xingzhong Li, J. Y. Jiang, L. Tan
Department of Engineering Mechanics: Faculty Publications
To investigate the self-assembled growth of organosilane molecules carrying Si, C and H to form multiple layers, samples were prepared in toluene and then transferred to TEM Cu grids coated with thin C films for TEM observation. It is surprising that micrometer sized flakes with a main composition of Mg and Si (or Al and Si) were occasionally observed in the TEM specimens, later were identified as lizardite-1T phase. To trace down the source of the inorganic particles, all procedures in the sample preparation were carefully checked. The particles of the lizardite-1T phase were confirmed from the organic solvent of …
Real-Time Depth Sectioning: Isolating The Effect Of Stress On Structure Development In Pressure-Driven Flow, Lucia Fernandez-Ballester, Derek W. Thurman, Julia A Kornfield
Real-Time Depth Sectioning: Isolating The Effect Of Stress On Structure Development In Pressure-Driven Flow, Lucia Fernandez-Ballester, Derek W. Thurman, Julia A Kornfield
Department of Engineering Mechanics: Faculty Publications
Transient structure development at a specific distance from the channel wall in a pressure-driven flow is obtained from a set of real-time measurements that integrate contributions throughout the thickness of a rectangular channel. This “depth sectioning method” retains the advantages of pressure-driven flow while revealing flow-induced structures as a function of stress. The method is illustrated by applying it to isothermal shear-induced crystallization of an isotactic polypropylene using both synchrotron x-ray scattering and optical retardance. Real-time, depth-resolved information about the development of oriented precursors reveals features that cannot be extracted from ex-situ observation of the final morphology and that are …