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research-article  
Majid Jabbari, Mostafa Ghayour and Hamid Reza Mirdamadi
J. Eng. Mater. Technol   doi: 10.1115/1.4036241
This paper presents to verify the energy harvesting of a nonlinear piezoelectric multilayer beam under harmonic excitation. In this paper, a numerical program is developed with Matlab software. In the program, the Newmark technique for dynamic analysis is used, and the Newton-Raphson iterative and Simpson methods are used for the nonlinear solution. Numerical approximation of the nonlinear equations uses a mixed finite element formulation in terms of displacement and potential electrical variables. To verify the numerical results, the experimental results for the energy harvesting of a piezoelectric multilayer beam with harmonic base excitation are used. The multilayer piezoelectric beam used consists of two bimorphs in the case of a series connection and a substructure layer of aluminum. For the considered electrical circuit, the piezoelectric energy harvesting model is connected to the resistive load and the generated power in multilayer piezoelectric beam is sent to load resistance. The influence of the type of layer connection on the output voltage value is investigated. The generated voltage and electrical power of the resistive load are verified using a ‘31’ mode piezoelectric multilayer beam in both resonance and off-resonance cases. The effect of the energy loss factor, resistive load, and excitation frequency on the results of the power and voltage generated are studied.
TOPICS: Resonance, Energy harvesting, Stress, Excitation, Electromotive force, Matlab, Nonlinear equations, Electricity (Physics), Aluminum, Energy dissipation, Dynamic analysis, Finite element analysis, Approximation, Circuits, Computer software, Displacement
research-article  
Yue Zheng, Hassan Bahaloo, Davood Mousanezhad, Ashkan Vaziri and Hamid Nayeb-Hashemi
J. Eng. Mater. Technol   doi: 10.1115/1.4036242
Displacement and stress fields in a functionally graded (FG) fiber-reinforced rotating disk of non-uniform thickness subjected to angular deceleration are obtained. The disk has a central hole, which is assumed to be mounted on a rotating shaft. Unidirectional fibers are considered to be circumferentially distributed within the disk with a variable volume fraction along the radius. The governing equations for displacement and stress fields are derived and solved using finite difference method. The results show that for disks with fiber rich at the outer radius, the displacement field is lower in radial direction but higher in circumferential direction compared to the disk with the fiber rich at the inner radius. The circumferential stress value at the outer radius is substantially higher for disk with fiber rich at the outer radius compared to the disk with the fiber rich at the inner radius. It is also observed a considerable amount of compressive stress developed in the radial direction in a region close to the outer radius. These compressive stresses may prevent any crack growth in the circumferential direction of such disks. For disks with fiber rich at the inner radius, the presence of fibers results in minimal changes in the displacement and stress fields when compared to a homogenous disk made from the matrix material. In addition, we concluded that disk deceleration has no effect on the radial and hoop stresses. However, deceleration will affect the shear stress. Tsai-Wu failure criterion is evaluated for decelerating disks. For disks with fiber rich at the inner radius, the failure is initiated between inner and outer radii. However, for disks with fiber rich at the outer radius, the failure location depends on the fiber distribution.
TOPICS: Fibers, Stress, Displacement, Rotating Disks, Disks, Failure, Hoop stress, Compressive stress, Fracture (Materials), Shear stress, Finite difference methods
research-article  
Felipe Lopez Rivarola, J.G. Etse and Paula Cecilia Folino
J. Eng. Mater. Technol   doi: 10.1115/1.4036243
In this paper the necessary and sufficient conditions for fulfilling the thermodynamic consistency of computational homogenisation schemes in the framework of hierarchical multiscale theories are defined. The proposal is valid for arbitrary homogenisation based multiscale procedures, including continuum and discontinuum methods in either scale. It is demonstrated that the well-known Hill-Mandel variational criterion for homogenisation scheme is a necessary, but not a sufficient condition for the micro-macro thermodynamic consistency when dissipative material responses are involved at any scale. In this sense, the additional condition to be fulfilled regarding multiscale thermodynamic consistency is established. The general case of temperature-dependent, higher order elastoplasticity is considered as theoretical framework to account for the material dissipation at micro and macro scales of observation. It is shown that the thermodynamic consistency enforces the homogenisation of the non-local terms of the finer scale's free energy density, however this does not lead to non-local gradient effects on the coarse scale. Then, the particular cases of local isothermal elastoplasticity and continuum damage are considered for the purpose of the proposed thermodynamically consistent approach for multiscale homogenisations.
TOPICS: Density, Temperature, Energy dissipation, Elastoplasticity, Damage
research-article  
P. Vijayasarathi, S. Ilaiyavel and P. Suresh Prabhu
J. Eng. Mater. Technol   doi: 10.1115/1.4036067
In order to study the microstructure and wear characteristics of Uncoated, TiAlN, AlCrN and TiCN multilayer coated AISI 410 stainless steel. Tribological properties of the coatings were investigated by high carbon steel ball friction in dry sliding, and sliding velocity of 0.3927 ms-1, and sliding distance of 248.43 m, and under a load range of 2N to 4N at room temperature. Among all the multilayer coatings tested, TiCN gave the superior wear resistance, followed by TiAlN and AlCrN. This indicates presence of C in TiCN coating leads to increase the wear resistance. At 2N to 3N load in which oxidation was present, AlCrN coating shows the excellent wear resistance followed by TiAlN and TiCN coating. The coating with a TiAlN proven good to acceptable wear resistance between 3N to 4N load. The wear rates and worn surfaces were investigated with scanning electron microscopy (SEM) (with EDS attachment), XRD and Talysurf profilometry analysis, which demonstrates that the grooved regions, pits, ploughing ridge and cavities were found along the worn surface of the Uncoated, TiAlN and AlCrN coated surface. This result exposed hard coated particles were observed on the high carbon steel ball surface.
TOPICS: Coatings, Wear resistance, Stress, Wear, Carbon steel, Particulate matter, Temperature, Tribology, Friction, Scanning electron microscopy, Cavities, oxidation, Stainless steel

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