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Design and fabrication of a new fiber-cement-piezoelectric composite sensor for measurement of inner stress in concrete structures

Lezgy-Nazargah M., Saeidi-Aminabadi S., Yousefzadeh M. A.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

405--416

EN

Rare suitable sensors are reported till now for the accurate measurement of inner forces at the concrete structures. In this study, a novel sensor is designed and fabricated for the evaluation of inner stress in the concrete structures under dynamical loads. By embedding this sensor in the critical points of the modern concrete structures (e.g. high-rise buildings, large-span bridges, dams, etc.), the heath monitoring of such structures may be easily done. The proposed sensor is a 5 cm × 5 cm × 5 cm cube made of a novel cement-resin-fiber composite matrix. A number of circular piezoelectric sheets with the same polarization alignment are embedded at the center of the cube with the certain distance from each other. The composite material used in the construction of the proposed sensor is in fact a new matrix composed of Portland cement, resin, water, fine silica and polymeric fibers which guarantees the strength, safety and sensitivity of the sensor at high level of stresses. The performance and reliability of the presented sensor has been proved through experimental tests. By considering different range of input force frequency (ω), it was found that the simple exponential law ΔV = 0.8 exp(−0.037ω)ΔF exists between the amplitude of output sensor (ΔV) and amplitude of input force (ΔF). Compared to optical sensors and other available types of sensors which usually require special fabrication technology, the proposed sensor is low-price and easy to build and install. High sensitivity and precision in the range of 0.5–50 Hz, good compatibility with concrete, high durability, and the generating of strong output signals are other advantages of the proposed sensor.

2

A new mixed-field theory for bending and vibration analysis of multi-layered composite plate

Lezgy-Nazargah M., Salahshuran S.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

818--832

EN

A novel mixed-field theory with relatively low number of unknown variables is introduced for bending and vibration analysis of multi-layered composite plates. The presented plate theory is derived from a parametrized mixed variational principle which is introduced recently by the first author. A global-local kinematic with a layer-independent number of variables is assumed for the description of the displacements of the plate. The considered kinematic stratifies the displacement and transverse stress continuity conditions at the mutual interfaces of the layers. It also fulfill the homogenous boundary conditions of the shear stresses on the upper/lower surfaces of the plates without using the shear correction factor. One-unknown variable fields which satisfy a priori the continuity conditions at the adjacent interfaces between layers and the zero boundary conditions on the bounding surfaces are considered for the approximation of the transverse shear stresses. The transverse normal stress along the total thickness of the multi-layered plate is approximated via a quadratic polynomial. The presented mixed-field plate theory has been validated through comparison of the bending and vibration analysis results with those obtained from the three-dimensional (3D) theory of elasticity and the results of the other classical and high-order plate theories.

3

A three-dimensional exact state-space solution for cylindrical bending of continuously non-homogenous piezoelectric laminated plates with arbitrary gradient composition

Lezgy-Nazargah M.

Archives of Mechanics

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2015

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Vol. 67, nr 1

25--51

EN

Most of exact solutions reported for the analysis of functionally graded piezoelectric (FGP) plates are based on the assumption, that the graded plate consists of a number of layers, where the material properties within each layer are invariant. The limited works that consider the continuous variation of electro-mechanical properties are restricted to FGP materials with the exponent-law dependence on the thickness-coordinate. In the present paper, a three-dimensional (3D) exact solution is presented for cylindrical bending of the FGP laminated plates based on the state space formalism. In contrast to the other reported solutions which are restricted to FGP materials with the exponent-law dependence on the thickness-coordinate, the present exact solution considers materials with arbitrary compositional gradient. Moreover, no assumption on displacement components and the electric potential along the thickness direction of FGP layers is introduced. Regardless of the number of layers, equations of motion, charge equation, and the boundary and interface conditions are satisfied exactly. The obtained exact solution can be used to assess the accuracy of different FGP laminated plate theories and/or for validating finite element codes.