Browsing by Author "Moslemi, N."

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Open Access
Analytical solution of the electro-mechanical flexural coupling between piezoelectric actuators and flexible-spring boundary structure in smart composite plates
(Elsevier, 2021-02-18) Gohari, S.; Mozafari, Farzin; Moslemi, N.; Mouloodi, S.; Sharifi, S.; Rahmanpanah, H.; Burvill, C.
An analytical solution is developed in this research for electro-mechanical flexural response of smart laminated piezoelectric composite rectangular plates encompassing flexible-spring boundary conditions at two opposite edges. Flexible-spring boundary structure is introduced to the system by inclusion of rotational springs of adjustable stiffness which can vary depending on changes in the rotational fixity factor of the springs. To add to the case study complexity, the two other edges are kept free. Three advantages of employing the proposed analytical method include: (1) the electro-mechanical flexural coupling between the piezoelectric actuators and the plate’s rotational springs of adjustable stiffness is addressed; (2) there is no need for trial deformation and characteristic function – therefore, it has higher accuracy than conventional semi-inverse methods; (3) there is no restriction imposed to the position, type, and number of applied loads. The Linear Theory of Piezoelectricity and Classical Plate Theory are adopted to derive the exact elasticity equation. The higher-order Fourier integral and higher-order unit step function differential equations are combined to derive the analytical equations. The analytical results are validated against those obtained from Abaqus Finite Element (FE) package. The results comparison showed good agreement. The proposed smart plates can potentially be applied to real-life structural systems such as smart floors and bridges and the proposed analytical solution can be used to analyze the flexural deformation response.
Open Access
Mechanical characterization of particulated FRP composite pipes: A comprehensive experimental study
(Elsevier, 2020-12-04) Saghir, F.; Gohari, S.; Mozafari, Farzin; Moslemi, N.; Burvill, C.; Smith, A.; Lucas, S.
Particulated fiber reinforced polymer (FRP) composite pipes encompass unidirectional continuous glass fibers (hoop glass), resin (thermoset polymer vinylester) matrix, chop glass (discontinuous short fibers), and particulate reinforcement (sand) impregnated into resin. They are categorized based on their nominal diameter, pressure class, and stiffness class. Mechanical characteristics of this class of composite materials have not, to date, been comprehensively studied. As such, this paper presents a systematic approach toward comprehensive experimental investigation into their mechanical characterizations in terms of the axial and hoop tensile strengths. The particulated FRP composite pipes used in the current study have glass fibers reinforced along the hoop direction at approximately 89° angle. To assure the experimental data accuracy and reliability, three batches associated with each pipe category were selected which slightly differ in the composition of their constituents. Three specimens per batch were selected and two types of tests were conducted on each specimen. 18 tests (2 × 3 batches × 3 specimens)) were conducted per pipe category (9 tests for hoop and 9 tests for axial). Therefore, 648 tests were conducted in total on 36 pipe categories. Instron 5569A and Instron 8801 universal testing machines were utilized for the axial tensile tests and a split disc hydraulic testing machine for the hoop tensile tests. The mean tensile and the hoop axial stresses and their associated standard deviations were calculated based on the Population Standard Deviation (PSD) equation and then plotted against the material constituents. The results demonstrated that an increase in the composition of particulate reinforcement results in a decrease in the axial and the hoop tensile strengths. However, increasing the ratio of resin, chop glass, and glass fibers contributes to the enhancement of the axial and the hoop tensile strengths. This study provides comprehensive design guidelines for engineers and manufacturing industries.
Open Access
A new analytical solution for elastic flexure of thick multi-layered composite hybrid plates resting on Winkler elastic foundation in air and water
(Elsevier, 2021-07-28) Gohari, S.; Mouloodi, S.; Mozafari, Farzin; Alebrahim, R.; Moslemi, N.; Burvill, C.; Albarody, T. M. B.
A new analytical flexural solution based on double finite integral Fourier transform and trigonometric series differentiation procedures was developed for thick multi-layered composite hybrid rectangular plates resting on Winkler elastic foundation in air and water. The effect of material anisotropy, coupled hydro-mechanical loads, and underwater floor inclination angle,which were overlooked in the literature, is considered in this study. Furthermore, the predetermination of the shape deformation function is not required in our proposed analytical solution, which offers more accurate results. For the particular cases where the plate made of isotropic material is in air, the analytical results are compared with, and verified by the literature. Literature is lacking to investigate thick multi-layered composite hybrid rectangular plates with free edges and under hydro-mechanical load; hence our analytical results are compared with, and verified by,numerical analysis employing finite element method (FEM). The analytical results provide excellent agreement with both literature and the proposed FEM. FEM is shown to be time-intensive since the results converge after 60 seconds runtime with definition of 12159 elements during mesh refinement, yet the proposed analytical method demonstrates that the convergence can easily be achieved after 5 seconds runtime through selecting small values for Fourier terms.