Study of the effects of shear piezoelectric actuators on the performance of laminated composite shells by an isogeometric approach

2020 ◽  
pp. 109963622094291
Author(s):  
Sajjad Nikoei ◽  
Behrooz Hassani
Keyword(s):  
Boundary Conditions ◽  
Piezoelectric Actuator ◽  
Single Layer ◽  
Laminated Composite ◽  
Piezoelectric Actuators ◽  
Open Circuit ◽  
Radius Of Curvature ◽  
Composite Shells ◽  
Vibration Responses ◽  
Shell Formulation

This paper presents an isogeometric approach based on the Non-Uniform Rational B-Splines (NURBS) to investigate static and free vibration responses of smart composite shells integrated with shear piezoelectric actuators. The degenerated shell formulation according to the Mindlin-Reissner shell theory is combined with the isogeometric approach. To model the laminated smart shells, the Equivalent Single Layer (ESL) theory is used. To consider the electric potential in the shear piezoelectric actuator layers, a sub-layer approach is adopted that assumes linear variation in the thickness direction of the sub-layer. The effect of different mechanical and electrical boundary conditions on transverse deformation and natural frequencies of laminated smart shells by applying the electric field have been investigated. In the case studies, two parallel edges of the considered shell structures are assumed simply supported and the other two with an arbitrary combination of boundary conditions including clamped, free or simply supports. Also, open-circuit and closed-circuit conditions are used as electric boundary conditions. Investigation of the effects of the shear piezoelectric actuator layers on various factors, including the simultaneous mechanical and electrical loadings as well as the radius of curvature of the shell are amongst the objects of this paper. Also, several numerical examples are presented to demonstrate the efficiency and accuracy of the isogeometric approach in the study of shear effects of the piezoelectric actuator layers. The obtained results indicate the reliability and desirability of the proposed approach.

The study of the nonlinear vibration of S-S and C-C laminated composite conical shells on elastic foundations through an approximate method

2021 ◽  
pp. 095440622110214
Author(s):  
Shahin Mohammadrezazadeh ◽  
Ali Asghar Jafari
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Vibration ◽  
Approximate Method ◽  
Laminated Composite ◽  
Vertex Angle ◽  
Nonlinear Frequency ◽  
Conical Shells ◽  
Elastic Foundations ◽  
Vibration Responses ◽  
Comparison Of The Results

This paper investigates the nonlinear vibration responses of laminated composite conical shells surrounded by elastic foundations under S-S and C-C boundary conditions via an approximate approach. The laminated composite conical shells are modeled based on classical shell theory of Love employing von Karman nonlinear theory. Nonlinear vibration equation of the conical shells is extracted by handling Lagrange method. The linear and nonlinear vibration responses are obtained via an approximate method which combines Lindstedt-Poincare method with modal analysis. The validation of this study is carried out through the comparison of the results of this study with results of published literature. The effects of several parameters including the constants of elastic foundations, boundary conditions, total thickness, length, large edge radius and semi-vertex angle on the values of fundamental linear frequency and curves of amplitude parameter versus nonlinear frequency ratio for laminated composite conical shells with both S-S and C-C boundary conditions are investigated.

Isogeometric analysis of laminated smart shell structures covered with piezoelectric sensors and actuators using degenerated shell formulation

2019 ◽  
Vol 30 (13) ◽  
pp. 1913-1931 ◽  
Author(s):  
Sajjad Nikoei ◽  
Behrooz Hassani
Keyword(s):  
Single Layer ◽  
Laminated Composite ◽  
Piezoelectric Sensor ◽  
Basis Functions ◽  
Shell Structures ◽  
Free Form ◽  
Control Analysis ◽  
Sensors And Actuators ◽  
Spline Basis ◽  
Shell Formulation

An isogeometric approach to the analysis of laminated composite smart shell structures based on the degenerated formulation and Mindlin–Reissner assumptions using non-uniform rational B-spline basis functions is the subject of this article. To model the laminated orthotropic smart free-form shells, the equivalent single layer theory is adopted, and an accurate approach to construct the local basis systems is used. To consider the electric potential in the piezoelectric layers, a sub-layer approach is employed that assumes linear variation over the thickness of the sub-layer. To investigate the performance of the approach, static, free vibration, and static control analysis of laminated composite shells covered with piezoelectric sensor and actuator layers with different degrees of basis functions is performed. Also, the effect of mechanical loading, various input voltages, and different boundary conditions on the static response and natural frequencies have been investigated. Several numerical examples are presented to demonstrate the efficiency and accuracy of the approach and validated with the existing results from the literature.

Configurations of Single-Layer Barrel Vaults

2001 ◽  
Vol 4 (2) ◽  
pp. 53-64 ◽  
Author(s):  
Ahmed El-Sheikh
Keyword(s):  
Stress Distribution ◽  
Aspect Ratio ◽  
Boundary Conditions ◽  
Failure Mechanisms ◽  
Single Layer ◽  
Radius Of Curvature ◽  
Weight Value ◽  
Joint Rigidity ◽  
Barrel Vaults

Single-layer barrel vaults with one radius of curvature may be fabricated with several common grid configurations. With different configurations, the vault' s performance and aesthetics vary considerably affecting both its competitiveness and suitability for different applications. The study presented in this paper is an assessment of the most commonly adopted vault configurations and their effect on the vault stiffness/weight value, member stress distribution, number, length and weight of members, degree of statical redundancy, resistance to failure mechanisms, reliance on joint rigidity and cost. The study is parametric and covers wide variations of the vault aspect ratio, span/rise ratio and boundary conditions. The results of this study should be of significant value to the design of future barrel vault structures.

Natural Frequencies and Mode Shapes of Laminated Composite Skew Hypar Shells with Complicated Boundary Conditions Using Finite Element Method

2012 ◽  
Vol 585 ◽  
pp. 44-48 ◽  
Author(s):  
Ajay Kumar ◽  
Pradeep Bhargava ◽  
Anupam Chakrabarti
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Higher Order ◽  
Finite Element Formulation ◽  
Mode Shapes ◽  
Radius Of Curvature ◽  
Element Formulation

In the present investigation, free vibration behaviour is studied for the laminated composite skew hypar shells having twist radius of curvature. A higher-order shear deformation theory is employed in the C0 finite element formulation. Higher-order terms in the Taylor’s series expansion are used to represent the higher-order transverse cross sectional deformation modes. The formulation includes Sanders’ approximation for doubly curved shells considering the effect of transverse shear. The structural system is considered to be undamped. The correctness of the formulation is established by comparing the present results of problems with those available in the published literature. The effects of different parameters are studied on the free vibration aspects of laminated composite skew hypar shells. Effect of cross curvature is included in the formulation. The C0 finite element formulation has been done quite efficiently to overcome the problem of C1 continuity associated with the HSDT. The isoparametric FE used in the present model consists of nine nodes with seven nodal unknowns per node. Since there is no result available in the literature based on HSDT on the problem of free vibration of laminated composite skew hypar shells, new results are presented by varying geometry, boundary conditions, ply orientations and skew angles which will serve as benchmark for future researchers.

scholarly journals ESL Based Cylindrical Shell Elements with Hierarchical Shape Functions for Laminated Composite Shells

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Jae S. Ahn ◽  
Seung H. Yang ◽  
Kwang S. Woo
Keyword(s):  
Cylindrical Shell ◽  
Three Dimensional ◽  
Single Layer ◽  
Laminated Composite ◽  
Shell Element ◽  
Composite Shells ◽  
Shell Elements ◽  
Cylindrical Coordinate ◽  
Laminated Composite Shells ◽  
Geometry Mapping

We introduce higher-order cylindrical shell element based on ESL (equivalent single-layer) theory for the analysis of laminated composite shells. The proposed elements are formulated by the dimensional reduction technique from three-dimensional solid to two-dimensional cylindrical surface with plane stress assumption. It allows the first-order shear deformation and considers anisotropic materials due to fiber orientation. The element displacement approximation is established by the integrals of Legendre polynomials with hierarchical concept to ensure theC0-continuity at the interface between adjacent elements as well asC1-continuity at the interface between adjacent layers. For geometry mapping, cylindrical coordinate is adopted to implement the exact mapping of curved shell configuration with a constant curvature with respect to any direction in the plane. The verification and characteristics of the proposed element are investigated through the analyses of three cylindrical shell problems with different shapes, loadings, and boundary conditions.

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