Dynamics properties of multi-layered composite sandwich doubly-curved shells

2021 ◽  
Vol 256 ◽  
pp. 113142
Author(s):  
Yanchun Zhai ◽  
Jiaxing Ma ◽  
Sen Liang
Keyword(s):  
Layered Composite ◽  
Composite Sandwich ◽  
Doubly Curved Shells ◽  
Doubly Curved

scholarly journals Foam core composite sandwich plates and shells with variable stiffness: Effect of the curvilinear fiber path on the modal response

2017 ◽  
Vol 21 (1) ◽  
pp. 320-365 ◽  
Author(s):  
Francesco Tornabene ◽  
Nicholas Fantuzzi ◽  
Michele Bacciocchi
Keyword(s):  
Kinematic Model ◽  
Free Vibration Analysis ◽  
Variable Stiffness ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Doubly Curved Shells ◽  
Present Solution ◽  
Reinforcing Fibers ◽  
Doubly Curved ◽  
Composite Sandwich Plates

This paper presents the free vibration analysis of composite sandwich plates and doubly curved shells with variable stiffness. The reinforcing fibers are located in the external skins of the sandwich structures according to curved paths. These curvilinear paths are described by a general expression that combines power-law, sinusoidal, exponential, Gaussian and ellipse-shaped functions. As a consequence, the reinforcing fibers are placed in these orthotropic layers in an arbitrary manner, in order to achieve the desired mechanical properties. The effect of this variable fiber orientation on the natural frequencies is investigated by means of several parametric studies. As far as the structural theory is concerned, an equivalent single layer approach based on the well-known Carrera Unified Formulation is employed. The Murakami’s function is added to the kinematic model to capture the zig-zag effect, when the soft-core effect is significant. Thus, several higher order shear deformation theories are taken into account in a unified manner. The differential geometry is employed to describe the reference surface of doubly curved shells and panels, which are characterized by variable radii of curvature. The numerical solution is obtained using the generalized differential quadrature method, due to its accuracy and stability features. The present solution is compared with the results available in the literature or obtained by finite element commercial codes.

scholarly journals Universally bistable shells with nonzero Gaussian curvature for two-way transition waves

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nikolaos Vasios ◽  
Bolei Deng ◽  
Benjamin Gorissen ◽  
Katia Bertoldi
Keyword(s):  
Gaussian Curvature ◽  
Energy Landscape ◽  
Propagation Distance ◽  
Energy Landscapes ◽  
Bending Energy ◽  
Nonlinear Dynamic Response ◽  
One Dimensional ◽  
Doubly Curved Shells ◽  
Doubly Curved ◽  
The Waves

AbstractMulti-welled energy landscapes arising in shells with nonzero Gaussian curvature typically fade away as their thickness becomes larger because of the increased bending energy required for inversion. Motivated by this limitation, we propose a strategy to realize doubly curved shells that are bistable for any thickness. We then study the nonlinear dynamic response of one-dimensional (1D) arrays of our universally bistable shells when coupled by compressible fluid cavities. We find that the system supports the propagation of bidirectional transition waves whose characteristics can be tuned by varying both geometric parameters as well as the amount of energy supplied to initiate the waves. However, since our bistable shells have equal energy minima, the distance traveled by such waves is limited by dissipation. To overcome this limitation, we identify a strategy to realize thick bistable shells with tunable energy landscape and show that their strategic placement within the 1D array can extend the propagation distance of the supported bidirectional transition waves.

Pressure Stability of Orthotropic Prolate Spheroids

1968 ◽  
Vol 12 (03) ◽  
pp. 163-164
Author(s):  
Herbert Becker
Keyword(s):  
External Pressure ◽  
Stress Fields ◽  
Membrane Stress ◽  
Doubly Curved Shells ◽  
Instability Theory ◽  
Mathematical Relation ◽  
Prolate Spheroids ◽  
Pressure Stability ◽  
Doubly Curved ◽  
Orthotropic Shells

Through the use of general instability theory for doubly curved orthotropic shells, a mathematical relation was developed to predict external pressure buckling of stiffened prolate spheroids. The procedure was applied to two experiments which were found to be in fair agreement with theory. In general, the method is applicable to doubly curved shells with orthotropic material properties (composites) as well as geometric orthotropicity, and subject to arbitrary membrane stress fields. It is not limited to pressure alone. Furthermore, because of the closed form of the solutions to many problems, the procedure would be particularly useful for optimization purposes.

On the Nonlinear Intrinsic Dynamics of Doubly Curved Shells

1981 ◽  
Vol 48 (4) ◽  
pp. 909-914 ◽  
Author(s):  
A. Libai
Keyword(s):  
Equations Of Motion ◽  
Time Integration ◽  
Constant Load ◽  
Field Equations ◽  
Integration Schemes ◽  
Doubly Curved Shells ◽  
External Reference ◽  
Time Integration Schemes ◽  
Intrinsic Form ◽  
Doubly Curved

The field equations of motion and compatibility for the nonlinear dynamics of doubly curved shells are recast in an intrinsic form, in terms of the metric and curvature functions of their reference surfaces. For appropriate input, the motion of the shell is described without the need for an external reference coordinate system or the use of vector quantities such as position, velocity, and acceleration. The equations are shown to be readily applicable to time integration schemes. Such cases, as the (spatially) constant load problem and the inextensional dynamics problem, are also considered. The need for further work in the area is emphasized.

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