Response of Spherical Shells of Composite Materials to Localized Loads

1974 ◽  
Vol 96 (4) ◽  
pp. 305-310
Author(s):  
H. S. Kliger ◽  
J. R. Vinson
Keyword(s):  
Composite Materials ◽  
Shear Modulus ◽  
Transverse Shear ◽  
Modulus Of Elasticity ◽  
Bessel Functions ◽  
Analytic Solutions ◽  
Pressure Vessels ◽  
Spherical Shells ◽  
Various Boundary Conditions ◽  
Polar Orthotropic

In order to better understand the response of spherical portions of composite material pressure vessels, the stresses and deformations in a thin, specially polar orthotropic shallow spherical shell subjected to a localized loading at the apex are analyzed. Although the shell studied is geometrically thin, transverse shear deformation is included because the ratio of in-plane modulus of elasticity to transverse shear modulus is between 20 and 50 for many composite materials of interest. Methods of analysis are presently available for analyzing the effects of localized loads on thin isotropic spherical and cylindrical shells, and isotropic, shallow spherical, sandwich shells. The methods presented herein provide the ability to treat the use of composite materials. The analytic solutions are obtained in terms of modified Bessel functions of noninteger order and complex argument. In digital computation these functions are transformed into a set of nondimensionalized, rapidly convergent infinite series. Over 500 computer runs have been made and reported on herein to provide a better understanding of the effects of parameters such as ratio of circumferential to meridional modulus of elasticity, ratio of circumferential modulus of elasticity to transverse shear modulus, various boundary conditions, degree of shell shallowness, and loaded area.

On the Effect of Transverse Shear Deformability on Stress Concentration Factors for Twisted and Sheared Shallow Spherical Shells

1986 ◽  
Vol 53 (3) ◽  
pp. 597-601 ◽  
Author(s):  
E. Reissner ◽  
F. Y. M. Wan
Keyword(s):  
Stress Concentration ◽  
Transverse Shear ◽  
Shell Theory ◽  
Bessel Functions ◽  
Plate Theory ◽  
Modified Bessel Functions ◽  
Spherical Shells ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Shear Deformable

Explicit solutions are obtained, in terms of modified Bessel functions, for the problems of transverse twisting and of tangential shearing of transversely shear-deformable shallow spherical shells with a small circular hole. The relevant stress concentration factors are calculated for the entire range of a rise-to-thickness ratio parameter and a transverse shear deformability parameter. The modification of known results obtained previously by shear deformable plate theory, and by shallow shell theory without consideration of transverse shear deformation effects, is delineated.

Test Method for Evaluation of Shear Modulus and Modulus of Elasticity of Laminated Anisotropic Composite Materials

1985 ◽  
Vol 13 (5) ◽  
pp. 387 ◽  
Author(s):  
AS Kleinberg ◽  
RL Meltzer ◽  
JR Schroeder ◽  
B Benzing ◽  
MB Vieth ◽  
...  
Keyword(s):  
Composite Materials ◽  
Shear Modulus ◽  
Modulus Of Elasticity ◽  
Test Method ◽  
Anisotropic Composite

A fast approach for acoustic source localization on a thin spherical shell

2021 ◽  
pp. 147592172110419
Author(s):  
Zixian Zhou ◽  
Zhiwen Cui ◽  
Tribikram Kundu
Keyword(s):  
Velocity Profile ◽  
Spherical Shell ◽  
Source Localization ◽  
Pressure Vessels ◽  
Solution Technique ◽  
Acoustic Source ◽  
Spherical Shells ◽  
Fast Approach ◽  
Acoustic Source Localization ◽  
Thin Spherical Shell

Thin spherical shell structures are wildly used as pressure vessels in the industry because of their property of having equal in-plane normal stresses in all directions. Since very large pressure difference between the inside and outside of the wall exists, any formation of defects in the pressure vessel wall has a huge safety risk. Therefore, it is necessary to quickly locate the area where the defect maybe located in the early stage of defect formation and make repair on time. The conventional acoustic source localization techniques for spherical shells require either direction-dependent velocity profile knowledge or a large number of sensors to form an array. In this study, we propose a fast approach for acoustic source localization on thin isotropic and anisotropic spherical shells. A solution technique based on the time difference of arrival on a thin spherical shell without the prior knowledge of direction-dependent velocity profile is provided. With the help of “L”-shaped sensor clusters, only 6 sensors are required to quickly predict the acoustic source location for anisotropic spherical shells. For isotropic spherical shells, only 4 sensors are required. Simulation and experimental results show that this technique works well for both isotropic and anisotropic spherical shells.

Features of nonlinear in-plane shear deformation of a unidirectional and orthogonally reinforced polymer sheets of composite materials

2021 ◽  
Vol 87 (5) ◽  
pp. 47-55
Author(s):  
A. O. Polovyi ◽  
N. V. Matiushevski ◽  
N. G. Lisachenko
Keyword(s):  
Experimental Data ◽  
Composite Materials ◽  
Shear Modulus ◽  
Maximum Deviation ◽  
Linear Section ◽  
Stress Strain ◽  
Plane Shear ◽  
End Point ◽  
Reinforced Polymer ◽  
Failure Point

A comparative analysis of typical stress-strain diagrams obtained for in-plain shear of the 25 unidirectional and cross-ply reinforced polymer matrix composites under quasi-static loading was carried out. Three of them were tested in the framework of this study, and the experimental data on other materials were taken from the literature. The analysis of the generalized shear-strength curves showed that most of the tested materials exhibit the similar deformation pattern depending on their initial shear modulus: a linear section is observed at the beginning of loading, whereas further increase of the load decreases the slope of the curve reaching the minimum in the failure point. For the three parameters (end point the linear part, maximum reduced deviation of the diagram, tangent shear modulus at the failure point) characterizing the individual features of the presented stress-strain diagrams, approximating their dependences on the value of the reduced initial shear modulus are obtained. At the characteristic points of the deformation diagrams, boundary conditions are determined that can be used to find the parameters of the approximating functions. A condition is proposed for determination of the end point of the linear section on the experimental stress-strain curve, according to which the maximum deviation between the experimental and calculated (according to Hooke’s law) values of the shear stress in this section is no more than 1%, thus ensuring rather high accuracy of approximation on the linear section of the diagram. The results of this study are recommended to use when developing universal and relatively simple in structure approximating functions that take into account the characteristic properties of the experimental curves of deformation of polymer composite materials under in-plane shear of the sheet. The minimum set of experimental data is required to determine the parameters of these functions.

Dynamic Behavior of Aircraft Wings Modeled as Doubly-Tapered Composite Thin-Walled Beams

1999 ◽  
Author(s):  
Sungsoo Na ◽  
Liviu Librescu
Keyword(s):  
Composite Materials ◽  
Free Vibration ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Transverse Shear ◽  
Dynamical Behavior ◽  
Time Dependent ◽  
Aircraft Wings ◽  
Helicopter Blades ◽  
Thin Walled

Abstract A study of the dynamical behavior of aircraft wings modeled as doubly-tapered thin-walled beams, made from advanced anisotropic composite materials, and incorporating a number of non-classical effects such as transverse shear, and warping inhibition is presented. The supplied numerical results illustrate the effects played by the taper ratio, anisotropy of constituent materials, transverse shear flexibility, and warping inhibition on free vibration and dynamic response to time-dependent external excitations. Although considered for aircraft wings, this analysis and results can be also applied to a large number of structures such as helicopter blades, robotic manipulator arms, space booms, tall cantilever chimneys, etc.

Building Protection with Composite Materials Application

2017 ◽  
Vol 755 ◽  
pp. 286-291 ◽  
Author(s):  
Dávid Ágoston Balázs ◽  
Zoltán Nyikes ◽  
Tünde Kovács
Keyword(s):  
Composite Materials ◽  
Material Science ◽  
Terrorist Attacks ◽  
Syntactic Foams ◽  
Reinforced Composites ◽  
New Materials ◽  
Spherical Shells ◽  
Secondary Damage ◽  
Blast Effects ◽  
Blast Effect

Building protection on our century is very important because of the terrorist attacks. The old buildings in Europe aren’t enough strong again blast loads. Nowadays we know many different explosives and theirs effects of walls and human bodies. The detonation caused blast effect provokes building damage and fragmentation effects. The explosion caused damages, parts of bricks and fragments produce other secondary damage in other buildings and human bodies.It can’t protect the historical and old buildings by new walls and fences because of the cityscape. It needs to find new possibilities to improve the buildings resistance again blast effects. It needs a effectively thin and strong materials to reinforced the buildings walls. The new materials innovated by material science can be good solution for this project. These materials usually composites likes syntactic foams, spherical shells or carbon fields reinforced composites.

Investigation of Fracture in Transparent Glass Fiber Reinforced Polymer Composites Using Photoelasticity

2002 ◽  
Author(s):  
Sanjeev K. Khanna ◽  
Marius D. Ellingsen ◽  
Robb M. Winter
Keyword(s):  
Composite Materials ◽  
Fatigue Cracks ◽  
Large Body ◽  
Mechanical Analysis ◽  
Pressure Vessels ◽  
High Ratio ◽  
Material Behavior ◽  
Engineering Structures ◽  
Glass Fiber Reinforced ◽  
Fiber Reinforced Polymer Composites

Composite materials are widely used in mechanical structures where a high ratio of strength or stiffness to weight is desired. Not only are composite materials widely used in building recreational equipment such as skis, snowboards or even sports cars, but also multiple types of military aircraft are built from composite materials. Airplane bodies are in principle cyclically loaded pressure vessels and are susceptible to the formation of fatigue cracks, and it is necessary to possess knowledge of how the material behaves with a crack present. In fact, all engineering structures have to be designed with the presence of crack like defects in mind. For traditional engineering materials such as steel and aluminum there exists a large body of knowledge regarding material behavior in the presence of a crack. Furthermore, their isotropic nature eases the process of mechanical analysis. Photoelasticity, an optical method, has been widely used to study fracture in isotropic transparent materials (Irwin, 1962, 1980; Dally, 1979; Daniel, 1984; Kobayashi, et al, 1973; Chona, 1987).

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