On the Torsion of Rectangular Sandwich Plates

1956 ◽  
Vol 23 (2) ◽  
pp. 191-194
Author(s):  
Paul Seide
Keyword(s):  
Cross Sections ◽  
Torsional Rigidity ◽  
Constant Thickness ◽  
Sandwich Plates ◽  
The Core ◽  
Equal Thickness ◽  
Rectangular Sandwich Plates

Abstract The torsional rigidity of rectangular sandwich plates of constant thickness is calculated, with cross sections assumed free to warp. The faces are isotropic and of equal thickness while the core may be orthotropic, the axes of orthotropy coinciding with co-ordinate axes of the structure.

scholarly journals Analytical solution of some delamination scenarios in thick structural sandwich plates

2017 ◽  
Vol 21 (4) ◽  
pp. 1271-1315 ◽  
Author(s):  
András Szekrényes
Keyword(s):  
Finite Element ◽  
State Space Model ◽  
Sandwich Plates ◽  
Third Order ◽  
Element Analysis ◽  
The Core ◽  
Integral Distribution ◽  
Type Boundary ◽  
Delamination Front ◽  
Rectangular Sandwich Plates

The first-, second- and third-order shear deformation plate theories are applied in this work to model thick rectangular sandwich plates with through-width delamination. The models are based on the concept of the four equivalent single layers and the system of exact kinematic conditions. Three different scenarios are considered: the failure of the core, the delamination between the top facesheet and the core, and finally, the case when the delamination takes place in the local midplane of the top facesheet. A general model is derived and applied to sandwich plates with Lévy type boundary conditions. The governing equations are summarized and the state-space model of the system is created. The mechanical fields are calculated and compared to finite element results. The comparison shows that the first-order sandwich plate model is inaccurate, on the other hand, the second- and third-order theories capture very well the mechanical fields compared to finite element results. The J-integral distribution is also calculated along the delamination front and it is concluded that the third- and second-order models give very good approximations of the results by finite element analysis and the virtual crack closure technique.

Torsion of Sandwich Plates of Trapezoidal Cross Section

1961 ◽  
Vol 28 (3) ◽  
pp. 363-366 ◽  
Author(s):  
Shun Cheng
Keyword(s):  
Cross Section ◽  
Plane Stress ◽  
Sandwich Plates ◽  
Stress Strain ◽  
Trapezoidal Cross Section ◽  
The Core ◽  
Isotropic Solid ◽  
Stress Components ◽  
Equal Thickness

A system of suitable stress-strain relations as well as equations of equilibrium are derived and solved for the torsion of sandwich plates of trapezoidal cross section. The facings are treated as isotropic solid membranes of equal thickness while the core is of such a nature that its stiffnesses associated with plane-stress components are negligibly small.

Stress Analysis of Sandwich Plates With Unidirectional Thickness Variation

1986 ◽  
Vol 53 (3) ◽  
pp. 609-613 ◽  
Author(s):  
N. Paydar ◽  
C. Libove
Keyword(s):  
Cross Sections ◽  
Transverse Shear ◽  
Middle Surface ◽  
Thickness Variation ◽  
Sandwich Plates ◽  
The Core ◽  
Small Deflection ◽  
The Face ◽  
Deflection Theory ◽  
Sheet Membrane

A small deflection theory is presented for the stresses and deformations in variable thickness elastic sandwich plates that are symmetric about a middle surface. In this analysis the face sheets are treated as membranes; the core is assumed to be inextensible in the thickness direction, to carry only transverse shear stress on its cross sections normal to middle surface, and to be deformable in transverse shear. The theory takes into account the contribution of the face sheet membrane forces (by virtue of their slopes) to the transverse shear.

Large Deflection of Rectangular Sandwich Plates

AIAA Journal ◽  
1967 ◽  
Vol 5 (9) ◽  
pp. 1706-1708 ◽  
Author(s):  
HAN-PIN KAN ◽  
JU-CHIN HUANG
Keyword(s):  
Large Deflection ◽  
Sandwich Plates ◽  
Rectangular Sandwich Plates

scholarly journals Morphology and Degradation of Multicompartment Microparticles Based on Semi-Crystalline Polystyrene-block-Polybutadiene-block-Poly(L-lactide) Triblock Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4358
Author(s):  
Nicole Janoszka ◽  
Suna Azhdari ◽  
Christian Hils ◽  
Deniz Coban ◽  
Holger Schmalz ◽  
...  
Keyword(s):  
Cross Sections ◽  
Ring Opening ◽  
Particle Diameter ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Selective Degradation ◽  
The Core ◽  
Transmission Electron ◽  
And Control ◽  
Triblock Terpolymers

The confinement assembly of block copolymers shows great potential regarding the formation of functional microparticles with compartmentalized structure. Although a large variety of block chemistries have already been used, less is known about microdomain degradation, which could lead to mesoporous microparticles with particularly complex morphologies for ABC triblock terpolymers. Here, we report on the formation of triblock terpolymer-based, multicompartment microparticles (MMs) and the selective degradation of domains into mesoporous microparticles. A series of polystyrene-block-polybutadiene-block-poly(L-lactide) (PS-b-PB-b-PLLA, SBL) triblock terpolymers was synthesized by a combination of anionic vinyl and ring-opening polymerization, which were transformed into microparticles through evaporation-induced confinement assembly. Despite different block compositions and the presence of a crystallizable PLLA block, we mainly identified hexagonally packed cylinders with a PLLA core and PB shell embedded in a PS matrix. Emulsions were prepared with Shirasu Porous Glass (SPG) membranes leading to a narrow size distribution of the microparticles and control of the average particle diameter, d ≈ 0.4 µm–1.8 µm. The core–shell cylinders lie parallel to the surface for particle diameters d < 0.5 µm and progressively more perpendicular for larger particles d > 0.8 µm as verified with scanning and transmission electron microscopy and particle cross-sections. Finally, the selective degradation of the PLLA cylinders under basic conditions resulted in mesoporous microparticles with a pronounced surface roughness.

scholarly journals GEOMETRIC MODELING OF A SHAPE OF PARALLELOGRAM PLATES IN A PROBLEM OF FREE VIBRATIONS USING CONFORMAL RADII

2021 ◽  
pp. 143-159
Author(s):  
A.A. Chernyaev ◽  
Keyword(s):  
Cross Sections ◽  
Geometric Modeling ◽  
Interpolation Method ◽  
Geometric Characteristic ◽  
Free Vibrations ◽  
Theory Of Elasticity ◽  
Constant Thickness ◽  
Basic Frequency ◽  
Plate Vibrations ◽  
The Subject

The paper considers a method of geometric modeling applied when solving basic twodimensional problems of the theory of elasticity and structural mechanics, in particular the applied problems of engineering. The subject of this study is vibrations of thin elastic parallelogram plates of constant thickness. To determine a basic frequency of vibrations, the interpolation method based on the geometric characteristic of the shape of plates (membrane, cross sections of a rod) is proposed. This characteristic represents a ratio of interior and exterior conformal radii of the plate. As is known from the theory of conformal mappings, conformal radii are those obtained by mapping of a plate onto the interior and exterior of a unit disk. The paper presents basic terms, tables, and formulas related to the considered geometric method with a comparative analysis of the curve diagrams obtained using various interpolation formulas. The original computer program is also developed. The main advantage of the proposed method of determining the basic frequency of plate vibrations is a graphic representation of results that allows one to accurately determine the required solution on the graph among the other solutions corresponding to the considered case of parallelogram plates. Although there are many known approximate approaches, which are used to solve the considered problems, only geometric modeling technique based on the conformal radii ratio gives such an opportunity.

scholarly journals Free Vibration of Sandwich Plates and Shells by Using Zig-Zag Function

2009 ◽  
Vol 16 (5) ◽  
pp. 495-503 ◽  
Author(s):  
S. Brischetto ◽  
E. Carrera ◽  
L. Demasi
Keyword(s):  
Free Vibration ◽  
Free Vibration Analysis ◽  
Sandwich Plates ◽  
Vibration Modes ◽  
Fundamental Vibration ◽  
First Derivative ◽  
The Core ◽  
Sandwich Plates And Shells ◽  
Plates And Shells ◽  
Free Vibration Response

This paper analyses the free vibration response of sandwich curved and flat panels by introducing the zig-zag function (—1)kζk(ZZF) in the displacement models of classical and higher order two-dimensional shell theories. The main advantage of ZZF is the introduction of a discontinuity in the first derivative, zig-zag effect, of the displacements distribution with correspondence to the core/faces interfaces. Results including and discarding ZZF are compared. Several values of face-to-core stiffness ratio (FCSR) and geometrical plate/shell parameters have been analyzed. Both fundamental vibration modes and those corresponding to high wave numbers are considered in the analysis. It is concluded that: (1) ZZF is highly recommended in the free vibration analysis of sandwich plates and shells; (2) the use of ZZF makes the error almost independent by FCSR parameter; (3) ZZF is easy to implement and its use should be preferred with respect to other `more cumbersome' refined theories.

Calculation for Elastic Global Buckling of Sandwich Plates with Ribs

2012 ◽  
Vol 188 ◽  
pp. 25-30 ◽  
Author(s):  
Qi Chao Xue ◽  
Guang Ping Zou ◽  
Ye Wu ◽  
Hai Lin Xiong ◽  
Meng Chai
Keyword(s):  
Energy Method ◽  
Sandwich Plate ◽  
Plate Theory ◽  
Sandwich Plates ◽  
Buckling Stress ◽  
Global Buckling ◽  
Simple Support ◽  
Rectangular Sandwich Plate ◽  
Two Sides ◽  
Rectangular Sandwich Plates

Based on Reissner’s sandwich plate theory, the critical globlal buckling equation of sandwich plate with ribs is deduced by energy method under simple support boundary conditions. And the critical buckling solution is obtained and discussed here. Afterwards a rectangular sandwich plate with steel faceplate and polyurthane core is taken as an example. The influence on critical global buckling stress with different inertia moments in rectangular sandwich plates are discussed. simularly the effect of the lengh ratio of two sides and the thickness of rectangular sandwich plate are also studied.

Lanthanum Staining of Neurotubules in Axons from Cockroach Ganglia

1970 ◽  
Vol 7 (1) ◽  
pp. 217-231
Author(s):  
NANCY J. LANE ◽  
J. E. TREHERNE
Keyword(s):  
Cross Sections ◽  
Periplaneta Americana ◽  
Water Soluble ◽  
Clear Zone ◽  
Lanthanum Hydroxide ◽  
Small Water ◽  
The Core ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Form Part

The axoplasm of the neurons of Periplaneta americana contains numerous neurotubules which are morphologically similar to the microtubules found in non-nervous tissues after sectioning or negative staining. In cross-sections of fixed material such tubules usually appear as electron-dense circles containing a less dense core and surrounded by a non-opaque ‘clear zone’. However, when cockroach ganglia are fixed and incubated in lanthanum hydroxide, the lanthanum is taken up intracellularly by the axoplasm of certain of the neurons and in these is found to stain the entire core of the neurotubules, as well as the clear zone. At least part of the wall of the tubules remains unstained and appears as a ring of non-opaque subunits against an electron-dense, lanthanum-stained background. Since lanthanum staining, under the conditions used here, is sometimes considered to demonstrate the presence of acid muco-polysaccharides, its uptake by the neurotubules may indicate that they contain carbohydrate as well as the protein that is generally considered to form part of the microtubular wall. Alternatively, the lanthanum could indicate the location of other anionic molecules, possibly undergoing extra- or intratubular translocation. The extent to which neurotubules could mediate movements of relatively small water-soluble ions and molecules is considered in relation to their diffusion through the polyanion matrix represented by the core of the tubules.

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