scholarly journals Stability Analysis of a Tapered Symmetric Sandwich Beam Resting on a Variable Pasternak Foundation

2019 ◽  
Vol 24 (2) ◽  
pp. 228-240 ◽  
Author(s):  
Madhusmita Pradhan ◽  
P. R. Dash ◽  
Mrunal Kanti Mishra ◽  
Prasanta Kumar Pradhan
Keyword(s):  
Stability Analysis ◽  
Parametric Instability ◽  
Core Loss ◽  
Sandwich Beam ◽  
Weight Ratio ◽  
High Strength ◽  
Computational Method ◽  
Space Vehicles ◽  
Density Parameter ◽  
Pasternak Foundation

The static and dynamic stability analysis of a three-layered, tapered and symmetric sandwich beam resting on a variable Pasternak foundation and undergoing a periodic axial load has been carried out for two different boundary conditions by using a computational method. The governing equation of motion has been derived by using Hamilton’s principle along with generalized Galerkin’s method. The effects of elastic foundation parameter, core-loss factor, the ratio of length of the beam to the thickness of the elastic layer, the ratio of thickness of shear-layer of Pasternak foundation to the length of the beam, different modulus ratios, taper parameter, core thickness parameter, core-density parameter and geometric parameter on the non-dimensional static buckling load and on the regions of parametric instability are studied. This type of study will help the designers to achieve a system with high strength to weight ratio and better stability which are the desirable parameters for many modern engineering applications, such as in the attitude stability of spinning satellites, stability of helicopter components, stability of space vehicles etc.

scholarly journals Static and Dynamic Stability Analysis of an Asymmetric Rotating Tapered Sandwich Beam Subjected to Pulsating Axial Load with Thermal Gradient

2019 ◽  
Vol 24 (4) ◽  
pp. 665-676
Author(s):  
Madhusmita Pradhan ◽  
Pushparaj Dash
Keyword(s):  
Boundary Conditions ◽  
Dynamic Stability ◽  
Thermal Gradient ◽  
Axial Load ◽  
Equations Of Motion ◽  
Core Loss ◽  
Sandwich Beam ◽  
Density Parameter ◽  
Static And Dynamic Stability ◽  
Elastic Layers

The static and dynamic stability of an asymmetric rotating tapered sandwich beam subjected to pulsating axial load in temperature environment is studied under two different boundary conditions. The non-dimensional equations of motion and the boundary conditions are derived by applying Hamilton's energy principle. A coupled Hill's equations with complex coefficients are derived from the non-dimensional equations of motion by the application of the generalized Galerkin method. By the application of the Saito-Otomi conditions, zones of instabilities are obtained and presented graphically. For the calculation of the Young's module for the elastic layers, the effect of temperature has been taken in to consideration by means of a uniform thermal gradient along the longitudinal axes for both the upper and lower elastic layers. The effects of the taper parameter, core loss factor, thermal gradient, rotational speed, hub radius, and core density parameter on the static buckling loads and the regions of instability are investigated.

scholarly journals Dynamic Instability of MRE Embedded Soft Cored Sandwich Beam with Non-Conductive Skins

2011 ◽  
Vol 18 (6) ◽  
pp. 759-788 ◽  
Author(s):  
S.K. Dwivedy ◽  
M. Srinivas
Keyword(s):  
Dynamic Instability ◽  
Parametric Instability ◽  
Core Loss ◽  
Sandwich Beam ◽  
Beam Theory ◽  
Skin Thickness ◽  
Axial Loads ◽  
Parametric Resonances ◽  
Complex Coefficients ◽  
Equations Of Motions

In this work the governing temporal equations of motions with complex coefficients have been derived for a three-layered unsymmetric sandwich beam with nonconductive skins and magnetorheological elastomer (MRE) embedded soft-viscoelastic core subjected to periodic axial loads using higher order sandwich beam theory, extended Hamilton's principle, and generalized Galerkin's method. The parametric instability regions for principal parametric and combination parametric resonances for first three modes have been determined for various end conditions with different shear modulus, core loss factors, number of MRE patches and different skin thickness. This work will find application in the design and application of sandwich structures for active and passive vibration control using soft core and MRE patches.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

TUNGUM ALLOY

Alloy Digest ◽  
2012 ◽  
Vol 61 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Properties ◽  
Excellent Corrosion Resistance

Abstract Tungum alloy combines an unusually high strength-to-weight ratio, with ductility, excellent corrosion resistance, and good fatigue properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Cu-806. Producer or source: Tungum Ltd.

SANDVIK Ti-3Al-2.5V GRADE 9

Alloy Digest ◽  
1997 ◽  
Vol 46 (9) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Endurance Limit ◽  
Weight Ratio ◽  
High Strength ◽  
Strain Ratio ◽  
Bend Strength ◽  
Aerospace Applications ◽  
Excellent Corrosion Resistance ◽  
Titanium Aluminum ◽  
Fatigue Endurance

Abstract Sandvik Ti-3Al-2.5V Grade 9 titanium-aluminum alloy offers excellent corrosion resistance, especially to chloride media, and has a high strength-to-weight ratio, which is especially suitable for use in aerospace applications. Tubing can be produced having a CSR (contractile strain ratio) that enhances the fatigue endurance limit. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as fatigue. It also includes information on corrosion resistance as well as forming, machining, and joining. Filing Code: TI-109. Producer or source: Sandvik.

DONEGAL DC-50

Alloy Digest ◽  
1954 ◽  
Vol 3 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Heat Treating

Abstract Donegal DC-50 is a precipitation hardening stainless steel having high strength-weight ratio. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, joining, and surface treatment. Filing Code: SS-17. Producer or source: Donegal Manufacturing Corporation.

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