scholarly journals An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method

2020 ◽  
Vol 4 (6) ◽  
pp. 37-44
Author(s):  
Najmadeen Mohammed Saeed ◽  
Ahmed Aulla Manguri
Keyword(s):  
Simple Technique ◽  
Geometrical Property ◽  
Current Approach ◽  
Geometrically Nonlinear ◽  
Force Method ◽  
Internal Forces ◽  
Small Change ◽  
Nodal Displacements ◽  
Good Agreement ◽  
Incremental Loading

A relatively simple technique has been introduced in this paper. The approach is based on the Linear Force Method (FM) with discretion of the applied loads to the subsequence steps and updating coordinates in each iteration to have new geometrical property. The accuracy of the technique depends on the size of the discretion which depends on the number of iterations. A small change in the configuration could hugely affect the displacement and internal forces in geometrically nonlinear structures, that’s why the current approach is vital. The proposed technique is validated with other techniques of nonlinear analysis of the structures with a very good agreement in both terms of external nodal displacements and internal bar forces.

scholarly journals An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method

2020 ◽  
Vol 4 (6) ◽  
pp. 37-44
Author(s):  
Najmadeen Mohammed Saeed ◽  
Ahmed Aulla Manguri
Keyword(s):  
Simple Technique ◽  
Geometrical Property ◽  
Current Approach ◽  
Geometrically Nonlinear ◽  
Force Method ◽  
Internal Forces ◽  
Small Change ◽  
Nodal Displacements ◽  
Good Agreement ◽  
Incremental Loading

A relatively simple technique has been introduced in this paper. The approach is based on the Linear Force Method (FM) with discretion of the applied loads to the subsequence steps and updating coordinates in each iteration to have new geometrical property. The accuracy of the technique depends on the size of the discretion which depends on the number of iterations. A small change in the configuration could hugely affect the displacement and internal forces in geometrically nonlinear structures, that’s why the current approach is vital. The proposed technique is validated with other techniques of nonlinear analysis of the structures with a very good agreement in both terms of external nodal displacements and internal bar forces.

THE SUPPORT BONDS RIGIDITY INFLUENCES ON THE CARRYING CAPACITY REDUCTION OF THE SHALLOW SHELLS ON A RECTANGULAR PLAN

2020 ◽  
Vol 92 (6) ◽  
pp. 3-12
Author(s):  
A.G. KOLESNIKOV ◽  
Keyword(s):  
Variable Thickness ◽  
Carrying Capacity ◽  
Geometric Nonlinearity ◽  
Progressive Collapse ◽  
Geometrically Nonlinear ◽  
Loss Of Stability ◽  
Shallow Shells ◽  
Capacity Reduction ◽  
Internal Forces ◽  
Hinged Support

Geometric nonlinearity shallow shells on a square and rectangular plan with constant and variable thickness are considered. Loss of stability of a structure due to a decrease in the rigidity of one of the support (transition from fixed support to hinged support) is considered. The Bubnov-Galerkin method is used to solve differential equations of shallow geometrically nonlinear shells. The Vlasov's beam functions are used for approximating. The use of dimensionless quantities makes it possible to repeat the calculations and obtain similar dependences. The graphs are given that make it possible to assess the reduction in the critical load in the shell at each stage of reducing the rigidity of the support and to predict the further behavior of the structure. Regularities of changes in internal forces for various types of structure support are shown. Conclusions are made about the necessary design solutions to prevent the progressive collapse of the shell due to a decrease in the rigidity of one of the supports.

Structural Analysis of an Offshore Jacket Model Under Seismic Excitation

2008 ◽  
Author(s):  
Helder J. D. Correia ◽  
Anto´nio C. Mendes ◽  
Carlos A. F. S. Oliveira
Keyword(s):  
Point Of View ◽  
Shaking Table ◽  
Seismic Excitation ◽  
Model Structure ◽  
Structural Members ◽  
Jacket Structures ◽  
Reaction Forces ◽  
Nodal Displacements ◽  
Good Agreement

In the present work the action of earthquakes upon offshore jacket structures is analysed by means of ADINA software. Our case-study refers to an existing model structure, previously constructed at the Laboratory of Fluid Mechanics of UBI, which has been analysed from the hydrodynamic point of view — Mendes et al. [1, 2]. The seismic excitation will be imposed at the base of this model structure, with frequencies and amplitudes corresponding to actual earthquake conditions transposed to the model scale of 1:45. The FEM software is utilised to calculate the natural frequencies of the model and to obtain stresses at selected members, as well as their nodal displacements. Our purpose is to quantify maximum stresses occurring in critical structural members and to verify the survivability criterion. The predictions of the numerical model, in terms of the reaction forces at the base and acceleration at the top of the structure, are then correlated with the experimental measurements performed when the model structure is excited in an especially designed shaking table (Correia [3]), revealing a good agreement between both results.

scholarly journals Design, Synthesis, Spectral and Theoretical Studies of Some Picrates

2019 ◽  
Vol 32 (1) ◽  
pp. 174-182
Author(s):  
S. Amala ◽  
G. Rajarajan ◽  
E. Dhineshkumar ◽  
M. Arockia doss ◽  
V. Thanikachalam
Keyword(s):  
Geometrical Parameters ◽  
Slight Effect ◽  
Design Synthesis ◽  
1H And 13C Nmr ◽  
Visible Spectra ◽  
Ft Ir ◽  
Uv Visible ◽  
Small Change ◽  
Experimental Values ◽  
Good Agreement

The structures of newly synthesized compounds (1-3) viz. 3-ethyl-5-methyl-2,6-bis(4- chlorophenyl)piperidin-1-ium picrate (1), 3-ethyl-5-methyl-2,6-bis(4-methylphenyl)piperidin-1-ium picrate (2) and 3-ethyl-5-methyl-2,6-bis(3,4-dimethoxyphenyl)piperidin-1-ium picrate (3) were confirmed by elemental analysis, FT-IR, 1H and 13C NMR. The UV-visible spectra, fluoresence, emission properties of synthesized 1-3 in different solvents were studied. Compounds 1-3 solvatochromic displays a slight effect of the emission and absorption spectrum, indicating a small change in the dipole moment upon excitation of compounds 1-3. All the compounds were investigated by DFT. The theoretical geometrical parameters are in good agreement with experimental values.

A Finite Element Based Method to Determine the Properties of Planar Soft Tissue

1998 ◽  
Vol 120 (2) ◽  
pp. 202-210 ◽  
Author(s):  
D. M. Flynn ◽  
G. D. Peura ◽  
P. Grigg ◽  
A. H. Hoffman
Keyword(s):  
Finite Element ◽  
Analytical Data ◽  
Rat Skin ◽  
Quadrilateral Element ◽  
Rubber Sheet ◽  
Tangent Stiffness Matrix ◽  
Nodal Displacements ◽  
Planar Membranes ◽  
Orthotropic Behavior ◽  
Incremental Loading

A finite element based method to determine the incremental elastic material properties of planar membranes was developed and evaluated. The method is applicable to tissues that exhibit inhomogeneity, geometric and material nonlinearity, and anisotropy. Markers are placed on the tissue to form a four-node quadrilateral element. The specimen is loaded to an initial reference state, then three incremental loading sets are applied and the nodal displacements recorded. One of these loadings must include shear. These data are used to solve an over-determined system of equations for the tangent stiffness matrix. The method was first verified using analytical data. Next, data obtained from a latex rubber sheet were used to evaluate experimental procedures. Finally, experiments conducted on preconditioned rat skin revealed non-linear orthotropic behavior. The vector norm comparing the applied and calculated nodal force vectors was used to evaluate the accuracy of the solutions.

Experimental and Theoretical Studies of Nonlinear Resonances in a Si Microcantilever Constrained by a Polymer Attachment

2016 ◽  
Author(s):  
Keivan Asadi ◽  
Snehan Peshin ◽  
Junghoon Yeom ◽  
Hanna Cho
Keyword(s):  
Multiple Scales ◽  
Geometrically Nonlinear ◽  
Flexural Mode ◽  
Nonlinear Characteristics ◽  
Nonlinear Responses ◽  
Intentional Nonlinearity ◽  
Stiffness And Damping ◽  
Experimental And Theoretical Studies ◽  
Nonlinear Hardening ◽  
Good Agreement

In micro/nanometer scale mechanical resonators, constructive utilization of intentional nonlinearity has suggested ways to leverage beneficial nonlinear characteristics in their design for various applications. Previous studies have also shown that the geometric nonlinearity is effectively implemented and tailored through integration of nonlinear couplings to an otherwise linear microcantilever. Here, we demonstrate experimentally a nonlinear micromechanical resonator consisting of a silicon microcantilever axially constrained by a polymer attachment exhibiting a strong nonlinear hardening behavior not only in its first flexural mode but also in higher modes. A theoretical model representing the system with geometrically nonlinear stiffness and damping is analyzed by the method of multiple scales, which is favorably validated by good agreement with experimentally obtained nonlinear responses.

Power Dependence and Turn-On Dynamics of Polymer Photocells - Extracting Mobilities and Analyzing Morphologies

2005 ◽  
Vol 871 ◽  
Author(s):  
Noam Rappaport ◽  
Nir Tessler
Keyword(s):  
Simple Technique ◽  
Analytic Description ◽  
Power Dependence ◽  
Measured Intensity ◽  
Semiconducting Polymer ◽  
Charge Effects ◽  
Intensity Dependence ◽  
Turn On ◽  
Independent Verification ◽  
Good Agreement

AbstractWe present an analytic description for the loss of photocurrent efficiency at moderate light intensities and demonstrate a simple technique for extracting the mobility of electrons in semiconducting polymer layers. The underlying theoretical analysis, which is based on a simple drift-recombination scheme, shows good agreement with the measured intensity dependent photocurrent quantum efficiency. The electron mobility extraction is demonstrated for pristine MEH-PPV. The same physical framework is then used to describe the switch on of the photocurrent and the buildup of electron and hole concentrations inside the device. By analyzing the time evolution of the measured photocurrent transient we find an independent verification for the results extracted from the intensity dependence measurements. We use the combination of theoretical and experimental study to discuss the role recombination and space charge effects in reducing photocurrent efficiency.

Geometrically nonlinear calculation of trailing rod designs. Part 2. Matrix calculation of trailing systems

10.12737/336 ◽  
2013 ◽  
Vol 1 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Андрей Свентиков
Keyword(s):  
Successive Approximations ◽  
Method Of Successive Approximations ◽  
Geometrically Nonlinear ◽  
Matrix Algorithms ◽  
Nonlinear Matrix ◽  
Matrix Calculation ◽  
Good Agreement

Is treated geometrically nonlinear matrix calculation of core construction with the use of flexible threads. The second part of the article is devoted to the study of matrix algorithms nonlinear calculation of hanging systems. For the geometrically nonlinear calculation was applied the method of elastic solutions, and for the constructive nonlinear basis of the method of successive approximations. The proposed methods have been tested on the well-known plane examples of the calculation, as well as on the example of study of the spatial hanging rod cover. The results found on the proposed methods have shown good agreement with the corresponding data of other authors. Also it is established that the greatest imbalance nodes in the cantilevered system is observed in the nodes of a fle­xible bearing thread, as well as in the nodes of the greatest intensity of the load.

Alignment of Buckingham Parameters to Generalized Lennard-Jones Potential Functions

2009 ◽  
Vol 64 (3-4) ◽  
pp. 200-204 ◽  
Author(s):  
Teik-Cheng Lim
Keyword(s):  
Interatomic Distance ◽  
Potential Functions ◽  
Lennard Jones Potential ◽  
Jones Potential ◽  
Lennard Jones ◽  
Interatomic Separation ◽  
Total Separation ◽  
Small Change ◽  
Good Agreement ◽  
Interatomic Energy

Abstract The Lennard-Jones(12-6) and the Exponential-6 potential functions are commonly used in computational softwares for describing the van der Waals interaction energy. Some softwares allow switching between these two potentials under prescribed condition(s) that attempt to connect the parameter relationship between the two functions. Here we propose a technique by which the parameter relationship between both potentials is extracted by simultaneously imposing an equal force constant at the well depth’s minimum and an equal mean interatomic energy from the point of equilibrium to the point of total separation. The former imposition induces good agreement for the interatomic compression and a small change in the interatomic distance near the equilibrium while the latter enables good agreement for large interatomic separation. The excellent agreement exhibited by the plots validates the technique of combined criteria proposed herein

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