Elastic Bounds of Bioinspired Nanocomposites

2013 ◽  
Vol 80 (6) ◽  
Author(s):  
H. J. Lei ◽  
Z. Q. Zhang ◽  
F. Han ◽  
B. Liu ◽  
Y.-W. Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Lower Bounds ◽  
Analytical Solutions ◽  
Volume Fraction ◽  
Upper And Lower Bounds ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Synthetic Materials

Biological materials in nature serve as a valuable source of inspiration for developing novel synthetic materials with extraordinary properties or functions. Much effort to date has been directed toward fabricating and understanding bio-inspired nanocomposites with internal architectures mimicking those of nacre and collagen fibril. Here we establish simple and explicit analytical solutions for both upper and lower bounds of the elastic properties of biocomposites in terms of various physical and geometrical parameters including volume fraction and moduli of constituents, and aspect ratio and alignment pattern of stiff reinforcements. Numerical analyses based on the finite element method are performed to validate the derived elastic bounds.

Local Hydrostatic Pressure Test for Cylindrical Vessels

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
H. Al-Gahtani ◽  
A. Khathlan ◽  
M. Sunar ◽  
M. Naffa'a
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hydrostatic Pressure ◽  
Cylindrical Vessel ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Wide Range ◽  
Pressure Test ◽  
Local Test ◽  
Alternative Test

The juncture of a small cylindrical nozzle to a large cylindrical vessel is very common in the pressure vessel industry. Upon fabrication, it is required that the whole structure is subjected to pressure testing. The test can be expensive as it necessitates pressurizing the whole structure typically having a large volume. Hence, it is proposed to make a “local test,” which is considerably simpler as it involves capping the small nozzle and testing only a relatively small portion of the structure. This paper investigates the accuracy and reliability of such an alternative test, using the finite-element method. Two different finite-element types are used in the study, specifically a shell-based element and a solid-based element. The verification of the finite-element results for two different cases shows that the models used in the study are valid. It also proves that the two element types yield very similar stress results. In addition, the study includes a numerical investigation of more than 40 different nozzle-to-vessel junctures with a wide range of parameters for the nozzle and vessel. The results indicate that the use of cylindrical caps that are slightly larger than the nozzle is not recommended as it produces stresses that are significantly different from those for the original required pressure test. As such, the study provides an estimate of the smallest size of the cap that may be used in the local test to generate stresses that agree with the full test. For most practical geometries, it is shown that the size of the cap needs to be at least 2–30 times larger than that of the nozzle, depending on the geometrical parameters of the juncture.

The Computation of Elastic Constants of Double Wall Carbon Nanotubes Based on the Finite Element Method Considering Van Der Waals' Force

2012 ◽  
Vol 562-564 ◽  
pp. 334-338 ◽  
Author(s):  
Li Jie Chen ◽  
Lin Bo Li ◽  
Qi Zhao
Keyword(s):  
Finite Element Method ◽  
Carbon Nanotubes ◽  
Finite Element ◽  
Aspect Ratio ◽  
Elastic Constants ◽  
Van Der Waals ◽  
Van Der Waals Force ◽  
Internal Layer ◽  
The Finite Element Method ◽  
Double Wall

Based on the finite element method (FEM), we study the elastic constants of double-wall carbon nanotubes (DWCNTs). In the models, the Lennard-Jones potential function is used to consider the Van der Waals' force between non-bond atoms from different layers. The variations of the elastic constants with the diameter and the aspect ratio of the internal layer nanotube are investigated systematically. The computational results indicate that for both the armchair and the zigzag DWCNTs, the elastic moduli are generally lower than those of the single-wall carbon nanotubes with the same chirality as the internal and external layers. With the increase of the diameter and the aspect ratio of the internal layer carbon nanotubes, the elastic constant of DWCNTs will fall to a stable value.

scholarly journals Derivation and optimization of deflection equations for tapered cantilever beams using the finite element method

2020 ◽  
Vol 39 (2) ◽  
pp. 351-362
Author(s):  
M.M. Ufe ◽  
S.N. Apebo ◽  
A.Y. Iorliam
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Analysis ◽  
Cantilever Beam ◽  
Analytical Solutions ◽  
Point Load ◽  
Structural Systems ◽  
The Finite Element Method ◽  
Tapered Cantilever Beam ◽  
Element Method

This study derived analytical solutions for the deflection of a rectangular cross sectional uniformly tapered cantilever beam with varying configurations of width and breadth acting under an end point load. The deflection equations were derived using a numerical analysis method known as the finite element method. The verification of these analytical solutions was done by deterministic optimisation of the equations using the ModelCenter reliability analysis software and the Abaqus finite element modelling and optimisation software. The results obtained show that the best element type for the finite element analysis of a tapered cantilever beam acting under an end point load is the C3D20RH (A 20-node quadratic brick, hybrid element with linear pressure and reduced integration) beam element; it predicted an end displacement of 0.05035 m for the tapered width, constant height cantilever beam which was the closest value to the analytical optimum of 0.05352 m. The little difference in the deflection value accounted for the numerical error which is inevitably present in the analyses of structural systems. It is recommended that detailed and accurate numerical analysis be adopted in the design of complex structural systems in order to ascertain the degree of uncertainty in design. Keywords: Deflection, Finite element method, deterministic optimisation, numerical error, cantilever beam.

scholarly journals Application of Finite Element Method for Analysis of Nanostructures

2017 ◽  
Vol 11 (2) ◽  
pp. 116-120 ◽  
Author(s):  
Jozef Bocko ◽  
Pavol Lengvarský
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Element Model ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Beam Elements ◽  
Stiffness Properties ◽  
Force Displacement ◽  
The Finite Element Model ◽  
Element Method

AbstractThe paper deals with application of the finite element method in modelling and simulation of nanostructures. The finite element model is based on beam elements with stiffness properties gained from the quantum mechanics and nonlinear spring elements with force-displacement relation are gained from Morse potential. Several basic mechanical properties of structures are computed by homogenization of nanostructure, e.g. Young's modulus, Poisson's ratio. The problems connecting with geometrical parameters of nanostructures are considered and their influences to resulting homogenized quantities are mentioned.

scholarly journals Interaction between Edge-Crack and Aggregate in Silicate-Based Composite

2017 ◽  
Vol 17 (2) ◽  
pp. 59-64
Author(s):  
Lucie Malíková ◽  
Jan Klusák
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Edge Crack ◽  
Matrix Material ◽  
Interfacial Transition Zone ◽  
Bending Test ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Three Point Bending

Abstract The paper deals with investigation of the interaction between an edge-crack and an aggregate in a silicate-based composite, because adding of aggregates into basic matrix material can improve the fracture mechanical properties of the material significantly. In this work, the three-point-bending test is modelled by means of the finite element method and the dependences of fracture parameters on various material and geometrical parameters of the aggregate and the interfacial transition zone are studied. The results are discussed thoroughly.

An analytical approach to evaluate effective coefficients of 1–3 piezoelectric composites

2021 ◽  
Author(s):  
Sanjeev Kumar Singh ◽  
Saroja Kanta Panda
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Volume Fraction ◽  
Numerical Study ◽  
The Finite Element Method ◽  
Effective Coefficients ◽  
Square Packing ◽  
Packing Arrangement ◽  
Piezoelectric Fiber ◽  
Element Method

In this paper, a micromechanics method is developed to evaluate effective coefficients of piezoelectric fiber-reinforced composites. An exact solution is derived for effective elastic, piezoelectric and dielectric coefficients of such piezocomposites subjected to the applied load in the direction transverse to the fiber orientation. Simultaneously, based on finite element method, a numerical study is performed on a representative volume element of such piezo composite containing fiber in square packing arrangement. The finite element method provides a numerical solution to evaluate effective elastic, piezoelectric and dielectric coefficients for discrete volume fraction of fiber, the range being 0.1–0.6 for this study. The results are interpolated to understand the overall behavior of such piezocomposites. The results obtained from the micromechanics method and the finite element method are compared with the results obtained from other models based on strength of materials method given in the literature. It is observed that the method developed in this study provides better results for effective coefficients susceptible to fiber packing arrangements.

scholarly journals ВЛИЯНИЕ ИЗГИБА ПЛУНЖЕРА НА ИЗМЕНЕНИЕ ОБЪЕМА В ЦИЛИНДРОВОЙ ПОЛОСТИ АВИАЦИОННОГО АКСИАЛЬНО-ПЛУНЖЕРНОГО НАСОСА

2019 ◽  
pp. 88-94
Author(s):  
Владимир Николаевич Доценко ◽  
Иван Григорьевич Лихошерст ◽  
Мелания Николаевна Бурда
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Smooth Function ◽  
Cylinder Block ◽  
Geometrical Parameters ◽  
Contact Deformation ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Rigid Cylinder ◽  
Element Method

In this article, the task is to consider the effect of the piston bending in an axial- piston pump under the action of hydraulic force on the kinematics of the pump. The change in kinematics due to the elastic deformation of the piston is estimated by the axial displacement of the piston face. The study takes into account the bias of the plunger in the gap, the elastic bending deformation of the plunger, the contact deformation of the plunger and the cylinder block. The task is considered on three models: a rigid piston in a rigid cylinder block; deformable piston in a rigid cylinder block; deformable piston, block, shoe, and disk. The values of the displacement of the piston, caused by elastic forces and misalignment in the gap depending on its position were obtained for the first time as a result of the analysis. The problem is solved both analytically and numerically using the finite element method. In the analytical solution of the problem, the piston is represented as a beam supported by pin and roller at the points of contact of the piston with the walls of the cylinder block. The three-dimensional model of the pump is applied to solve the problem by the finite element method, the contact deformation of the piston and the block is considered. According to the simulation results, the displacement of the piston is obtained depending on the position of the piston. The results of modeling an analytical model are presented in the form of a smooth function, and the results of numerical simulation using the finite-element method obtained for several points are interpolated by a smooth function. The conclusions suggest that the greatest deformations are achieved in the piston located at the bottom dead center, and the gap between the piston and the sleeve and the overall stiffness of the contact parts have the greatest effect. The results of the work can be used to correct the geometrical parameters of a heavily loaded aviation axial-plunger pump to reduce flow and pressure pulsations caused by the kinematics of the pump.

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