Deformation, Stress and Natural Frequency Analysis of the Fullerene by Finite Super Element Method

Author(s):  
Masoud Nasiri Sarvi ◽  
M. T. Ahmadian

Accurate prediction of static and dynamic response of nano structures is one of the important interests of scientists in the last decade. Nano bearing as an important part of nano machines has been extensively implemented in recognizing and disassembling cancerous cells and building molecular support structures for strengthening bones. For this reason, Molecular Dynamic Method and some experimental methods are implemented in this area. As nano ball bearing is one of the most important components of nano machines, a large number of studies are concentrated to analyze it statically and dynamically. In this paper, a Fullerene is simulated by a spherical super element whose stress, deformation and natural frequency are calculated. The Fullerene is considered to be the C60 which is properly similar with a 66 surface-node spherical super element. In this study the mechanical properties of the fullerene and boundary conditions of the nano ball bearing under loading are introduced and stress and natural frequency of a fullerene under concentrated load is presented with two different strategies, super element and conventional elements. Compatible findings of these two methods validate and confirm the results. Findings indicate that applying 1 super element for the simulation of the fullerene leads to same results as implementing 154764 conventional elements.

Author(s):  
Masoud Nasiri Sarvi ◽  
M. T. Ahmadian ◽  
Ahmad Barari

Accurate prediction of static and dynamic response of nano structures is one of the important interests of scientists in the last decade. Nano bearing as an important part of nano machines has been extensively implemented in recognizing and disassembling cancerous cells and building molecular support structures for strengthening bones. For this reason, Molecular Dynamic Method and some experimental methods are implemented in this area. As nano ball bearing is one of the most important components of nano machines, a large number of studies are concentrated to analyze it statically and dynamically. In this paper, a Fullerene is simulated by a spherical super element whose stress, deformation and natural frequency are calculated. The Fullerene is considered to be the C60 which is properly similar with a 66 surface-node spherical super element. In this study the mechanical properties of the fullerene and boundary conditions of the nano ball bearing under loading are introduced and stress and natural frequency of a fullerene under concentrated load is presented with two different strategies, super element and conventional elements. Compatible findings of these two methods validate and confirm the results. Findings indicate that applying 1 super element for the simulation of the fullerene leads to same results as implementing 154764 conventional elements.


2007 ◽  
Vol 35 (5) ◽  
pp. 817-824 ◽  
Author(s):  
F. Shao ◽  
W. Xu ◽  
A. Crocombe ◽  
D. Ewins

2019 ◽  
Vol 889 ◽  
pp. 484-488
Author(s):  
Van Thuan Nguyen ◽  
Duy Liem Nguyen

This paper applies the stochastic finite element method (SFEM) to perform the natural frequency analysis of functionally graded material (FGM). It is assumed that the elastic modulus and width of the FGM beam vary along the thickness and width directions following exponential functions. The stochastic eigenvalue problem is solved independently by first-order perturbation and Monte Carlo simulation (MCS) method through changing elastic modulus as spatial randomness. The results show that the first-order perturbation method based SFEM produces a very close value to MCS method.


2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Qingjun Yang ◽  
Rui Zhu ◽  
Zhenguo Niu ◽  
Chen Chen ◽  
Qi Mao ◽  
...  

Abstract Hydraulic quadruped robots can adapt to very complex ground conditions, as they have good maneuverability and high load capacity and, therefore, have received great attention in military research fields all over the world. However, there is no mature theory on how to ensure stable, efficient, and fast walking of robots. In this paper, from the point of view of the natural frequency of the hydraulic system, we first calculate the natural frequency of the robot's legs during the whole motion period of the robot and verify the accuracy of calculation through system identification. Then, through the analysis of the state equation and transfer function matrix of the multiple-input multiple-output system, it is found that the zero and pole of the system are very close, this is why the natural frequency is low but the system response is acceptable and then we prove that no parameter for the simultaneous zero-pole cancelation of two hydraulic cylinders exists. With the goal of increasing the natural frequency, we optimized the leg structure of the robot to find the best structural parameters. Finally, a single-leg test bench was built. The experimental results show that the optimization of the structure can actually increase the natural frequency of the system and significantly improve the response characteristics of the robot.


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