scholarly journals High Aspect Ratio Nanoimprint Mold-Cavity Filling and Stress Simulation Based on Finite-Element Analysis

Micromachines ◽  
2017 ◽  
Vol 8 (8) ◽  
pp. 243 ◽  
Author(s):  
Hongwen Sun ◽  
Minqi Yin ◽  
Haibin Wang
Author(s):  
Ebrahim Soleimani ◽  
Mohammad Reza Tabeshpour ◽  
Mohammad Saeed Seif

Metal plates are essential parts of structures such as ship hulls and offshore oil platforms. These plates are typically under compressive axial forces. Hence, one of the main mechanisms for failure and collapse of such structures is buckling of plates. Thus, for safe and secure design, buckling strength of plates should be evaluated. Finite element analysis techniques are perfect tools for this purpose because of the accuracy and flexibility for performing simulations with different variables. In this study, the strength of aluminum plates has been studied using finite element analysis software and it was tried to study the influence of variables such as initial imperfections, plate thickness and aspect ratio on plate strength. It was found that increase in the imperfection magnitude leads to a decrease in the strength of the plate. This is mostly noticed in thin plates because of the plate’s stiffness reduction. Although the plate’s aspect ratio has a slight effect on strength, it has a considerable impact on the failure mechanism. In order to study a combination of plates and stiffeners buckling behavior, part of a high-aspect-ratio twin hull vessel hull structure is assessed under bending moment. It is observed that longitudinal stiffeners at the bottom of the hull in linear analysis undergo the maximum stress, while in non-linear analysis, the maximum stress is spread along with the structure of the deck and bottom, and neutral axis tolerates the minimum stress.


2014 ◽  
Vol 716-717 ◽  
pp. 1643-1647
Author(s):  
Yu Liang Luan ◽  
Wei Bin Rong ◽  
Li Ning Sun

In order to achieve greater workspace motion, it’s designed a high aspect ratio 3-PPSR flexible parallel robot, driven by a piezoelectric motor, connected by flexible hinges, which has the advantages of simple structure, non singular, seamless, high motion precision. Because of the stiffness of the system directly affecting the motion accuracy, load bearing performance, according to the characteristics of high aspect ratio flexible hinge, It’s established the mathematical model of flexible hinge through finite element method. Using method of integral stiffness, conbined coordination equation with force balance equation, the flexible stiffness model of system is obtained. Finally, through using Ansys, it’s confirmed the validity of the theoretical model by comparing of the theoretical stiffness model results with the finite element analysis of the model results, to provide a reliable guarantee for optimization and analysis of kinematics and dynamics of flexible parallel robot.


Author(s):  
Yuhui Huang ◽  
Chengcheng Wang ◽  
Shan-Tung Tu ◽  
Fu-Zhen Xuan ◽  
Takamoto Itoh

Finite element analysis is adopted to study the stress concentration of pit area under tension-torsion loading. The stress concentration factors under regular evolution and irregular evolution of pits are investigated by conducting a series of three-dimensional semi-elliptical pitted models. Based on the finite element analysis, it can be concluded that pit aspect ratio (a/2c) is a significant parameter affecting stress concentration factor (SCF) for regular evolution pits. Pits, having higher aspect ratio, are very dangerous form and can cause significant reduction in the load carrying capacity. When local dissolution occurs in the pitting area, SCF will have a sharp increase, it is more probable for a crack to initiate from these areas compared with pits for regular evolution. Furthermore, local dissolution coefficient is proposed to study effect of local dissolution within the pit on SCF.


2013 ◽  
Vol 22 (1) ◽  
pp. 018103 ◽  
Author(s):  
Jian Feng ◽  
Jun-Feng Zhang ◽  
Sen-Xiang Lu ◽  
Hong-Yang Wang ◽  
Rui-Ze Ma

2019 ◽  
Vol 801 ◽  
pp. 65-70
Author(s):  
Jian Hong Gao ◽  
Xiao Xiang Yang

RVE combined with finite element analysis (FEA) is a very popular method to predict the mechanical property of the composite reinforced by short fibers. In the conventional method, generally the “tie” approach is used. By this method, the FE model with high fiber aspect ratio can not be achieved and the non-convergence of the numerical calculation may appear because of the complex mesh. The embedded element techinique is considered to be a replaceable method . Using this method, the mechanical behavior of composite with high fiber aspect ratio would be simulated. Therefore, in this study, the 3D solid element was employed for the FE model with multi cylinder particles. The comparisions of the Mise stress and the displacement between the embedded and conventional method indicate that compared with the stress transfer, the simulated result of composite stiffness is more accurate. In addition, the effects of model size, fiber orientated angle, fiber volume fraction and fiber aspect ratio were investigated. The numerical results were compared with the Mori-Tanaka model and the good agreements verify the applicability of the embedded element technique we studied in this paper.


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