Interval finite element method for complex eigenvalues of closed-loop systems with uncertain parameters

2007 ◽  
Vol 26 (2) ◽  
pp. 163-178 ◽  
Author(s):  
XiaoMing Zhang ◽  
Han Ding
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Closed Loop ◽  
Uncertain Parameters ◽  
Closed Loop Systems ◽  
Complex Eigenvalues ◽  
Interval Finite Element Method ◽  
Element Method

An Effect of Nozzle Flexibilities/Stiffness on Equipment Nozzle Loads and Local Stresses

2018 ◽  
Author(s):  
Sujay S. Pathre ◽  
K. Govindan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Analysis ◽  
Pressure Vessel ◽  
Closed Loop ◽  
Closed Loop Systems ◽  
Local Stresses ◽  
Load Evaluation ◽  
Element Method

The loads on the equipment nozzles are generally generated by the piping stress engineer by doing the stress analysis of entire closed loop systems. Subsequently the nozzle loads are passed on to the engineers of the pressure vessel equipment. The value of the loads which have been worked out for the nozzle mostly depends upon the methods/concept by which the piping stress engineer has evaluated the piping loop. Nozzle flexibility/stiffness is the important parameter in evaluation of various components of nozzle loads. The objective of this paper is to explain the effect/influence of flexibility/stiffness generated from three different methods (Anchor, WRC and Finite element method) on nozzle load evaluation and shell/nozzle junction stresses. WRC297 bulletin [6] gives the reference to nozzle flexibility in the appendix A, example no.3. The work presented in this paper is an attempt to compare the nozzle loads calculated by evaluating the flexibilities/stiffness in various methods. Further an attempt has been made to consolidate the results of junction local stresses obtained by the various methods of stiffness/flexibilities which would result in realistic results and overall code acceptable stresses without the results being either overly conservative or unconservative.

An interval finite element method for electromagnetic problems with spatially uncertain parameters

2019 ◽  
Vol 63 (1) ◽  
pp. 25-43
Author(s):  
ZhongHua Wang ◽  
Chao Jiang ◽  
BingYu Ni ◽  
CongSi Wang ◽  
JianFeng Zhong ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Uncertain Parameters ◽  
Electromagnetic Problems ◽  
Interval Finite Element Method ◽  
Element Method

scholarly journals A substructure-based interval finite element method for problems with uncertain but bounded parameters

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668407
Author(s):  
Yihuan Zhu ◽  
Guojian Shao ◽  
Jingbo Su ◽  
Ang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Evaluation System ◽  
Nonlinear Problems ◽  
Expansion Method ◽  
Constant Matrix ◽  
Approximation Solution ◽  
Interval Finite Element Method ◽  
Necessary Constraints ◽  
Element Method

In this article, the dependency between different elements in solid structures is considered and a substructure-based interval finite element method is used to model the interval properties. The penalty method is applied to impose the necessary constraints for compatibility. In order to obtain the interval stresses, an approximation solution based on the Taylor expansion method is presented. Then, the proposed interval substructure model is expanded to nonlinear problems. In consideration of the nonlinear property of the elasticity modulus, an interval elastoplastic substructure analysis method using constant matrix based on the incremental theory is proposed and the interval expression of the interval stress updated formation is derived. Finally, numerical examples are carried out to demonstrate the reasonability and feasibility of the proposed method and evaluation system.

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