Predicting Creep Behavior of Silicon Nitride Components Using Finite Element Techniques

Author(s):  
JA Wade ◽  
CS White ◽  
FJ Wu
1998 ◽  
Vol 546 ◽  
Author(s):  
V. Ziebartl ◽  
O. Paul ◽  
H. Baltes

AbstractWe report a new method to measure the temperature-dependent coefficient of thermal expansion α(T) of thin films. The method exploits the temperature dependent buckling of clamped square plates. This buckling was investigated numerically using an energy minimization method and finite element simulations. Both approaches show excellent agreement even far away from simple critical buckling. The numerical results were used to extract Cα(T) = α0+α1(T−T0 ) of PECVD silicon nitride between 20° and 140°C with α0 = (1.803±0.006)×10−6°C−1, α1 = (7.5±0.5)×10−9 °C−2, and T0 = 25°C.


2015 ◽  
Vol 750 ◽  
pp. 266-271 ◽  
Author(s):  
Yu Zhou ◽  
Xue Dong Chen ◽  
Zhi Chao Fan ◽  
Yi Chun Han

The creep behavior of 2.25Cr-1Mo-0.25V ferritic steel was investigated using a set of physically-based creep damage constitutive equations. The material constants were determined according to the creep experimental data, using an efficient genetic algorithm. The user-defined subroutine for creep damage evolution was developed based on the commercial finite element software ANSYS and its user programmable features (UPFs), and the numerical simulation of the stress distribution and the damage evolution of the semi V-type notched specimen during creep were studied. The results showed that the genetic algorithm is a very efficient optimization approach for the parameter identification of the creep damage constitutive equations, and finite element simulation based on continuum damage mechanics can be used to analyze and predict the creep damage evolution under multi-axial stress states.


2008 ◽  
Vol 485 (1-2) ◽  
pp. 422-427
Author(s):  
Cosme Roberto Moreira da Silva ◽  
Flaminio Levy Neto ◽  
José Alexander Araújo ◽  
Claudinei dos Santos

Author(s):  
Lun Qiu ◽  
John Zhang

The fluid barrier in an unbonded flexible pipe seals the pressure from the internal fluid. Since the barrier is usually made of polymer materials, it is unable to hold the pressure by itself. A metal reinforced hoop layer is usually needed outside the barrier layer in order to resist the pressure. The hoop layer is usually a steel bar with a cross-section of an irregular shape. It is helically wrapped at the outside of the barrier layer. When the pipe is pressurized, the barrier will be supported by the hoop reinforcement layer from outside. However, at the gap between the steel wraps where the barrier layer bridges, material of the barrier will be forced to extrude into the gap. The amount of the extrusion is a function of many parameters such as temperature, material property, and internal pressure and so on. In addition, it is time dependent. The creep effect needs be considered. It is critical to have a proper barrier design for a flexible pipe structure. This article presents a practical finite element method for evaluation of the barrier/gap design. The creep behavior of the polymers is multi-parameter related. Therefore, a series of material tests has been conducted under various stresses and temperatures for nylon, polyethylene and Polyvinylidene Fluoride. In this work a method is given to determine the creep behavior parameters through parameter matching based on the tests. The creep deformation of barrier was analyzed with a finite element model using these parameters.


Author(s):  
Brian Rose ◽  
James Widrig

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.


2014 ◽  
Vol 47 (1) ◽  
pp. 297-301 ◽  
Author(s):  
A.P.G. Castro ◽  
W. Wilson ◽  
J.M. Huyghe ◽  
K. Ito ◽  
J.L. Alves

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