Stochastic Study on Discontinuous Slow Crack Growth Kinetics from an Arbitrarily Located Defect of Polyethylene Based on the Crack Layer Theory

2021 ◽  
Vol 197 ◽  
pp. 106326
Author(s):  
Jung-Wook Wee ◽  
Min-Seok Choi ◽  
Alexander Chudnovsky ◽  
Byoung-Ho Choi
Keyword(s):  
Crack Growth ◽  
Growth Kinetics ◽  
Slow Crack Growth ◽  
Crack Layer

Application of Crack Layer in Modeling of Slow Crack Growth in High-Density Polyethylene

2013 ◽  
Author(s):  
Haiying Zhang ◽  
Zhenwen Zhou ◽  
Alexander Chudnovsky
Keyword(s):  
Crack Growth ◽  
High Density Polyethylene ◽  
Slow Crack Growth ◽  
Growth Failure ◽  
High Density ◽  
Large Set ◽  
Layer Model ◽  
Crack Layer ◽  
Basic Parameters ◽  
Engineering Polymers

Crack layer model provides a comprehensive foundation for modeling of fracture growth, failure analysis, and lifetime prediction. During the past two decades, it has been widely applied for modeling various aspects of brittle fracture in general. This paper illustrates in details the procedure of implementation by an example of slow crack growth in a commercialized high-density polyethylene undergoing creep conditions. Firstly, we determine experimentally the basic parameters employed in constitutive equations of crack layer model such as draw ratio λ, the specific energy of transformation γtr, and drawing stress σdr, etc.. Secondly, we implement crack layer model numerically in lab-developed “Simulator”. The paper provides a paradigm for implementation of crack layer model in slow crack growth, and a blueprint for potential software development that can be used in ranking and the lifetime assessment of a large set of engineering polymers.

Development and Application of Slow Crack Propagation of Polyethylene Based on Crack Layer Theory

2007 ◽  
Vol 345-346 ◽  
pp. 489-492 ◽  
Author(s):  
Byoung Ho Choi ◽  
Alexander Chudnovsky
Keyword(s):  
Numerical Simulation ◽  
Crack Propagation ◽  
Crack Growth ◽  
Driving Forces ◽  
Slow Crack Growth ◽  
Layer Model ◽  
Elapsed Time ◽  
Simulation Based ◽  
Crack Layer

For explaining the SCG behavior of polyethylene, the crack layer theory is applied based on the description of two driving forces: crack and PZ. The relations between the speed of SCG, crack length and elapsed time are the most important characteristics of polyethylene resistance to crack propagation, or long-term brittle fracture. The crack layer model of slow crack growth in polyethylene is designed in such a way that it qualitatively reproduces the main features of the process indicated above and makes it possible to quantitatively match any pattern of step-wise crack growth. In this paper, the behavior of SCG of polyethylene is developed for numerical simulation based on the crack layer theory. Some parametric study and applications are addressed based on the developed simulation program.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

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