A closed form solution of stress intensity factors for three dimensional finite bodies with unsymmetric cracks by energy release rate method

1991 ◽  
Vol 47 (4) ◽  
pp. 257-290 ◽  
Author(s):  
Wang Qi Zhi ◽  
Zhang Xing ◽  
Ren Bing Yi
Keyword(s):  
Stress Intensity ◽  
Energy Release Rate ◽  
Closed Form ◽  
Release Rate ◽  
Stress Intensity Factors ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Form Solution ◽  
Intensity Factors ◽  
Rate Method

scholarly journals Stress Intensity Factors for Layered Pressure Vessel Inner Layer Through Cracks

2019 ◽  
Author(s):  
Joel R. Hobbs
Keyword(s):  
Elastic Modulus ◽  
Stress Intensity ◽  
Closed Form ◽  
Stress Intensity Factors ◽  
Pressure Vessel ◽  
Closed Form Solution ◽  
Pressure Vessels ◽  
Form Solution ◽  
Intensity Factors ◽  
Friction Forces

Abstract A difficulty encountered when performing Fitness-for-Service assessments for layered pressure vessels (LPVs) is the lack of stress intensity factor solution in literature that produce accurate results for inner layer longitudinal through cracks. Using surrogate solutions such as a through crack in a plate or cylinder produce results that can be overly conservative especially for longer cracks. This is largely due to the ability of a layered pressure vessel to redistribute hoop load to other layers, the restricted radial movement of the cracked layer, and the friction forces applied in the cracked region. To understand this problem, a parametric finite element model (FEM) generator was developed that is capable of producing layered pressure vessel models with inner layer through cracks. The results from the FEMs were used to create a dataset of inner layer through crack stress intensity factors (Ki) for layered pressure vessels corresponding to variations of internal pressure, radius, layer thicknesses, friction factor, and crack length. The elastic modulus of the material also has an effect on Ki but, for this dataset, the elastic modulus was fixed at the typical value for steel – 29,500 ksi (203 GPa). Finally, a non-dimensional model was developed and calibrated using the dataset. This allows Ki to be calculated without the need of a FEM using a closed-form equation. The results of the closed-form solution were then compared to FEM results showing accuracy was generally within 10%.

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