Numerical investigation on the effect of thickness and stress level on fatigue crack growth in notched specimens

2021 ◽  
pp. 103138
Author(s):  
Ramy Gadallah ◽  
Hidekazu Murakawa ◽  
Kazuki Ikushima ◽  
Masakazu Shibahara ◽  
Seiichiro Tsutsumi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Numerical Investigation ◽  
Crack Growth ◽  
Stress Level ◽  
Notched Specimens

Fatigue Crack Growth in Notched Parts With Compressive Mean Load

1972 ◽  
Vol 94 (1) ◽  
pp. 243-247 ◽  
Author(s):  
H. Saal
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Residual Stresses ◽  
Mild Steel ◽  
Crack Growth ◽  
Notch Root ◽  
Compressive Load ◽  
Notched Specimens ◽  
Mechanics Model

A fracture mechanics model is proposed to describe fatigue crack propagation in notched specimens. This model accounts for residual stresses which are present at the notch root after unloading from maximum compressive load. This is of particular interest for specimens subjected to compressive mean load. According to the model, cracks will stop growing at the boundary of the plastically deformed zone if the specimen is subjected to compressive load only. Validity of the model was verified with notched specimens of mild steel.

On Material Qualification and Strength Design for Hydrogen Service

2015 ◽  
Author(s):  
Junichiro Yamabe ◽  
Hisao Matsunaga ◽  
Yoshiyuki Furuya ◽  
Saburo Matsuoka
Keyword(s):  
High Pressure ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Safety Factor ◽  
Fatigue Testing ◽  
Hydrogen Gas ◽  
Multiplier Method ◽  
Notched Specimens ◽  
Pressure Hydrogen

To clarify the usefulness of the safety factor multiplier method for hydrogen components given in the CHMC1-2014 standard, we performed slow-strain-rate tensile and fatigue testing by using smooth and notched specimens in air and in high-pressure hydrogen gas. We also conducted fatigue-crack growth tests by using compact tension specimens in air and in hydrogen gas. Testing of notched specimens sampled from a Cr–Mo steel gave a safety factor multiplier of 3.0. This value agreed well with that predicted by crack growth analysis taking into account hydrogen-enhanced fatigue-crack growth. The safety factor multipliers of types 304, 316, and 316L austenitic stainless steels were predicted to be 2.0, 1.6, and 1.3, respectively, from their fatigue-crack growth behaviors. The safety factor based on the safety factor multiplier method seems to be overly conservative for the various steels in high-pressure hydrogen gas service. We therefore propose a new and promising design method for specific component applications that is based on design by rule and design by analysis. The importance of operational histories of components for hydrogen service is introduced to permit the precise prediction of their fatigue lives.

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