Use of Fracture Mechanics Methods for Establishing Inspection Level for Turbine Wheels

1979 ◽  
Vol 101 (1) ◽  
pp. 75-79 ◽  
Author(s):  
R. E. Frishmuth
Keyword(s):  
Fracture Mechanics ◽  
Ferritic Steels ◽  
Remaining Life ◽  
Turbine Wheel ◽  
Complex Issue ◽  
General Application ◽  
Linear Elastic ◽  
Safety And Reliability ◽  
Elastic Fracture ◽  
Non Destructive

The establishment of inspection criteria for wheels in rotating machinery is frequently a complex issue. On one hand, safety and reliability of the parts and equipment must be assured while on the other, economical use must be made of available materials. In addition to these often opposing criteria, account must be taken of the limitations and cost of non-destructive evaluation methods. One way of considering all these factors and establishing safe inspection and acceptance criteria for wheels is to employ linear elastic fracture mechanics (LEFM) methods. The purpose of this paper is to outline a method for using LEFM to establish allowable stress levels or fracture toughness required in turbine wheel ferritic steels. The methods proposed are discussed in schematic fashion and it is shown that general application of a single “design curve” to many situations is possible if accuracy in specific cases is sacrificed. If this sacrifice is made so that results are conservative then the resulting plots can be used during the design of the wheel, the acceptance of a part or the evaluation of remaining life of an in-service wheel.

Fracture-mechanics-based analytical prediction of remaining life of tubular T- and Y-joints

2005 ◽  
Vol 219 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A R C Murthy ◽  
G S Palani ◽  
N R Iyer
Keyword(s):  
Fracture Mechanics ◽  
Life Prediction ◽  
Analytical Prediction ◽  
Remaining Life ◽  
Constant Amplitude ◽  
Linear Elastic ◽  
Tubular Joints ◽  
Elastic Fracture ◽  
Experimental Values ◽  
Good Agreement

This paper presents methodologies for analytical prediction of remaining life of tubular T- and Y-joints by using linear elastic fracture mechanics principles. Bowness and Lee proposed expressions for the computation of the stress intensity factor (SIF) for T-butt plates which can be used for SIF computation of tubular joints and which are also recommended in BS 7910. It is observed from the literature that these expressions have not been used for the remaining life prediction of tubular joints. In this paper, these expressions have been used for analytical prediction of remaining life of tubular T- and Y-joints under constant amplitude loading. The predicted remaining life for T- and Y-joints is found to be in good agreement with those of experimental values reported in the literature. The effect of the degree of bending (DoB) on remaining life has been studied. It is observed from the studies that, the higher the DoB, the longer is the remaining life.

Fracture Mechanics Assessment of Hydrogen Storage Vessel

2021 ◽  
Author(s):  
Xiaoliang Jia ◽  
Zhiwei Chen ◽  
Fang Ji
Keyword(s):  
High Pressure ◽  
Fracture Mechanics ◽  
Hydrogen Storage ◽  
High Strength Steel ◽  
High Strength ◽  
Linear Elastic Fracture Mechanics ◽  
Storage Vessel ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Hydrogen Storage Vessel

Abstract High strength steel is usually used in fabrication of hydrogen storage vessel. The fracture toughness of high strength steel will be decreased and the crack sensitivity of the structures will be increased when high strength steels are applied in hydrogen environment with high pressure. Hence, the small cracks on the surface of pressure vessel may grow rapidly then lead to rupture. Therefore, this paper makes a series of research on how to evaluate the 4130X steel hydrogen storage vessel with fracture mechanics. This study is based on the assumption that there is a semi-elliptic crack on internal surface of hydrogen storage vessel. First of all, based on linear elastic fracture mechanics, the stress intensity factors and crack tolerance of 4130X steel hydrogen storage vessel have been calculated by means of finite element method based on interaction integral theory and polynomial-approximated approach from GB/T 34019 Ultra-high pressure vessels. Then, a comparative study has been made from the results of above methods to find out the difference between them. At last, the fatigue life of a 4130X steel hydrogen storage vessel has been predicted based on linear elastic fracture mechanics and Paris formula. The calculation methods and analysis conclusion can be used to direct the design and manufacture of hydrogen storage vessel.

Stress Corrosion Cracking Behavior of Uranium Alloys

CORROSION ◽  
1974 ◽  
Vol 30 (5) ◽  
pp. 181-189 ◽  
Author(s):  
W. F. CZYRKLIS ◽  
M. LEVY
Keyword(s):  
Fracture Mechanics ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Threshold Stress ◽  
Crack Extension ◽  
Corrosion Cracking ◽  
Nacl Solution ◽  
Cracking Behavior ◽  
Linear Elastic ◽  
Elastic Fracture

Abstract The stress corrosion cracking (SCC) behavior of U-3/4% Ti, and uranium alloys 3/4% Quad, 1% Quad, and 1% Quint have been studied utilizing a linear elastic fracture mechanics approach. The threshold stress intensities for stress corrosion crack propagation for these alloys have been determined in distilled H2O and NaCl solutions containing 50 ppm Cl− and 21,000 ppm Cl−. All of the alloys studied may be classified as very susceptible to SCC in aqueous solutions since they exhibit SCC in distilled H2O (<1 ppm Cl−) and have low KIscc values in NaCl solutions. Crack extension in all of the alloys in all environments was transgranular and failure occurred by brittle quasicleavage fracture in NaCl solution.

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