Fracture mechanics in design and service: ‘living with defects’ - Fracture mechanics of non-metallic materials

1981 ◽  
Vol 299 (1446) ◽  
pp. 59-72 ◽  
Keyword(s):  
Fracture Mechanics ◽  
Plane Strain ◽  
Design Criterion ◽  
Simple Extension ◽  
Metallic Materials ◽  
Environmental Behaviour ◽  
Linear Elastic ◽  
Wide Range ◽  
Elastic Fracture

An outline of linear elastic fracture mechanics (l.e.f.m.) is given with an emphasis on those aspects most relevant to non-metallic materials. Provided that the nonlinear zone of energy absorption surrounding the crack tip is small compared with other dimensions, then a K e or G e value may be used. A simple extension of this concept can include elastically nonlinear materials such as rubber. Examples of the use of this method are then given for polymers, rubber and wood, and include some discussion of the difficulties involving plane strain-plane stress transitions. The role of K e as a characterizing parameter in time-dependent, fatigue and environmental behaviour is then described with several examples, and it is concluded that plane strain fractures may be achieved with a wide range of values for any material. The consequences of this in choosing a design criterion are then discussed.

Limits of Linear Elastic Fracture Mechanics

1984 ◽  
Vol 106 (2) ◽  
pp. 196-200 ◽  
Author(s):  
J. M. Bloom ◽  
J. L. Hechmer
Keyword(s):  
Fracture Mechanics ◽  
Plane Strain ◽  
Simple Procedure ◽  
Linear Elastic Fracture Mechanics ◽  
Plastic Behavior ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Strain Fracture ◽  
Elastic Fracture ◽  
Flaw Location

This paper presents a simple procedure for determining the validity limits of linear elastic fracture mechanics (LEFM) calculations for low alloy steel (ferritic) structures. The procedure is limited to structures with flaws whose depths are 50 percent or less of the wall thickness of the component at the flaw location and to components which can be considered to be in a plane strain state. Typical yield and ultimate strengths are assumed to be 60 and 80 ksi (414 and 552 MPa), respectively. The procedure is based upon failure assessment curves derived for typical nuclear vessels and components. Calculations of the ratios of the linear elastic stress intensity factor to the plane strain fracture toughness and the applied load to the plastic collapse load are used in conjunction with these curves to determine the validity limits of LEFM. The procedure is limited to the consideration of primary loading. When the load calculated by LEFM deviates significantly from the load calculated assuming elastic-plastic behavior, LEFM is deemed to be invalid and an elastic-plastic calculation procedure is recommended. Example problems are given which demonstrate the applicability of LEFM analysis in one case and the inapplicability in another case. The paper is an extension of the ideas and work generated from the Electric Power Research Institute research project RP 1237-2.

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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