A Simplified Small Scale Yielding Estimate Method for Determination of Second Elastic-Plastic Fracture Mechanics Parameter

2018 ◽  
Author(s):  
Ping Ding ◽  
Xin Wang
Keyword(s):  
Fracture Mechanics ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Elastic Plastic ◽  
Estimate Method ◽  
Scale Yielding

Finite Element Solutions for Crack-Tip Behavior in Small-Scale Yielding

1976 ◽  
Vol 98 (2) ◽  
pp. 146-151 ◽  
Author(s):  
D. M. Tracey
Keyword(s):  
Finite Element ◽  
Plastic Region ◽  
Crack Tip ◽  
Small Scale ◽  
Element Formulation ◽  
Small Scale Yielding ◽  
Field Problem ◽  
Hardening Material ◽  
Elastic Plastic ◽  
Scale Yielding

The subject considered is the stress and deformation fields in a cracked elastic-plastic power law hardening material under plane strain tensile loading. An incremental plasticity finite element formulation is developed for accurate analysis of the complete field problem including the extensively deformed near tip region, the elastic-plastic region, and the remote elastic region. The formulation has general applicability and was used to solve the small scale yielding problem for a set of material hardening exponents. Distributions of stress, strain, and crack opening displacement at the crack tip and through the elastic-plastic zone are presented as a function of the elastic stress intensity factor and material properties.

scholarly journals Elastic-plastic analysis of crack on bimaterial interface

2005 ◽  
Vol 32 (3) ◽  
pp. 193-207
Author(s):  
Ruzica Nikolic ◽  
Jelena Veljkovic
Keyword(s):  
Phase Angle ◽  
Plastic Material ◽  
Crack Tip ◽  
Bimaterial Interface ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Elastic Plastic ◽  
Singular Form ◽  
Scale Yielding ◽  
New Phase

In this paper are presented solutions for the stress and dis?placement fields for a crack that lies along the interface of an elastic and elastic - plastic material and for a crack between two different elastic - plastic materials. These solutions are obtained using the J2-deformation theory with the power - law strain hardening. In this paper results are described for a small scale yielding at the crack tip. The near tip fields do not have a separable singular form, of the HRR type fields, as in homogeneous media, they do, however bare interesting similarities to certain mixed -mode HRR fields. Under the small scale yielding the elastic fields are specified by a complex stress intensity factor and phase angle loading, while plastic field is characterized by a new phase angle. The size of plastic zone in plane strain and plane stress and displacement fields at the crack tip for the new phase angle are obtained. The crack tip opens smoothly and the crack opening displacement is scaled by the J-integral. The whole analysis is performed by application of the Mathematica symbolic programming routine.

Numerical Analysis of JNES Seismic Tests on Degraded Combined Piping System

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Tao Zhang ◽  
Frederick W. Brust ◽  
Gery Wilkowski ◽  
Do-Jun Shim ◽  
Jinsuo Nie ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Low Cycle Fatigue ◽  
Small Scale ◽  
Cycle Fatigue ◽  
Small Scale Yielding ◽  
Scale Yielding

Nuclear power plant safety under seismic conditions is an important consideration. The piping systems may have some defects caused by fatigue, stress corrosion cracking, etc., in aged plants. These cracks may not only affect the seismic response but also grow and break through causing loss of coolant. Therefore, an evaluation method needs to be developed to predict crack growth behavior under seismic excitation. This paper describes efforts conducted to analyze and better understand a series of degraded pipe tests under seismic loading that was conducted by Japan Nuclear Energy Safety Organization (JNES). A special “cracked-pipe element” (CPE) concept, where the element represented the global moment-rotation response due to the crack, was developed. This approach was developed to significantly simplify the dynamic finite element analysis in fracture mechanics fields. In this paper, model validation was conducted by comparisons with a series of pipe tests with circumferential through-wall and surface cracks under different excitation conditions. These analyses showed that reasonably accurate predictions could be made using the abaqus connector element to model the complete transition of a circumferential surface crack to a through-wall crack under cyclic dynamic loading. The JNES primary loop recirculation piping test was analyzed in detail. This combined-component test had three crack locations and multiple applied simulated seismic block loadings. Comparisons were also made between the ABAQUS finite element (FE) analyses results to the measured displacements in the experiment. Good agreement was obtained, and it was confirmed that the simplified modeling is applicable to a seismic analysis for a cracked pipe on the basis of fracture mechanics. Pipe system leakage did occur in the JNES tests. The analytical predictions using the CPE approach did not predict leakage, suggesting that cyclic ductile tearing with large-scale plasticity was not the crack growth mode for the acceleration excitations considered here. Hence, the leakage was caused by low-cycle fatigue with small-scale yielding. The procedure used to make predictions of low-cycle fatigue crack growth with small-scale yielding was based on the Dowling ΔJ procedure, which is an extension of linear-elastic fatigue crack growth methodology into the nonlinear plasticity region. The predicted moments from the CPE approach were used using a cycle-by-cycle crack growth procedure. The predictions compare quite well with the experimental measurements.

Two-Parameter Elastic-Plastic Fracture Mechanics Analysis of Surface Cracked Plates Under Uniaxial and Biaxial Loading

2011 ◽  
Author(s):  
Xin Wang
Keyword(s):  
Fracture Mechanics ◽  
Cleavage Fracture ◽  
Crack Front ◽  
Biaxial Loading ◽  
Small Scale ◽  
Elastic Plastic ◽  
Cracked Plates ◽  
Scale Yielding ◽  
Two Parameter ◽  
Uniaxial And Biaxial Loading

In this paper, the J-Q two-parameter elastic-plastic fracture mechanics approach is used to analyse the surface cracked plates under uniaxial and biaxial loading. First, the J-Q characterization of crack front stress fields of surface cracked plates under uniaxial and biaxial tension loadings are discussed. The complete J-Q trajectories for points along the crack fronts as load increases from small-scale yielding to large-scale yielding were obtained. Based on the materials toughness locus, (resistance to fracture JC as a function of Q), the assessments of the onset of cleavage fracture are conducted. The critical location along the 3D crack front, and the corresponding maximum load carrying capacity are obtained. The results are consistent with experimental observations. It is demonstrated the J-Q two-parameter approach is capable of providing comprehensive assessments of cleavage fracture of surface cracked plates under uniaxial/biaxial loadings, capturing all the important aspects of the problem.

Effectiveness of Linear Notch Mechanics under the Condition of Small Scale Yielding

2010 ◽  
Vol 452-453 ◽  
pp. 21-24
Author(s):  
T. Teranishi ◽  
Hironobu Nisitani
Keyword(s):  
Real Object ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Notched Specimen ◽  
Elastic Plastic ◽  
Scale Yielding

The linear notch mechanics (LNM) was proposed by H. Nisitani in 1983. The concept of LNM can assure the occurrence of the same phenomena in a notched specimen and a real object. The effectiveness of LNM under the condition of small scale yielding has not been confirmed sufficiently. In this paper, the effectiveness of LNM under the condition of small scale yielding is discussed based on the results of FEM elastic-plastic analyses.

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