Investigation on Spb Method Based on Nondimensional Load Separation Principle for SEB and CT Specimens

2011 ◽  
Vol 117-119 ◽  
pp. 480-488 ◽  
Author(s):  
Chen Bao ◽  
Li Xun Cai
Keyword(s):  
Crack Length ◽  
Physical Phenomenon ◽  
Initial Crack ◽  
Resistance Curve ◽  
Curve Estimation ◽  
Separation Parameter ◽  
Length Estimation ◽  
Model Sample ◽  
Load Separation ◽  
Final Crack

In this work, a nondimensional load separation conforming to similarity principle was proposed. Based on this new principle, similarity simulation of the physical phenomenon between the prototype sample and the dimension-changed model sample can be implemented. Then, a modified separation parameter Spbmethod was developed, which can absolutely eliminate the effect of referencing blunt cracked specimen on the instantaneous crack length estimation of the sharp cracked specimen, and the forced blunt-corrected initial crack length and the final crack length are recommended as the calibration points for J-resistance curve estimation. Finally, the modified Spbmethod is successfully applied in the J-resistance curve estimation of two steels with CT and SEB specimens, respectively.

scholarly journals Influence of static strength on the fatigue resistance of welds

2018 ◽  
Vol 165 ◽  
pp. 13010 ◽  
Author(s):  
Ceferino Steimbreger ◽  
Nenad Gubeljak ◽  
Norbert Enzinger ◽  
Wolfgang Ernst ◽  
Mirco Chapetti
Keyword(s):  
Crack Length ◽  
Driving Force ◽  
Base Material ◽  
Initial Crack ◽  
Static Strength ◽  
Resistance Curve ◽  
Weld Geometry ◽  
Curve Method ◽  
Mechanic Approach ◽  
Local Properties

The present paper deals with a fracture mechanic approach that employs the Resistance-Curve concept, in order to predict fatigue endurances of welded components, with different tensile strengths of the base metal. The Resistance-Curve method compares the total driving force applied to a crack with its threshold for propagation, both defined as a function of crack length. The former depends on load scheme and weld geometry and it can be obtained from finite element analyses, while the second is inherently related to weld resistance. Results obtained herein showed that threshold curve shape is changed when static strength of the base material is modified. Consequently, its interaction with the driving force differed, giving raise to different fatigue endurances for various values of the tensile strength. However, this effect is only likely to be leveraged, provided that the initial crack length is small enough. In real welded structures, the presence of defects demands longer initial crack lengths to be used in calculations, at which the benefit of enhanced strength is minimised or even inverted. Moreover, at these lengths, the growing process is mainly controlled by weld geometry and long crack propagation threshold, whereas local properties become less important in fatigue limit prediction.

Development of Experimental Procedure Based on the Load Separation Method to Measure the Fracture Toughness of Zr-2.5Nb Tubes

2007 ◽  
Vol 345-346 ◽  
pp. 449-452 ◽  
Author(s):  
Young Suk Kim ◽  
Yu.G. Matvienko ◽  
H.C. Jeong
Keyword(s):  
Peak Load ◽  
Separation Method ◽  
Reference Curve ◽  
Precracked Specimen ◽  
Experimental Procedure ◽  
Separation Parameter ◽  
Length Estimation ◽  
Growing Crack ◽  
Load Separation ◽  
Tip Radius

The load separation method was employed to measure the pl η -factor, the growing crack length and the applied J-integral during the course of the test of small curved CT specimen of Z-2.5Nb pressure tube material. The effect of the notch tip radius of the notched (reference) CT specimen on the separation parameter was analyzed to predict the crack growing length in the precracked specimen. To avoid the effect of load relaxation in the reference specimen on the separation parameter and the crack growing length estimation, the load was assumed to be maximum and constant value behind the peak load in the reference curve.

Prediction of the Fatigue Life of Tires Using CED and VCCT

2005 ◽  
Vol 297-300 ◽  
pp. 102-107 ◽  
Author(s):  
T.W. Kim ◽  
H.Y. Jeong ◽  
J.H. Choe ◽  
Y.H. Kim
Keyword(s):  
Fatigue Life ◽  
Crack Length ◽  
Test Data ◽  
Fem Simulation ◽  
Strain Energy Release ◽  
Initial Crack ◽  
Tire Model ◽  
Initial Crack Length ◽  
Paris Law ◽  
Final Crack

A new simulation methodology using the finite element method (FEM) was proposed to predict the fatigue life of tires. In the FEM simulation the cracking energy density (CED) was calculated, and the virtual crack closure technique (VCCT) was used to calculate the strain energy release rate (SERR) for a crack. First, a plane in an element on which CED had its maximum was determined, and a crack was created on the plane. Once a crack was introduced, another plane on which CED had its maximum was again determined, and the crack was further elongated along the plane. In addition, SERR was calculated for every crack increment by using VCCT, and it was represented as a function of the crack length. Then, the fatigue life of a tire was determined using Paris law. For Paris law, the initial crack length and the final crack length as well as the material constants should be known. In this paper, the initial crack length was set in a way that the fatigue life predicted by using Paris law became the same as the test data for a tire model (Tire A), and the final crack length was determined from the cross-section views of failed tires which showed cracks grown about halfway toward the carcass from the carcass turn-up edge. Finally, the fatigue life for another tire model (Tire B) was predicted by using Paris law, and the predicted fatigue life was compared with the test data.

Crack Growth Rates of Vertical Split Rim Wheel Failures

2017 ◽  
Author(s):  
Daniel H. Stone ◽  
Steven L. Dedmon
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Growth Rates ◽  
Initial Crack ◽  
Growth Equation ◽  
Initial Crack Length ◽  
Crack Growth Rates ◽  
Final Crack

The fatigue crack growth rates of three vertical split rim (VSR) wheel fractures are calculated using the Paris-Erdogan fatigue crack growth equation. Initial crack length, final crack length were measured for three wheels that have experienced VSR failures. The results of the calculations indicate the lives after crack initiation are relatively short. The results of these calculations indicate the timely reduction of the number of VSR failures should emphasize the prevention of the initiation of the VSR cracks.

Quantification of the Complex Crack Geometry Effect On Fracture Resistance Using Strain Based FE Damage Analysis

2021 ◽  
Author(s):  
Seung-Jae Kim ◽  
Ho-Wan Ryu ◽  
Jin Weon Kim ◽  
Young-Jin Oh ◽  
Yun-Jae Kim
Keyword(s):  
Crack Length ◽  
Surface Crack ◽  
Crack Depth ◽  
Damage Model ◽  
Simulation Method ◽  
Resistance Curve ◽  
Crack Geometry ◽  
Model And Simulation ◽  
Resistance Curves ◽  
Complex Crack

Abstract This paper examines the effect of complex crack geometry on the J-resistance curves obtained by strain-based ductile tearing simulation of complex cracked tension (CC(T)) specimens. The damage model is determined by analyzing the results of a smooth bar tensile test and a C(T) specimen toughness test on an SA508 Gr.1a low-alloy steel at 316 ?. The validity of the damage model and simulation method is checked by comparing the fracture test data for two CC(T) specimen tests. To investigate the effect of the complex crack geometry on the crack growth profiles and J-resistance curves, two geometric parameters (namely, the through-wall crack length and the surface crack depth) are systematically varied. It is found that the J-resistance curves for the CC(T) specimens with various through-wall crack lengths and surface crack depths are consistently lower than the corresponding 1T C(T) J-resistance curves. The effect of the through-wall crack length upon the J-resistance curve is found to be less significant than that of the surface crack depth. Moreover, the J-resistance curve decreases continuously with increasing surface crack depth.

Initial crack length on the interlaminar fracture of woven carbon/epoxy laminates

2015 ◽  
Vol 16 (4) ◽  
pp. 894-901 ◽  
Author(s):  
P. N. B. Reis ◽  
J. A. M. Ferreira ◽  
F. V. Antunes ◽  
J. D. M. Costa
Keyword(s):  
Crack Length ◽  
Initial Crack ◽  
Initial Crack Length ◽  
Interlaminar Fracture
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