Stress Intensity Factor Solutions for Welds Between Two Sheets of Different Materials and Thicknesses Under Plane Strain Conditions

2013 ◽  
Author(s):  
Wei-Jen Lai ◽  
Jwo Pan ◽  
Van-Xuan Tran
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Plane Strain ◽  
Specimen Thickness ◽  
Steel Sheets ◽  
Lap Shear ◽  
Dimensional Finite Element ◽  
Structural Stresses ◽  
Different Thickness

In this paper, analytical stress intensity factor solutions for welds in lap-shear specimens of different materials and thicknesses under plane strain conditions are presented in the normalized forms. The stress intensity factor solutions for welds are expressed in terms of the structural stresses based on a strip model. The analytical stress intensity factor solutions are selectively verified by the results of the two-dimensional finite element analyses. The interface crack parameters for the stress intensity factor solutions for welds in lap-shear specimens of dissimilar steel, aluminum, magnesium, and copper sheets are listed for different thickness ratios. The analytical stress intensity factor solutions are obtained and selectively presented in the normalized forms as functions of the specimen thickness ratio for the combination of aluminum and steel sheets for fracture and fatigue analyses.

Critical Stress Intensity Factor Determination for AZ61 Magnesium Alloy

2011 ◽  
Vol 462-463 ◽  
pp. 1121-1126
Author(s):  
M.A.M. Daud ◽  
Zainuddin Sajuri ◽  
Mohd Zaidi Omar ◽  
Junaidi Syarif
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Magnesium Alloy ◽  
Intensity Factor ◽  
Plane Strain ◽  
Specimen Thickness ◽  
Plane Strain Fracture Toughness ◽  
Az61 Magnesium Alloy ◽  
Strain Fracture

A stress intensity factor K was used as a fracture parameter to determine the plane strain fracture toughness KIC of AZ61 magnesium alloy using a single edge notch bend (SENB) specimen in accordance to ASTM E399 testing method. Five different specimen thicknesses of 2 to 10 mm were used in the test. A sharp fatigue pre-crack was initiated and propagated to half of specimen width at a constant crack propagation rate of about 1 x 10-8 m/cycle before the specimen was loaded in tension until the fracture stress is reached and then rapid fracture occurred. The fracture toughness KC values obtained for different thicknesses showed that KC value decreased with increasing specimen thickness. The highest KC value obtained was 16.5 MPa√m for 2 mm thickness specimen. The value of KC became relatively constant at about 13 MPa√m when the specimen thickness exceeds 8 mm. This value was then considered as the plane strain fracture toughness KIC of AZ61 magnesium alloy. Calculation of the minimum thickness requirement for plane strain condition and the size of the shear lips of the fracture surface validate the obtained KIC value.

Stress Intensity Factor for Repaired Circumferential Cracks in Pipe With Bonded Composite Wrap

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
F. Benyahia ◽  
A. Albedah ◽  
B. Bachir Bouiadjra
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Criterion ◽  
Three Dimensional ◽  
Element Analysis ◽  
Composite Systems ◽  
Bonded Composite ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The use of composite systems as a repair methodology in the pipeline industry has grown in recent years. In this study, the analysis of the behavior of circumferential through cracks in repaired pipe with bonded composite wrap subjected to internal pressure is performed using three-dimensional finite element analysis. The fracture criterion used in the analysis is the stress intensity factor (SIF). The obtained results show that the bonded composite repair reduces significantly the stress intensity factor at the tip of repaired cracks in the steel pipe, which can improve the residual lifespan of the pipe.

An Efficient Way to Characterize the Fatigue Crack Growth Based on Numerical Analysis

2009 ◽  
Vol 417-418 ◽  
pp. 653-656
Author(s):  
Ya Zhi Li ◽  
Jing He ◽  
Zi Peng Zhang
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Length ◽  
Crack Growth ◽  
Crack Closure ◽  
Load Ratio ◽  
Specimen Thickness

The behavior of plasticity induced fatigue crack closure (PICC) in middle tension specimen was analyzed by the elastic-plastic finite element method. For the constant-K (CK) loading cases, the opening stress intensity factor are independent of crack length. The level of increases with the maximal applied stress intensity factor for given load ratio and increases with for fixed . The in plane strain state is much smaller than that in plane stress state. The results under CK loadings can be deduced to constant amplitude cyclic loading case during which the load ratio, maximal load level, crack length and specimen thickness are all the factors affecting the crack closure effect. The phenomena revealed in the analysis are beneficial in understanding the driving force mechanism of the fatigue crack growth.

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