scholarly journals Stress intensity factor solutions for adhesive-bonded lap-shear specimens of magnesium and steel sheets with and without kinked cracks for fatigue life estimations

2014 ◽  
Vol 131 ◽  
pp. 454-470 ◽  
Author(s):  
Wei-Jen Lai ◽  
Jwo Pan
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Steel Sheets ◽  
Lap Shear ◽  
Kinked Cracks

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.

scholarly journals Effect of Pre-Corrosion Pits on Residual Fatigue Life for 42CrMo Steel

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2130 ◽  
Author(s):  
Dezheng Liu ◽  
Yan Li ◽  
Xiangdong Xie ◽  
Jing Zhao
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Research Work ◽  
Residual Fatigue Life ◽  
42Crmo Steel ◽  
Regression Formula ◽  
Residual Fatigue ◽  
Corrosion Pits

The effect of pre-corrosion pits on residual fatigue life for the 42CrMo steel (American grade: AISI 4140) is investigated using the accelerated pre-corrosion specimen in the saline environment. Different pre-corroded times are used for the specimens, and fatigue tests with different loads are then carried out on specimens. The pre-corrosion fatigue life is studied, and the fatigue fracture surfaces are examined by a surface profiler and a scanning electron microscope (SEM) to identify the crack nucleation sites and to determine the size and geometry of corrosion pits. Moreover, the stress intensity factor varying with corrosion pits in different size parameters is analyzed based on finite element (FE) software ABAQUS to derive the regression formula of the stress intensity factor. Subsequently, by integrating the regression formula with the Paris formula, the residual fatigue life is predicted and compared with experimental results, and the relationship of the stress intensity factor, pit depth, and residual fatigue life are given under different corrosion degrees. The fatigue life predicted by the coupled formula agrees well with experiment results. It is observed from the SEM images that higher stress amplitude and longer pre-corroded time can significantly decrease the residual fatigue life of the steel. Additionally, the research work has brought about the discovery that the rate of crack extension accelerates when the crack length increases. The research in this paper also demonstrates that the corrosion pit size can be used as a damage index to assess the residual fatigue life.

Fatigue Damage Analysis on Crack Growth and Fatigue Life of Welded Bridge Members with Initial Crack

2006 ◽  
Vol 324-325 ◽  
pp. 251-254 ◽  
Author(s):  
Tai Quan Zhou ◽  
Tommy Hung Tin Chan ◽  
Yuan Hua
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Initial Crack ◽  
Traffic Loading

The behavior of crack growth with a view to fatigue damage accumulation on the tip of cracks is discussed. Fatigue life of welded components with initial crack in bridges under traffic loading is investigated. The study is presented in two parts. Firstly, a new model of fatigue crack growth for welded bridge member under traffic loading is presented. And the calculate method of the stress intensity factor necessary for evaluation of the fatigue life of welded bridge members with cracks is discussed. Based on the concept of continuum damage accumulated on the tip of fatigue cracks, the fatigue damage law suitable for steel bridge member under traffic loading is modified to consider the crack growth. The proposed fatigue crack growth can describe the relationship between the cracking count rate and the effective stress intensity factor. The proposed fatigue crack growth model is then applied to calculate the crack growth and the fatigue life of two types of welded components with fatigue experimental results. The stress intensity factors are modified by the factor of geometric shape for the welded components in order to reflect the influence of the welding type and geometry on the stress intensity factor. The calculated and measured fatigue lives are generally in good agreement, at some of the initial conditions of cracking, for a welded component widely used in steel bridges.

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