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.

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.

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.

Effects of Weld Geometry on Residual Stress and Crack Driving Force for Centerhole Control Rod Drive Mechanism Nozzles: Part I — Weld Residual Stress

2005 ◽  
Author(s):  
Wentao Cheng ◽  
David L. Rudland ◽  
Gery Wilkowski ◽  
Wallace Norris
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Driving Force ◽  
Nuclear Regulatory Commission ◽  
Crack Driving Force ◽  
Control Rod ◽  
Drive Mechanism ◽  
Weld Geometry ◽  
Weld Residual Stress ◽  
Regulatory Commission

The U.S. Nuclear Regulatory Commission (NRC) has undertaken a program to assess the integrity of control rod drive mechanism (CRDM) nozzles in existing plants that are not immediately replacing their RPV heads. This two-part paper summarizes some of the efforts undertaken on the behalf of the U.S.NRC for the development of detailed residual stress and circumferential crack-driving force solutions to be used in probabilistic determinations of the time from detectable leakage to failure. In this first paper, the finite element (FE) simulations were conducted to investigate the effects of weld geometry on the residual stresses in the J-weld for a centerhole CRDM nozzle. The variables of weld geometry included three weld heights (weld sizes) and three groove angles for each weld height while keeping the same weld size. The analysis results indicate that the overall weld residual stress decreases as the groove angle increases and higher residual stress magnitude is associated with certain weld height. The results also reveal that the axial residual stresses in the Alloy 600 tube are very sensitive to the weld height, and that the tube hoop stresses above the J-weld root increase with the increasing weld height.

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

Experimental Study of the High Temperature Mechanical Behaviors of TLP Bonding of Two Ni-Base Single Crystals

2005 ◽  
Vol 297-300 ◽  
pp. 1489-1494 ◽  
Author(s):  
T. Li ◽  
Qing Yuan Wang ◽  
Ai Qin Wang ◽  
Z.X. Wen ◽  
Zhu Feng Yue
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Base Material ◽  
Static Strength ◽  
Loading Conditions ◽  
Mechanical Behaviors ◽  
Tensile Direction ◽  
Tlp Bonding

In this paper, the mechanical behavior of Ni-base single crystals joint created by TLP bonding is presented. Experimental study has been performed on the TLP single crystal under loading conditions of static uniaxial tension, creep and Three-points-bending (T-P-B) at temperature of 850 °C. Specimens made of the base material, Ni-base single crystal specimens without bonding, were also tested under the same loading conditions. The mechanical behaviors of TLP single crystal is compared to the behaviors of base material. It was found that the static strength of the TLP specimens with the boundary normal to the tensile direction was 63% of the strength of the base material. The creep strength and the fracture ductile strength was more than 57% and 55% of that of the single crystal base material, respectively. The macro and micro graphs of fracture surfaces of specimens indicated that the fracture modes of the samples were brittle fracture.

Sign in / Sign up

Export Citation Format

Share Document