Estimation for Fatigue Behavior of Notched Plate with Mean Stress Effect

2013 ◽  
Vol 750 ◽  
pp. 256-259
Author(s):  
Chihiro Ogata ◽  
Kenji Shojima ◽  
Keiji Yanase
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Simple Calculation ◽  
Growth Equation ◽  
Stress Effect ◽  
Mean Stress ◽  
Initiation And Propagation

In this paper, McEvily’s fatigue crack growth equation is modified and newly combined with the modified Goodman equation to estimate the fatigue strength with arbitrary mean stress, σm. Firstly, based on McEvily’s equation, the threshold stresses for fatigue crack initiation and propagation with stress ratio R = –1 or σm = 0 are predicted with reasonable accuracy. Then, a simple calculation is presented to predict the fatigue strength with arbitrary mean stress. The adequacy of present method is examined based on the comparison with the available experimental data in the literature.

scholarly journals Effect of Mean Stress on Fatigue Crack Initiation and Propagation

1969 ◽  
Vol 12 (53) ◽  
pp. 958-965 ◽  
Author(s):  
Hajime NAKAZAWA ◽  
Takashi KOIZUMI ◽  
Hiroomi HONMA ◽  
Hisao SAYANAGI
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Mean Stress ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation

High-Cycle Fatigue Behavior of Type 4340 Steel Pressurized Blocks Including Mean Stress Effect

2019 ◽  
Author(s):  
Elie A. Badr ◽  
Joanne Ishak
Keyword(s):  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Ultimate Stress ◽  
Stress Effect ◽  
Mean Stress ◽  
Test Results ◽  
Linear Correction ◽  
The Mean

Abstract Mean stress effects in pressurized steel blocks were examined under constant amplitude fatigue loading. The tests were performed to provide experimental data needed to study the effect of mean stress on fatigue lives of subject specimen, and to substantiate the use of analytical expressions to account for the mean stress. The mean stress was the result of subjecting the specimens to an autofrettage pressure which induced compressive residual stresses at the crossbore intersection of the specimens. Fatigue tests were carried out under both tensile and compressive mean stress levels. Test results were compared to several mean stress accounting relationships such as the Smith-Watson Topper, Bergmann and Seeger, modified Goodman, Gerber and Soderberg. Test results indicated that the modified Goodman equation is favorable in accounting for the effect of both tensile and compressive mean stresses on fatigue life (up to a compressive mean stress to ultimate stress ratio of −0.2). The behavior under compressive mean stress to ultimate stress ratio of less than −0.2 indicated that a linear correction relationship was required.

scholarly journals On the Influence of Capillary-Based Structural Health Monitoring on Fatigue Crack Initiation and Propagation in Straight Lugs

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2965 ◽  
Author(s):  
Marc Moonens ◽  
Eric Wyart ◽  
Dieter De De Baere ◽  
Michaël Hinderdael ◽  
Julien Ertveldt ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Structural Health Monitoring ◽  
Finite Elements ◽  
Crack Initiation ◽  
Health Monitoring ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Structural Health ◽  
Initiation And Propagation ◽  
The Impact

This paper addresses the influence on the fatigue life induced by the implementation of a capillary-based structural health monitoring methodology, patented under the name eSHM. It consists in integrating structurally small and pressurized capillaries into the component, so that when a fatigue crack breaches the capillary network, it results in a leak flow to the open atmosphere and loss of pressure in the galleries which is detected by a pressure sensor. The novelty of the proposed system resides in the opportunity to locate the capillary according to the designer’s need, as one resorts to additive manufacturing for the part production. However, the presence of these galleries in highly stressed regions raises concerns about crack initiation at the capillary itself and accelerated fatigue crack growth. This paper aims at the quantification of the influence the eSHM has on the fatigue behavior of the component and the determination whether this influence is significant or not. To that purpose, numerical simulations on a straight lug component, using the finite elements and eXtended Finite Elements Methods (XFEM), are performed. Various capillary sizes and shapes are assessed, so as to enable a general conclusion on the impact of the eSHM methodology in straight lugs.

High Cycle Fatigue of Ti-6Al-4V Alloy in Simulated Steam Environment

2015 ◽  
Author(s):  
Yu-Jia Li ◽  
Lin-Bo Mei ◽  
Fu-Zhen Xuan
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Saturated Steam ◽  
Fracture Mechanisms ◽  
Low Oxygen ◽  
Critical Problems ◽  
Stress Ratios ◽  
Corrosion Pits

Fatigue life and reliability are the critical problems for long blades design due to complicated stress state, wet steam and aggressive environment. In this report, the effects of stress ratio, surface properties, steam, and sodium-chloride (NaCl) aqueous environments on the fatigue strength and fracture mechanisms of Ti-6Al-4V alloy have been investigated. Results indicate that residual compressive stress decreases and vanishes finally with increasing stress ratio. Compared to fatigue crack originating from surface for annealed specimens, the fatigue crack initiation sites are located in the interior of the specimen due to the effect of residual stress when low stress ratios are present. Fatigue experiments have been performed in saturated steam with low oxygen content at 100°C and NaCl aqueous at 80 °C. Results indicate that, for 0.1 stress ratio loading conditions, steam environment demonstrates the most serious effect on the endurance limit with 12.3% reduction of fatigue strength. NaCl aqueous leads to the 9.6% drop in fatigue strength corresponding to 107 cycles of design life. For all corrosion environments, cracks originated from the surface and no corrosion pits were observed.

Sign in / Sign up

Export Citation Format

Share Document