The Influence of Fatigue Life for Shoulder Fillet Parameter in Stepped Shaft under Torsion Load

2013 ◽  
Vol 404 ◽  
pp. 228-231 ◽  
Author(s):  
Yong Zhuang Yuan
Keyword(s):  
Fatigue Life ◽  
Fatigue Crack Initiation ◽  
Local Stress ◽  
Element Model ◽  
Stress Strain ◽  
Stepped Shaft ◽  
Transition Radius ◽  
Crack Initiation Life ◽  
Set Up ◽  
Strain Method

The principle of fatigue life computation was presented on the basis of local stress-strain method. It was set up that the finite element model of stepped shaft with different radii of round corner and radius ratios. The local stress and strain were computed at shaft shoulder fillet under torsion load. The fatigue crack initiation life was determined by means of local stress-strain method under symmetric cyclic torsion load. The result showed that the fatigue life increased with the values of fillet increase and decreased with the values of radius ratio increase, and the smaller of the transition radius was, the shorter of the life would be.

Local Stress-Strain Method for the Effects of Scratch on Fatigue Performances of Cabin Glass

2011 ◽  
Vol 299-300 ◽  
pp. 51-56
Author(s):  
Hua Ding ◽  
Yu Ting He ◽  
Jin Qiang Du ◽  
Li Ming Wu ◽  
Hai Wei Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Three Dimensional ◽  
Local Stress ◽  
Element Model ◽  
Fatigue Tests ◽  
Three Dimensional Model ◽  
Stress Strain ◽  
Finite Element Software ◽  
Strain Method

The three-dimensional finite element model of cabin glass with surface scratch is built using the finite element software ANSYS, which is aimed to analyze the detailed stress around the scratch route tip. Then the fatigue notch factor can be gained through utilizing of results from three-dimensional model, which is followed by the estimation of fatigue life based on local stress-strain method. It is found that the stress around scratch route tip is nearly linearly increased with the increasing of tip depth (0.2mm<h<0.8mm) and the fatigue performances of cabin glass with surface scratch are sensitive to scratch depth. Finally, fatigue tests are carried out with the specimens of different scratch route tip depths, and validation against fatigue life by local stress-strain method and experimental data shows a good agreement, which indicates that the scratch model and the local stress-strain method for the effects of scratch on cabin glass fatigue performances are valid.

Stress Strain Analysis of Steel Specimens Not Wholly Quenched

2011 ◽  
Vol 261-263 ◽  
pp. 702-706
Author(s):  
Rui Jie Wang ◽  
He Ming Cheng ◽  
Bao Dong Shao ◽  
Jian Yun Li
Keyword(s):  
Finite Element ◽  
Fatigue Crack Initiation ◽  
Strain Analysis ◽  
Element Model ◽  
Cyclic Strength ◽  
Work Piece ◽  
Stress Strain ◽  
Element Analysis ◽  
Quenched Steel ◽  
Crack Initiation Life

A finite element model of not wholly quenched steel fatigue specimen is established. Hardness value of some distance to work piece surface are assumed different and cyclic strength coefficients of different zones are different, both is assumed to be proportional to hardness value. Elasto-plastic finite element analysis was carried out for this model. According to the stress-strain distribution on transverse section, the effect of not wholly quenched on fatigue crack initiation life is analyzed.

Internal Versus External Cracking—Their Impact on the Fatigue Life of Modern Smoothbore Autofrettaged Tank Gun Barrels

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
M. Perl ◽  
T. Saley
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Crack Depth ◽  
Fatigue Crack Initiation ◽  
Element Model ◽  
Initial Crack ◽  
Factors Affecting ◽  
External Crack ◽  
Crack Initiation Life ◽  
Major Factors

Abstract An extensive analysis of the fatigue life of a typical modern autofrettaged smoothbore tank barrel, cracked either internally or externally, in terms of the initial crack depth and shape, type and level of autofrettage, was conducted. Five overstraining cases were considered: no-autofrettage, 70% and 100% hydraulic autofrettage, and 70% and 100% swage autofrettage. KINmax, the maximum combined stress intensity factor (SIF) KINmax = (KIP + KIA) max, due to both internal pressure and autofrettage, as a function of crack depth for a large number of internal and external crack configurations was determined by the finite element method (FEM). A novel realistic experimentally based autofrettage model, incorporating the Bauschinger effect, was integrated into the finite element model, replicating both the hydraulic and swage autofrettage residual stress fields (RSFs) accurately. Fatigue lives were evaluated by integrating Paris' Law using the above values of KINmax. The following conclusions can be drawn from the results: hydraulic and swage autofrettage have a dramatic beneficial effect in extending the fatigue life of an overstrained barrel 4–11 times as compared to an identical nonautofrettaged tube. The fatigue life of overstrained barrels is controlled by internal cracking, for barrels overstrained by up to ε = 100% hydraulic autofrettage, by up to ε = 70% in the case of swage autofrettage, and by external cracking for ε = 100% swage autofrettaged. Eliminating or carefully designing stress concentrators on the tube's external face and keeping away from corrosive agents thus, extending the fatigue-crack initiation life of an external crack, enables the increase of the level of swage autofrettage to up to ε = 100%. Swage autofrettage is much more superior to hydraulic autofrettage. The fatigue life of a 70% swaged autofrettaged barrel is 1.5 times higher than that of a 100% hydraulically autofrettaged tube. If full swage autofrettage is permissible, the fatigue life of such a barrel is twofold that of a fully hydraulically autofrettaged tube. Unlike the commonly accepted concept, the level of hydraulic autofrettage should not be limited to 70%, and full hydraulic autofrettage should be used. Similarly, in the case of swage autofrettage, if the detrimental effect of external cracking is removed by proper design and maintenance of the tube's outer surface, the level of autofrettage can be increased to up to ε = 100%, thus, gaining an increase of 33% in the fatigue life as compared to overstraining the barrel to only ε = 70%. Initial crack depth and shape are major factors affecting the fatigue life of the barrel. The deeper the initial crack depth, a0, and the slenderer its shape, a/c→ 0, the shorter the fatigue life of the barrel.

scholarly journals Fatigue Life Prediction of High Modulus Asphalt Concrete Based on the Local Stress-Strain Method

2017 ◽  
Vol 7 (3) ◽  
pp. 305 ◽  
Author(s):  
Mulian Zheng ◽  
Peng Li ◽  
Jiangang Yang ◽  
Hongyin Li ◽  
Yangyang Qiu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Concrete ◽  
Life Prediction ◽  
Local Stress ◽  
Fatigue Life Prediction ◽  
High Modulus ◽  
Stress Strain ◽  
Strain Method

Fatigue Behavior of Circumferentially Notched Round Bars of Austenitic Stainless Steel Under Torsional and Axial Loads

2010 ◽  
Author(s):  
Masao Itatani ◽  
Keisuke Tanaka ◽  
Isao Ohkawa ◽  
Takehisa Yamada ◽  
Toshiyuki Saito
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Static Tension ◽  
Cyclic Torsion ◽  
Cyclic Tension ◽  
Crack Initiation Life

Fatigue tests of smooth and notched round bars of austenitic stainless steels SUS316NG and SUS316L were conducted under cyclic tension and cyclic torsion with and without static tension. Fatigue strength under fully reversed (R=−1) cyclic tension once increased with increasing stress concentration factor up to Kt=1.5, but it decreased from Kt=1.5 to 2.5. Fatigue life increased with increasing stress concentration under pure cyclic torsion, while it decreased with increasing stress concentration under cyclic torsion with static tension. From the measurement of fatigue crack initiation and propagation lives using electric potential drop method, it was found that the crack initiation life decreased with increasing stress concentration and the crack propagation life increased with increasing stress concentration under pure cyclic torsion. Under cyclic torsion with static tension, the crack initiation life also decreased with increasing stress concentration but the crack propagation life decreased or not changed with increasing stress concentration then the total fatigue life of sharper notched specimen decreased. It was also found that the fatigue life of smooth specimen under cyclic torsion with static tension was longer than that under pure cyclic torsion. This behavior could be explained based on the cyclic strain hardening under non-proportional loading and the difference in crack path with and without static tension.

A Probabilistic Micromechanical Code for Predicting Fatigue Life Variability: Model Development and Application

2005 ◽  
Vol 128 (4) ◽  
pp. 889-895 ◽  
Author(s):  
K. S. Chan ◽  
M. P. Enright
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Initiation ◽  
Crack Growth ◽  
Model Development ◽  
Fatigue Crack Initiation ◽  
Crack Size ◽  
Crack Initiation Life ◽  
Variability Model

This paper summarizes the development of a probabilistic micromechanical code for treating fatigue life variability resulting from material variations. Dubbed MICROFAVA (micromechanical fatigue variability), the code is based on a set of physics-based fatigue models that predict fatigue crack initiation life, fatigue crack growth life, fatigue limit, fatigue crack growth threshold, crack size at initiation, and fracture toughness. Using microstructure information as material input, the code is capable of predicting the average behavior and the confidence limits of the crack initiation and crack growth lives of structural alloys under LCF or HCF loading. This paper presents a summary of the development of the code and highlights applications of the model to predicting the effects of microstructure on the fatigue crack growth response and life variability of the α+β Ti-alloy Ti-6Al-4V.

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