A Simple and Efficient Reformulation of the Classical Manson–Coffin Curve to Predict Lifetime Under Multiaxial Fatigue Loading—Part II: Notches

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Luca Susmel ◽  
Giovanni Meneghetti ◽  
Bruno Atzori
Keyword(s):  
Notch Root ◽  
Constitutive Relations ◽  
Complex Loading ◽  
Fatigue Loading ◽  
Initiation Site ◽  
Multiaxial Fatigue ◽  
Stress Strain ◽  
Maximum Shear Strain ◽  
Curve Method ◽  
Number Of Cycles

The present study is concerned with the use of the modified Manson–Coffin curve method to estimate the lifetime of notched components subjected to multiaxial cyclic loading. The above criterion postulates that fatigue strength under complex loading paths can efficiently be evaluated in terms of maximum shear strain amplitude, provided that the reference Manson–Coffin curve used to predict the number of cycles to failure is defined by taking into account the actual degree of multiaxiality/nonproportionality of the stress/strain state damaging the assumed crack initiation site. The accuracy and reliability of the above fatigue life estimation technique was checked by considering about 300 experimental results taken from the literature. Such data were generated by testing notched cylindrical samples made of four different metallic materials and subjected to in-phase and out-of-phase biaxial nominal loading. The accuracy of our criterion in taking into account the presence of nonzero mean stresses was also investigated in depth. To calculate the stress/strain quantities needed for the in-field use of the modified Manson–Coffin curve method, notch root stresses and strains were estimated by using not only the well-known analytical tool due to Köttgen et al. (1995, “Pseudo Stress and Pseudo Strain Based Approaches to Multiaxial Notch Analysis,” Fatigue Fract. Eng. Mater. Struct., 18(9), pp. 981–1006) (applied along with the ratchetting plasticity model devised by Jiang and Sehitoglu (1996, “Modelling of Cyclic Ratchetting Plasticity, Part I: Development and Constitutive Relations. Transactions of the ASME,” ASME J. Appl. Mech., 63, pp. 720–725; 1996, “Modelling of Cyclic Ratchetting Plasticity, Part I: Development and Constitutive Relations,” Trans. ASME J. Appl. Mech., 63, pp. 720–725)) but also by taking full advantage of the finite element method to perform some calibration analyses. The systematic use of our approach was seen to result in estimates falling within an error factor of about 3.

scholarly journals A Multiaxial Notch Fatigue Methodology to Estimate In-Service Lifetime of Corroded Cast Iron Water Pipes

2013 ◽  
Vol 577-578 ◽  
pp. 125-128
Author(s):  
W. Brevis ◽  
Luca Susmel ◽  
J.B. Boxall
Keyword(s):  
Cast Iron ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Variable Amplitude ◽  
Water Pipes ◽  
Service Lifetime ◽  
Curve Method ◽  
Over Time

The present paper summarises an attempt of using the so-called Modified Wöhler Curve Method (MWCM) to estimate fatigue damage in pitted cast iron water pipes subjected to in-service variable amplitude multiaxial fatigue loading. In this setting, pits are treated as hemispherical/hyperbolic notches whose depth increases over time due to conventional corrosion processes taking places in buried cast-iron pipes. The validity of such an approach is proven by showing, through a case study, that, under particular circumstances, the combined effect of corrosion and fatigue can remarkably shorten the in-service lifetime of cast-iron pipes as observed in the case study.

Crack Growth Orientation in Two Structural Materials under Multiaxial Fatigue Loading

2008 ◽  
Vol 587-588 ◽  
pp. 892-897
Author(s):  
Luís G. Reis ◽  
Bin Li ◽  
Manuel de Freitas
Keyword(s):  
Testing Machine ◽  
Experimental Studies ◽  
Complex Loading ◽  
Fatigue Loading ◽  
Structural Materials ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Loading Path ◽  
Biaxial Testing

In real engineering components and structures, many accidental failures are due to unexpected or additional loadings, such as additional bending or torsion, etc. Therefore, it has attracted more research attentions to study the mechanical behavior of materials under complex loading conditions. Two typical structural materials are studied and compared in this paper: AISI 303 stainless steel and 6060-T5 Aluminum alloy. The objective is to study the effects of multiaxial loading paths on the crack initiation and orientation of the two materials studied. Fatigue tests were conducted in a biaxial testing machine. Fractographic analyses of the fracture surface were carried out by optical microscope and SEM approaches. In addition to the experimental studies, theoretical predictions of the damage plane were made using critical plane approaches. Comparisons of the predicted orientation of the damage plane with the experimental observations are shown. The applicability of the multiaxial fatigue criteria for the two materials is discussed. It was shown that the two materials studied have different crack orientations under the same loading path. This observation appears to show that the applicability of the fatigue models is dependent on the material type and multiaxial microstructure characteristics.

Fatigue Life Prediction of Notched Components Based on Multiaxial Local Stress-Strain Approach

2009 ◽  
Author(s):  
Baoxiang Qiu ◽  
Zengliang Gao ◽  
Xiaogui Wang
Keyword(s):  
Strain State ◽  
Notch Root ◽  
Constitutive Relations ◽  
Local Stress ◽  
Cyclic Plasticity ◽  
Multiaxial Stress ◽  
Stress Strain ◽  
Stress Strain State ◽  
Multiaxial Stress State ◽  
Notched Components

A multiaxial local stress-strain approach based on the Armstrong-Frederick type cyclic plasticity theory was proposed to perform the stress analysis and the fatigue analysis on the notched components. A robust cyclic plasticity model was adopted to describe the non-Masing behavior of 16MnR steel. The incremental form of the multiaxial local stress-strain approach was formulated with the incremental constitutive relations and the incremental Neuber’s rule. The multiaxial stress-strain state at the notch root of notched components subjected to proportional and nonproportional loading was predicted by the multiaxial approximate approach. On the basis of the multiaxial local stress-strain state and the Fatemi-Socie criterion, the fatigue lives of the notched components were predicted. The analytical results show that the proposed multiaxial local stress-strain method can describe the multiaxial stress state at the notch root very well, and the predicted fatigue lives correlate well with the experimental data.

Life Prediction and Verification under Multiaxial Fatigue Loading

2013 ◽  
Vol 365-366 ◽  
pp. 991-994
Author(s):  
Lei Wang ◽  
Tian Zhong Sui ◽  
Qiu Cheng Tian
Keyword(s):  
Strain Amplitude ◽  
Life Prediction ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Normal Strain ◽  
Critical Plane ◽  
Proportional Loading ◽  
Maximum Shear Strain ◽  
Change Characteristics ◽  
Strain Change

The strain change characteristics of multiaxial fatigue are analyzed under the condition of the combined tension and torsion loading for thin-tube specimen. Based on the principle of multiaxial critical plane approach, a multiaxial fatigue damage parameter is established, which takes account of the effect of not only the maximum shear strain amplitude and normal strain amplitude on the critical plane but also the parameter of non-proportionality. The non-proportionality is the function of loading parameters which is closely contact with the strain change characteristics of multiaxial fatigue and it can indicate the whole material damage. The experiments under the tension-torsion proportional and non-proportional loading were conducted to verify the multiaxial fatigue life model proposed in this paper. The life prediction has a good correlation with the experimental results.

A General Criterion for Low-Cycle Multiaxial Fatigue Failure

1989 ◽  
Vol 111 (3) ◽  
pp. 263-269 ◽  
Author(s):  
A. Makinde ◽  
K. W. Neale
Keyword(s):  
Shear Strain ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Multiaxial Fatigue ◽  
General Criterion ◽  
Cycle Fatigue ◽  
Maximum Shear Strain ◽  
Number Of Cycles ◽  
New Criterion ◽  
Cycles To Failure

A new, general criterion is proposed for multiaxial low-cycle fatigue failure. Contours of constant fatigue life on a plot of maximum shear strain against the tensile strain acting normal to the plane of maximum shear strain are represented by a parametric criterion of the form g(θ,Nf)=kf1(θ)f2(Nf). Here g is the magnitude of the vector from the origin to a point on the constant life contour, θ is the angle associated with g in this space, Nf is the number of cycles to failure, k is a constant and f1 (θ) and f2(Nf) are two separate functions of θ and Nf, respectively. It is shown that all previously proposed macroscopic criteria are particular cases of the failure function g(θ, Nf). Experimental results from several authors are analyzed using the new criterion.

Determination of the Critical Plane under the Multiaxial Complex Loading

2012 ◽  
Vol 544 ◽  
pp. 182-187
Author(s):  
Lei Wang ◽  
Tian Zhong Sui ◽  
Yu Ma ◽  
Yan Sun
Keyword(s):  
Shear Strain ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Complex Loading ◽  
Research Field ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Random Loading ◽  
Maximum Shear Strain

Engineering components and structures in service are generally subjected to the multiaxial complex loads. The approach of critical plane has been widely accepted by most researchers as the best method in the multiaxial fatigue research field. It can be used well in the constant multiaxial fatigue loads, but not in the complex loads. Basis on analyzing characteristics of shear strain on material planes, the concept of weight-averaged maximum shear strain plane is proposed. A procedure is presented to determine the critical plane under multiaxial random loading. The angle values of the planes that experience peak values of maximum shear strains are averaged by employing the weight function, which is assumed to take into account the main factors of influencing the fatigue behavior, e.g. fatigue damage. The proposed algorithm is applied to the multiaxial in- and out-of-phase experiments to assess the correlation between the weight-averaged maximum shear strain direction and the position of the experimental fatigue crack initiation plane.

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