Probabilistic modeling of fatigue life distribution and size effect of components with random defects

Ai, Yunfeng; Zhu, Shibai; Liao, Ding; Correia, José A.F.O.; Souto, Carlos d’Andrade; Jesus, Abílio M.P. De; Keshtegar, Behrooz

doi:10.1016/j.ijfatigue.2019.05.005

Cited by 133 publications

(51 citation statements)

References 57 publications

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“…It can be seen that the largest pores have the lowest sphericity and a complex shape. This tendency has also been observed in the previous works [13,29,31]. According to Buffiere classification [29,31], this repartition tend to indicate the presence of shrinkage porosity and gas pores.…”

Section: Porosity Analysessupporting

confidence: 85%

Experimental investigation of the size effect in high cycle fatigue: Role of the defect population in cast aluminium alloys

Khoukhi

Morel

Saintier

et al. 2019

International Journal of Fatigue

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Cast Al-Si alloys have been widely used in automotive applications with regard to their low density and excellent thermal conductivity. Many components made of these alloys are subjected to cyclic loads which can lead to fatigue failure. Furthermore, for these materials the well know size effect in fatigue, whereby the fatigue strength is reduced when the size is increased, can be significant and need to be properly evaluated. This paper analyses the role of casting defects on the fatigue strength's size effect sensitivity. A uniaxial fatigue testing campaign (R=0.1) has been conducted using two cast aluminium alloys, fabricated by different casting processes (gravity die casting and lost foam casting), associated with the T7 heat treatment, and with different degrees of porosity. The fatigue response of different specimens (smooth and notched) with different stressed volumes has been investigated. The first part of this article is dedicated to the experimental characterization of the size effect in both alloys via the concept of the Highly Stressed Volume. The second part investigates the effect of the Highly Stressed Volume on the critical defect size via Kitagawa-Takahashi diagrams. The results show that the magnitude of the size effect and the experimental scatter are strongly linked to the characteristics of the defect population present in the alloy. It is revealed that the alloy B, with a high density of pore and a population of defects with relatively large size, shows non-significant size effect and less scatter in fatigue strength. In comparison, alloy A that exhibits a low density of pore and a population of defects of relatively small size manifests significant size effect and high scatter in fatigue strength.

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Section: Porosity Analysessupporting

confidence: 85%

Experimental investigation of the size effect in high cycle fatigue: Role of the defect population in cast aluminium alloys

Khoukhi

Morel

Saintier

et al. 2019

International Journal of Fatigue

View full text Add to dashboard Cite

show abstract

“…It is known that the scatter is an intrinsic feature in fatigue . Therefore, the probabilistic fatigue S ‐ N curve has become an important tool to evaluate and predict the fatigue strength of engineering structural materials.…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the scatter is an intrinsic feature in fatigue. [46][47][48] Therefore, the probabilistic fatigue S-N curve has become an important tool to evaluate and predict the fatigue strength of engineering structural materials. Figure 8 shows the lifetime trends from standard specimens made of G20Mn5 cast steel and MAG welded joints.…”

Section: Hcf Life Curvesmentioning

confidence: 99%

The microstructure, mechanical, and fatigue behaviours of MAG welded G20Mn5 cast steel

Qin

Branco

et al. 2020

Fatigue Fract Eng Mat Struct

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The microstructure, mechanical strength, and fatigue response of metal active gas (MAG) butt‐welded G20Mn5 cast steel was thoroughly investigated for exploring the service safety and reliability of new‐generation railway bogie frames. The fatigue properties of the matrix and welded joints were determined by both low‐ and high‐cycle service regimes. On the basis of nanoindentation testing, the fatigue crack growth (FCG) was derived by correlating with cyclic plastic response of microdomain materials across the MAG joint. The results show that the MAG induces considerable changes in microstructures and hardness of the G20Mn5 matrix and resultantly produces an overmatching welded joint but show comparatively low‐ and high‐cycle fatigue properties to as‐received material. The calculated threshold FCG range based on the Murakami model indicates that the maximum 1.5‐mm defect might be the cracking site subjected to fatigue loading from the structural integrity viewpoint.

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“…It is indicated that FEA combined with cyclic plasticity model can yield more accurate results. [17][18][19] The user-defined material subroutine of FEA software (such as UMAT in ABAQUS) provides designers a good choice to establish a sufficiently accurate material model. Various models 20 have been proposed to describe material's nonlinear elastic-plastic behavior under cyclic loading.…”

Section: Cyclic Plasticity Modelmentioning

confidence: 99%

A reliability‐based fatigue design for mechanical components under material variability

Wang

Luo

2019

Quality & Reliability Eng

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The mechanical components subjected cyclic load unusually fail due to fatigue.The traditional deterministic design method still has the risk of failure while the safety factor method sometimes is overconservative and uneconomic. In this study, reliability-based design optimization is applied in structural design of components under low cycle fatigue. A constitutive model (Jiang and Sehitoglu model) was written into user-defined material subroutine of finite element software to make simulation more accurate. In addition, an adaptive least squares support vector machines (LS-SVM)-based response surface method is employed to improve the efficiency of design process. After constructing the implicit life model, a hybrid directional step method is employed to implement the performance measure approach. Finally, a simple case (thickness optimization for cantilever tube) is used to demonstrate the whole procedure of proposed design procedure.z KEYWORDS fatigue design, performance function approach, reliability-based optimization design

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Probabilistic modeling of fatigue life distribution and size effect of components with random defects

Cited by 133 publications

References 57 publications

Experimental investigation of the size effect in high cycle fatigue: Role of the defect population in cast aluminium alloys

Experimental investigation of the size effect in high cycle fatigue: Role of the defect population in cast aluminium alloys

The microstructure, mechanical, and fatigue behaviours of MAG welded G20Mn5 cast steel

A reliability‐based fatigue design for mechanical components under material variability

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