A new method for estimating the fatigue life of ship structures

1975 ◽  
Vol 22 (254) ◽  
pp. 349-363
Author(s):  
M.M. El Gammal
Keyword(s):  
Fatigue Life ◽  
New Method ◽  
Ship Structures

High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II

2018 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Steel Structures ◽  
New Method ◽  
Microplastic Deformation ◽  
Surface Phenomenon ◽  
Cyclic Loads ◽  
Cycle Fatigue ◽  
Indentation Tests

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.

A new method for fatigue life estimation of steels

2000 ◽  
Vol 5 (1-2) ◽  
pp. 9-14
Author(s):  
Akira Kato ◽  
Mitsue Hayashi
Keyword(s):  
Fatigue Life ◽  
New Method ◽  
Life Estimation ◽  
Fatigue Life Estimation

A New Method for Evaluating Fatigue Life of Micro-Solder Joints in Semiconductor Structures

2005 ◽  
Author(s):  
Hisashi Tanie ◽  
Takeshi Terasaki ◽  
Yasuhiro Naka
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Solder Joints ◽  
Crack Path ◽  
New Method ◽  
Semiconductor Structures ◽  
Element Size ◽  
Solder Mask ◽  
Conventional Methods ◽  
Crack Paths

Conventionally, the fatigue life of solder joints in semiconductor structures is estimated using Coffin-Manson’s law. However, as the structures have become miniaturized or thinner, accurately estimate fatigue life has become difficult using conventional methods. This is because the fatigue life is strongly affected by crack propagation in miniaturized or thinner joints, and the conventional methods cannot evaluate this phenomenon well. We have therefore developed a new method for evaluating fatigue life that takes into account the influence of crack propagation in micro-solder joints. In micro-solder joints, a solder crack path might propagate not only at the solder and land interface itself, but also near the interface. Many crack-propagation have been proposed, but a model that can reproduce a crack path has yet to be proposed. The fatigue life of a solder in our crack-propagation model is evaluated based on the damage that accumulates during crack propagation, and the crack paths are automatically calculated. Using this model, we analyzed the crack path of a ball grid array (BGA) structure, and we determined that the model could reproduce the above-mentioned characteristic crack paths. When the fatigue life is calculated using a finite element method, one of the most difficult issues is correcting for the effect of element size. We determined the calculated life dependency on element size, and we developed a formula for approximating this dependency in the proposed model. We then used this formula to calculate the fatigue life of three different size BGA solder joints that were subjected to mechanical fatigue testing. The calculated lives were found to correspond with the measured lives. Furthermore, we applied this method to evaluate the differences in the fatigue life of a solder-mask-defined (SMD) structure and a non-solder-mask-defined (NSMD) structure. Both are typical structures of BGA solder joints. We determined that the fatigue life of the NSMD structure was longer than that of the SMD structure. The main cause for this difference is that the crack-propagation life of the NSMD structure was longer than that of the SMD structure, even though the crack-initiation lives of both structures were the same.

A new method for fatigue life prediction based on the Thick Level Set approach

2017 ◽  
Vol 182 ◽  
pp. 449-466 ◽  
Author(s):  
L.O. Voormeeren ◽  
F.P. van der Meer ◽  
J. Maljaars ◽  
L.J. Sluys
Keyword(s):  
Fatigue Life ◽  
Level Set ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
New Method ◽  
Level Set Approach

scholarly journals Dominance distributions for fatigue performance of materials and its application in material selection

2020 ◽  
Author(s):  
Xin Bai ◽  
Peng Zhang ◽  
Enna Yang ◽  
Qiqiang Duan ◽  
Hao Bo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Fatigue Life ◽  
Probability Distribution ◽  
Reliability Index ◽  
Material Selection ◽  
Fatigue Property ◽  
Fatigue Performance ◽  
New Method ◽  
Variable Amplitude ◽  
Casting Alloys

A new method for the comparison of fatigue performance among different materials is proposed by using Monte-Carlo technology. The uncertainty of material’s fatigue property and the diversity of service loads are respectively described as a reliability index and a probability distribution. Using fatigue life as the standard measure of fatigue performance, two kinds of diagrams are developed as the dominance distributions for fatigue performance of materials. After the implication in the material selection from two casting alloys, the results show that the new method can evaluate the fatigue performance among different materials no matter withsanding constant or variable amplitude loading, which is very easy to guide the judgment whether the material has better fatigue performance or not.

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