A model for ultra low cycle fatigue damage prediction of structural steel

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

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Low Cycle Fatigue Analysis of Marine Structures

Volume 3: Safety and Reliability; Materials Technology; Douglas Faulkner Symposium on Reliability and Ultimate Strength of Marine Structures ◽

10.1115/omae2006-92268 ◽

2006 ◽

Cited By ~ 2

Author(s):

Xiaozhi Wang ◽

Joong-Kyoo Kang ◽

Yooil Kim ◽

Paul H. Wirsching

Keyword(s):

Welded Joints ◽

Low Cycle Fatigue ◽

Prediction Method ◽

Local Stress ◽

Cyclic Plasticity ◽

Cycle Fatigue ◽

Stress Concentrations ◽

Damage Prediction ◽

Marine Structure ◽

Number Of Cycles

There are situations where a marine structure is subjected to stress cycles of such large magnitude that small, but significant, parts of the structural component in question experiences cyclic plasticity. Welded joints are particularly vulnerable because of high local stress concentrations. Fatigue caused by oscillating strain in the plastic range is called “low cycle fatigue”. Cycles to failure are typically below 104. Traditional welded joint S-N curves do not describe the fatigue strength in the low cycle region (< 104 number of cycles). Typical Class Society Rules do not directly address the low cycle fatigue problem. It is therefore the objective of this paper to present a credible fatigue damage prediction method of welded joints in the low cycle fatigue regime.

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Failure Analysis of Thinned Wall Elbows Under Excessive Seismic Loading

Seismic Engineering, Volume 2 ◽

10.1115/pvp2002-1391 ◽

2002 ◽

Author(s):

Masaki Shiratori ◽

Yoji Ochi ◽

Izumi Nakamura ◽

Akihito Otani

Keyword(s):

Finite Element ◽

Fatigue Damage ◽

Failure Modes ◽

Low Cycle Fatigue ◽

Local Buckling ◽

Seismic Loading ◽

Cycle Fatigue ◽

Finite Element Analyses ◽

Residual Thickness ◽

Limited Period

A series of finite element analyses has been carried out in order to investigate the failure behaviors of degraded bent pipes with local thinning against seismic loading. The sensitivity of such parameters as the residual thickness, locations and width of the local thinning to the failure modes such as ovaling and local buckling and to the low cycle fatigue damage has been studied. It has been found that this approach is useful to make a reasonable experimental plan, which has to be carried out under the condition of limited cost and limited period.

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