Comparison of different approaches for estimation of creep crack initiation

Mueller, Falk; Scholz, Alfred; Berger, Christina

doi:10.1016/j.engfailanal.2006.12.004

Cited by 14 publications

(6 citation statements)

References 8 publications

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“…This is similar to the relationships between material toughness and creep crack incubation times shown in other work on steels tested at high temperature. 22 As with the results illustrated in Figure 12, the combined loading and elastic follow-up tests results in Figure 14 show longer crack incubation times for the same values of K mat achieved for load control tests. However, the microstructural evidence in Figure 10 indicates that there was no change in the mechanism of creep crack incubation between constant load tests and combined loading tests.…”

Section: Creep Crack Incubationsupporting

confidence: 75%

The effects of long-range residual stress, elastic follow-up and applied load on creep crack incubation and material toughness

Smith

Shirahatti

2015

The Journal of Strain Analysis for Engineering Design

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Creep crack incubation of Type 316H stainless steel at 550°C is explored in this article. Fracture mechanics specimens, subjected to combinations of residual and applied loads and in the presence of elastic follow-up, are tested. The design of two new test rigs is described. The rigs introduce planned levels of elastic follow-up together with combined residual and applied loading conditions to the specimens. A series of high-temperature elastic-plastic and elastic-plastic-creep experiments are undertaken to compare the experimentally determined values of elastic follow-up with the theoretical values. A further series of fracture mechanics tests are performed to measure creep crack incubation and material toughness for samples subjected to constant load and for tests under combined loading with elastic follow-up. It is demonstrated that for tests subjected to the same initial reference stresses, longer incubation times are attained for elastic follow-up tests compared to constant load tests. Also, combined loading tests exhibit longer creep crack incubation times based on the same measured material toughness obtained from constant load tests. This suggests that not all the available strain energy provided by combined loading to a specimen at high temperature contributes to creep crack incubation.

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Section: Creep Crack Incubationsupporting

confidence: 75%

The effects of long-range residual stress, elastic follow-up and applied load on creep crack incubation and material toughness

Smith

Shirahatti

2015

The Journal of Strain Analysis for Engineering Design

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“…They developed nonlinear governing equations of motion for the cracked rotor system with asymmetrical visco elastic supports. Mueller et al [51] have presented a comparison of different approaches for estimation of a creep crack initiation and compared the time dependent failure assessment diagram (TDFAD), two criteria diagram (ZCD), and Nikbin-Smith Webster model (NSWmodel) approaches for predicting creep crack initiation. It has been found that TDFAD and NSW-model method are costly but ZCD is a simple method.…”

Section: Recent Developments In Cracked Rotor Analysismentioning

confidence: 99%

A Brief Review on Dynamics of a Cracked Rotor

Kumar

Rastogi

2009

International Journal of Rotating Machinery

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Fatigue crack is an important rotor fault, which can lead to catastrophic failure if undetected properly and in time. Study and Investigation of dynamics of cracked shafts are continuing since last four decades. Some review papers were also published during this period. The aim of this paper is to present a review on recent studies and investigations done on cracked rotor. It is not the intention of the authors to provide all literatures related with the cracked rotor. However, the main emphasis is to provide all the methodologies adopted by various researchers to investigate a cracked rotor. The paper incorporates a candid commentary on various methodologies. The paper further deals an extended Lagrangian formulation to investigate dynamics of cracked rotor.

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“…Methods for evaluation or estimating the K c mat parameter have been developed and modified over recent years. A considerable amount of creep toughness data have been determined for austenitic type 316H stainless steel in the region of 500-700 • C, though mainly at 550 • C. 8,9 Limited K c mat data have also been determined for a range of ferritic steels, 4,5,8,[10][11][12] , and in some cases TDFADs have also been produced. Creep toughness data often show appreciable scatter 8,9 which must be considered when obtaining CCI time predictions.…”

Section: T D F a D ' S C C I P R E D I C T I O N S I N A U S T E N I mentioning

confidence: 99%

Predicting creep crack initiation in austenitic and ferritic steels using the creep toughness parameter and time‐dependent failure assessment diagram

Davies

2009

Fatigue Fract Eng Mat Struct

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Methods for evaluating the creep toughness parameter, mat c K , are reviewed and mat c K data are determined for a ferritic P22 steel from CCG tests on compact tension, C(T), specimens of homogenous parent material (PM) and heterogeneous specimen weldments at 565 ° C and compared to similar tests on austenitic 316H stainless steel at 550 °C. Appropriate relations describing the time dependency of mat c K are determined accounting for data scatter. Considerable differences are observed in the form of the mat c K data and the time dependent failure assessment diagrams (TDFADs) for both the 316H and P22 steel. The TDFAD for P22 shows a strong time dependency but is insensitive to time for 316H. Creep crack initiation (CCI) times predictions are obtained using the TDFAD approach and compared to experimental results from C(T) specimens and feature components. The TDFAD based on PM properties can be used to obtain conservative prediction of the CCI on the weldments. Conservative predictions are almost always obtained when lower bound

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Comparison of different approaches for estimation of creep crack initiation

Cited by 14 publications

References 8 publications

The effects of long-range residual stress, elastic follow-up and applied load on creep crack incubation and material toughness

The effects of long-range residual stress, elastic follow-up and applied load on creep crack incubation and material toughness

A Brief Review on Dynamics of a Cracked Rotor

Predicting creep crack initiation in austenitic and ferritic steels using the creep toughness parameter and time‐dependent failure assessment diagram

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