On the prediction of fatigue life subjected to variable loading sequence

2021 ◽  
Author(s):  
Joonyoung Jang ◽  
Michael M. Khonsari
Keyword(s):  
Fatigue Life ◽  
Variable Loading ◽  
Loading Sequence

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

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.

Effects of Variable Loading on Residual Fatigue Life of the Railway Wheelset

2013 ◽  
Vol 577-578 ◽  
pp. 121-124 ◽  
Author(s):  
Pavel Pokorný ◽  
Luboš Náhlík ◽  
M. Ševčík ◽  
Pavel Hutař
Keyword(s):  
Growth Rate ◽  
Fatigue Life ◽  
Life Time ◽  
Interaction Effects ◽  
Classical Approach ◽  
Variable Loading ◽  
Know How ◽  
Residual Fatigue Life ◽  
Residual Fatigue ◽  
Account Interaction

The paper deals with the effects of variable loading on residual fatigue life of the railway wheelset. The railway wheelsets can include some cracks created during manufacturing process or during previous operation. Therefore, it is important to know how the existing cracks will behave during further service of the train. The experiments show that the fatigue crack growth rate depends not only on size of the load amplitudes in a loading spectrum, but it depends also on the sequence of load amplitudes. Taking into account interaction effects of overloading cycles requires use a method that calculates increments of crack length in each cycle, i.e. cycle-by-cycle. One of such methods represents generalized Willenborg model. This model was used for residual fatigue life time estimations of railway wheelset and results obtained were compared with classical approach, which did not take into account interaction effects. Results obtained can be used for establishing of service intervals of railway wheelsets.

Fatigue Life Prediction for Variable Strain at a Mixing Tee by Use of Effective Strain Amplitude

2020 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Hot Spot ◽  
Effective Strain ◽  
Single Overload ◽  
Loading Sequence

Abstract Mixing flow causes fluid temperature fluctuations near the pipe walls and may result in fatigue crack initiation. The authors have previously reported the loading sequence effect on thermal fatigue in a mixing tee. The fatigue damage around the hot spot, which was heated by the hot jet flow from the branch pipe, obtained by Miner’s rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. In this study, the effect of a single overload on the fatigue crack growth rate was investigated in order to clarify the reduction of the fatigue life at the mixing tee due to strain with periodic overload. In addition, the prediction method of the fatigue life for the variable thermal strain at the mixing tee was discussed. It was shown the crack growth rate increased after an overload for both cases of tensile and compressive overloads. The effective strain amplitude increased after the application of a single overload. The fatigue life curve was modified by considering the increment of the effective strain range. The fatigue damage recalculated using the modified fatigue life curve was larger than 1.0 except in a few cases. The fatigue life could be assessed conservatively for variable strain at the mixing tee using the developed fatigue curve and Miner’s rule.

A First Investigation on Cumulative Fatigue Life for a Type 304-L Stainless Steel Used for Pressure Water Reactor

2009 ◽  
Author(s):  
A. Fissolo ◽  
J. M. Stelmaszyk
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Damage Effect ◽  
Final Conclusion ◽  
Variable Loading ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Type 304

In order to estimate the crack initiation damage, and also the water leakage conditions on PWR pipes, uniaxial fatigue curves are often used. They were deduced from strain or stress load control tests using normalised cylindrical specimens. However, severe thermo-mechanical loading fluctuations are observed in operating conditions. Components may also be submitted to transient loadings. The purpose of the present work is to start investigation on the fatigue life with a variable loading, in order to examine cumulative damage effect in fatigue. In this frame, multilevel strain controlled fatigue tests have been performed on a Type 304-L stainless steel (elaborated in accordance with the RCC-M specifications). The experimental results show that linear Miner’s rule is not verified in our conditions. When the strains are applied in a decreasing order (High-Low strain sequence), the summation of cycle ratios is smaller than unity, whatever the number of applied levels, whereas this summation is higher than one for an increasing order (Low-High strain sequence). A loading sequence effect is clearly evidenced. Different cumulative fatigue damage theories, proposed in literature, have been also tested. Some of them have been given better estimation than the Miner’s rule. That is the case of the so-called “Hybrid Theory” proposed and tested before by Bui Quoc on a Type 304-L steel. Extension of a model proposed by S. Taheri would seem also promising. At this stage, final conclusion cannot be yet deduced, additional investigations are needed.

Fatigue life prediction under variable loading based on a new damage model

2011 ◽  
Vol 32 (1) ◽  
pp. 183-191 ◽  
Author(s):  
A. Aid ◽  
A. Amrouche ◽  
B. Bachir Bouiadjra ◽  
M. Benguediab ◽  
G. Mesmacque
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Damage Model ◽  
Fatigue Life Prediction ◽  
Variable Loading

Investigation on Fatigue Life Prediction of Riveted Cantilever Beam Using FEA Approach

2021 ◽  
Author(s):  
Yemineni Siva Sankara Rao ◽  
Kutchibotla Mallikarjuna Rao ◽  
V. V. Subba Rao
Keyword(s):  
Fatigue Life ◽  
Loading Condition ◽  
Technological Development ◽  
Fatigue Loading ◽  
Cantilever Beams ◽  
Structural Elements ◽  
Variable Loading ◽  
Variable Parameters ◽  
Aircraft Wings ◽  
Reversed Cyclic

Abstract Different structural elements of automobiles, ships, aircraft wings and fuselages, turbines, nuclear reactors, and other machine components are susceptible to variable loading condition. Due to this type of loading situation all the mentioned structures are undergone to the formation of internal cracks, these cracks will be grown and eventually lead to the failure of the structures. Hence, the fatigue phenomenon due to variable loading conditions is a major threat and has come into address with the technological development that happening is now a days. To avoid the failure of structures due to fatigue loading condition structures are provided with different fasteners like rivets, bolts, tack welds, etc. In this study, the structures analyzed are cantilever beams, the fasteners considered are rivets, the loading considered for analysis is fully reversed cyclic loading, and the analysis considered is the fatigue analysis, the mode of analysis is a simulation using FEA software named ANSYS R19.2 WORKBENCH software. The variable parameters considered are rivet diameter, load, and coefficient of friction at the common interface of riveted specimens. Here in this analysis, the beam dimensions are kept constant. Besides, in this study, the comparison of fatigue life for solid and riveted cantilever beams of identical dimensions is presented. The material considered for the rivets and beams is aluminum alloy.

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